Geant4 11.2.2
Toolkit for the simulation of the passage of particles through matter
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Functions
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.

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 const *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}
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:255

Referenced by inflate(), and inflateBack().