text: /*
  ** DynASM PPC/PPC64 encoding engine.
  ** Copyright (C) 2005-2021 Mike Pall. All rights reserved.
  ** Released under the MIT license. See dynasm.lua for full copyright notice.
  */
  
  #include <stddef.h>
  #include <stdarg.h>
  #include <string.h>
  #include <stdlib.h>
  
  #define DASM_ARCH		"ppc"
  
  #ifndef DASM_EXTERN
  #define DASM_EXTERN(a,b,c,d)	0
  #endif
  
  /* Action definitions. */
  enum {
    DASM_STOP, DASM_SECTION, DASM_ESC, DASM_REL_EXT,
    /* The following actions need a buffer position. */
    DASM_ALIGN, DASM_REL_LG, DASM_LABEL_LG,
    /* The following actions also have an argument. */
    DASM_REL_PC, DASM_LABEL_PC, DASM_IMM, DASM_IMMSH,
    DASM__MAX
  };
  
  /* Maximum number of section buffer positions for a single dasm_put() call. */
  #define DASM_MAXSECPOS		25
  
  /* DynASM encoder status codes. Action list offset or number are or'ed in. */
  #define DASM_S_OK		0x00000000
  #define DASM_S_NOMEM		0x01000000
  #define DASM_S_PHASE		0x02000000
  #define DASM_S_MATCH_SEC	0x03000000
  #define DASM_S_RANGE_I		0x11000000
  #define DASM_S_RANGE_SEC	0x12000000
  #define DASM_S_RANGE_LG		0x13000000
  #define DASM_S_RANGE_PC		0x14000000
  #define DASM_S_RANGE_REL	0x15000000
  #define DASM_S_UNDEF_LG		0x21000000
  #define DASM_S_UNDEF_PC		0x22000000
  
  /* Macros to convert positions (8 bit section + 24 bit index). */
  #define DASM_POS2IDX(pos)	((pos)&0x00ffffff)
  #define DASM_POS2BIAS(pos)	((pos)&0xff000000)
  #define DASM_SEC2POS(sec)	((sec)<<24)
  #define DASM_POS2SEC(pos)	((pos)>>24)
  #define DASM_POS2PTR(D, pos)	(D->sections[DASM_POS2SEC(pos)].rbuf + (pos))
  
  /* Action list type. */
  typedef const unsigned int *dasm_ActList;
  
  /* Per-section structure. */
  typedef struct dasm_Section {
    int *rbuf;		/* Biased buffer pointer (negative section bias). */
    int *buf;		/* True buffer pointer. */
    size_t bsize;		/* Buffer size in bytes. */
    int pos;		/* Biased buffer position. */
    int epos;		/* End of biased buffer position - max single put. */
    int ofs;		/* Byte offset into section. */
  } dasm_Section;
  
  /* Core structure holding the DynASM encoding state. */
  struct dasm_State {
    size_t psize;			/* Allocated size of this structure. */
    dasm_ActList actionlist;	/* Current actionlist pointer. */
    int *lglabels;		/* Local/global chain/pos ptrs. */
    size_t lgsize;
    int *pclabels;		/* PC label chains/pos ptrs. */
    size_t pcsize;
    void **globals;		/* Array of globals (bias -10). */
    dasm_Section *section;	/* Pointer to active section. */
    size_t codesize;		/* Total size of all code sections. */
    int maxsection;		/* 0 <= sectionidx < maxsection. */
    int status;			/* Status code. */
    dasm_Section sections[1];	/* All sections. Alloc-extended. */
  };
  
  /* The size of the core structure depends on the max. number of sections. */
  #define DASM_PSZ(ms)	(sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
  
  
  /* Initialize DynASM state. */
  void dasm_init(Dst_DECL, int maxsection)
  {
    dasm_State *D;
    size_t psz = 0;
    int i;
    Dst_REF = NULL;
    DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
    D = Dst_REF;
    D->psize = psz;
    D->lglabels = NULL;
    D->lgsize = 0;
    D->pclabels = NULL;
    D->pcsize = 0;
    D->globals = NULL;
    D->maxsection = maxsection;
    for (i = 0; i < maxsection; i++) {
      D->sections[i].buf = NULL;  /* Need this for pass3. */
      D->sections[i].rbuf = D->sections[i].buf - DASM_SEC2POS(i);
      D->sections[i].bsize = 0;
      D->sections[i].epos = 0;  /* Wrong, but is recalculated after resize. */
    }
  }
  
  /* Free DynASM state. */
  void dasm_free(Dst_DECL)
  {
    dasm_State *D = Dst_REF;
    int i;
    for (i = 0; i < D->maxsection; i++)
      if (D->sections[i].buf)
        DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
    if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
    if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
    DASM_M_FREE(Dst, D, D->psize);
  }
  
  /* Setup global label array. Must be called before dasm_setup(). */
  void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
  {
    dasm_State *D = Dst_REF;
    D->globals = gl - 10;  /* Negative bias to compensate for locals. */
    DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
  }
  
  /* Grow PC label array. Can be called after dasm_setup(), too. */
  void dasm_growpc(Dst_DECL, unsigned int maxpc)
  {
    dasm_State *D = Dst_REF;
    size_t osz = D->pcsize;
    DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
    memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
  }
  
  /* Setup encoder. */
  void dasm_setup(Dst_DECL, const void *actionlist)
  {
    dasm_State *D = Dst_REF;
    int i;
    D->actionlist = (dasm_ActList)actionlist;
    D->status = DASM_S_OK;
    D->section = &D->sections[0];
    memset((void *)D->lglabels, 0, D->lgsize);
    if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
    for (i = 0; i < D->maxsection; i++) {
      D->sections[i].pos = DASM_SEC2POS(i);
      D->sections[i].ofs = 0;
    }
  }
  
  
  #ifdef DASM_CHECKS
  #define CK(x, st) \
    do { if (!(x)) { \
      D->status = DASM_S_##st|(p-D->actionlist-1); return; } } while (0)
  #define CKPL(kind, st) \
    do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
      D->status = DASM_S_RANGE_##st|(p-D->actionlist-1); return; } } while (0)
  #else
  #define CK(x, st)	((void)0)
  #define CKPL(kind, st)	((void)0)
  #endif
  
  /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
  void dasm_put(Dst_DECL, int start, ...)
  {
    va_list ap;
    dasm_State *D = Dst_REF;
    dasm_ActList p = D->actionlist + start;
    dasm_Section *sec = D->section;
    int pos = sec->pos, ofs = sec->ofs;
    int *b;
  
    if (pos >= sec->epos) {
      DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
        sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
      sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
      sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
    }
  
    b = sec->rbuf;
    b[pos++] = start;
  
    va_start(ap, start);
    while (1) {
      unsigned int ins = *p++;
      unsigned int action = (ins >> 16);
      if (action >= DASM__MAX) {
        ofs += 4;
      } else {
        int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
        switch (action) {
        case DASM_STOP: goto stop;
        case DASM_SECTION:
  	n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
  	D->section = &D->sections[n]; goto stop;
        case DASM_ESC: p++; ofs += 4; break;
        case DASM_REL_EXT: break;
        case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
        case DASM_REL_LG:
  	n = (ins & 2047) - 10; pl = D->lglabels + n;
  	/* Bkwd rel or global. */
  	if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
  	pl += 10; n = *pl;
  	if (n < 0) n = 0;  /* Start new chain for fwd rel if label exists. */
  	goto linkrel;
        case DASM_REL_PC:
  	pl = D->pclabels + n; CKPL(pc, PC);
        putrel:
  	n = *pl;
  	if (n < 0) {  /* Label exists. Get label pos and store it. */
  	  b[pos] = -n;
  	} else {
        linkrel:
  	  b[pos] = n;  /* Else link to rel chain, anchored at label. */
  	  *pl = pos;
  	}
  	pos++;
  	break;
        case DASM_LABEL_LG:
  	pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
        case DASM_LABEL_PC:
  	pl = D->pclabels + n; CKPL(pc, PC);
        putlabel:
  	n = *pl;  /* n > 0: Collapse rel chain and replace with label pos. */
  	while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
  	}
  	*pl = -pos;  /* Label exists now. */
  	b[pos++] = ofs;  /* Store pass1 offset estimate. */
  	break;
        case DASM_IMM:
  #ifdef DASM_CHECKS
  	CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
  #endif
  	n >>= ((ins>>10)&31);
  #ifdef DASM_CHECKS
  	if (ins & 0x8000)
  	  CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
  	else
  	  CK((n>>((ins>>5)&31)) == 0, RANGE_I);
  #endif
  	b[pos++] = n;
  	break;
        case DASM_IMMSH:
  	CK((n >> 6) == 0, RANGE_I);
  	b[pos++] = n;
  	break;
        }
      }
    }
  stop:
    va_end(ap);
    sec->pos = pos;
    sec->ofs = ofs;
  }
  #undef CK
  
  /* Pass 2: Link sections, shrink aligns, fix label offsets. */
  int dasm_link(Dst_DECL, size_t *szp)
  {
    dasm_State *D = Dst_REF;
    int secnum;
    int ofs = 0;
  
  #ifdef DASM_CHECKS
    *szp = 0;
    if (D->status != DASM_S_OK) return D->status;
    {
      int pc;
      for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
        if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
    }
  #endif
  
    { /* Handle globals not defined in this translation unit. */
      int idx;
      for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) {
        int n = D->lglabels[idx];
        /* Undefined label: Collapse rel chain and replace with marker (< 0). */
        while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
      }
    }
  
    /* Combine all code sections. No support for data sections (yet). */
    for (secnum = 0; secnum < D->maxsection; secnum++) {
      dasm_Section *sec = D->sections + secnum;
      int *b = sec->rbuf;
      int pos = DASM_SEC2POS(secnum);
      int lastpos = sec->pos;
  
      while (pos != lastpos) {
        dasm_ActList p = D->actionlist + b[pos++];
        while (1) {
  	unsigned int ins = *p++;
  	unsigned int action = (ins >> 16);
  	switch (action) {
  	case DASM_STOP: case DASM_SECTION: goto stop;
  	case DASM_ESC: p++; break;
  	case DASM_REL_EXT: break;
  	case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
  	case DASM_REL_LG: case DASM_REL_PC: pos++; break;
  	case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
  	case DASM_IMM: case DASM_IMMSH: pos++; break;
  	}
        }
        stop: (void)0;
      }
      ofs += sec->ofs;  /* Next section starts right after current section. */
    }
  
    D->codesize = ofs;  /* Total size of all code sections */
    *szp = ofs;
    return DASM_S_OK;
  }
  
  #ifdef DASM_CHECKS
  #define CK(x, st) \
    do { if (!(x)) return DASM_S_##st|(p-D->actionlist-1); } while (0)
  #else
  #define CK(x, st)	((void)0)
  #endif
  
  /* Pass 3: Encode sections. */
  int dasm_encode(Dst_DECL, void *buffer)
  {
    dasm_State *D = Dst_REF;
    char *base = (char *)buffer;
    unsigned int *cp = (unsigned int *)buffer;
    int secnum;
  
    /* Encode all code sections. No support for data sections (yet). */
    for (secnum = 0; secnum < D->maxsection; secnum++) {
      dasm_Section *sec = D->sections + secnum;
      int *b = sec->buf;
      int *endb = sec->rbuf + sec->pos;
  
      while (b != endb) {
        dasm_ActList p = D->actionlist + *b++;
        while (1) {
  	unsigned int ins = *p++;
  	unsigned int action = (ins >> 16);
  	int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
  	switch (action) {
  	case DASM_STOP: case DASM_SECTION: goto stop;
  	case DASM_ESC: *cp++ = *p++; break;
  	case DASM_REL_EXT:
  	  n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins & 2047), 1) - 4;
  	  goto patchrel;
  	case DASM_ALIGN:
  	  ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0x60000000;
  	  break;
  	case DASM_REL_LG:
  	  if (n < 0) {
  	    n = (int)((ptrdiff_t)D->globals[-n] - (ptrdiff_t)cp);
  	    goto patchrel;
  	  }
  	  /* fallthrough */
  	case DASM_REL_PC:
  	  CK(n >= 0, UNDEF_PC);
  	  n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base);
  	patchrel:
  	  CK((n & 3) == 0 &&
  	      (((n+4) + ((ins & 2048) ? 0x00008000 : 0x02000000)) >>
  	       ((ins & 2048) ? 16 : 26)) == 0, RANGE_REL);
  	  cp[-1] |= ((n+4) & ((ins & 2048) ? 0x0000fffc: 0x03fffffc));
  	  break;
  	case DASM_LABEL_LG:
  	  ins &= 2047; if (ins >= 20) D->globals[ins-10] = (void *)(base + n);
  	  break;
  	case DASM_LABEL_PC: break;
  	case DASM_IMM:
  	  cp[-1] |= (n & ((1<<((ins>>5)&31))-1)) << (ins&31);
  	  break;
  	case DASM_IMMSH:
  	  cp[-1] |= (ins & 1) ? ((n&31)<<11)|((n&32)>>4) : ((n&31)<<6)|(n&32);
  	  break;
  	default: *cp++ = ins; break;
  	}
        }
        stop: (void)0;
      }
    }
  
    if (base + D->codesize != (char *)cp)  /* Check for phase errors. */
      return DASM_S_PHASE;
    return DASM_S_OK;
  }
  #undef CK
  
  /* Get PC label offset. */
  int dasm_getpclabel(Dst_DECL, unsigned int pc)
  {
    dasm_State *D = Dst_REF;
    if (pc*sizeof(int) < D->pcsize) {
      int pos = D->pclabels[pc];
      if (pos < 0) return *DASM_POS2PTR(D, -pos);
      if (pos > 0) return -1;  /* Undefined. */
    }
    return -2;  /* Unused or out of range. */
  }
  
  #ifdef DASM_CHECKS
  /* Optional sanity checker to call between isolated encoding steps. */
  int dasm_checkstep(Dst_DECL, int secmatch)
  {
    dasm_State *D = Dst_REF;
    if (D->status == DASM_S_OK) {
      int i;
      for (i = 1; i <= 9; i++) {
        if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
        D->lglabels[i] = 0;
      }
    }
    if (D->status == DASM_S_OK && secmatch >= 0 &&
        D->section != &D->sections[secmatch])
      D->status = DASM_S_MATCH_SEC|(D->section-D->sections);
    return D->status;
  }
  #endif
  
  