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Functions
inffast.c File Reference
#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"
Include dependency graph for inffast.c:

Go to the source code of this file.

Functions

void ZLIB_INTERNAL inflate_fast (z_streamp strm, unsigned start)
 

Function Documentation

◆ inflate_fast()

void ZLIB_INTERNAL inflate_fast ( z_streamp  strm,
unsigned  start 
)

Definition at line 50 of file inffast.c.

53 {
54  struct inflate_state FAR *state;
55  z_const unsigned char FAR *in; /* local strm->next_in */
56  z_const unsigned char FAR *last; /* have enough input while in < last */
57  unsigned char FAR *out; /* local strm->next_out */
58  unsigned char FAR *beg; /* inflate()'s initial strm->next_out */
59  unsigned char FAR *end; /* while out < end, enough space available */
60 #ifdef INFLATE_STRICT
61  unsigned dmax; /* maximum distance from zlib header */
62 #endif
63  unsigned wsize; /* window size or zero if not using window */
64  unsigned whave; /* valid bytes in the window */
65  unsigned wnext; /* window write index */
66  unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */
67  unsigned long hold; /* local strm->hold */
68  unsigned bits; /* local strm->bits */
69  code const FAR *lcode; /* local strm->lencode */
70  code const FAR *dcode; /* local strm->distcode */
71  unsigned lmask; /* mask for first level of length codes */
72  unsigned dmask; /* mask for first level of distance codes */
73  code here; /* retrieved table entry */
74  unsigned op; /* code bits, operation, extra bits, or */
75  /* window position, window bytes to copy */
76  unsigned len; /* match length, unused bytes */
77  unsigned dist; /* match distance */
78  unsigned char FAR *from; /* where to copy match from */
79 
80  /* copy state to local variables */
81  state = (struct inflate_state FAR *)strm->state;
82  in = strm->next_in;
83  last = in + (strm->avail_in - 5);
84  out = strm->next_out;
85  beg = out - (start - strm->avail_out);
86  end = out + (strm->avail_out - 257);
87 #ifdef INFLATE_STRICT
88  dmax = state->dmax;
89 #endif
90  wsize = state->wsize;
91  whave = state->whave;
92  wnext = state->wnext;
93  window = state->window;
94  hold = state->hold;
95  bits = state->bits;
96  lcode = state->lencode;
97  dcode = state->distcode;
98  lmask = (1U << state->lenbits) - 1;
99  dmask = (1U << state->distbits) - 1;
100 
101  /* decode literals and length/distances until end-of-block or not enough
102  input data or output space */
103  do {
104  if (bits < 15) {
105  hold += (unsigned long)(*in++) << bits;
106  bits += 8;
107  hold += (unsigned long)(*in++) << bits;
108  bits += 8;
109  }
110  here = lcode[hold & lmask];
111  dolen:
112  op = (unsigned)(here.bits);
113  hold >>= op;
114  bits -= op;
115  op = (unsigned)(here.op);
116  if (op == 0) { /* literal */
117  Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
118  "inflate: literal '%c'\n" :
119  "inflate: literal 0x%02x\n", here.val));
120  *out++ = (unsigned char)(here.val);
121  }
122  else if (op & 16) { /* length base */
123  len = (unsigned)(here.val);
124  op &= 15; /* number of extra bits */
125  if (op) {
126  if (bits < op) {
127  hold += (unsigned long)(*in++) << bits;
128  bits += 8;
129  }
130  len += (unsigned)hold & ((1U << op) - 1);
131  hold >>= op;
132  bits -= op;
133  }
134  Tracevv((stderr, "inflate: length %u\n", len));
135  if (bits < 15) {
136  hold += (unsigned long)(*in++) << bits;
137  bits += 8;
138  hold += (unsigned long)(*in++) << bits;
139  bits += 8;
140  }
141  here = dcode[hold & dmask];
142  dodist:
143  op = (unsigned)(here.bits);
144  hold >>= op;
145  bits -= op;
146  op = (unsigned)(here.op);
147  if (op & 16) { /* distance base */
148  dist = (unsigned)(here.val);
149  op &= 15; /* number of extra bits */
150  if (bits < op) {
151  hold += (unsigned long)(*in++) << bits;
152  bits += 8;
153  if (bits < op) {
154  hold += (unsigned long)(*in++) << bits;
155  bits += 8;
156  }
157  }
158  dist += (unsigned)hold & ((1U << op) - 1);
159 #ifdef INFLATE_STRICT
160  if (dist > dmax) {
161  strm->msg = (char *)"invalid distance too far back";
162  state->mode = BAD;
163  break;
164  }
165 #endif
166  hold >>= op;
167  bits -= op;
168  Tracevv((stderr, "inflate: distance %u\n", dist));
169  op = (unsigned)(out - beg); /* max distance in output */
170  if (dist > op) { /* see if copy from window */
171  op = dist - op; /* distance back in window */
172  if (op > whave) {
173  if (state->sane) {
174  strm->msg =
175  (char *)"invalid distance too far back";
176  state->mode = BAD;
177  break;
178  }
179 #ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
180  if (len <= op - whave) {
181  do {
182  *out++ = 0;
183  } while (--len);
184  continue;
185  }
186  len -= op - whave;
187  do {
188  *out++ = 0;
189  } while (--op > whave);
190  if (op == 0) {
191  from = out - dist;
192  do {
193  *out++ = *from++;
194  } while (--len);
195  continue;
196  }
197 #endif
198  }
199  from = window;
200  if (wnext == 0) { /* very common case */
201  from += wsize - op;
202  if (op < len) { /* some from window */
203  len -= op;
204  do {
205  *out++ = *from++;
206  } while (--op);
207  from = out - dist; /* rest from output */
208  }
209  }
210  else if (wnext < op) { /* wrap around window */
211  from += wsize + wnext - op;
212  op -= wnext;
213  if (op < len) { /* some from end of window */
214  len -= op;
215  do {
216  *out++ = *from++;
217  } while (--op);
218  from = window;
219  if (wnext < len) { /* some from start of window */
220  op = wnext;
221  len -= op;
222  do {
223  *out++ = *from++;
224  } while (--op);
225  from = out - dist; /* rest from output */
226  }
227  }
228  }
229  else { /* contiguous in window */
230  from += wnext - op;
231  if (op < len) { /* some from window */
232  len -= op;
233  do {
234  *out++ = *from++;
235  } while (--op);
236  from = out - dist; /* rest from output */
237  }
238  }
239  while (len > 2) {
240  *out++ = *from++;
241  *out++ = *from++;
242  *out++ = *from++;
243  len -= 3;
244  }
245  if (len) {
246  *out++ = *from++;
247  if (len > 1)
248  *out++ = *from++;
249  }
250  }
251  else {
252  from = out - dist; /* copy direct from output */
253  do { /* minimum length is three */
254  *out++ = *from++;
255  *out++ = *from++;
256  *out++ = *from++;
257  len -= 3;
258  } while (len > 2);
259  if (len) {
260  *out++ = *from++;
261  if (len > 1)
262  *out++ = *from++;
263  }
264  }
265  }
266  else if ((op & 64) == 0) { /* 2nd level distance code */
267  here = dcode[here.val + (hold & ((1U << op) - 1))];
268  goto dodist;
269  }
270  else {
271  strm->msg = (char *)"invalid distance code";
272  state->mode = BAD;
273  break;
274  }
275  }
276  else if ((op & 64) == 0) { /* 2nd level length code */
277  here = lcode[here.val + (hold & ((1U << op) - 1))];
278  goto dolen;
279  }
280  else if (op & 32) { /* end-of-block */
281  Tracevv((stderr, "inflate: end of block\n"));
282  state->mode = TYPE;
283  break;
284  }
285  else {
286  strm->msg = (char *)"invalid literal/length code";
287  state->mode = BAD;
288  break;
289  }
290  } while (in < last && out < end);
291 
292  /* return unused bytes (on entry, bits < 8, so in won't go too far back) */
293  len = bits >> 3;
294  in -= len;
295  bits -= len << 3;
296  hold &= (1U << bits) - 1;
297 
298  /* update state and return */
299  strm->next_in = in;
300  strm->next_out = out;
301  strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
302  strm->avail_out = (unsigned)(out < end ?
303  257 + (end - out) : 257 - (out - end));
304  state->hold = hold;
305  state->bits = bits;
306  return;
307 }
code::val
unsigned short val
Definition: inftrees.h:27
inflate_state
Definition: inflate.h:82
last
POINT last
Definition: font.c:46
inflate_state::wnext
unsigned wnext
Definition: inflate.h:98
U
#define U(x)
Definition: wordpad.c:44
inflate_state::strm
z_streamp strm
Definition: inflate.h:83
inflate_state::wsize
unsigned wsize
Definition: inflate.h:96
end
GLuint GLuint end
Definition: gl.h:1545
bits
GLenum GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * bits
Definition: glext.h:10929
code::op
unsigned char op
Definition: inftrees.h:25
z_const
#define z_const
Definition: zconf.h:237
FAR
#define FAR
Definition: guiddef.h:36
char
unsigned char
Definition: typeof.h:29
BAD
#define BAD
Definition: inflate.c:10
inflate_state::hold
unsigned long hold
Definition: inflate.h:101
Tracevv
#define Tracevv(x)
Definition: zutil.h:199
out
static FILE * out
Definition: regtests2xml.c:44
code::bits
unsigned char bits
Definition: inftrees.h:26
state
static int state
Definition: maze.c:121
len
GLenum GLsizei len
Definition: glext.h:6722
window
static IHTMLWindow2 * window
Definition: events.c:77
inflate_state::dmax
unsigned dmax
Definition: inflate.h:90
in
GLuint in
Definition: glext.h:9616
TYPE
TYPE
Definition: eventcreate.c:651
start
GLuint start
Definition: gl.h:1545
long
#define long
Definition: qsort.c:33
inflate_state::whave
unsigned whave
Definition: inflate.h:97
stderr
FILE * stderr
op
UINT op
Definition: effect.c:223
from
CardRegion * from
Definition: spigame.cpp:19

Referenced by inflate(), inflate_codes(), and inflateBack().