Geant4 11.4.0
Toolkit for the simulation of the passage of particles through matter
Loading...
Searching...
No Matches
inffast.c File Reference
#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"

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.

50 {
51 struct inflate_state FAR *state;
52 z_const unsigned char FAR *in; /* local strm->next_in */
53 z_const unsigned char FAR *last; /* have enough input while in < last */
54 unsigned char FAR *out; /* local strm->next_out */
55 unsigned char FAR *beg; /* inflate()'s initial strm->next_out */
56 unsigned char FAR *end; /* while out < end, enough space available */
57#ifdef INFLATE_STRICT
58 unsigned dmax; /* maximum distance from zlib header */
59#endif
60 unsigned wsize; /* window size or zero if not using window */
61 unsigned whave; /* valid bytes in the window */
62 unsigned wnext; /* window write index */
63 unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */
64 unsigned long hold; /* local strm->hold */
65 unsigned bits; /* local strm->bits */
66 code const FAR *lcode; /* local strm->lencode */
67 code const FAR *dcode; /* local strm->distcode */
68 unsigned lmask; /* mask for first level of length codes */
69 unsigned dmask; /* mask for first level of distance codes */
70 code const *here; /* retrieved table entry */
71 unsigned op; /* code bits, operation, extra bits, or */
72 /* window position, window bytes to copy */
73 unsigned len; /* match length, unused bytes */
74 unsigned dist; /* match distance */
75 unsigned char FAR *from; /* where to copy match from */
76
77 /* copy state to local variables */
78 state = (struct inflate_state FAR *)strm->state;
79 in = strm->next_in;
80 last = in + (strm->avail_in - 5);
81 out = strm->next_out;
82 beg = out - (start - strm->avail_out);
83 end = out + (strm->avail_out - 257);
84#ifdef INFLATE_STRICT
85 dmax = state->dmax;
86#endif
87 wsize = state->wsize;
88 whave = state->whave;
89 wnext = state->wnext;
90 window = state->window;
91 hold = state->hold;
92 bits = state->bits;
93 lcode = state->lencode;
94 dcode = state->distcode;
95 lmask = (1U << state->lenbits) - 1;
96 dmask = (1U << state->distbits) - 1;
97
98 /* decode literals and length/distances until end-of-block or not enough
99 input data or output space */
100 do {
101 if (bits < 15) {
102 hold += (unsigned long)(*in++) << bits;
103 bits += 8;
104 hold += (unsigned long)(*in++) << bits;
105 bits += 8;
106 }
107 here = lcode + (hold & lmask);
108 dolen:
109 op = (unsigned)(here->bits);
110 hold >>= op;
111 bits -= op;
112 op = (unsigned)(here->op);
113 if (op == 0) { /* literal */
114 Tracevv((stderr, here->val >= 0x20 && here->val < 0x7f ?
115 "inflate: literal '%c'\n" :
116 "inflate: literal 0x%02x\n", here->val));
117 *out++ = (unsigned char)(here->val);
118 }
119 else if (op & 16) { /* length base */
120 len = (unsigned)(here->val);
121 op &= 15; /* number of extra bits */
122 if (op) {
123 if (bits < op) {
124 hold += (unsigned long)(*in++) << bits;
125 bits += 8;
126 }
127 len += (unsigned)hold & ((1U << op) - 1);
128 hold >>= op;
129 bits -= op;
130 }
131 Tracevv((stderr, "inflate: length %u\n", len));
132 if (bits < 15) {
133 hold += (unsigned long)(*in++) << bits;
134 bits += 8;
135 hold += (unsigned long)(*in++) << bits;
136 bits += 8;
137 }
138 here = dcode + (hold & dmask);
139 dodist:
140 op = (unsigned)(here->bits);
141 hold >>= op;
142 bits -= op;
143 op = (unsigned)(here->op);
144 if (op & 16) { /* distance base */
145 dist = (unsigned)(here->val);
146 op &= 15; /* number of extra bits */
147 if (bits < op) {
148 hold += (unsigned long)(*in++) << bits;
149 bits += 8;
150 if (bits < op) {
151 hold += (unsigned long)(*in++) << bits;
152 bits += 8;
153 }
154 }
155 dist += (unsigned)hold & ((1U << op) - 1);
156#ifdef INFLATE_STRICT
157 if (dist > dmax) {
158 strm->msg = (char *)"invalid distance too far back";
159 state->mode = BAD;
160 break;
161 }
162#endif
163 hold >>= op;
164 bits -= op;
165 Tracevv((stderr, "inflate: distance %u\n", dist));
166 op = (unsigned)(out - beg); /* max distance in output */
167 if (dist > op) { /* see if copy from window */
168 op = dist - op; /* distance back in window */
169 if (op > whave) {
170 if (state->sane) {
171 strm->msg =
172 (char *)"invalid distance too far back";
173 state->mode = BAD;
174 break;
175 }
176#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
177 if (len <= op - whave) {
178 do {
179 *out++ = 0;
180 } while (--len);
181 continue;
182 }
183 len -= op - whave;
184 do {
185 *out++ = 0;
186 } while (--op > whave);
187 if (op == 0) {
188 from = out - dist;
189 do {
190 *out++ = *from++;
191 } while (--len);
192 continue;
193 }
194#endif
195 }
196 from = window;
197 if (wnext == 0) { /* very common case */
198 from += wsize - op;
199 if (op < len) { /* some from window */
200 len -= op;
201 do {
202 *out++ = *from++;
203 } while (--op);
204 from = out - dist; /* rest from output */
205 }
206 }
207 else if (wnext < op) { /* wrap around window */
208 from += wsize + wnext - op;
209 op -= wnext;
210 if (op < len) { /* some from end of window */
211 len -= op;
212 do {
213 *out++ = *from++;
214 } while (--op);
215 from = window;
216 if (wnext < len) { /* some from start of window */
217 op = wnext;
218 len -= op;
219 do {
220 *out++ = *from++;
221 } while (--op);
222 from = out - dist; /* rest from output */
223 }
224 }
225 }
226 else { /* contiguous in window */
227 from += wnext - op;
228 if (op < len) { /* some from window */
229 len -= op;
230 do {
231 *out++ = *from++;
232 } while (--op);
233 from = out - dist; /* rest from output */
234 }
235 }
236 while (len > 2) {
237 *out++ = *from++;
238 *out++ = *from++;
239 *out++ = *from++;
240 len -= 3;
241 }
242 if (len) {
243 *out++ = *from++;
244 if (len > 1)
245 *out++ = *from++;
246 }
247 }
248 else {
249 from = out - dist; /* copy direct from output */
250 do { /* minimum length is three */
251 *out++ = *from++;
252 *out++ = *from++;
253 *out++ = *from++;
254 len -= 3;
255 } while (len > 2);
256 if (len) {
257 *out++ = *from++;
258 if (len > 1)
259 *out++ = *from++;
260 }
261 }
262 }
263 else if ((op & 64) == 0) { /* 2nd level distance code */
264 here = dcode + here->val + (hold & ((1U << op) - 1));
265 goto dodist;
266 }
267 else {
268 strm->msg = (char *)"invalid distance code";
269 state->mode = BAD;
270 break;
271 }
272 }
273 else if ((op & 64) == 0) { /* 2nd level length code */
274 here = lcode + here->val + (hold & ((1U << op) - 1));
275 goto dolen;
276 }
277 else if (op & 32) { /* end-of-block */
278 Tracevv((stderr, "inflate: end of block\n"));
279 state->mode = TYPE;
280 break;
281 }
282 else {
283 strm->msg = (char *)"invalid literal/length code";
284 state->mode = BAD;
285 break;
286 }
287 } while (in < last && out < end);
288
289 /* return unused bytes (on entry, bits < 8, so in won't go too far back) */
290 len = bits >> 3;
291 in -= len;
292 bits -= len << 3;
293 hold &= (1U << bits) - 1;
294
295 /* update state and return */
296 strm->next_in = in;
297 strm->next_out = out;
298 strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
299 strm->avail_out = (unsigned)(out < end ?
300 257 + (end - out) : 257 - (out - end));
301 state->hold = hold;
302 state->bits = bits;
303 return;
304}
TYPE
@ TYPE
Definition inflate.h:32
BAD
@ BAD
Definition inflate.h:50
inflate_state
Definition inflate.h:82
inflate_state::wnext
unsigned wnext
Definition inflate.h:99
inflate_state::hold
unsigned long hold
Definition inflate.h:102
inflate_state::strm
z_streamp strm
Definition inflate.h:83
inflate_state::whave
unsigned whave
Definition inflate.h:98
inflate_state::window
unsigned char FAR * window
Definition inflate.h:100
inflate_state::bits
unsigned bits
Definition inflate.h:103
inflate_state::last
int last
Definition inflate.h:85
inflate_state::wsize
unsigned wsize
Definition inflate.h:97
inflate_state::dmax
unsigned dmax
Definition inflate.h:91
Tracevv
#define Tracevv(x)
Definition zutil.h:230

Referenced by inflate(), and inflateBack().