text: /*
   * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
   * All rights reserved.
   *
   * This source code is licensed under both the BSD-style license (found in the
   * LICENSE file in the root directory of this source tree) and the GPLv2 (found
   * in the COPYING file in the root directory of this source tree).
   * You may select, at your option, one of the above-listed licenses.
   */
  
  
  /* ======   Compiler specifics   ====== */
  #if defined(_MSC_VER)
  #  pragma warning(disable : 4204)   /* disable: C4204: non-constant aggregate initializer */
  #endif
  
  
  /* ======   Constants   ====== */
  #define ZSTDMT_OVERLAPLOG_DEFAULT 0
  
  
  /* ======   Dependencies   ====== */
  #include <string.h>      /* memcpy, memset */
  #include <limits.h>      /* INT_MAX, UINT_MAX */
  #include "mem.h"         /* MEM_STATIC */
  #include "pool.h"        /* threadpool */
  #include "threading.h"   /* mutex */
  #include "zstd_compress_internal.h"  /* MIN, ERROR, ZSTD_*, ZSTD_highbit32 */
  #include "zstd_ldm.h"
  #include "zstdmt_compress.h"
  
  /* Guards code to support resizing the SeqPool.
   * We will want to resize the SeqPool to save memory in the future.
   * Until then, comment the code out since it is unused.
   */
  #define ZSTD_RESIZE_SEQPOOL 0
  
  /* ======   Debug   ====== */
  #if defined(DEBUGLEVEL) && (DEBUGLEVEL>=2) \
      && !defined(_MSC_VER) \
      && !defined(__MINGW32__)
  
  #  include <stdio.h>
  #  include <unistd.h>
  #  include <sys/times.h>
  
  #  define DEBUG_PRINTHEX(l,p,n) {            \
      unsigned debug_u;                        \
      for (debug_u=0; debug_u<(n); debug_u++)  \
          RAWLOG(l, "%02X ", ((const unsigned char*)(p))[debug_u]); \
      RAWLOG(l, " \n");                        \
  }
  
  static unsigned long long GetCurrentClockTimeMicroseconds(void)
  {
     static clock_t _ticksPerSecond = 0;
     if (_ticksPerSecond <= 0) _ticksPerSecond = sysconf(_SC_CLK_TCK);
  
     {   struct tms junk; clock_t newTicks = (clock_t) times(&junk);
         return ((((unsigned long long)newTicks)*(1000000))/_ticksPerSecond);
  }  }
  
  #define MUTEX_WAIT_TIME_DLEVEL 6
  #define ZSTD_PTHREAD_MUTEX_LOCK(mutex) {          \
      if (DEBUGLEVEL >= MUTEX_WAIT_TIME_DLEVEL) {   \
          unsigned long long const beforeTime = GetCurrentClockTimeMicroseconds(); \
          ZSTD_pthread_mutex_lock(mutex);           \
          {   unsigned long long const afterTime = GetCurrentClockTimeMicroseconds(); \
              unsigned long long const elapsedTime = (afterTime-beforeTime); \
              if (elapsedTime > 1000) {  /* or whatever threshold you like; I'm using 1 millisecond here */ \
                  DEBUGLOG(MUTEX_WAIT_TIME_DLEVEL, "Thread took %llu microseconds to acquire mutex %s \n", \
                     elapsedTime, #mutex);          \
          }   }                                     \
      } else {                                      \
          ZSTD_pthread_mutex_lock(mutex);           \
      }                                             \
  }
  
  #else
  
  #  define ZSTD_PTHREAD_MUTEX_LOCK(m) ZSTD_pthread_mutex_lock(m)
  #  define DEBUG_PRINTHEX(l,p,n) {}
  
  #endif
  
  
  /* =====   Buffer Pool   ===== */
  /* a single Buffer Pool can be invoked from multiple threads in parallel */
  
  typedef struct buffer_s {
      void* start;
      size_t capacity;
  } buffer_t;
  
  static const buffer_t g_nullBuffer = { NULL, 0 };
  
  typedef struct ZSTDMT_bufferPool_s {
      ZSTD_pthread_mutex_t poolMutex;
      size_t bufferSize;
      unsigned totalBuffers;
      unsigned nbBuffers;
      ZSTD_customMem cMem;
      buffer_t bTable[1];   /* variable size */
  } ZSTDMT_bufferPool;
  
  static ZSTDMT_bufferPool* ZSTDMT_createBufferPool(unsigned nbWorkers, ZSTD_customMem cMem)
  {
      unsigned const maxNbBuffers = 2*nbWorkers + 3;
      ZSTDMT_bufferPool* const bufPool = (ZSTDMT_bufferPool*)ZSTD_calloc(
          sizeof(ZSTDMT_bufferPool) + (maxNbBuffers-1) * sizeof(buffer_t), cMem);
      if (bufPool==NULL) return NULL;
      if (ZSTD_pthread_mutex_init(&bufPool->poolMutex, NULL)) {
          ZSTD_free(bufPool, cMem);
          return NULL;
      }
      bufPool->bufferSize = 64 KB;
      bufPool->totalBuffers = maxNbBuffers;
      bufPool->nbBuffers = 0;
      bufPool->cMem = cMem;
      return bufPool;
  }
  
  static void ZSTDMT_freeBufferPool(ZSTDMT_bufferPool* bufPool)
  {
      unsigned u;
      DEBUGLOG(3, "ZSTDMT_freeBufferPool (address:%08X)", (U32)(size_t)bufPool);
      if (!bufPool) return;   /* compatibility with free on NULL */
      for (u=0; u<bufPool->totalBuffers; u++) {
          DEBUGLOG(4, "free buffer %2u (address:%08X)", u, (U32)(size_t)bufPool->bTable[u].start);
          ZSTD_free(bufPool->bTable[u].start, bufPool->cMem);
      }
      ZSTD_pthread_mutex_destroy(&bufPool->poolMutex);
      ZSTD_free(bufPool, bufPool->cMem);
  }
  
  /* only works at initialization, not during compression */
  static size_t ZSTDMT_sizeof_bufferPool(ZSTDMT_bufferPool* bufPool)
  {
      size_t const poolSize = sizeof(*bufPool)
                            + (bufPool->totalBuffers - 1) * sizeof(buffer_t);
      unsigned u;
      size_t totalBufferSize = 0;
      ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
      for (u=0; u<bufPool->totalBuffers; u++)
          totalBufferSize += bufPool->bTable[u].capacity;
      ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
  
      return poolSize + totalBufferSize;
  }
  
  /* ZSTDMT_setBufferSize() :
   * all future buffers provided by this buffer pool will have _at least_ this size
   * note : it's better for all buffers to have same size,
   * as they become freely interchangeable, reducing malloc/free usages and memory fragmentation */
  static void ZSTDMT_setBufferSize(ZSTDMT_bufferPool* const bufPool, size_t const bSize)
  {
      ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
      DEBUGLOG(4, "ZSTDMT_setBufferSize: bSize = %u", (U32)bSize);
      bufPool->bufferSize = bSize;
      ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
  }
  
  
  static ZSTDMT_bufferPool* ZSTDMT_expandBufferPool(ZSTDMT_bufferPool* srcBufPool, U32 nbWorkers)
  {
      unsigned const maxNbBuffers = 2*nbWorkers + 3;
      if (srcBufPool==NULL) return NULL;
      if (srcBufPool->totalBuffers >= maxNbBuffers) /* good enough */
          return srcBufPool;
      /* need a larger buffer pool */
      {   ZSTD_customMem const cMem = srcBufPool->cMem;
          size_t const bSize = srcBufPool->bufferSize;   /* forward parameters */
          ZSTDMT_bufferPool* newBufPool;
          ZSTDMT_freeBufferPool(srcBufPool);
          newBufPool = ZSTDMT_createBufferPool(nbWorkers, cMem);
          if (newBufPool==NULL) return newBufPool;
          ZSTDMT_setBufferSize(newBufPool, bSize);
          return newBufPool;
      }
  }
  
  /** ZSTDMT_getBuffer() :
   *  assumption : bufPool must be valid
   * @return : a buffer, with start pointer and size
   *  note: allocation may fail, in this case, start==NULL and size==0 */
  static buffer_t ZSTDMT_getBuffer(ZSTDMT_bufferPool* bufPool)
  {
      size_t const bSize = bufPool->bufferSize;
      DEBUGLOG(5, "ZSTDMT_getBuffer: bSize = %u", (U32)bufPool->bufferSize);
      ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
      if (bufPool->nbBuffers) {   /* try to use an existing buffer */
          buffer_t const buf = bufPool->bTable[--(bufPool->nbBuffers)];
          size_t const availBufferSize = buf.capacity;
          bufPool->bTable[bufPool->nbBuffers] = g_nullBuffer;
          if ((availBufferSize >= bSize) & ((availBufferSize>>3) <= bSize)) {
              /* large enough, but not too much */
              DEBUGLOG(5, "ZSTDMT_getBuffer: provide buffer %u of size %u",
                          bufPool->nbBuffers, (U32)buf.capacity);
              ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
              return buf;
          }
          /* size conditions not respected : scratch this buffer, create new one */
          DEBUGLOG(5, "ZSTDMT_getBuffer: existing buffer does not meet size conditions => freeing");
          ZSTD_free(buf.start, bufPool->cMem);
      }
      ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
      /* create new buffer */
      DEBUGLOG(5, "ZSTDMT_getBuffer: create a new buffer");
      {   buffer_t buffer;
          void* const start = ZSTD_malloc(bSize, bufPool->cMem);
          buffer.start = start;   /* note : start can be NULL if malloc fails ! */
          buffer.capacity = (start==NULL) ? 0 : bSize;
          if (start==NULL) {
              DEBUGLOG(5, "ZSTDMT_getBuffer: buffer allocation failure !!");
          } else {
              DEBUGLOG(5, "ZSTDMT_getBuffer: created buffer of size %u", (U32)bSize);
          }
          return buffer;
      }
  }
  
  #if ZSTD_RESIZE_SEQPOOL
  /** ZSTDMT_resizeBuffer() :
   * assumption : bufPool must be valid
   * @return : a buffer that is at least the buffer pool buffer size.
   *           If a reallocation happens, the data in the input buffer is copied.
   */
  static buffer_t ZSTDMT_resizeBuffer(ZSTDMT_bufferPool* bufPool, buffer_t buffer)
  {
      size_t const bSize = bufPool->bufferSize;
      if (buffer.capacity < bSize) {
          void* const start = ZSTD_malloc(bSize, bufPool->cMem);
          buffer_t newBuffer;
          newBuffer.start = start;
          newBuffer.capacity = start == NULL ? 0 : bSize;
          if (start != NULL) {
              assert(newBuffer.capacity >= buffer.capacity);
              memcpy(newBuffer.start, buffer.start, buffer.capacity);
              DEBUGLOG(5, "ZSTDMT_resizeBuffer: created buffer of size %u", (U32)bSize);
              return newBuffer;
          }
          DEBUGLOG(5, "ZSTDMT_resizeBuffer: buffer allocation failure !!");
      }
      return buffer;
  }
  #endif
  
  /* store buffer for later re-use, up to pool capacity */
  static void ZSTDMT_releaseBuffer(ZSTDMT_bufferPool* bufPool, buffer_t buf)
  {
      DEBUGLOG(5, "ZSTDMT_releaseBuffer");
      if (buf.start == NULL) return;   /* compatible with release on NULL */
      ZSTD_pthread_mutex_lock(&bufPool->poolMutex);
      if (bufPool->nbBuffers < bufPool->totalBuffers) {
          bufPool->bTable[bufPool->nbBuffers++] = buf;  /* stored for later use */
          DEBUGLOG(5, "ZSTDMT_releaseBuffer: stored buffer of size %u in slot %u",
                      (U32)buf.capacity, (U32)(bufPool->nbBuffers-1));
          ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
          return;
      }
      ZSTD_pthread_mutex_unlock(&bufPool->poolMutex);
      /* Reached bufferPool capacity (should not happen) */
      DEBUGLOG(5, "ZSTDMT_releaseBuffer: pool capacity reached => freeing ");
      ZSTD_free(buf.start, bufPool->cMem);
  }
  
  
  /* =====   Seq Pool Wrapper   ====== */
  
  static rawSeqStore_t kNullRawSeqStore = {NULL, 0, 0, 0};
  
  typedef ZSTDMT_bufferPool ZSTDMT_seqPool;
  
  static size_t ZSTDMT_sizeof_seqPool(ZSTDMT_seqPool* seqPool)
  {
      return ZSTDMT_sizeof_bufferPool(seqPool);
  }
  
  static rawSeqStore_t bufferToSeq(buffer_t buffer)
  {
      rawSeqStore_t seq = {NULL, 0, 0, 0};
      seq.seq = (rawSeq*)buffer.start;
      seq.capacity = buffer.capacity / sizeof(rawSeq);
      return seq;
  }
  
  static buffer_t seqToBuffer(rawSeqStore_t seq)
  {
      buffer_t buffer;
      buffer.start = seq.seq;
      buffer.capacity = seq.capacity * sizeof(rawSeq);
      return buffer;
  }
  
  static rawSeqStore_t ZSTDMT_getSeq(ZSTDMT_seqPool* seqPool)
  {
      if (seqPool->bufferSize == 0) {
          return kNullRawSeqStore;
      }
      return bufferToSeq(ZSTDMT_getBuffer(seqPool));
  }
  
  #if ZSTD_RESIZE_SEQPOOL
  static rawSeqStore_t ZSTDMT_resizeSeq(ZSTDMT_seqPool* seqPool, rawSeqStore_t seq)
  {
    return bufferToSeq(ZSTDMT_resizeBuffer(seqPool, seqToBuffer(seq)));
  }
  #endif
  
  static void ZSTDMT_releaseSeq(ZSTDMT_seqPool* seqPool, rawSeqStore_t seq)
  {
    ZSTDMT_releaseBuffer(seqPool, seqToBuffer(seq));
  }
  
  static void ZSTDMT_setNbSeq(ZSTDMT_seqPool* const seqPool, size_t const nbSeq)
  {
    ZSTDMT_setBufferSize(seqPool, nbSeq * sizeof(rawSeq));
  }
  
  static ZSTDMT_seqPool* ZSTDMT_createSeqPool(unsigned nbWorkers, ZSTD_customMem cMem)
  {
      ZSTDMT_seqPool* const seqPool = ZSTDMT_createBufferPool(nbWorkers, cMem);
      if (seqPool == NULL) return NULL;
      ZSTDMT_setNbSeq(seqPool, 0);
      return seqPool;
  }
  
  static void ZSTDMT_freeSeqPool(ZSTDMT_seqPool* seqPool)
  {
      ZSTDMT_freeBufferPool(seqPool);
  }
  
  static ZSTDMT_seqPool* ZSTDMT_expandSeqPool(ZSTDMT_seqPool* pool, U32 nbWorkers)
  {
      return ZSTDMT_expandBufferPool(pool, nbWorkers);
  }
  
  
  /* =====   CCtx Pool   ===== */
  /* a single CCtx Pool can be invoked from multiple threads in parallel */
  
  typedef struct {
      ZSTD_pthread_mutex_t poolMutex;
      int totalCCtx;
      int availCCtx;
      ZSTD_customMem cMem;
      ZSTD_CCtx* cctx[1];   /* variable size */
  } ZSTDMT_CCtxPool;
  
  /* note : all CCtx borrowed from the pool should be released back to the pool _before_ freeing the pool */
  static void ZSTDMT_freeCCtxPool(ZSTDMT_CCtxPool* pool)
  {
      int cid;
      for (cid=0; cid<pool->totalCCtx; cid++)
          ZSTD_freeCCtx(pool->cctx[cid]);  /* note : compatible with free on NULL */
      ZSTD_pthread_mutex_destroy(&pool->poolMutex);
      ZSTD_free(pool, pool->cMem);
  }
  
  /* ZSTDMT_createCCtxPool() :
   * implies nbWorkers >= 1 , checked by caller ZSTDMT_createCCtx() */
  static ZSTDMT_CCtxPool* ZSTDMT_createCCtxPool(int nbWorkers,
                                                ZSTD_customMem cMem)
  {
      ZSTDMT_CCtxPool* const cctxPool = (ZSTDMT_CCtxPool*) ZSTD_calloc(
          sizeof(ZSTDMT_CCtxPool) + (nbWorkers-1)*sizeof(ZSTD_CCtx*), cMem);
      assert(nbWorkers > 0);
      if (!cctxPool) return NULL;
      if (ZSTD_pthread_mutex_init(&cctxPool->poolMutex, NULL)) {
          ZSTD_free(cctxPool, cMem);
          return NULL;
      }
      cctxPool->cMem = cMem;
      cctxPool->totalCCtx = nbWorkers;
      cctxPool->availCCtx = 1;   /* at least one cctx for single-thread mode */
      cctxPool->cctx[0] = ZSTD_createCCtx_advanced(cMem);
      if (!cctxPool->cctx[0]) { ZSTDMT_freeCCtxPool(cctxPool); return NULL; }
      DEBUGLOG(3, "cctxPool created, with %u workers", nbWorkers);
      return cctxPool;
  }
  
  static ZSTDMT_CCtxPool* ZSTDMT_expandCCtxPool(ZSTDMT_CCtxPool* srcPool,
                                                int nbWorkers)
  {
      if (srcPool==NULL) return NULL;
      if (nbWorkers <= srcPool->totalCCtx) return srcPool;   /* good enough */
      /* need a larger cctx pool */
      {   ZSTD_customMem const cMem = srcPool->cMem;
          ZSTDMT_freeCCtxPool(srcPool);
          return ZSTDMT_createCCtxPool(nbWorkers, cMem);
      }
  }
  
  /* only works during initialization phase, not during compression */
  static size_t ZSTDMT_sizeof_CCtxPool(ZSTDMT_CCtxPool* cctxPool)
  {
      ZSTD_pthread_mutex_lock(&cctxPool->poolMutex);
      {   unsigned const nbWorkers = cctxPool->totalCCtx;
          size_t const poolSize = sizeof(*cctxPool)
                                  + (nbWorkers-1) * sizeof(ZSTD_CCtx*);
          unsigned u;
          size_t totalCCtxSize = 0;
          for (u=0; u<nbWorkers; u++) {
              totalCCtxSize += ZSTD_sizeof_CCtx(cctxPool->cctx[u]);
          }
          ZSTD_pthread_mutex_unlock(&cctxPool->poolMutex);
          assert(nbWorkers > 0);
          return poolSize + totalCCtxSize;
      }
  }
  
  static ZSTD_CCtx* ZSTDMT_getCCtx(ZSTDMT_CCtxPool* cctxPool)
  {
      DEBUGLOG(5, "ZSTDMT_getCCtx");
      ZSTD_pthread_mutex_lock(&cctxPool->poolMutex);
      if (cctxPool->availCCtx) {
          cctxPool->availCCtx--;
          {   ZSTD_CCtx* const cctx = cctxPool->cctx[cctxPool->availCCtx];
              ZSTD_pthread_mutex_unlock(&cctxPool->poolMutex);
              return cctx;
      }   }
      ZSTD_pthread_mutex_unlock(&cctxPool->poolMutex);
      DEBUGLOG(5, "create one more CCtx");
      return ZSTD_createCCtx_advanced(cctxPool->cMem);   /* note : can be NULL, when creation fails ! */
  }
  
  static void ZSTDMT_releaseCCtx(ZSTDMT_CCtxPool* pool, ZSTD_CCtx* cctx)
  {
      if (cctx==NULL) return;   /* compatibility with release on NULL */
      ZSTD_pthread_mutex_lock(&pool->poolMutex);
      if (pool->availCCtx < pool->totalCCtx)
          pool->cctx[pool->availCCtx++] = cctx;
      else {
          /* pool overflow : should not happen, since totalCCtx==nbWorkers */
          DEBUGLOG(4, "CCtx pool overflow : free cctx");
          ZSTD_freeCCtx(cctx);
      }
      ZSTD_pthread_mutex_unlock(&pool->poolMutex);
  }
  
  /* ====   Serial State   ==== */
  
  typedef struct {
      void const* start;
      size_t size;
  } range_t;
  
  typedef struct {
      /* All variables in the struct are protected by mutex. */
      ZSTD_pthread_mutex_t mutex;
      ZSTD_pthread_cond_t cond;
      ZSTD_CCtx_params params;
      ldmState_t ldmState;
      XXH64_state_t xxhState;
      unsigned nextJobID;
      /* Protects ldmWindow.
       * Must be acquired after the main mutex when acquiring both.
       */
      ZSTD_pthread_mutex_t ldmWindowMutex;
      ZSTD_pthread_cond_t ldmWindowCond;  /* Signaled when ldmWindow is updated */
      ZSTD_window_t ldmWindow;  /* A thread-safe copy of ldmState.window */
  } serialState_t;
  
  static int ZSTDMT_serialState_reset(serialState_t* serialState, ZSTDMT_seqPool* seqPool, ZSTD_CCtx_params params, size_t jobSize)
  {
      /* Adjust parameters */
      if (params.ldmParams.enableLdm) {
          DEBUGLOG(4, "LDM window size = %u KB", (1U << params.cParams.windowLog) >> 10);
          ZSTD_ldm_adjustParameters(&params.ldmParams, &params.cParams);
          assert(params.ldmParams.hashLog >= params.ldmParams.bucketSizeLog);
          assert(params.ldmParams.hashRateLog < 32);
          serialState->ldmState.hashPower =
                  ZSTD_rollingHash_primePower(params.ldmParams.minMatchLength);
      } else {
          memset(&params.ldmParams, 0, sizeof(params.ldmParams));
      }
      serialState->nextJobID = 0;
      if (params.fParams.checksumFlag)
          XXH64_reset(&serialState->xxhState, 0);
      if (params.ldmParams.enableLdm) {
          ZSTD_customMem cMem = params.customMem;
          unsigned const hashLog = params.ldmParams.hashLog;
          size_t const hashSize = ((size_t)1 << hashLog) * sizeof(ldmEntry_t);
          unsigned const bucketLog =
              params.ldmParams.hashLog - params.ldmParams.bucketSizeLog;
          size_t const bucketSize = (size_t)1 << bucketLog;
          unsigned const prevBucketLog =
              serialState->params.ldmParams.hashLog -
              serialState->params.ldmParams.bucketSizeLog;
          /* Size the seq pool tables */
          ZSTDMT_setNbSeq(seqPool, ZSTD_ldm_getMaxNbSeq(params.ldmParams, jobSize));
          /* Reset the window */
          ZSTD_window_clear(&serialState->ldmState.window);
          serialState->ldmWindow = serialState->ldmState.window;
          /* Resize tables and output space if necessary. */
          if (serialState->ldmState.hashTable == NULL || serialState->params.ldmParams.hashLog < hashLog) {
              ZSTD_free(serialState->ldmState.hashTable, cMem);
              serialState->ldmState.hashTable = (ldmEntry_t*)ZSTD_malloc(hashSize, cMem);
          }
          if (serialState->ldmState.bucketOffsets == NULL || prevBucketLog < bucketLog) {
              ZSTD_free(serialState->ldmState.bucketOffsets, cMem);
              serialState->ldmState.bucketOffsets = (BYTE*)ZSTD_malloc(bucketSize, cMem);
          }
          if (!serialState->ldmState.hashTable || !serialState->ldmState.bucketOffsets)
              return 1;
          /* Zero the tables */
          memset(serialState->ldmState.hashTable, 0, hashSize);
          memset(serialState->ldmState.bucketOffsets, 0, bucketSize);
      }
      serialState->params = params;
      serialState->params.jobSize = (U32)jobSize;
      return 0;
  }
  
  static int ZSTDMT_serialState_init(serialState_t* serialState)
  {
      int initError = 0;
      memset(serialState, 0, sizeof(*serialState));
      initError |= ZSTD_pthread_mutex_init(&serialState->mutex, NULL);
      initError |= ZSTD_pthread_cond_init(&serialState->cond, NULL);
      initError |= ZSTD_pthread_mutex_init(&serialState->ldmWindowMutex, NULL);
      initError |= ZSTD_pthread_cond_init(&serialState->ldmWindowCond, NULL);
      return initError;
  }
  
  static void ZSTDMT_serialState_free(serialState_t* serialState)
  {
      ZSTD_customMem cMem = serialState->params.customMem;
      ZSTD_pthread_mutex_destroy(&serialState->mutex);
      ZSTD_pthread_cond_destroy(&serialState->cond);
      ZSTD_pthread_mutex_destroy(&serialState->ldmWindowMutex);
      ZSTD_pthread_cond_destroy(&serialState->ldmWindowCond);
      ZSTD_free(serialState->ldmState.hashTable, cMem);
      ZSTD_free(serialState->ldmState.bucketOffsets, cMem);
  }
  
  static void ZSTDMT_serialState_update(serialState_t* serialState,
                                        ZSTD_CCtx* jobCCtx, rawSeqStore_t seqStore,
                                        range_t src, unsigned jobID)
  {
      /* Wait for our turn */
      ZSTD_PTHREAD_MUTEX_LOCK(&serialState->mutex);
      while (serialState->nextJobID < jobID) {
          DEBUGLOG(5, "wait for serialState->cond");
          ZSTD_pthread_cond_wait(&serialState->cond, &serialState->mutex);
      }
      /* A future job may error and skip our job */
      if (serialState->nextJobID == jobID) {
          /* It is now our turn, do any processing necessary */
          if (serialState->params.ldmParams.enableLdm) {
              size_t error;
              assert(seqStore.seq != NULL && seqStore.pos == 0 &&
                     seqStore.size == 0 && seqStore.capacity > 0);
              assert(src.size <= serialState->params.jobSize);
              ZSTD_window_update(&serialState->ldmState.window, src.start, src.size);
              error = ZSTD_ldm_generateSequences(
                  &serialState->ldmState, &seqStore,
                  &serialState->params.ldmParams, src.start, src.size);
              /* We provide a large enough buffer to never fail. */
              assert(!ZSTD_isError(error)); (void)error;
              /* Update ldmWindow to match the ldmState.window and signal the main
               * thread if it is waiting for a buffer.
               */
              ZSTD_PTHREAD_MUTEX_LOCK(&serialState->ldmWindowMutex);
              serialState->ldmWindow = serialState->ldmState.window;
              ZSTD_pthread_cond_signal(&serialState->ldmWindowCond);
              ZSTD_pthread_mutex_unlock(&serialState->ldmWindowMutex);
          }
          if (serialState->params.fParams.checksumFlag && src.size > 0)
              XXH64_update(&serialState->xxhState, src.start, src.size);
      }
      /* Now it is the next jobs turn */
      serialState->nextJobID++;
      ZSTD_pthread_cond_broadcast(&serialState->cond);
      ZSTD_pthread_mutex_unlock(&serialState->mutex);
  
      if (seqStore.size > 0) {
          size_t const err = ZSTD_referenceExternalSequences(
              jobCCtx, seqStore.seq, seqStore.size);
          assert(serialState->params.ldmParams.enableLdm);
          assert(!ZSTD_isError(err));
          (void)err;
      }
  }
  
  static void ZSTDMT_serialState_ensureFinished(serialState_t* serialState,
                                                unsigned jobID, size_t cSize)
  {
      ZSTD_PTHREAD_MUTEX_LOCK(&serialState->mutex);
      if (serialState->nextJobID <= jobID) {
          assert(ZSTD_isError(cSize)); (void)cSize;
          DEBUGLOG(5, "Skipping past job %u because of error", jobID);
          serialState->nextJobID = jobID + 1;
          ZSTD_pthread_cond_broadcast(&serialState->cond);
  
          ZSTD_PTHREAD_MUTEX_LOCK(&serialState->ldmWindowMutex);
          ZSTD_window_clear(&serialState->ldmWindow);
          ZSTD_pthread_cond_signal(&serialState->ldmWindowCond);
          ZSTD_pthread_mutex_unlock(&serialState->ldmWindowMutex);
      }
      ZSTD_pthread_mutex_unlock(&serialState->mutex);
  
  }
  
  
  /* ------------------------------------------ */
  /* =====          Worker thread         ===== */
  /* ------------------------------------------ */
  
  static const range_t kNullRange = { NULL, 0 };
  
  typedef struct {
      size_t   consumed;                   /* SHARED - set0 by mtctx, then modified by worker AND read by mtctx */
      size_t   cSize;                      /* SHARED - set0 by mtctx, then modified by worker AND read by mtctx, then set0 by mtctx */
      ZSTD_pthread_mutex_t job_mutex;      /* Thread-safe - used by mtctx and worker */
      ZSTD_pthread_cond_t job_cond;        /* Thread-safe - used by mtctx and worker */
      ZSTDMT_CCtxPool* cctxPool;           /* Thread-safe - used by mtctx and (all) workers */
      ZSTDMT_bufferPool* bufPool;          /* Thread-safe - used by mtctx and (all) workers */
      ZSTDMT_seqPool* seqPool;             /* Thread-safe - used by mtctx and (all) workers */
      serialState_t* serial;               /* Thread-safe - used by mtctx and (all) workers */
      buffer_t dstBuff;                    /* set by worker (or mtctx), then read by worker & mtctx, then modified by mtctx => no barrier */
      range_t prefix;                      /* set by mtctx, then read by worker & mtctx => no barrier */
      range_t src;                         /* set by mtctx, then read by worker & mtctx => no barrier */
      unsigned jobID;                      /* set by mtctx, then read by worker => no barrier */
      unsigned firstJob;                   /* set by mtctx, then read by worker => no barrier */
      unsigned lastJob;                    /* set by mtctx, then read by worker => no barrier */
      ZSTD_CCtx_params params;             /* set by mtctx, then read by worker => no barrier */
      const ZSTD_CDict* cdict;             /* set by mtctx, then read by worker => no barrier */
      unsigned long long fullFrameSize;    /* set by mtctx, then read by worker => no barrier */
      size_t   dstFlushed;                 /* used only by mtctx */
      unsigned frameChecksumNeeded;        /* used only by mtctx */
  } ZSTDMT_jobDescription;
  
  #define JOB_ERROR(e) {                          \
      ZSTD_PTHREAD_MUTEX_LOCK(&job->job_mutex);   \
      job->cSize = e;                             \
      ZSTD_pthread_mutex_unlock(&job->job_mutex); \
      goto _endJob;                               \
  }
  
  /* ZSTDMT_compressionJob() is a POOL_function type */
  static void ZSTDMT_compressionJob(void* jobDescription)
  {
      ZSTDMT_jobDescription* const job = (ZSTDMT_jobDescription*)jobDescription;
      ZSTD_CCtx_params jobParams = job->params;   /* do not modify job->params ! copy it, modify the copy */
      ZSTD_CCtx* const cctx = ZSTDMT_getCCtx(job->cctxPool);
      rawSeqStore_t rawSeqStore = ZSTDMT_getSeq(job->seqPool);
      buffer_t dstBuff = job->dstBuff;
      size_t lastCBlockSize = 0;
  
      /* resources */
      if (cctx==NULL) JOB_ERROR(ERROR(memory_allocation));
      if (dstBuff.start == NULL) {   /* streaming job : doesn't provide a dstBuffer */
          dstBuff = ZSTDMT_getBuffer(job->bufPool);
          if (dstBuff.start==NULL) JOB_ERROR(ERROR(memory_allocation));
          job->dstBuff = dstBuff;   /* this value can be read in ZSTDMT_flush, when it copies the whole job */
      }
      if (jobParams.ldmParams.enableLdm && rawSeqStore.seq == NULL)
          JOB_ERROR(ERROR(memory_allocation));
  
      /* Don't compute the checksum for chunks, since we compute it externally,
       * but write it in the header.
       */
      if (job->jobID != 0) jobParams.fParams.checksumFlag = 0;
      /* Don't run LDM for the chunks, since we handle it externally */
      jobParams.ldmParams.enableLdm = 0;
  
  
      /* init */
      if (job->cdict) {
          size_t const initError = ZSTD_compressBegin_advanced_internal(cctx, NULL, 0, ZSTD_dct_auto, ZSTD_dtlm_fast, job->cdict, &jobParams, job->fullFrameSize);
          assert(job->firstJob);  /* only allowed for first job */
          if (ZSTD_isError(initError)) JOB_ERROR(initError);
      } else {  /* srcStart points at reloaded section */
          U64 const pledgedSrcSize = job->firstJob ? job->fullFrameSize : job->src.size;
          {   size_t const forceWindowError = ZSTD_CCtxParams_setParameter(&jobParams, ZSTD_c_forceMaxWindow, !job->firstJob);
              if (ZSTD_isError(forceWindowError)) JOB_ERROR(forceWindowError);
          }
          {   size_t const initError = ZSTD_compressBegin_advanced_internal(cctx,
                                          job->prefix.start, job->prefix.size, ZSTD_dct_rawContent, /* load dictionary in "content-only" mode (no header analysis) */
                                          ZSTD_dtlm_fast,
                                          NULL, /*cdict*/
                                          &jobParams, pledgedSrcSize);
              if (ZSTD_isError(initError)) JOB_ERROR(initError);
      }   }
  
      /* Perform serial step as early as possible, but after CCtx initialization */
      ZSTDMT_serialState_update(job->serial, cctx, rawSeqStore, job->src, job->jobID);
  
      if (!job->firstJob) {  /* flush and overwrite frame header when it's not first job */
          size_t const hSize = ZSTD_compressContinue(cctx, dstBuff.start, dstBuff.capacity, job->src.start, 0);
          if (ZSTD_isError(hSize)) JOB_ERROR(hSize);
          DEBUGLOG(5, "ZSTDMT_compressionJob: flush and overwrite %u bytes of frame header (not first job)", (U32)hSize);
          ZSTD_invalidateRepCodes(cctx);
      }
  
      /* compress */
      {   size_t const chunkSize = 4*ZSTD_BLOCKSIZE_MAX;
          int const nbChunks = (int)((job->src.size + (chunkSize-1)) / chunkSize);
          const BYTE* ip = (const BYTE*) job->src.start;
          BYTE* const ostart = (BYTE*)dstBuff.start;
          BYTE* op = ostart;
          BYTE* oend = op + dstBuff.capacity;
          int chunkNb;
          if (sizeof(size_t) > sizeof(int)) assert(job->src.size < ((size_t)INT_MAX) * chunkSize);   /* check overflow */
          DEBUGLOG(5, "ZSTDMT_compressionJob: compress %u bytes in %i blocks", (U32)job->src.size, nbChunks);
          assert(job->cSize == 0);
          for (chunkNb = 1; chunkNb < nbChunks; chunkNb++) {
              size_t const cSize = ZSTD_compressContinue(cctx, op, oend-op, ip, chunkSize);
              if (ZSTD_isError(cSize)) JOB_ERROR(cSize);
              ip += chunkSize;
              op += cSize; assert(op < oend);
              /* stats */
              ZSTD_PTHREAD_MUTEX_LOCK(&job->job_mutex);
              job->cSize += cSize;
              job->consumed = chunkSize * chunkNb;
              DEBUGLOG(5, "ZSTDMT_compressionJob: compress new block : cSize==%u bytes (total: %u)",
                          (U32)cSize, (U32)job->cSize);
              ZSTD_pthread_cond_signal(&job->job_cond);   /* warns some more data is ready to be flushed */
              ZSTD_pthread_mutex_unlock(&job->job_mutex);
          }
          /* last block */
          assert(chunkSize > 0);
          assert((chunkSize & (chunkSize - 1)) == 0);  /* chunkSize must be power of 2 for mask==(chunkSize-1) to work */
          if ((nbChunks > 0) | job->lastJob /*must output a "last block" flag*/ ) {
              size_t const lastBlockSize1 = job->src.size & (chunkSize-1);
              size_t const lastBlockSize = ((lastBlockSize1==0) & (job->src.size>=chunkSize)) ? chunkSize : lastBlockSize1;
              size_t const cSize = (job->lastJob) ?
                   ZSTD_compressEnd     (cctx, op, oend-op, ip, lastBlockSize) :
                   ZSTD_compressContinue(cctx, op, oend-op, ip, lastBlockSize);
              if (ZSTD_isError(cSize)) JOB_ERROR(cSize);
              lastCBlockSize = cSize;
      }   }
  
  _endJob:
      ZSTDMT_serialState_ensureFinished(job->serial, job->jobID, job->cSize);
      if (job->prefix.size > 0)
          DEBUGLOG(5, "Finished with prefix: %zx", (size_t)job->prefix.start);
      DEBUGLOG(5, "Finished with source: %zx", (size_t)job->src.start);
      /* release resources */
      ZSTDMT_releaseSeq(job->seqPool, rawSeqStore);
      ZSTDMT_releaseCCtx(job->cctxPool, cctx);
      /* report */
      ZSTD_PTHREAD_MUTEX_LOCK(&job->job_mutex);
      if (ZSTD_isError(job->cSize)) assert(lastCBlockSize == 0);
      job->cSize += lastCBlockSize;
      job->consumed = job->src.size;  /* when job->consumed == job->src.size , compression job is presumed completed */
      ZSTD_pthread_cond_signal(&job->job_cond);
      ZSTD_pthread_mutex_unlock(&job->job_mutex);
  }
  
  
  /* ------------------------------------------ */
  /* =====   Multi-threaded compression   ===== */
  /* ------------------------------------------ */
  
  typedef struct {
      range_t prefix;         /* read-only non-owned prefix buffer */
      buffer_t buffer;
      size_t filled;
  } inBuff_t;
  
  typedef struct {
    BYTE* buffer;     /* The round input buffer. All jobs get references
                       * to pieces of the buffer. ZSTDMT_tryGetInputRange()
                       * handles handing out job input buffers, and makes
                       * sure it doesn't overlap with any pieces still in use.
                       */
    size_t capacity;  /* The capacity of buffer. */
    size_t pos;       /* The position of the current inBuff in the round
                       * buffer. Updated past the end if the inBuff once
                       * the inBuff is sent to the worker thread.
                       * pos <= capacity.
                       */
  } roundBuff_t;
  
  static const roundBuff_t kNullRoundBuff = {NULL, 0, 0};
  
  #define RSYNC_LENGTH 32
  
  typedef struct {
    U64 hash;
    U64 hitMask;
    U64 primePower;
  } rsyncState_t;
  
  struct ZSTDMT_CCtx_s {
      POOL_ctx* factory;
      ZSTDMT_jobDescription* jobs;
      ZSTDMT_bufferPool* bufPool;
      ZSTDMT_CCtxPool* cctxPool;
      ZSTDMT_seqPool* seqPool;
      ZSTD_CCtx_params params;
      size_t targetSectionSize;
      size_t targetPrefixSize;
      int jobReady;        /* 1 => one job is already prepared, but pool has shortage of workers. Don't create a new job. */
      inBuff_t inBuff;
      roundBuff_t roundBuff;
      serialState_t serial;
      rsyncState_t rsync;
      unsigned singleBlockingThread;
      unsigned jobIDMask;
      unsigned doneJobID;
      unsigned nextJobID;
      unsigned frameEnded;
      unsigned allJobsCompleted;
      unsigned long long frameContentSize;
      unsigned long long consumed;
      unsigned long long produced;
      ZSTD_customMem cMem;
      ZSTD_CDict* cdictLocal;
      const ZSTD_CDict* cdict;
  };
  
  static void ZSTDMT_freeJobsTable(ZSTDMT_jobDescription* jobTable, U32 nbJobs, ZSTD_customMem cMem)
  {
      U32 jobNb;
      if (jobTable == NULL) return;
      for (jobNb=0; jobNb<nbJobs; jobNb++) {
          ZSTD_pthread_mutex_destroy(&jobTable[jobNb].job_mutex);
          ZSTD_pthread_cond_destroy(&jobTable[jobNb].job_cond);
      }
      ZSTD_free(jobTable, cMem);
  }
  
  /* ZSTDMT_allocJobsTable()
   * allocate and init a job table.
   * update *nbJobsPtr to next power of 2 value, as size of table */
  static ZSTDMT_jobDescription* ZSTDMT_createJobsTable(U32* nbJobsPtr, ZSTD_customMem cMem)
  {
      U32 const nbJobsLog2 = ZSTD_highbit32(*nbJobsPtr) + 1;
      U32 const nbJobs = 1 << nbJobsLog2;
      U32 jobNb;
      ZSTDMT_jobDescription* const jobTable = (ZSTDMT_jobDescription*)
                  ZSTD_calloc(nbJobs * sizeof(ZSTDMT_jobDescription), cMem);
      int initError = 0;
      if (jobTable==NULL) return NULL;
      *nbJobsPtr = nbJobs;
      for (jobNb=0; jobNb<nbJobs; jobNb++) {
          initError |= ZSTD_pthread_mutex_init(&jobTable[jobNb].job_mutex, NULL);
          initError |= ZSTD_pthread_cond_init(&jobTable[jobNb].job_cond, NULL);
      }
      if (initError != 0) {
          ZSTDMT_freeJobsTable(jobTable, nbJobs, cMem);
          return NULL;
      }
      return jobTable;
  }
  
  static size_t ZSTDMT_expandJobsTable (ZSTDMT_CCtx* mtctx, U32 nbWorkers) {
      U32 nbJobs = nbWorkers + 2;
      if (nbJobs > mtctx->jobIDMask+1) {  /* need more job capacity */
          ZSTDMT_freeJobsTable(mtctx->jobs, mtctx->jobIDMask+1, mtctx->cMem);
          mtctx->jobIDMask = 0;
          mtctx->jobs = ZSTDMT_createJobsTable(&nbJobs, mtctx->cMem);
          if (mtctx->jobs==NULL) return ERROR(memory_allocation);
          assert((nbJobs != 0) && ((nbJobs & (nbJobs - 1)) == 0));  /* ensure nbJobs is a power of 2 */
          mtctx->jobIDMask = nbJobs - 1;
      }
      return 0;
  }
  
  
  /* ZSTDMT_CCtxParam_setNbWorkers():
   * Internal use only */
  size_t ZSTDMT_CCtxParam_setNbWorkers(ZSTD_CCtx_params* params, unsigned nbWorkers)
  {
      return ZSTD_CCtxParams_setParameter(params, ZSTD_c_nbWorkers, (int)nbWorkers);
  }
  
  MEM_STATIC ZSTDMT_CCtx* ZSTDMT_createCCtx_advanced_internal(unsigned nbWorkers, ZSTD_customMem cMem)
  {
      ZSTDMT_CCtx* mtctx;
      U32 nbJobs = nbWorkers + 2;
      int initError;
      DEBUGLOG(3, "ZSTDMT_createCCtx_advanced (nbWorkers = %u)", nbWorkers);
  
      if (nbWorkers < 1) return NULL;
      nbWorkers = MIN(nbWorkers , ZSTDMT_NBWORKERS_MAX);
      if ((cMem.customAlloc!=NULL) ^ (cMem.customFree!=NULL))
          /* invalid custom allocator */
          return NULL;
  
      mtctx = (ZSTDMT_CCtx*) ZSTD_calloc(sizeof(ZSTDMT_CCtx), cMem);
      if (!mtctx) return NULL;
      ZSTDMT_CCtxParam_setNbWorkers(&mtctx->params, nbWorkers);
      mtctx->cMem = cMem;
      mtctx->allJobsCompleted = 1;
      mtctx->factory = POOL_create_advanced(nbWorkers, 0, cMem);
      mtctx->jobs = ZSTDMT_createJobsTable(&nbJobs, cMem);
      assert(nbJobs > 0); assert((nbJobs & (nbJobs - 1)) == 0);  /* ensure nbJobs is a power of 2 */
      mtctx->jobIDMask = nbJobs - 1;
      mtctx->bufPool = ZSTDMT_createBufferPool(nbWorkers, cMem);
      mtctx->cctxPool = ZSTDMT_createCCtxPool(nbWorkers, cMem);
      mtctx->seqPool = ZSTDMT_createSeqPool(nbWorkers, cMem);
      initError = ZSTDMT_serialState_init(&mtctx->serial);
      mtctx->roundBuff = kNullRoundBuff;
      if (!mtctx->factory | !mtctx->jobs | !mtctx->bufPool | !mtctx->cctxPool | !mtctx->seqPool | initError) {
          ZSTDMT_freeCCtx(mtctx);
          return NULL;
      }
      DEBUGLOG(3, "mt_cctx created, for %u threads", nbWorkers);
      return mtctx;
  }
  
  ZSTDMT_CCtx* ZSTDMT_createCCtx_advanced(unsigned nbWorkers, ZSTD_customMem cMem)
  {
  #ifdef ZSTD_MULTITHREAD
      return ZSTDMT_createCCtx_advanced_internal(nbWorkers, cMem);
  #else
      (void)nbWorkers;
      (void)cMem;
      return NULL;
  #endif
  }
  
  ZSTDMT_CCtx* ZSTDMT_createCCtx(unsigned nbWorkers)
  {
      return ZSTDMT_createCCtx_advanced(nbWorkers, ZSTD_defaultCMem);
  }
  
  
  /* ZSTDMT_releaseAllJobResources() :
   * note : ensure all workers are killed first ! */
  static void ZSTDMT_releaseAllJobResources(ZSTDMT_CCtx* mtctx)
  {
      unsigned jobID;
      DEBUGLOG(3, "ZSTDMT_releaseAllJobResources");
      for (jobID=0; jobID <= mtctx->jobIDMask; jobID++) {
          DEBUGLOG(4, "job%02u: release dst address %08X", jobID, (U32)(size_t)mtctx->jobs[jobID].dstBuff.start);
          ZSTDMT_releaseBuffer(mtctx->bufPool, mtctx->jobs[jobID].dstBuff);
          mtctx->jobs[jobID].dstBuff = g_nullBuffer;
          mtctx->jobs[jobID].cSize = 0;
      }
      memset(mtctx->jobs, 0, (mtctx->jobIDMask+1)*sizeof(ZSTDMT_jobDescription));
      mtctx->inBuff.buffer = g_nullBuffer;
      mtctx->inBuff.filled = 0;
      mtctx->allJobsCompleted = 1;
  }
  
  static void ZSTDMT_waitForAllJobsCompleted(ZSTDMT_CCtx* mtctx)
  {
      DEBUGLOG(4, "ZSTDMT_waitForAllJobsCompleted");
      while (mtctx->doneJobID < mtctx->nextJobID) {
          unsigned const jobID = mtctx->doneJobID & mtctx->jobIDMask;
          ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[jobID].job_mutex);
          while (mtctx->jobs[jobID].consumed < mtctx->jobs[jobID].src.size) {
              DEBUGLOG(4, "waiting for jobCompleted signal from job %u", mtctx->doneJobID);   /* we want to block when waiting for data to flush */
              ZSTD_pthread_cond_wait(&mtctx->jobs[jobID].job_cond, &mtctx->jobs[jobID].job_mutex);
          }
          ZSTD_pthread_mutex_unlock(&mtctx->jobs[jobID].job_mutex);
          mtctx->doneJobID++;
      }
  }
  
  size_t ZSTDMT_freeCCtx(ZSTDMT_CCtx* mtctx)
  {
      if (mtctx==NULL) return 0;   /* compatible with free on NULL */
      POOL_free(mtctx->factory);   /* stop and free worker threads */
      ZSTDMT_releaseAllJobResources(mtctx);  /* release job resources into pools first */
      ZSTDMT_freeJobsTable(mtctx->jobs, mtctx->jobIDMask+1, mtctx->cMem);
      ZSTDMT_freeBufferPool(mtctx->bufPool);
      ZSTDMT_freeCCtxPool(mtctx->cctxPool);
      ZSTDMT_freeSeqPool(mtctx->seqPool);
      ZSTDMT_serialState_free(&mtctx->serial);
      ZSTD_freeCDict(mtctx->cdictLocal);
      if (mtctx->roundBuff.buffer)
          ZSTD_free(mtctx->roundBuff.buffer, mtctx->cMem);
      ZSTD_free(mtctx, mtctx->cMem);
      return 0;
  }
  
  size_t ZSTDMT_sizeof_CCtx(ZSTDMT_CCtx* mtctx)
  {
      if (mtctx == NULL) return 0;   /* supports sizeof NULL */
      return sizeof(*mtctx)
              + POOL_sizeof(mtctx->factory)
              + ZSTDMT_sizeof_bufferPool(mtctx->bufPool)
              + (mtctx->jobIDMask+1) * sizeof(ZSTDMT_jobDescription)
              + ZSTDMT_sizeof_CCtxPool(mtctx->cctxPool)
              + ZSTDMT_sizeof_seqPool(mtctx->seqPool)
              + ZSTD_sizeof_CDict(mtctx->cdictLocal)
              + mtctx->roundBuff.capacity;
  }
  
  /* Internal only */
  size_t
  ZSTDMT_CCtxParam_setMTCtxParameter(ZSTD_CCtx_params* params,
                                     ZSTDMT_parameter parameter,
                                     int value)
  {
      DEBUGLOG(4, "ZSTDMT_CCtxParam_setMTCtxParameter");
      switch(parameter)
      {
      case ZSTDMT_p_jobSize :
          DEBUGLOG(4, "ZSTDMT_CCtxParam_setMTCtxParameter : set jobSize to %i", value);
          return ZSTD_CCtxParams_setParameter(params, ZSTD_c_jobSize, value);
      case ZSTDMT_p_overlapLog :
          DEBUGLOG(4, "ZSTDMT_p_overlapLog : %i", value);
          return ZSTD_CCtxParams_setParameter(params, ZSTD_c_overlapLog, value);
      case ZSTDMT_p_rsyncable :
          DEBUGLOG(4, "ZSTD_p_rsyncable : %i", value);
          return ZSTD_CCtxParams_setParameter(params, ZSTD_c_rsyncable, value);
      default :
          return ERROR(parameter_unsupported);
      }
  }
  
  size_t ZSTDMT_setMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter, int value)
  {
      DEBUGLOG(4, "ZSTDMT_setMTCtxParameter");
      return ZSTDMT_CCtxParam_setMTCtxParameter(&mtctx->params, parameter, value);
  }
  
  size_t ZSTDMT_getMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSTDMT_parameter parameter, int* value)
  {
      switch (parameter) {
      case ZSTDMT_p_jobSize:
          return ZSTD_CCtxParams_getParameter(&mtctx->params, ZSTD_c_jobSize, value);
      case ZSTDMT_p_overlapLog:
          return ZSTD_CCtxParams_getParameter(&mtctx->params, ZSTD_c_overlapLog, value);
      case ZSTDMT_p_rsyncable:
          return ZSTD_CCtxParams_getParameter(&mtctx->params, ZSTD_c_rsyncable, value);
      default:
          return ERROR(parameter_unsupported);
      }
  }
  
  /* Sets parameters relevant to the compression job,
   * initializing others to default values. */
  static ZSTD_CCtx_params ZSTDMT_initJobCCtxParams(const ZSTD_CCtx_params* params)
  {
      ZSTD_CCtx_params jobParams = *params;
      /* Clear parameters related to multithreading */
      jobParams.forceWindow = 0;
      jobParams.nbWorkers = 0;
      jobParams.jobSize = 0;
      jobParams.overlapLog = 0;
      jobParams.rsyncable = 0;
      memset(&jobParams.ldmParams, 0, sizeof(ldmParams_t));
      memset(&jobParams.customMem, 0, sizeof(ZSTD_customMem));
      return jobParams;
  }
  
  
  /* ZSTDMT_resize() :
   * @return : error code if fails, 0 on success */
  static size_t ZSTDMT_resize(ZSTDMT_CCtx* mtctx, unsigned nbWorkers)
  {
      if (POOL_resize(mtctx->factory, nbWorkers)) return ERROR(memory_allocation);
      FORWARD_IF_ERROR( ZSTDMT_expandJobsTable(mtctx, nbWorkers) );
      mtctx->bufPool = ZSTDMT_expandBufferPool(mtctx->bufPool, nbWorkers);
      if (mtctx->bufPool == NULL) return ERROR(memory_allocation);
      mtctx->cctxPool = ZSTDMT_expandCCtxPool(mtctx->cctxPool, nbWorkers);
      if (mtctx->cctxPool == NULL) return ERROR(memory_allocation);
      mtctx->seqPool = ZSTDMT_expandSeqPool(mtctx->seqPool, nbWorkers);
      if (mtctx->seqPool == NULL) return ERROR(memory_allocation);
      ZSTDMT_CCtxParam_setNbWorkers(&mtctx->params, nbWorkers);
      return 0;
  }
  
  
  /*! ZSTDMT_updateCParams_whileCompressing() :
   *  Updates a selected set of compression parameters, remaining compatible with currently active frame.
   *  New parameters will be applied to next compression job. */
  void ZSTDMT_updateCParams_whileCompressing(ZSTDMT_CCtx* mtctx, const ZSTD_CCtx_params* cctxParams)
  {
      U32 const saved_wlog = mtctx->params.cParams.windowLog;   /* Do not modify windowLog while compressing */
      int const compressionLevel = cctxParams->compressionLevel;
      DEBUGLOG(5, "ZSTDMT_updateCParams_whileCompressing (level:%i)",
                  compressionLevel);
      mtctx->params.compressionLevel = compressionLevel;
      {   ZSTD_compressionParameters cParams = ZSTD_getCParamsFromCCtxParams(cctxParams, 0, 0);
          cParams.windowLog = saved_wlog;
          mtctx->params.cParams = cParams;
      }
  }
  
  /* ZSTDMT_getFrameProgression():
   * tells how much data has been consumed (input) and produced (output) for current frame.
   * able to count progression inside worker threads.
   * Note : mutex will be acquired during statistics collection inside workers. */
  ZSTD_frameProgression ZSTDMT_getFrameProgression(ZSTDMT_CCtx* mtctx)
  {
      ZSTD_frameProgression fps;
      DEBUGLOG(5, "ZSTDMT_getFrameProgression");
      fps.ingested = mtctx->consumed + mtctx->inBuff.filled;
      fps.consumed = mtctx->consumed;
      fps.produced = fps.flushed = mtctx->produced;
      fps.currentJobID = mtctx->nextJobID;
      fps.nbActiveWorkers = 0;
      {   unsigned jobNb;
          unsigned lastJobNb = mtctx->nextJobID + mtctx->jobReady; assert(mtctx->jobReady <= 1);
          DEBUGLOG(6, "ZSTDMT_getFrameProgression: jobs: from %u to <%u (jobReady:%u)",
                      mtctx->doneJobID, lastJobNb, mtctx->jobReady)
          for (jobNb = mtctx->doneJobID ; jobNb < lastJobNb ; jobNb++) {
              unsigned const wJobID = jobNb & mtctx->jobIDMask;
              ZSTDMT_jobDescription* jobPtr = &mtctx->jobs[wJobID];
              ZSTD_pthread_mutex_lock(&jobPtr->job_mutex);
              {   size_t const cResult = jobPtr->cSize;
                  size_t const produced = ZSTD_isError(cResult) ? 0 : cResult;
                  size_t const flushed = ZSTD_isError(cResult) ? 0 : jobPtr->dstFlushed;
                  assert(flushed <= produced);
                  fps.ingested += jobPtr->src.size;
                  fps.consumed += jobPtr->consumed;
                  fps.produced += produced;
                  fps.flushed  += flushed;
                  fps.nbActiveWorkers += (jobPtr->consumed < jobPtr->src.size);
              }
              ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
          }
      }
      return fps;
  }
  
  
  size_t ZSTDMT_toFlushNow(ZSTDMT_CCtx* mtctx)
  {
      size_t toFlush;
      unsigned const jobID = mtctx->doneJobID;
      assert(jobID <= mtctx->nextJobID);
      if (jobID == mtctx->nextJobID) return 0;   /* no active job => nothing to flush */
  
      /* look into oldest non-fully-flushed job */
      {   unsigned const wJobID = jobID & mtctx->jobIDMask;
          ZSTDMT_jobDescription* const jobPtr = &mtctx->jobs[wJobID];
          ZSTD_pthread_mutex_lock(&jobPtr->job_mutex);
          {   size_t const cResult = jobPtr->cSize;
              size_t const produced = ZSTD_isError(cResult) ? 0 : cResult;
              size_t const flushed = ZSTD_isError(cResult) ? 0 : jobPtr->dstFlushed;
              assert(flushed <= produced);
              assert(jobPtr->consumed <= jobPtr->src.size);
              toFlush = produced - flushed;
              /* if toFlush==0, nothing is available to flush.
               * However, jobID is expected to still be active:
               * if jobID was already completed and fully flushed,
               * ZSTDMT_flushProduced() should have already moved onto next job.
               * Therefore, some input has not yet been consumed. */
              if (toFlush==0) {
                  assert(jobPtr->consumed < jobPtr->src.size);
              }
          }
          ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
      }
  
      return toFlush;
  }
  
  
  /* ------------------------------------------ */
  /* =====   Multi-threaded compression   ===== */
  /* ------------------------------------------ */
  
  static unsigned ZSTDMT_computeTargetJobLog(const ZSTD_CCtx_params* params)
  {
      unsigned jobLog;
      if (params->ldmParams.enableLdm) {
          /* In Long Range Mode, the windowLog is typically oversized.
           * In which case, it's preferable to determine the jobSize
           * based on chainLog instead. */
          jobLog = MAX(21, params->cParams.chainLog + 4);
      } else {
          jobLog = MAX(20, params->cParams.windowLog + 2);
      }
      return MIN(jobLog, (unsigned)ZSTDMT_JOBLOG_MAX);
  }
  
  static int ZSTDMT_overlapLog_default(ZSTD_strategy strat)
  {
      switch(strat)
      {
          case ZSTD_btultra2:
              return 9;
          case ZSTD_btultra:
          case ZSTD_btopt:
              return 8;
          case ZSTD_btlazy2:
          case ZSTD_lazy2:
              return 7;
          case ZSTD_lazy:
          case ZSTD_greedy:
          case ZSTD_dfast:
          case ZSTD_fast:
          default:;
      }
      return 6;
  }
  
  static int ZSTDMT_overlapLog(int ovlog, ZSTD_strategy strat)
  {
      assert(0 <= ovlog && ovlog <= 9);
      if (ovlog == 0) return ZSTDMT_overlapLog_default(strat);
      return ovlog;
  }
  
  static size_t ZSTDMT_computeOverlapSize(const ZSTD_CCtx_params* params)
  {
      int const overlapRLog = 9 - ZSTDMT_overlapLog(params->overlapLog, params->cParams.strategy);
      int ovLog = (overlapRLog >= 8) ? 0 : (params->cParams.windowLog - overlapRLog);
      assert(0 <= overlapRLog && overlapRLog <= 8);
      if (params->ldmParams.enableLdm) {
          /* In Long Range Mode, the windowLog is typically oversized.
           * In which case, it's preferable to determine the jobSize
           * based on chainLog instead.
           * Then, ovLog becomes a fraction of the jobSize, rather than windowSize */
          ovLog = MIN(params->cParams.windowLog, ZSTDMT_computeTargetJobLog(params) - 2)
                  - overlapRLog;
      }
      assert(0 <= ovLog && ovLog <= ZSTD_WINDOWLOG_MAX);
      DEBUGLOG(4, "overlapLog : %i", params->overlapLog);
      DEBUGLOG(4, "overlap size : %i", 1 << ovLog);
      return (ovLog==0) ? 0 : (size_t)1 << ovLog;
  }
  
  static unsigned
  ZSTDMT_computeNbJobs(const ZSTD_CCtx_params* params, size_t srcSize, unsigned nbWorkers)
  {
      assert(nbWorkers>0);
      {   size_t const jobSizeTarget = (size_t)1 << ZSTDMT_computeTargetJobLog(params);
          size_t const jobMaxSize = jobSizeTarget << 2;
          size_t const passSizeMax = jobMaxSize * nbWorkers;
          unsigned const multiplier = (unsigned)(srcSize / passSizeMax) + 1;
          unsigned const nbJobsLarge = multiplier * nbWorkers;
          unsigned const nbJobsMax = (unsigned)(srcSize / jobSizeTarget) + 1;
          unsigned const nbJobsSmall = MIN(nbJobsMax, nbWorkers);
          return (multiplier>1) ? nbJobsLarge : nbJobsSmall;
  }   }
  
  /* ZSTDMT_compress_advanced_internal() :
   * This is a blocking function : it will only give back control to caller after finishing its compression job.
   */
  static size_t ZSTDMT_compress_advanced_internal(
                  ZSTDMT_CCtx* mtctx,
                  void* dst, size_t dstCapacity,
            const void* src, size_t srcSize,
            const ZSTD_CDict* cdict,
                  ZSTD_CCtx_params params)
  {
      ZSTD_CCtx_params const jobParams = ZSTDMT_initJobCCtxParams(&params);
      size_t const overlapSize = ZSTDMT_computeOverlapSize(&params);
      unsigned const nbJobs = ZSTDMT_computeNbJobs(&params, srcSize, params.nbWorkers);
      size_t const proposedJobSize = (srcSize + (nbJobs-1)) / nbJobs;
      size_t const avgJobSize = (((proposedJobSize-1) & 0x1FFFF) < 0x7FFF) ? proposedJobSize + 0xFFFF : proposedJobSize;   /* avoid too small last block */
      const char* const srcStart = (const char*)src;
      size_t remainingSrcSize = srcSize;
      unsigned const compressWithinDst = (dstCapacity >= ZSTD_compressBound(srcSize)) ? nbJobs : (unsigned)(dstCapacity / ZSTD_compressBound(avgJobSize));  /* presumes avgJobSize >= 256 KB, which should be the case */
      size_t frameStartPos = 0, dstBufferPos = 0;
      assert(jobParams.nbWorkers == 0);
      assert(mtctx->cctxPool->totalCCtx == params.nbWorkers);
  
      params.jobSize = (U32)avgJobSize;
      DEBUGLOG(4, "ZSTDMT_compress_advanced_internal: nbJobs=%2u (rawSize=%u bytes; fixedSize=%u) ",
                  nbJobs, (U32)proposedJobSize, (U32)avgJobSize);
  
      if ((nbJobs==1) | (params.nbWorkers<=1)) {   /* fallback to single-thread mode : this is a blocking invocation anyway */
          ZSTD_CCtx* const cctx = mtctx->cctxPool->cctx[0];
          DEBUGLOG(4, "ZSTDMT_compress_advanced_internal: fallback to single-thread mode");
          if (cdict) return ZSTD_compress_usingCDict_advanced(cctx, dst, dstCapacity, src, srcSize, cdict, jobParams.fParams);
          return ZSTD_compress_advanced_internal(cctx, dst, dstCapacity, src, srcSize, NULL, 0, &jobParams);
      }
  
      assert(avgJobSize >= 256 KB);  /* condition for ZSTD_compressBound(A) + ZSTD_compressBound(B) <= ZSTD_compressBound(A+B), required to compress directly into Dst (no additional buffer) */
      ZSTDMT_setBufferSize(mtctx->bufPool, ZSTD_compressBound(avgJobSize) );
      if (ZSTDMT_serialState_reset(&mtctx->serial, mtctx->seqPool, params, avgJobSize))
          return ERROR(memory_allocation);
  
      FORWARD_IF_ERROR( ZSTDMT_expandJobsTable(mtctx, nbJobs) );  /* only expands if necessary */
  
      {   unsigned u;
          for (u=0; u<nbJobs; u++) {
              size_t const jobSize = MIN(remainingSrcSize, avgJobSize);
              size_t const dstBufferCapacity = ZSTD_compressBound(jobSize);
              buffer_t const dstAsBuffer = { (char*)dst + dstBufferPos, dstBufferCapacity };
              buffer_t const dstBuffer = u < compressWithinDst ? dstAsBuffer : g_nullBuffer;
              size_t dictSize = u ? overlapSize : 0;
  
              mtctx->jobs[u].prefix.start = srcStart + frameStartPos - dictSize;
              mtctx->jobs[u].prefix.size = dictSize;
              mtctx->jobs[u].src.start = srcStart + frameStartPos;
              mtctx->jobs[u].src.size = jobSize; assert(jobSize > 0);  /* avoid job.src.size == 0 */
              mtctx->jobs[u].consumed = 0;
              mtctx->jobs[u].cSize = 0;
              mtctx->jobs[u].cdict = (u==0) ? cdict : NULL;
              mtctx->jobs[u].fullFrameSize = srcSize;
              mtctx->jobs[u].params = jobParams;
              /* do not calculate checksum within sections, but write it in header for first section */
              mtctx->jobs[u].dstBuff = dstBuffer;
              mtctx->jobs[u].cctxPool = mtctx->cctxPool;
              mtctx->jobs[u].bufPool = mtctx->bufPool;
              mtctx->jobs[u].seqPool = mtctx->seqPool;
              mtctx->jobs[u].serial = &mtctx->serial;
              mtctx->jobs[u].jobID = u;
              mtctx->jobs[u].firstJob = (u==0);
              mtctx->jobs[u].lastJob = (u==nbJobs-1);
  
              DEBUGLOG(5, "ZSTDMT_compress_advanced_internal: posting job %u  (%u bytes)", u, (U32)jobSize);
              DEBUG_PRINTHEX(6, mtctx->jobs[u].prefix.start, 12);
              POOL_add(mtctx->factory, ZSTDMT_compressionJob, &mtctx->jobs[u]);
  
              frameStartPos += jobSize;
              dstBufferPos += dstBufferCapacity;
              remainingSrcSize -= jobSize;
      }   }
  
      /* collect result */
      {   size_t error = 0, dstPos = 0;
          unsigned jobID;
          for (jobID=0; jobID<nbJobs; jobID++) {
              DEBUGLOG(5, "waiting for job %u ", jobID);
              ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[jobID].job_mutex);
              while (mtctx->jobs[jobID].consumed < mtctx->jobs[jobID].src.size) {
                  DEBUGLOG(5, "waiting for jobCompleted signal from job %u", jobID);
                  ZSTD_pthread_cond_wait(&mtctx->jobs[jobID].job_cond, &mtctx->jobs[jobID].job_mutex);
              }
              ZSTD_pthread_mutex_unlock(&mtctx->jobs[jobID].job_mutex);
              DEBUGLOG(5, "ready to write job %u ", jobID);
  
              {   size_t const cSize = mtctx->jobs[jobID].cSize;
                  if (ZSTD_isError(cSize)) error = cSize;
                  if ((!error) && (dstPos + cSize > dstCapacity)) error = ERROR(dstSize_tooSmall);
                  if (jobID) {   /* note : job 0 is written directly at dst, which is correct position */
                      if (!error)
                          memmove((char*)dst + dstPos, mtctx->jobs[jobID].dstBuff.start, cSize);  /* may overlap when job compressed within dst */
                      if (jobID >= compressWithinDst) {  /* job compressed into its own buffer, which must be released */
                          DEBUGLOG(5, "releasing buffer %u>=%u", jobID, compressWithinDst);
                          ZSTDMT_releaseBuffer(mtctx->bufPool, mtctx->jobs[jobID].dstBuff);
                  }   }
                  mtctx->jobs[jobID].dstBuff = g_nullBuffer;
                  mtctx->jobs[jobID].cSize = 0;
                  dstPos += cSize ;
              }
          }  /* for (jobID=0; jobID<nbJobs; jobID++) */
  
          DEBUGLOG(4, "checksumFlag : %u ", params.fParams.checksumFlag);
          if (params.fParams.checksumFlag) {
              U32 const checksum = (U32)XXH64_digest(&mtctx->serial.xxhState);
              if (dstPos + 4 > dstCapacity) {
                  error = ERROR(dstSize_tooSmall);
              } else {
                  DEBUGLOG(4, "writing checksum : %08X \n", checksum);
                  MEM_writeLE32((char*)dst + dstPos, checksum);
                  dstPos += 4;
          }   }
  
          if (!error) DEBUGLOG(4, "compressed size : %u  ", (U32)dstPos);
          return error ? error : dstPos;
      }
  }
  
  size_t ZSTDMT_compress_advanced(ZSTDMT_CCtx* mtctx,
                                  void* dst, size_t dstCapacity,
                            const void* src, size_t srcSize,
                            const ZSTD_CDict* cdict,
                                  ZSTD_parameters params,
                                  int overlapLog)
  {
      ZSTD_CCtx_params cctxParams = mtctx->params;
      cctxParams.cParams = params.cParams;
      cctxParams.fParams = params.fParams;
      assert(ZSTD_OVERLAPLOG_MIN <= overlapLog && overlapLog <= ZSTD_OVERLAPLOG_MAX);
      cctxParams.overlapLog = overlapLog;
      return ZSTDMT_compress_advanced_internal(mtctx,
                                               dst, dstCapacity,
                                               src, srcSize,
                                               cdict, cctxParams);
  }
  
  
  size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* mtctx,
                             void* dst, size_t dstCapacity,
                       const void* src, size_t srcSize,
                             int compressionLevel)
  {
      ZSTD_parameters params = ZSTD_getParams(compressionLevel, srcSize, 0);
      int const overlapLog = ZSTDMT_overlapLog_default(params.cParams.strategy);
      params.fParams.contentSizeFlag = 1;
      return ZSTDMT_compress_advanced(mtctx, dst, dstCapacity, src, srcSize, NULL, params, overlapLog);
  }
  
  
  /* ====================================== */
  /* =======      Streaming API     ======= */
  /* ====================================== */
  
  size_t ZSTDMT_initCStream_internal(
          ZSTDMT_CCtx* mtctx,
          const void* dict, size_t dictSize, ZSTD_dictContentType_e dictContentType,
          const ZSTD_CDict* cdict, ZSTD_CCtx_params params,
          unsigned long long pledgedSrcSize)
  {
      DEBUGLOG(4, "ZSTDMT_initCStream_internal (pledgedSrcSize=%u, nbWorkers=%u, cctxPool=%u)",
                  (U32)pledgedSrcSize, params.nbWorkers, mtctx->cctxPool->totalCCtx);
  
      /* params supposed partially fully validated at this point */
      assert(!ZSTD_isError(ZSTD_checkCParams(params.cParams)));
      assert(!((dict) && (cdict)));  /* either dict or cdict, not both */
  
      /* init */
      if (params.nbWorkers != mtctx->params.nbWorkers)
          FORWARD_IF_ERROR( ZSTDMT_resize(mtctx, params.nbWorkers) );
  
      if (params.jobSize != 0 && params.jobSize < ZSTDMT_JOBSIZE_MIN) params.jobSize = ZSTDMT_JOBSIZE_MIN;
      if (params.jobSize > (size_t)ZSTDMT_JOBSIZE_MAX) params.jobSize = (size_t)ZSTDMT_JOBSIZE_MAX;
  
      mtctx->singleBlockingThread = (pledgedSrcSize <= ZSTDMT_JOBSIZE_MIN);  /* do not trigger multi-threading when srcSize is too small */
      if (mtctx->singleBlockingThread) {
          ZSTD_CCtx_params const singleThreadParams = ZSTDMT_initJobCCtxParams(&params);
          DEBUGLOG(5, "ZSTDMT_initCStream_internal: switch to single blocking thread mode");
          assert(singleThreadParams.nbWorkers == 0);
          return ZSTD_initCStream_internal(mtctx->cctxPool->cctx[0],
                                           dict, dictSize, cdict,
                                           &singleThreadParams, pledgedSrcSize);
      }
  
      DEBUGLOG(4, "ZSTDMT_initCStream_internal: %u workers", params.nbWorkers);
  
      if (mtctx->allJobsCompleted == 0) {   /* previous compression not correctly finished */
          ZSTDMT_waitForAllJobsCompleted(mtctx);
          ZSTDMT_releaseAllJobResources(mtctx);
          mtctx->allJobsCompleted = 1;
      }
  
      mtctx->params = params;
      mtctx->frameContentSize = pledgedSrcSize;
      if (dict) {
          ZSTD_freeCDict(mtctx->cdictLocal);
          mtctx->cdictLocal = ZSTD_createCDict_advanced(dict, dictSize,
                                                      ZSTD_dlm_byCopy, dictContentType, /* note : a loadPrefix becomes an internal CDict */
                                                      params.cParams, mtctx->cMem);
          mtctx->cdict = mtctx->cdictLocal;
          if (mtctx->cdictLocal == NULL) return ERROR(memory_allocation);
      } else {
          ZSTD_freeCDict(mtctx->cdictLocal);
          mtctx->cdictLocal = NULL;
          mtctx->cdict = cdict;
      }
  
      mtctx->targetPrefixSize = ZSTDMT_computeOverlapSize(&params);
      DEBUGLOG(4, "overlapLog=%i => %u KB", params.overlapLog, (U32)(mtctx->targetPrefixSize>>10));
      mtctx->targetSectionSize = params.jobSize;
      if (mtctx->targetSectionSize == 0) {
          mtctx->targetSectionSize = 1ULL << ZSTDMT_computeTargetJobLog(&params);
      }
      assert(mtctx->targetSectionSize <= (size_t)ZSTDMT_JOBSIZE_MAX);
  
      if (params.rsyncable) {
          /* Aim for the targetsectionSize as the average job size. */
          U32 const jobSizeMB = (U32)(mtctx->targetSectionSize >> 20);
          U32 const rsyncBits = ZSTD_highbit32(jobSizeMB) + 20;
          assert(jobSizeMB >= 1);
          DEBUGLOG(4, "rsyncLog = %u", rsyncBits);
          mtctx->rsync.hash = 0;
          mtctx->rsync.hitMask = (1ULL << rsyncBits) - 1;
          mtctx->rsync.primePower = ZSTD_rollingHash_primePower(RSYNC_LENGTH);
      }
      if (mtctx->targetSectionSize < mtctx->targetPrefixSize) mtctx->targetSectionSize = mtctx->targetPrefixSize;  /* job size must be >= overlap size */
      DEBUGLOG(4, "Job Size : %u KB (note : set to %u)", (U32)(mtctx->targetSectionSize>>10), (U32)params.jobSize);
      DEBUGLOG(4, "inBuff Size : %u KB", (U32)(mtctx->targetSectionSize>>10));
      ZSTDMT_setBufferSize(mtctx->bufPool, ZSTD_compressBound(mtctx->targetSectionSize));
      {
          /* If ldm is enabled we need windowSize space. */
          size_t const windowSize = mtctx->params.ldmParams.enableLdm ? (1U << mtctx->params.cParams.windowLog) : 0;
          /* Two buffers of slack, plus extra space for the overlap
           * This is the minimum slack that LDM works with. One extra because
           * flush might waste up to targetSectionSize-1 bytes. Another extra
           * for the overlap (if > 0), then one to fill which doesn't overlap
           * with the LDM window.
           */
          size_t const nbSlackBuffers = 2 + (mtctx->targetPrefixSize > 0);
          size_t const slackSize = mtctx->targetSectionSize * nbSlackBuffers;
          /* Compute the total size, and always have enough slack */
          size_t const nbWorkers = MAX(mtctx->params.nbWorkers, 1);
          size_t const sectionsSize = mtctx->targetSectionSize * nbWorkers;
          size_t const capacity = MAX(windowSize, sectionsSize) + slackSize;
          if (mtctx->roundBuff.capacity < capacity) {
              if (mtctx->roundBuff.buffer)
                  ZSTD_free(mtctx->roundBuff.buffer, mtctx->cMem);
              mtctx->roundBuff.buffer = (BYTE*)ZSTD_malloc(capacity, mtctx->cMem);
              if (mtctx->roundBuff.buffer == NULL) {
                  mtctx->roundBuff.capacity = 0;
                  return ERROR(memory_allocation);
              }
              mtctx->roundBuff.capacity = capacity;
          }
      }
      DEBUGLOG(4, "roundBuff capacity : %u KB", (U32)(mtctx->roundBuff.capacity>>10));
      mtctx->roundBuff.pos = 0;
      mtctx->inBuff.buffer = g_nullBuffer;
      mtctx->inBuff.filled = 0;
      mtctx->inBuff.prefix = kNullRange;
      mtctx->doneJobID = 0;
      mtctx->nextJobID = 0;
      mtctx->frameEnded = 0;
      mtctx->allJobsCompleted = 0;
      mtctx->consumed = 0;
      mtctx->produced = 0;
      if (ZSTDMT_serialState_reset(&mtctx->serial, mtctx->seqPool, params, mtctx->targetSectionSize))
          return ERROR(memory_allocation);
      return 0;
  }
  
  size_t ZSTDMT_initCStream_advanced(ZSTDMT_CCtx* mtctx,
                               const void* dict, size_t dictSize,
                                     ZSTD_parameters params,
                                     unsigned long long pledgedSrcSize)
  {
      ZSTD_CCtx_params cctxParams = mtctx->params;  /* retrieve sticky params */
      DEBUGLOG(4, "ZSTDMT_initCStream_advanced (pledgedSrcSize=%u)", (U32)pledgedSrcSize);
      cctxParams.cParams = params.cParams;
      cctxParams.fParams = params.fParams;
      return ZSTDMT_initCStream_internal(mtctx, dict, dictSize, ZSTD_dct_auto, NULL,
                                         cctxParams, pledgedSrcSize);
  }
  
  size_t ZSTDMT_initCStream_usingCDict(ZSTDMT_CCtx* mtctx,
                                 const ZSTD_CDict* cdict,
                                       ZSTD_frameParameters fParams,
                                       unsigned long long pledgedSrcSize)
  {
      ZSTD_CCtx_params cctxParams = mtctx->params;
      if (cdict==NULL) return ERROR(dictionary_wrong);   /* method incompatible with NULL cdict */
      cctxParams.cParams = ZSTD_getCParamsFromCDict(cdict);
      cctxParams.fParams = fParams;
      return ZSTDMT_initCStream_internal(mtctx, NULL, 0 /*dictSize*/, ZSTD_dct_auto, cdict,
                                         cctxParams, pledgedSrcSize);
  }
  
  
  /* ZSTDMT_resetCStream() :
   * pledgedSrcSize can be zero == unknown (for the time being)
   * prefer using ZSTD_CONTENTSIZE_UNKNOWN,
   * as `0` might mean "empty" in the future */
  size_t ZSTDMT_resetCStream(ZSTDMT_CCtx* mtctx, unsigned long long pledgedSrcSize)
  {
      if (!pledgedSrcSize) pledgedSrcSize = ZSTD_CONTENTSIZE_UNKNOWN;
      return ZSTDMT_initCStream_internal(mtctx, NULL, 0, ZSTD_dct_auto, 0, mtctx->params,
                                         pledgedSrcSize);
  }
  
  size_t ZSTDMT_initCStream(ZSTDMT_CCtx* mtctx, int compressionLevel) {
      ZSTD_parameters const params = ZSTD_getParams(compressionLevel, ZSTD_CONTENTSIZE_UNKNOWN, 0);
      ZSTD_CCtx_params cctxParams = mtctx->params;   /* retrieve sticky params */
      DEBUGLOG(4, "ZSTDMT_initCStream (cLevel=%i)", compressionLevel);
      cctxParams.cParams = params.cParams;
      cctxParams.fParams = params.fParams;
      return ZSTDMT_initCStream_internal(mtctx, NULL, 0, ZSTD_dct_auto, NULL, cctxParams, ZSTD_CONTENTSIZE_UNKNOWN);
  }
  
  
  /* ZSTDMT_writeLastEmptyBlock()
   * Write a single empty block with an end-of-frame to finish a frame.
   * Job must be created from streaming variant.
   * This function is always successful if expected conditions are fulfilled.
   */
  static void ZSTDMT_writeLastEmptyBlock(ZSTDMT_jobDescription* job)
  {
      assert(job->lastJob == 1);
      assert(job->src.size == 0);   /* last job is empty -> will be simplified into a last empty block */
      assert(job->firstJob == 0);   /* cannot be first job, as it also needs to create frame header */
      assert(job->dstBuff.start == NULL);   /* invoked from streaming variant only (otherwise, dstBuff might be user's output) */
      job->dstBuff = ZSTDMT_getBuffer(job->bufPool);
      if (job->dstBuff.start == NULL) {
        job->cSize = ERROR(memory_allocation);
        return;
      }
      assert(job->dstBuff.capacity >= ZSTD_blockHeaderSize);   /* no buffer should ever be that small */
      job->src = kNullRange;
      job->cSize = ZSTD_writeLastEmptyBlock(job->dstBuff.start, job->dstBuff.capacity);
      assert(!ZSTD_isError(job->cSize));
      assert(job->consumed == 0);
  }
  
  static size_t ZSTDMT_createCompressionJob(ZSTDMT_CCtx* mtctx, size_t srcSize, ZSTD_EndDirective endOp)
  {
      unsigned const jobID = mtctx->nextJobID & mtctx->jobIDMask;
      int const endFrame = (endOp == ZSTD_e_end);
  
      if (mtctx->nextJobID > mtctx->doneJobID + mtctx->jobIDMask) {
          DEBUGLOG(5, "ZSTDMT_createCompressionJob: will not create new job : table is full");
          assert((mtctx->nextJobID & mtctx->jobIDMask) == (mtctx->doneJobID & mtctx->jobIDMask));
          return 0;
      }
  
      if (!mtctx->jobReady) {
          BYTE const* src = (BYTE const*)mtctx->inBuff.buffer.start;
          DEBUGLOG(5, "ZSTDMT_createCompressionJob: preparing job %u to compress %u bytes with %u preload ",
                      mtctx->nextJobID, (U32)srcSize, (U32)mtctx->inBuff.prefix.size);
          mtctx->jobs[jobID].src.start = src;
          mtctx->jobs[jobID].src.size = srcSize;
          assert(mtctx->inBuff.filled >= srcSize);
          mtctx->jobs[jobID].prefix = mtctx->inBuff.prefix;
          mtctx->jobs[jobID].consumed = 0;
          mtctx->jobs[jobID].cSize = 0;
          mtctx->jobs[jobID].params = mtctx->params;
          mtctx->jobs[jobID].cdict = mtctx->nextJobID==0 ? mtctx->cdict : NULL;
          mtctx->jobs[jobID].fullFrameSize = mtctx->frameContentSize;
          mtctx->jobs[jobID].dstBuff = g_nullBuffer;
          mtctx->jobs[jobID].cctxPool = mtctx->cctxPool;
          mtctx->jobs[jobID].bufPool = mtctx->bufPool;
          mtctx->jobs[jobID].seqPool = mtctx->seqPool;
          mtctx->jobs[jobID].serial = &mtctx->serial;
          mtctx->jobs[jobID].jobID = mtctx->nextJobID;
          mtctx->jobs[jobID].firstJob = (mtctx->nextJobID==0);
          mtctx->jobs[jobID].lastJob = endFrame;
          mtctx->jobs[jobID].frameChecksumNeeded = mtctx->params.fParams.checksumFlag && endFrame && (mtctx->nextJobID>0);
          mtctx->jobs[jobID].dstFlushed = 0;
  
          /* Update the round buffer pos and clear the input buffer to be reset */
          mtctx->roundBuff.pos += srcSize;
          mtctx->inBuff.buffer = g_nullBuffer;
          mtctx->inBuff.filled = 0;
          /* Set the prefix */
          if (!endFrame) {
              size_t const newPrefixSize = MIN(srcSize, mtctx->targetPrefixSize);
              mtctx->inBuff.prefix.start = src + srcSize - newPrefixSize;
              mtctx->inBuff.prefix.size = newPrefixSize;
          } else {   /* endFrame==1 => no need for another input buffer */
              mtctx->inBuff.prefix = kNullRange;
              mtctx->frameEnded = endFrame;
              if (mtctx->nextJobID == 0) {
                  /* single job exception : checksum is already calculated directly within worker thread */
                  mtctx->params.fParams.checksumFlag = 0;
          }   }
  
          if ( (srcSize == 0)
            && (mtctx->nextJobID>0)/*single job must also write frame header*/ ) {
              DEBUGLOG(5, "ZSTDMT_createCompressionJob: creating a last empty block to end frame");
              assert(endOp == ZSTD_e_end);  /* only possible case : need to end the frame with an empty last block */
              ZSTDMT_writeLastEmptyBlock(mtctx->jobs + jobID);
              mtctx->nextJobID++;
              return 0;
          }
      }
  
      DEBUGLOG(5, "ZSTDMT_createCompressionJob: posting job %u : %u bytes  (end:%u, jobNb == %u (mod:%u))",
                  mtctx->nextJobID,
                  (U32)mtctx->jobs[jobID].src.size,
                  mtctx->jobs[jobID].lastJob,
                  mtctx->nextJobID,
                  jobID);
      if (POOL_tryAdd(mtctx->factory, ZSTDMT_compressionJob, &mtctx->jobs[jobID])) {
          mtctx->nextJobID++;
          mtctx->jobReady = 0;
      } else {
          DEBUGLOG(5, "ZSTDMT_createCompressionJob: no worker available for job %u", mtctx->nextJobID);
          mtctx->jobReady = 1;
      }
      return 0;
  }
  
  
  /*! ZSTDMT_flushProduced() :
   *  flush whatever data has been produced but not yet flushed in current job.
   *  move to next job if current one is fully flushed.
   * `output` : `pos` will be updated with amount of data flushed .
   * `blockToFlush` : if >0, the function will block and wait if there is no data available to flush .
   * @return : amount of data remaining within internal buffer, 0 if no more, 1 if unknown but > 0, or an error code */
  static size_t ZSTDMT_flushProduced(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, unsigned blockToFlush, ZSTD_EndDirective end)
  {
      unsigned const wJobID = mtctx->doneJobID & mtctx->jobIDMask;
      DEBUGLOG(5, "ZSTDMT_flushProduced (blocking:%u , job %u <= %u)",
                  blockToFlush, mtctx->doneJobID, mtctx->nextJobID);
      assert(output->size >= output->pos);
  
      ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[wJobID].job_mutex);
      if (  blockToFlush
        && (mtctx->doneJobID < mtctx->nextJobID) ) {
          assert(mtctx->jobs[wJobID].dstFlushed <= mtctx->jobs[wJobID].cSize);
          while (mtctx->jobs[wJobID].dstFlushed == mtctx->jobs[wJobID].cSize) {  /* nothing to flush */
              if (mtctx->jobs[wJobID].consumed == mtctx->jobs[wJobID].src.size) {
                  DEBUGLOG(5, "job %u is completely consumed (%u == %u) => don't wait for cond, there will be none",
                              mtctx->doneJobID, (U32)mtctx->jobs[wJobID].consumed, (U32)mtctx->jobs[wJobID].src.size);
                  break;
              }
              DEBUGLOG(5, "waiting for something to flush from job %u (currently flushed: %u bytes)",
                          mtctx->doneJobID, (U32)mtctx->jobs[wJobID].dstFlushed);
              ZSTD_pthread_cond_wait(&mtctx->jobs[wJobID].job_cond, &mtctx->jobs[wJobID].job_mutex);  /* block when nothing to flush but some to come */
      }   }
  
      /* try to flush something */
      {   size_t cSize = mtctx->jobs[wJobID].cSize;                  /* shared */
          size_t const srcConsumed = mtctx->jobs[wJobID].consumed;   /* shared */
          size_t const srcSize = mtctx->jobs[wJobID].src.size;       /* read-only, could be done after mutex lock, but no-declaration-after-statement */
          ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
          if (ZSTD_isError(cSize)) {
              DEBUGLOG(5, "ZSTDMT_flushProduced: job %u : compression error detected : %s",
                          mtctx->doneJobID, ZSTD_getErrorName(cSize));
              ZSTDMT_waitForAllJobsCompleted(mtctx);
              ZSTDMT_releaseAllJobResources(mtctx);
              return cSize;
          }
          /* add frame checksum if necessary (can only happen once) */
          assert(srcConsumed <= srcSize);
          if ( (srcConsumed == srcSize)   /* job completed -> worker no longer active */
            && mtctx->jobs[wJobID].frameChecksumNeeded ) {
              U32 const checksum = (U32)XXH64_digest(&mtctx->serial.xxhState);
              DEBUGLOG(4, "ZSTDMT_flushProduced: writing checksum : %08X \n", checksum);
              MEM_writeLE32((char*)mtctx->jobs[wJobID].dstBuff.start + mtctx->jobs[wJobID].cSize, checksum);
              cSize += 4;
              mtctx->jobs[wJobID].cSize += 4;  /* can write this shared value, as worker is no longer active */
              mtctx->jobs[wJobID].frameChecksumNeeded = 0;
          }
  
          if (cSize > 0) {   /* compression is ongoing or completed */
              size_t const toFlush = MIN(cSize - mtctx->jobs[wJobID].dstFlushed, output->size - output->pos);
              DEBUGLOG(5, "ZSTDMT_flushProduced: Flushing %u bytes from job %u (completion:%u/%u, generated:%u)",
                          (U32)toFlush, mtctx->doneJobID, (U32)srcConsumed, (U32)srcSize, (U32)cSize);
              assert(mtctx->doneJobID < mtctx->nextJobID);
              assert(cSize >= mtctx->jobs[wJobID].dstFlushed);
              assert(mtctx->jobs[wJobID].dstBuff.start != NULL);
              memcpy((char*)output->dst + output->pos,
                     (const char*)mtctx->jobs[wJobID].dstBuff.start + mtctx->jobs[wJobID].dstFlushed,
                     toFlush);
              output->pos += toFlush;
              mtctx->jobs[wJobID].dstFlushed += toFlush;  /* can write : this value is only used by mtctx */
  
              if ( (srcConsumed == srcSize)    /* job is completed */
                && (mtctx->jobs[wJobID].dstFlushed == cSize) ) {   /* output buffer fully flushed => free this job position */
                  DEBUGLOG(5, "Job %u completed (%u bytes), moving to next one",
                          mtctx->doneJobID, (U32)mtctx->jobs[wJobID].dstFlushed);
                  ZSTDMT_releaseBuffer(mtctx->bufPool, mtctx->jobs[wJobID].dstBuff);
                  DEBUGLOG(5, "dstBuffer released");
                  mtctx->jobs[wJobID].dstBuff = g_nullBuffer;
                  mtctx->jobs[wJobID].cSize = 0;   /* ensure this job slot is considered "not started" in future check */
                  mtctx->consumed += srcSize;
                  mtctx->produced += cSize;
                  mtctx->doneJobID++;
          }   }
  
          /* return value : how many bytes left in buffer ; fake it to 1 when unknown but >0 */
          if (cSize > mtctx->jobs[wJobID].dstFlushed) return (cSize - mtctx->jobs[wJobID].dstFlushed);
          if (srcSize > srcConsumed) return 1;   /* current job not completely compressed */
      }
      if (mtctx->doneJobID < mtctx->nextJobID) return 1;   /* some more jobs ongoing */
      if (mtctx->jobReady) return 1;      /* one job is ready to push, just not yet in the list */
      if (mtctx->inBuff.filled > 0) return 1;   /* input is not empty, and still needs to be converted into a job */
      mtctx->allJobsCompleted = mtctx->frameEnded;   /* all jobs are entirely flushed => if this one is last one, frame is completed */
      if (end == ZSTD_e_end) return !mtctx->frameEnded;  /* for ZSTD_e_end, question becomes : is frame completed ? instead of : are internal buffers fully flushed ? */
      return 0;   /* internal buffers fully flushed */
  }
  
  /**
   * Returns the range of data used by the earliest job that is not yet complete.
   * If the data of the first job is broken up into two segments, we cover both
   * sections.
   */
  static range_t ZSTDMT_getInputDataInUse(ZSTDMT_CCtx* mtctx)
  {
      unsigned const firstJobID = mtctx->doneJobID;
      unsigned const lastJobID = mtctx->nextJobID;
      unsigned jobID;
  
      for (jobID = firstJobID; jobID < lastJobID; ++jobID) {
          unsigned const wJobID = jobID & mtctx->jobIDMask;
          size_t consumed;
  
          ZSTD_PTHREAD_MUTEX_LOCK(&mtctx->jobs[wJobID].job_mutex);
          consumed = mtctx->jobs[wJobID].consumed;
          ZSTD_pthread_mutex_unlock(&mtctx->jobs[wJobID].job_mutex);
  
          if (consumed < mtctx->jobs[wJobID].src.size) {
              range_t range = mtctx->jobs[wJobID].prefix;
              if (range.size == 0) {
                  /* Empty prefix */
                  range = mtctx->jobs[wJobID].src;
              }
              /* Job source in multiple segments not supported yet */
              assert(range.start <= mtctx->jobs[wJobID].src.start);
              return range;
          }
      }
      return kNullRange;
  }
  
  /**
   * Returns non-zero iff buffer and range overlap.
   */
  static int ZSTDMT_isOverlapped(buffer_t buffer, range_t range)
  {
      BYTE const* const bufferStart = (BYTE const*)buffer.start;
      BYTE const* const bufferEnd = bufferStart + buffer.capacity;
      BYTE const* const rangeStart = (BYTE const*)range.start;
      BYTE const* const rangeEnd = rangeStart + range.size;
  
      if (rangeStart == NULL || bufferStart == NULL)
          return 0;
      /* Empty ranges cannot overlap */
      if (bufferStart == bufferEnd || rangeStart == rangeEnd)
          return 0;
  
      return bufferStart < rangeEnd && rangeStart < bufferEnd;
  }
  
  static int ZSTDMT_doesOverlapWindow(buffer_t buffer, ZSTD_window_t window)
  {
      range_t extDict;
      range_t prefix;
  
      DEBUGLOG(5, "ZSTDMT_doesOverlapWindow");
      extDict.start = window.dictBase + window.lowLimit;
      extDict.size = window.dictLimit - window.lowLimit;
  
      prefix.start = window.base + window.dictLimit;
      prefix.size = window.nextSrc - (window.base + window.dictLimit);
      DEBUGLOG(5, "extDict [0x%zx, 0x%zx)",
                  (size_t)extDict.start,
                  (size_t)extDict.start + extDict.size);
      DEBUGLOG(5, "prefix  [0x%zx, 0x%zx)",
                  (size_t)prefix.start,
                  (size_t)prefix.start + prefix.size);
  
      return ZSTDMT_isOverlapped(buffer, extDict)
          || ZSTDMT_isOverlapped(buffer, prefix);
  }
  
  static void ZSTDMT_waitForLdmComplete(ZSTDMT_CCtx* mtctx, buffer_t buffer)
  {
      if (mtctx->params.ldmParams.enableLdm) {
          ZSTD_pthread_mutex_t* mutex = &mtctx->serial.ldmWindowMutex;
          DEBUGLOG(5, "ZSTDMT_waitForLdmComplete");
          DEBUGLOG(5, "source  [0x%zx, 0x%zx)",
                      (size_t)buffer.start,
                      (size_t)buffer.start + buffer.capacity);
          ZSTD_PTHREAD_MUTEX_LOCK(mutex);
          while (ZSTDMT_doesOverlapWindow(buffer, mtctx->serial.ldmWindow)) {
              DEBUGLOG(5, "Waiting for LDM to finish...");
              ZSTD_pthread_cond_wait(&mtctx->serial.ldmWindowCond, mutex);
          }
          DEBUGLOG(6, "Done waiting for LDM to finish");
          ZSTD_pthread_mutex_unlock(mutex);
      }
  }
  
  /**
   * Attempts to set the inBuff to the next section to fill.
   * If any part of the new section is still in use we give up.
   * Returns non-zero if the buffer is filled.
   */
  static int ZSTDMT_tryGetInputRange(ZSTDMT_CCtx* mtctx)
  {
      range_t const inUse = ZSTDMT_getInputDataInUse(mtctx);
      size_t const spaceLeft = mtctx->roundBuff.capacity - mtctx->roundBuff.pos;
      size_t const target = mtctx->targetSectionSize;
      buffer_t buffer;
  
      DEBUGLOG(5, "ZSTDMT_tryGetInputRange");
      assert(mtctx->inBuff.buffer.start == NULL);
      assert(mtctx->roundBuff.capacity >= target);
  
      if (spaceLeft < target) {
          /* ZSTD_invalidateRepCodes() doesn't work for extDict variants.
           * Simply copy the prefix to the beginning in that case.
           */
          BYTE* const start = (BYTE*)mtctx->roundBuff.buffer;
          size_t const prefixSize = mtctx->inBuff.prefix.size;
  
          buffer.start = start;
          buffer.capacity = prefixSize;
          if (ZSTDMT_isOverlapped(buffer, inUse)) {
              DEBUGLOG(5, "Waiting for buffer...");
              return 0;
          }
          ZSTDMT_waitForLdmComplete(mtctx, buffer);
          memmove(start, mtctx->inBuff.prefix.start, prefixSize);
          mtctx->inBuff.prefix.start = start;
          mtctx->roundBuff.pos = prefixSize;
      }
      buffer.start = mtctx->roundBuff.buffer + mtctx->roundBuff.pos;
      buffer.capacity = target;
  
      if (ZSTDMT_isOverlapped(buffer, inUse)) {
          DEBUGLOG(5, "Waiting for buffer...");
          return 0;
      }
      assert(!ZSTDMT_isOverlapped(buffer, mtctx->inBuff.prefix));
  
      ZSTDMT_waitForLdmComplete(mtctx, buffer);
  
      DEBUGLOG(5, "Using prefix range [%zx, %zx)",
                  (size_t)mtctx->inBuff.prefix.start,
                  (size_t)mtctx->inBuff.prefix.start + mtctx->inBuff.prefix.size);
      DEBUGLOG(5, "Using source range [%zx, %zx)",
                  (size_t)buffer.start,
                  (size_t)buffer.start + buffer.capacity);
  
  
      mtctx->inBuff.buffer = buffer;
      mtctx->inBuff.filled = 0;
      assert(mtctx->roundBuff.pos + buffer.capacity <= mtctx->roundBuff.capacity);
      return 1;
  }
  
  typedef struct {
    size_t toLoad;  /* The number of bytes to load from the input. */
    int flush;      /* Boolean declaring if we must flush because we found a synchronization point. */
  } syncPoint_t;
  
  /**
   * Searches through the input for a synchronization point. If one is found, we
   * will instruct the caller to flush, and return the number of bytes to load.
   * Otherwise, we will load as many bytes as possible and instruct the caller
   * to continue as normal.
   */
  static syncPoint_t
  findSynchronizationPoint(ZSTDMT_CCtx const* mtctx, ZSTD_inBuffer const input)
  {
      BYTE const* const istart = (BYTE const*)input.src + input.pos;
      U64 const primePower = mtctx->rsync.primePower;
      U64 const hitMask = mtctx->rsync.hitMask;
  
      syncPoint_t syncPoint;
      U64 hash;
      BYTE const* prev;
      size_t pos;
  
      syncPoint.toLoad = MIN(input.size - input.pos, mtctx->targetSectionSize - mtctx->inBuff.filled);
      syncPoint.flush = 0;
      if (!mtctx->params.rsyncable)
          /* Rsync is disabled. */
          return syncPoint;
      if (mtctx->inBuff.filled + syncPoint.toLoad < RSYNC_LENGTH)
          /* Not enough to compute the hash.
           * We will miss any synchronization points in this RSYNC_LENGTH byte
           * window. However, since it depends only in the internal buffers, if the
           * state is already synchronized, we will remain synchronized.
           * Additionally, the probability that we miss a synchronization point is
           * low: RSYNC_LENGTH / targetSectionSize.
           */
          return syncPoint;
      /* Initialize the loop variables. */
      if (mtctx->inBuff.filled >= RSYNC_LENGTH) {
          /* We have enough bytes buffered to initialize the hash.
           * Start scanning at the beginning of the input.
           */
          pos = 0;
          prev = (BYTE const*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled - RSYNC_LENGTH;
          hash = ZSTD_rollingHash_compute(prev, RSYNC_LENGTH);
      } else {
          /* We don't have enough bytes buffered to initialize the hash, but
           * we know we have at least RSYNC_LENGTH bytes total.
           * Start scanning after the first RSYNC_LENGTH bytes less the bytes
           * already buffered.
           */
          pos = RSYNC_LENGTH - mtctx->inBuff.filled;
          prev = (BYTE const*)mtctx->inBuff.buffer.start - pos;
          hash = ZSTD_rollingHash_compute(mtctx->inBuff.buffer.start, mtctx->inBuff.filled);
          hash = ZSTD_rollingHash_append(hash, istart, pos);
      }
      /* Starting with the hash of the previous RSYNC_LENGTH bytes, roll
       * through the input. If we hit a synchronization point, then cut the
       * job off, and tell the compressor to flush the job. Otherwise, load
       * all the bytes and continue as normal.
       * If we go too long without a synchronization point (targetSectionSize)
       * then a block will be emitted anyways, but this is okay, since if we
       * are already synchronized we will remain synchronized.
       */
      for (; pos < syncPoint.toLoad; ++pos) {
          BYTE const toRemove = pos < RSYNC_LENGTH ? prev[pos] : istart[pos - RSYNC_LENGTH];
          /* if (pos >= RSYNC_LENGTH) assert(ZSTD_rollingHash_compute(istart + pos - RSYNC_LENGTH, RSYNC_LENGTH) == hash); */
          hash = ZSTD_rollingHash_rotate(hash, toRemove, istart[pos], primePower);
          if ((hash & hitMask) == hitMask) {
              syncPoint.toLoad = pos + 1;
              syncPoint.flush = 1;
              break;
          }
      }
      return syncPoint;
  }
  
  size_t ZSTDMT_nextInputSizeHint(const ZSTDMT_CCtx* mtctx)
  {
      size_t hintInSize = mtctx->targetSectionSize - mtctx->inBuff.filled;
      if (hintInSize==0) hintInSize = mtctx->targetSectionSize;
      return hintInSize;
  }
  
  /** ZSTDMT_compressStream_generic() :
   *  internal use only - exposed to be invoked from zstd_compress.c
   *  assumption : output and input are valid (pos <= size)
   * @return : minimum amount of data remaining to flush, 0 if none */
  size_t ZSTDMT_compressStream_generic(ZSTDMT_CCtx* mtctx,
                                       ZSTD_outBuffer* output,
                                       ZSTD_inBuffer* input,
                                       ZSTD_EndDirective endOp)
  {
      unsigned forwardInputProgress = 0;
      DEBUGLOG(5, "ZSTDMT_compressStream_generic (endOp=%u, srcSize=%u)",
                  (U32)endOp, (U32)(input->size - input->pos));
      assert(output->pos <= output->size);
      assert(input->pos  <= input->size);
  
      if (mtctx->singleBlockingThread) {  /* delegate to single-thread (synchronous) */
          return ZSTD_compressStream2(mtctx->cctxPool->cctx[0], output, input, endOp);
      }
  
      if ((mtctx->frameEnded) && (endOp==ZSTD_e_continue)) {
          /* current frame being ended. Only flush/end are allowed */
          return ERROR(stage_wrong);
      }
  
      /* single-pass shortcut (note : synchronous-mode) */
      if ( (!mtctx->params.rsyncable)   /* rsyncable mode is disabled */
        && (mtctx->nextJobID == 0)      /* just started */
        && (mtctx->inBuff.filled == 0)  /* nothing buffered */
        && (!mtctx->jobReady)           /* no job already created */
        && (endOp == ZSTD_e_end)        /* end order */
        && (output->size - output->pos >= ZSTD_compressBound(input->size - input->pos)) ) { /* enough space in dst */
          size_t const cSize = ZSTDMT_compress_advanced_internal(mtctx,
                  (char*)output->dst + output->pos, output->size - output->pos,
                  (const char*)input->src + input->pos, input->size - input->pos,
                  mtctx->cdict, mtctx->params);
          if (ZSTD_isError(cSize)) return cSize;
          input->pos = input->size;
          output->pos += cSize;
          mtctx->allJobsCompleted = 1;
          mtctx->frameEnded = 1;
          return 0;
      }
  
      /* fill input buffer */
      if ( (!mtctx->jobReady)
        && (input->size > input->pos) ) {   /* support NULL input */
          if (mtctx->inBuff.buffer.start == NULL) {
              assert(mtctx->inBuff.filled == 0); /* Can't fill an empty buffer */
              if (!ZSTDMT_tryGetInputRange(mtctx)) {
                  /* It is only possible for this operation to fail if there are
                   * still compression jobs ongoing.
                   */
                  DEBUGLOG(5, "ZSTDMT_tryGetInputRange failed");
                  assert(mtctx->doneJobID != mtctx->nextJobID);
              } else
                  DEBUGLOG(5, "ZSTDMT_tryGetInputRange completed successfully : mtctx->inBuff.buffer.start = %p", mtctx->inBuff.buffer.start);
          }
          if (mtctx->inBuff.buffer.start != NULL) {
              syncPoint_t const syncPoint = findSynchronizationPoint(mtctx, *input);
              if (syncPoint.flush && endOp == ZSTD_e_continue) {
                  endOp = ZSTD_e_flush;
              }
              assert(mtctx->inBuff.buffer.capacity >= mtctx->targetSectionSize);
              DEBUGLOG(5, "ZSTDMT_compressStream_generic: adding %u bytes on top of %u to buffer of size %u",
                          (U32)syncPoint.toLoad, (U32)mtctx->inBuff.filled, (U32)mtctx->targetSectionSize);
              memcpy((char*)mtctx->inBuff.buffer.start + mtctx->inBuff.filled, (const char*)input->src + input->pos, syncPoint.toLoad);
              input->pos += syncPoint.toLoad;
              mtctx->inBuff.filled += syncPoint.toLoad;
              forwardInputProgress = syncPoint.toLoad>0;
          }
          if ((input->pos < input->size) && (endOp == ZSTD_e_end))
              endOp = ZSTD_e_flush;   /* can't end now : not all input consumed */
      }
  
      if ( (mtctx->jobReady)
        || (mtctx->inBuff.filled >= mtctx->targetSectionSize)  /* filled enough : let's compress */
        || ((endOp != ZSTD_e_continue) && (mtctx->inBuff.filled > 0))  /* something to flush : let's go */
        || ((endOp == ZSTD_e_end) && (!mtctx->frameEnded)) ) {   /* must finish the frame with a zero-size block */
          size_t const jobSize = mtctx->inBuff.filled;
          assert(mtctx->inBuff.filled <= mtctx->targetSectionSize);
          FORWARD_IF_ERROR( ZSTDMT_createCompressionJob(mtctx, jobSize, endOp) );
      }
  
      /* check for potential compressed data ready to be flushed */
      {   size_t const remainingToFlush = ZSTDMT_flushProduced(mtctx, output, !forwardInputProgress, endOp); /* block if there was no forward input progress */
          if (input->pos < input->size) return MAX(remainingToFlush, 1);  /* input not consumed : do not end flush yet */
          DEBUGLOG(5, "end of ZSTDMT_compressStream_generic: remainingToFlush = %u", (U32)remainingToFlush);
          return remainingToFlush;
      }
  }
  
  
  size_t ZSTDMT_compressStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
  {
      FORWARD_IF_ERROR( ZSTDMT_compressStream_generic(mtctx, output, input, ZSTD_e_continue) );
  
      /* recommended next input size : fill current input buffer */
      return mtctx->targetSectionSize - mtctx->inBuff.filled;   /* note : could be zero when input buffer is fully filled and no more availability to create new job */
  }
  
  
  static size_t ZSTDMT_flushStream_internal(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, ZSTD_EndDirective endFrame)
  {
      size_t const srcSize = mtctx->inBuff.filled;
      DEBUGLOG(5, "ZSTDMT_flushStream_internal");
  
      if ( mtctx->jobReady     /* one job ready for a worker to pick up */
        || (srcSize > 0)       /* still some data within input buffer */
        || ((endFrame==ZSTD_e_end) && !mtctx->frameEnded)) {  /* need a last 0-size block to end frame */
             DEBUGLOG(5, "ZSTDMT_flushStream_internal : create a new job (%u bytes, end:%u)",
                          (U32)srcSize, (U32)endFrame);
          FORWARD_IF_ERROR( ZSTDMT_createCompressionJob(mtctx, srcSize, endFrame) );
      }
  
      /* check if there is any data available to flush */
      return ZSTDMT_flushProduced(mtctx, output, 1 /* blockToFlush */, endFrame);
  }
  
  
  size_t ZSTDMT_flushStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output)
  {
      DEBUGLOG(5, "ZSTDMT_flushStream");
      if (mtctx->singleBlockingThread)
          return ZSTD_flushStream(mtctx->cctxPool->cctx[0], output);
      return ZSTDMT_flushStream_internal(mtctx, output, ZSTD_e_flush);
  }
  
  size_t ZSTDMT_endStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output)
  {
      DEBUGLOG(4, "ZSTDMT_endStream");
      if (mtctx->singleBlockingThread)
          return ZSTD_endStream(mtctx->cctxPool->cctx[0], output);
      return ZSTDMT_flushStream_internal(mtctx, output, ZSTD_e_end);
  }
  