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/* infcodes.c -- process literals and length/distance pairs
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 * Copyright (C) 1995-2002 Mark Adler
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 * For conditions of distribution and use, see copyright notice in zlib.h
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 */
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#include "zutil.h"
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#include "inftrees.h"
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#include "infblock.h"
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#include "infcodes.h"
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#include "infutil.h"
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#include "inffast.h"
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/* simplify the use of the inflate_huft type with some defines */
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#define exop word.what.Exop
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#define bits word.what.Bits
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typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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      START,    /* x: set up for LEN */
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      LEN,      /* i: get length/literal/eob next */
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      LENEXT,   /* i: getting length extra (have base) */
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      DIST,     /* i: get distance next */
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      DISTEXT,  /* i: getting distance extra */
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      COPY,     /* o: copying bytes in window, waiting for space */
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      LIT,      /* o: got literal, waiting for output space */
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      WASH,     /* o: got eob, possibly still output waiting */
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      END,      /* x: got eob and all data flushed */
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      BADCODE}  /* x: got error */
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inflate_codes_mode;
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/* inflate codes private state */
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struct inflate_codes_state {
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  /* mode */
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  inflate_codes_mode mode;      /* current inflate_codes mode */
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  /* mode dependent information */
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  uInt len;
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  union {
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    struct {
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      inflate_huft *tree;       /* pointer into tree */
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      uInt need;                /* bits needed */
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    } code;             /* if LEN or DIST, where in tree */
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    uInt lit;           /* if LIT, literal */
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    struct {
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      uInt get;                 /* bits to get for extra */
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      uInt dist;                /* distance back to copy from */
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    } copy;             /* if EXT or COPY, where and how much */
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  } sub;                /* submode */
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  /* mode independent information */
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  Byte lbits;           /* ltree bits decoded per branch */
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  Byte dbits;           /* dtree bits decoder per branch */
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  inflate_huft *ltree;          /* literal/length/eob tree */
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  inflate_huft *dtree;          /* distance tree */
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};
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inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
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uInt bl, bd;
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inflate_huft *tl;
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inflate_huft *td; /* need separate declaration for Borland C++ */
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z_streamp z;
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{
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  inflate_codes_statef *c;
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  if ((c = (inflate_codes_statef *)
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       ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
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  {
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    c->mode = START;
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    c->lbits = (Byte)bl;
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    c->dbits = (Byte)bd;
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    c->ltree = tl;
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    c->dtree = td;
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    Tracev((stderr, "inflate:       codes new\n"));
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  }
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  return c;
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}
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int inflate_codes(s, z, r)
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inflate_blocks_statef *s;
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z_streamp z;
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int r;
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{
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  uInt j;               /* temporary storage */
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  inflate_huft *t;      /* temporary pointer */
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  uInt e;               /* extra bits or operation */
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  uLong b;              /* bit buffer */
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  uInt k;               /* bits in bit buffer */
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  Bytef *p;             /* input data pointer */
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  uInt n;               /* bytes available there */
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  Bytef *q;             /* output window write pointer */
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  uInt m;               /* bytes to end of window or read pointer */
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  Bytef *f;             /* pointer to copy strings from */
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  inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
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  /* copy input/output information to locals (UPDATE macro restores) */
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  LOAD
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  /* process input and output based on current state */
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  while (1) switch (c->mode)
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  {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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    case START:         /* x: set up for LEN */
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#ifndef SLOW
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      if (m >= 258 && n >= 10)
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      {
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        UPDATE
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        r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
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        LOAD
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        if (r != Z_OK)
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        {
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          c->mode = r == Z_STREAM_END ? WASH : BADCODE;
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          break;
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        }
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      }
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#endif /* !SLOW */
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      c->sub.code.need = c->lbits;
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      c->sub.code.tree = c->ltree;
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      c->mode = LEN;
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    case LEN:           /* i: get length/literal/eob next */
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      j = c->sub.code.need;
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      NEEDBITS(j)
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      t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
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      DUMPBITS(t->bits)
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      e = (uInt)(t->exop);
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      if (e == 0)               /* literal */
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      {
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        c->sub.lit = t->base;
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        Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
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                 "inflate:         literal '%c'\n" :
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                 "inflate:         literal 0x%02x\n", t->base));
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        c->mode = LIT;
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        break;
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      }
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      if (e & 16)               /* length */
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      {
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        c->sub.copy.get = e & 15;
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        c->len = t->base;
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        c->mode = LENEXT;
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        break;
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      }
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      if ((e & 64) == 0)        /* next table */
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      {
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        c->sub.code.need = e;
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        c->sub.code.tree = t + t->base;
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        break;
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      }
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      if (e & 32)               /* end of block */
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      {
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        Tracevv((stderr, "inflate:         end of block\n"));
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        c->mode = WASH;
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        break;
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      }
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      c->mode = BADCODE;        /* invalid code */
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      z->msg = (char*)"invalid literal/length code";
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      r = Z_DATA_ERROR;
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      LEAVE
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    case LENEXT:        /* i: getting length extra (have base) */
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      j = c->sub.copy.get;
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      NEEDBITS(j)
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      c->len += (uInt)b & inflate_mask[j];
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      DUMPBITS(j)
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      c->sub.code.need = c->dbits;
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      c->sub.code.tree = c->dtree;
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      Tracevv((stderr, "inflate:         length %u\n", c->len));
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      c->mode = DIST;
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    case DIST:          /* i: get distance next */
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      j = c->sub.code.need;
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      NEEDBITS(j)
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      t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
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      DUMPBITS(t->bits)
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      e = (uInt)(t->exop);
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      if (e & 16)               /* distance */
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      {
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        c->sub.copy.get = e & 15;
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        c->sub.copy.dist = t->base;
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        c->mode = DISTEXT;
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        break;
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      }
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      if ((e & 64) == 0)        /* next table */
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      {
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        c->sub.code.need = e;
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        c->sub.code.tree = t + t->base;
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        break;
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      }
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      c->mode = BADCODE;        /* invalid code */
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      z->msg = (char*)"invalid distance code";
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      r = Z_DATA_ERROR;
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      LEAVE
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    case DISTEXT:       /* i: getting distance extra */
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      j = c->sub.copy.get;
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      NEEDBITS(j)
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      c->sub.copy.dist += (uInt)b & inflate_mask[j];
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      DUMPBITS(j)
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      Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
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      c->mode = COPY;
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    case COPY:          /* o: copying bytes in window, waiting for space */
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      f = q - c->sub.copy.dist;
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      while (f < s->window)             /* modulo window size-"while" instead */
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        f += s->end - s->window;        /* of "if" handles invalid distances */
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      while (c->len)
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      {
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        NEEDOUT
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        OUTBYTE(*f++)
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        if (f == s->end)
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          f = s->window;
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        c->len--;
209
      }
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      c->mode = START;
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      break;
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    case LIT:           /* o: got literal, waiting for output space */
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      NEEDOUT
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      OUTBYTE(c->sub.lit)
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      c->mode = START;
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      break;
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    case WASH:          /* o: got eob, possibly more output */
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      if (k > 7)        /* return unused byte, if any */
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      {
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        Assert(k < 16, "inflate_codes grabbed too many bytes")
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        k -= 8;
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        n++;
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        p--;            /* can always return one */
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      }
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      FLUSH
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      if (s->read != s->write)
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        LEAVE
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      c->mode = END;
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    case END:
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      r = Z_STREAM_END;
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      LEAVE
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    case BADCODE:       /* x: got error */
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      r = Z_DATA_ERROR;
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      LEAVE
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    default:
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      r = Z_STREAM_ERROR;
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      LEAVE
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  }
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#ifdef NEED_DUMMY_RETURN
240
  return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
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#endif
242
}
243
 
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void inflate_codes_free(c, z)
246
inflate_codes_statef *c;
247
z_streamp z;
248
{
249
  ZFREE(z, c);
250
  Tracev((stderr, "inflate:       codes free\n"));
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}