/* infcodes.c -- process literals and length/distance pairs

 * Copyright (C) 1995-1998 Mark Adler

 * For conditions of distribution and use, see copyright notice in zlib.h 

 */

#include "zutil.h"

#include "inftrees.h"

#include "infblock.h"

#include "infcodes.h"

#include "infutil.h"

#include "inffast.h"

/* simplify the use of the inflate_huft type with some defines */

#define exop word.what.Exop

#define bits word.what.Bits

typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */

      START,    /* x: set up for LEN */

      LEN,      /* i: get length/literal/eob next */

      LENEXT,   /* i: getting length extra (have base) */

      DIST,     /* i: get distance next */

      DISTEXT,  /* i: getting distance extra */

      COPY,     /* o: copying bytes in window, waiting for space */

      LIT,      /* o: got literal, waiting for output space */

      WASH,     /* o: got eob, possibly still output waiting */

      END,      /* x: got eob and all data flushed */

      BADCODE}  /* x: got error */

inflate_codes_mode;

/* inflate codes private state */

struct inflate_codes_state {

  /* mode */

  inflate_codes_mode mode;      /* current inflate_codes mode */

  /* mode dependent information */

  uInt len;

  union {

    struct {

      inflate_huft *tree;       /* pointer into tree */

      uInt need;                /* bits needed */

    } code;             /* if LEN or DIST, where in tree */

    uInt lit;           /* if LIT, literal */

    struct {

      uInt get;                 /* bits to get for extra */

      uInt dist;                /* distance back to copy from */

    } copy;             /* if EXT or COPY, where and how much */

  } sub;                /* submode */

  /* mode independent information */

  Byte lbits;           /* ltree bits decoded per branch */

  Byte dbits;           /* dtree bits decoder per branch */

  inflate_huft *ltree;          /* literal/length/eob tree */

  inflate_huft *dtree;          /* distance tree */

};

inflate_codes_statef *inflate_codes_new(uInt bl, uInt bd, inflate_huft *tl, inflate_huft *td, z_streamp z)

/* inflate_huft *td        need separate declaration for Borland C++ */

{

  inflate_codes_statef *c;

  if ((c = (inflate_codes_statef *)

       ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)

  {

    c->mode = START;

    c->lbits = (Byte)bl;

    c->dbits = (Byte)bd;

    c->ltree = tl;

    c->dtree = td;

    Tracev((stderr, "inflate:       codes new\n"));

  }

  return c;

}

int inflate_codes(inflate_blocks_statef *s,z_streamp z, int r)

{

  uInt j;               /* temporary storage */

  inflate_huft *t;      /* temporary pointer */

  uInt e;               /* extra bits or operation */

  uLong b;              /* bit buffer */

  uInt k;               /* bits in bit buffer */

  Bytef *p;             /* input data pointer */

  uInt n;               /* bytes available there */

  Bytef *q;             /* output window write pointer */

  uInt m;               /* bytes to end of window or read pointer */

  Bytef *f;             /* pointer to copy strings from */

  inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */

  /* copy input/output information to locals (UPDATE macro restores) */

  LOAD

  /* process input and output based on current state */

  while (1) switch (c->mode)

  {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */

    case START:         /* x: set up for LEN */

#ifndef SLOW

      if (m >= 258 && n >= 10)

      {

        UPDATE

        r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);

        LOAD

        if (r != Z_OK)

        {

          c->mode = r == Z_STREAM_END ? WASH : BADCODE;

          break;

        }

      }

#endif /* !SLOW */

      c->sub.code.need = c->lbits;

      c->sub.code.tree = c->ltree;

      c->mode = LEN;

    case LEN:           /* i: get length/literal/eob next */

      j = c->sub.code.need;

      NEEDBITS(j)

      t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);

      DUMPBITS(t->bits)

      e = (uInt)(t->exop);

      if (e == 0)               /* literal */

      {

        c->sub.lit = t->base;

        Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?

                 "inflate:         literal '%c'\n" :

                 "inflate:         literal 0x%02x\n", t->base));

        c->mode = LIT;

        break;

      }

      if (e & 16)               /* length */

      {

        c->sub.copy.get = e & 15;

        c->len = t->base;

        c->mode = LENEXT;

        break;

      }

      if ((e & 64) == 0)        /* next table */

      {

        c->sub.code.need = e;

        c->sub.code.tree = t + t->base;

        break;

      }

      if (e & 32)               /* end of block */

      {

        Tracevv((stderr, "inflate:         end of block\n"));

        c->mode = WASH;

        break;

      }

      c->mode = BADCODE;        /* invalid code */

      z->msg = (char*)"invalid literal/length code";

      r = Z_DATA_ERROR;

      LEAVE

    case LENEXT:        /* i: getting length extra (have base) */

      j = c->sub.copy.get;

      NEEDBITS(j)

      c->len += (uInt)b & inflate_mask[j];

      DUMPBITS(j)

      c->sub.code.need = c->dbits;

      c->sub.code.tree = c->dtree;

      Tracevv((stderr, "inflate:         length %u\n", c->len));

      c->mode = DIST;

    case DIST:          /* i: get distance next */

      j = c->sub.code.need;

      NEEDBITS(j)

      t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);

      DUMPBITS(t->bits)

      e = (uInt)(t->exop);

      if (e & 16)               /* distance */

      {

        c->sub.copy.get = e & 15;

        c->sub.copy.dist = t->base;

        c->mode = DISTEXT;

        break;

      }

      if ((e & 64) == 0)        /* next table */

      {

        c->sub.code.need = e;

        c->sub.code.tree = t + t->base;

        break;

      }

      c->mode = BADCODE;        /* invalid code */

      z->msg = (char*)"invalid distance code";

      r = Z_DATA_ERROR;

      LEAVE

    case DISTEXT:       /* i: getting distance extra */

      j = c->sub.copy.get;

      NEEDBITS(j)

      c->sub.copy.dist += (uInt)b & inflate_mask[j];

      DUMPBITS(j)

      Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));

      c->mode = COPY;

    case COPY:          /* o: copying bytes in window, waiting for space */

#ifndef __TURBOC__ /* Turbo C bug for following expression */

      f = (uInt)(q - s->window) < c->sub.copy.dist ?

          s->end - (c->sub.copy.dist - (q - s->window)) :

          q - c->sub.copy.dist;

#else

      f = q - c->sub.copy.dist;

      if ((uInt)(q - s->window) < c->sub.copy.dist)

        f = s->end - (c->sub.copy.dist - (uInt)(q - s->window));

#endif

      while (c->len)

      {

        NEEDOUT

        OUTBYTE(*f++)

        if (f == s->end)

          f = s->window;

        c->len--;

      }

      c->mode = START;

      break;

    case LIT:           /* o: got literal, waiting for output space */

      NEEDOUT

      OUTBYTE(c->sub.lit)

      c->mode = START;

      break;

    case WASH:          /* o: got eob, possibly more output */

      if (k > 7)        /* return unused byte, if any */

      {

        Assert(k < 16, "inflate_codes grabbed too many bytes")

        k -= 8;

        n++;

        p--;            /* can always return one */

      }

      FLUSH

      if (s->read != s->write)

        LEAVE

      c->mode = END;

    case END:

      r = Z_STREAM_END;

      LEAVE

    case BADCODE:       /* x: got error */

      r = Z_DATA_ERROR;

      LEAVE

    default:

      r = Z_STREAM_ERROR;

      LEAVE

  }

#ifdef NEED_DUMMY_RETURN

  return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */

#endif

}

void inflate_codes_free(inflate_codes_statef *c, z_streamp z)

{

  ZFREE(z, c);

  Tracev((stderr, "inflate:       codes free\n"));

}