text: ///////////////////////////////////////////////////////////////////////////////
  //
  /// \file       filter_decoder.c
  /// \brief      Filter ID mapping to filter-specific functions
  //
  //  Author:     Lasse Collin
  //
  //  This file has been put into the public domain.
  //  You can do whatever you want with this file.
  //
  ///////////////////////////////////////////////////////////////////////////////
  
  #include "filter_encoder.h"
  
  #include "delta_encoder.h"
  #include "filter_common.h"
  #include "lzma2_encoder.h"
  #include "lzma_encoder.h"
  #include "simple_encoder.h"
  
  typedef struct
  {
      /// Filter ID
      lzma_vli id;
  
      /// Initializes the filter encoder and calls lzma_next_filter_init()
      /// for filters + 1.
      lzma_init_function init;
  
      /// Calculates memory usage of the encoder. If the options are
      /// invalid, UINT64_MAX is returned.
      uint64_t (*memusage)(const void* options);
  
      /// Calculates the recommended Uncompressed Size for .xz Blocks to
      /// which the input data can be split to make multithreaded
      /// encoding possible. If this is NULL, it is assumed that
      /// the encoder is fast enough with single thread.
      uint64_t (*block_size)(const void* options);
  
      /// Tells the size of the Filter Properties field. If options are
      /// invalid, UINT32_MAX is returned. If this is NULL, props_size_fixed
      /// is used.
      lzma_ret (*props_size_get)(uint32_t* size, const void* options);
      uint32_t props_size_fixed;
  
      /// Encodes Filter Properties.
      ///
      /// \return     - LZMA_OK: Properties encoded successfully.
      ///             - LZMA_OPTIONS_ERROR: Unsupported options
      ///             - LZMA_PROG_ERROR: Invalid options or not enough
      ///               output space
      lzma_ret (*props_encode)(const void* options, uint8_t* out);
  
  } lzma_filter_encoder;
  
  static const lzma_filter_encoder encoders[] = {
  #ifdef HAVE_ENCODER_LZMA1
      {
          .id = LZMA_FILTER_LZMA1,
          .init = &lzma_lzma_encoder_init,
          .memusage = &lzma_lzma_encoder_memusage,
          .block_size = NULL, // FIXME
          .props_size_get = NULL,
          .props_size_fixed = 5,
          .props_encode = &lzma_lzma_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_LZMA2
      {
          .id = LZMA_FILTER_LZMA2,
          .init = &lzma_lzma2_encoder_init,
          .memusage = &lzma_lzma2_encoder_memusage,
          .block_size = &lzma_lzma2_block_size, // FIXME
          .props_size_get = NULL,
          .props_size_fixed = 1,
          .props_encode = &lzma_lzma2_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_X86
      {
          .id = LZMA_FILTER_X86,
          .init = &lzma_simple_x86_encoder_init,
          .memusage = NULL,
          .block_size = NULL,
          .props_size_get = &lzma_simple_props_size,
          .props_encode = &lzma_simple_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_POWERPC
      {
          .id = LZMA_FILTER_POWERPC,
          .init = &lzma_simple_powerpc_encoder_init,
          .memusage = NULL,
          .block_size = NULL,
          .props_size_get = &lzma_simple_props_size,
          .props_encode = &lzma_simple_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_IA64
      {
          .id = LZMA_FILTER_IA64,
          .init = &lzma_simple_ia64_encoder_init,
          .memusage = NULL,
          .block_size = NULL,
          .props_size_get = &lzma_simple_props_size,
          .props_encode = &lzma_simple_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_ARM
      {
          .id = LZMA_FILTER_ARM,
          .init = &lzma_simple_arm_encoder_init,
          .memusage = NULL,
          .block_size = NULL,
          .props_size_get = &lzma_simple_props_size,
          .props_encode = &lzma_simple_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_ARMTHUMB
      {
          .id = LZMA_FILTER_ARMTHUMB,
          .init = &lzma_simple_armthumb_encoder_init,
          .memusage = NULL,
          .block_size = NULL,
          .props_size_get = &lzma_simple_props_size,
          .props_encode = &lzma_simple_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_SPARC
      {
          .id = LZMA_FILTER_SPARC,
          .init = &lzma_simple_sparc_encoder_init,
          .memusage = NULL,
          .block_size = NULL,
          .props_size_get = &lzma_simple_props_size,
          .props_encode = &lzma_simple_props_encode,
      },
  #endif
  #ifdef HAVE_ENCODER_DELTA
      {
          .id = LZMA_FILTER_DELTA,
          .init = &lzma_delta_encoder_init,
          .memusage = &lzma_delta_coder_memusage,
          .block_size = NULL,
          .props_size_get = NULL,
          .props_size_fixed = 1,
          .props_encode = &lzma_delta_props_encode,
      },
  #endif
  };
  
  static const lzma_filter_encoder* encoder_find(lzma_vli id)
  {
      for (size_t i = 0; i < ARRAY_SIZE(encoders); ++i)
          if (encoders[i].id == id)
              return encoders + i;
  
      return NULL;
  }
  
  extern LZMA_API(lzma_bool) lzma_filter_encoder_is_supported(lzma_vli id)
  {
      return encoder_find(id) != NULL;
  }
  
  extern LZMA_API(lzma_ret)
      lzma_filters_update(lzma_stream* strm, const lzma_filter* filters)
  {
      if (strm->internal->next.update == NULL)
          return LZMA_PROG_ERROR;
  
      // Validate the filter chain.
      if (lzma_raw_encoder_memusage(filters) == UINT64_MAX)
          return LZMA_OPTIONS_ERROR;
  
      // The actual filter chain in the encoder is reversed. Some things
      // still want the normal order chain, so we provide both.
      size_t count = 1;
      while (filters[count].id != LZMA_VLI_UNKNOWN)
          ++count;
  
      lzma_filter reversed_filters[LZMA_FILTERS_MAX + 1];
      for (size_t i = 0; i < count; ++i)
          reversed_filters[count - i - 1] = filters[i];
  
      reversed_filters[count].id = LZMA_VLI_UNKNOWN;
  
      return strm->internal->next.update(
          strm->internal->next.coder, strm->allocator, filters, reversed_filters);
  }
  
  extern lzma_ret lzma_raw_encoder_init(lzma_next_coder* next,
                                        const lzma_allocator* allocator,
                                        const lzma_filter* options)
  {
      return lzma_raw_coder_init(next, allocator, options,
                                 (lzma_filter_find)(&encoder_find), true);
  }
  
  extern LZMA_API(lzma_ret)
      lzma_raw_encoder(lzma_stream* strm, const lzma_filter* options)
  {
      lzma_next_strm_init(lzma_raw_coder_init, strm, options,
                          (lzma_filter_find)(&encoder_find), true);
  
      strm->internal->supported_actions[LZMA_RUN] = true;
      strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true;
      strm->internal->supported_actions[LZMA_FINISH] = true;
  
      return LZMA_OK;
  }
  
  extern LZMA_API(uint64_t) lzma_raw_encoder_memusage(const lzma_filter* filters)
  {
      return lzma_raw_coder_memusage((lzma_filter_find)(&encoder_find), filters);
  }
  
  extern uint64_t lzma_mt_block_size(const lzma_filter* filters)
  {
      uint64_t max = 0;
  
      for (size_t i = 0; filters[i].id != LZMA_VLI_UNKNOWN; ++i)
      {
          const lzma_filter_encoder* const fe = encoder_find(filters[i].id);
          if (fe->block_size != NULL)
          {
              const uint64_t size = fe->block_size(filters[i].options);
              if (size == 0)
                  return 0;
  
              if (size > max)
                  max = size;
          }
      }
  
      return max;
  }
  
  extern LZMA_API(lzma_ret)
      lzma_properties_size(uint32_t* size, const lzma_filter* filter)
  {
      const lzma_filter_encoder* const fe = encoder_find(filter->id);
      if (fe == NULL)
      {
          // Unknown filter - if the Filter ID is a proper VLI,
          // return LZMA_OPTIONS_ERROR instead of LZMA_PROG_ERROR,
          // because it's possible that we just don't have support
          // compiled in for the requested filter.
          return filter->id <= LZMA_VLI_MAX ? LZMA_OPTIONS_ERROR
                                            : LZMA_PROG_ERROR;
      }
  
      if (fe->props_size_get == NULL)
      {
          // No props_size_get() function, use props_size_fixed.
          *size = fe->props_size_fixed;
          return LZMA_OK;
      }
  
      return fe->props_size_get(size, filter->options);
  }
  
  extern LZMA_API(lzma_ret)
      lzma_properties_encode(const lzma_filter* filter, uint8_t* props)
  {
      const lzma_filter_encoder* const fe = encoder_find(filter->id);
      if (fe == NULL)
          return LZMA_PROG_ERROR;
  
      if (fe->props_encode == NULL)
          return LZMA_OK;
  
      return fe->props_encode(filter->options, props);
  }
  