/src/freetype/src/gzip/infcodes.c

  1/* infcodes.c -- process literals and length/distance pairs
  2 * Copyright (C) 1995-2002 Mark Adler
  3 * For conditions of distribution and use, see copyright notice in zlib.h
  4 */
  5
  6#include "zutil.h"
  7#include "inftrees.h"
  8#include "infblock.h"
  9#include "infcodes.h"
 10#include "infutil.h"
 11
 12/* simplify the use of the inflate_huft type with some defines */
 13#define exop word.what.Exop
 14#define bits word.what.Bits
 15
 16typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
 17      START,    /* x: set up for LEN */
 18      LEN,      /* i: get length/literal/eob next */
 19      LENEXT,   /* i: getting length extra (have base) */
 20      DIST,     /* i: get distance next */
 21      DISTEXT,  /* i: getting distance extra */
 22      COPY,     /* o: copying bytes in window, waiting for space */
 23      LIT,      /* o: got literal, waiting for output space */
 24      WASH,     /* o: got eob, possibly still output waiting */
 25      END,      /* x: got eob and all data flushed */
 26      BADCODE}  /* x: got error */
 27inflate_codes_mode;
 28
 29/* inflate codes private state */
 30struct inflate_codes_state {
 31
 32  /* mode */
 33  inflate_codes_mode mode;      /* current inflate_codes mode */
 34
 35  /* mode dependent information */
 36  uInt len;
 37  union {
 38    struct {
 39      inflate_huft *tree;       /* pointer into tree */
 40      uInt need;                /* bits needed */
 41    } code;             /* if LEN or DIST, where in tree */
 42    uInt lit;           /* if LIT, literal */
 43    struct {
 44      uInt get;                 /* bits to get for extra */
 45      uInt dist;                /* distance back to copy from */
 46    } copy;             /* if EXT or COPY, where and how much */
 47  } sub;                /* submode */
 48
 49  /* mode independent information */
 50  Byte lbits;           /* ltree bits decoded per branch */
 51  Byte dbits;           /* dtree bits decoder per branch */
 52  inflate_huft *ltree;          /* literal/length/eob tree */
 53  inflate_huft *dtree;          /* distance tree */
 54
 55};
 56
 57
 58local inflate_codes_statef *inflate_codes_new( /* bl, bd, tl, td, z) */
 59uInt bl, uInt bd,
 60inflate_huft *tl,
 61inflate_huft *td, /* need separate declaration for Borland C++ */
 62z_streamp z )
 63{
 64  inflate_codes_statef *c;
 65
 66  if ((c = (inflate_codes_statef *)
 67       ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
 68  {
 69    c->mode = START;
 70    c->lbits = (Byte)bl;
 71    c->dbits = (Byte)bd;
 72    c->ltree = tl;
 73    c->dtree = td;
 74    Tracev((stderr, "inflate:       codes new\n"));
 75  }
 76  return c;
 77}
 78
 79
 80local int inflate_codes( /* s, z, r) */
 81inflate_blocks_statef *s,
 82z_streamp z,
 83int r )
 84{
 85  uInt j;               /* temporary storage */
 86  inflate_huft *t;      /* temporary pointer */
 87  uInt e;               /* extra bits or operation */
 88  uLong b;              /* bit buffer */
 89  uInt k;               /* bits in bit buffer */
 90  Bytef *p;             /* input data pointer */
 91  uInt n;               /* bytes available there */
 92  Bytef *q;             /* output window write pointer */
 93  uInt m;               /* bytes to end of window or read pointer */
 94  Bytef *f;             /* pointer to copy strings from */
 95  inflate_codes_statef *c = s->sub.decode.codes;  /* codes state */
 96
 97  /* copy input/output information to locals (UPDATE macro restores) */
 98  LOAD
 99
100  /* process input and output based on current state */
101  while (1) switch (c->mode)
102  {             /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
103    case START:         /* x: set up for LEN */
104#ifndef SLOW
105      if (m >= 258 && n >= 10)
106      {
107        UPDATE
108        r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
109        LOAD
110        if (r != Z_OK)
111        {
112          c->mode = r == Z_STREAM_END ? WASH : BADCODE;
113          break;
114        }
115      }
116#endif /* !SLOW */
117      c->sub.code.need = c->lbits;
118      c->sub.code.tree = c->ltree;
119      c->mode = LEN;
120    case LEN:           /* i: get length/literal/eob next */
121      j = c->sub.code.need;
122      NEEDBITS(j)
123      t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
124      DUMPBITS(t->bits)
125      e = (uInt)(t->exop);
126      if (e == 0)               /* literal */
127      {
128        c->sub.lit = t->base;
129        Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
130                 "inflate:         literal '%c'\n" :
131                 "inflate:         literal 0x%02x\n", t->base));
132        c->mode = LIT;
133        break;
134      }
135      if (e & 16)               /* length */
136      {
137        c->sub.copy.get = e & 15;
138        c->len = t->base;
139        c->mode = LENEXT;
140        break;
141      }
142      if ((e & 64) == 0)        /* next table */
143      {
144        c->sub.code.need = e;
145        c->sub.code.tree = t + t->base;
146        break;
147      }
148      if (e & 32)               /* end of block */
149      {
150        Tracevv((stderr, "inflate:         end of block\n"));
151        c->mode = WASH;
152        break;
153      }
154      c->mode = BADCODE;        /* invalid code */
155      z->msg = (char*)"invalid literal/length code";
156      r = Z_DATA_ERROR;
157      LEAVE
158    case LENEXT:        /* i: getting length extra (have base) */
159      j = c->sub.copy.get;
160      NEEDBITS(j)
161      c->len += (uInt)b & inflate_mask[j];
162      DUMPBITS(j)
163      c->sub.code.need = c->dbits;
164      c->sub.code.tree = c->dtree;
165      Tracevv((stderr, "inflate:         length %u\n", c->len));
166      c->mode = DIST;
167    case DIST:          /* i: get distance next */
168      j = c->sub.code.need;
169      NEEDBITS(j)
170      t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
171      DUMPBITS(t->bits)
172      e = (uInt)(t->exop);
173      if (e & 16)               /* distance */
174      {
175        c->sub.copy.get = e & 15;
176        c->sub.copy.dist = t->base;
177        c->mode = DISTEXT;
178        break;
179      }
180      if ((e & 64) == 0)        /* next table */
181      {
182        c->sub.code.need = e;
183        c->sub.code.tree = t + t->base;
184        break;
185      }
186      c->mode = BADCODE;        /* invalid code */
187      z->msg = (char*)"invalid distance code";
188      r = Z_DATA_ERROR;
189      LEAVE
190    case DISTEXT:       /* i: getting distance extra */
191      j = c->sub.copy.get;
192      NEEDBITS(j)
193      c->sub.copy.dist += (uInt)b & inflate_mask[j];
194      DUMPBITS(j)
195      Tracevv((stderr, "inflate:         distance %u\n", c->sub.copy.dist));
196      c->mode = COPY;
197    case COPY:          /* o: copying bytes in window, waiting for space */
198      f = q - c->sub.copy.dist;
199      while (f < s->window)             /* modulo window size-"while" instead */
200        f += s->end - s->window;        /* of "if" handles invalid distances */
201      while (c->len)
202      {
203        NEEDOUT
204        OUTBYTE(*f++)
205        if (f == s->end)
206          f = s->window;
207        c->len--;
208      }
209      c->mode = START;
210      break;
211    case LIT:           /* o: got literal, waiting for output space */
212      NEEDOUT
213      OUTBYTE(c->sub.lit)
214      c->mode = START;
215      break;
216    case WASH:          /* o: got eob, possibly more output */
217      if (k > 7)        /* return unused byte, if any */
218      {
219        Assert(k < 16, "inflate_codes grabbed too many bytes")
220        k -= 8;
221        n++;
222        p--;            /* can always return one */
223      }
224      FLUSH
225      if (s->read != s->write)
226        LEAVE
227      c->mode = END;
228    case END:
229      r = Z_STREAM_END;
230      LEAVE
231    case BADCODE:       /* x: got error */
232      r = Z_DATA_ERROR;
233      LEAVE
234    default:
235      r = Z_STREAM_ERROR;
236      LEAVE
237  }
238#ifdef NEED_DUMMY_RETURN
239  return Z_STREAM_ERROR;  /* Some dumb compilers complain without this */
240#endif
241}
242
243
244local void inflate_codes_free( /* c, z) */
245inflate_codes_statef *c,
246z_streamp z )
247{
248  ZFREE(z, c);
249  Tracev((stderr, "inflate:       codes free\n"));
250}