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Mike Frysingere89516f2011-04-08 12:23:30 +00001/* inffast.c -- fast decoding
2 * Copyright (C) 1995-2004 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6/* U-boot: we already included these
7#include "zutil.h"
8#include "inftrees.h"
9#include "inflate.h"
10#include "inffast.h"
11*/
12
13#ifndef ASMINF
14
15/* Allow machine dependent optimization for post-increment or pre-increment.
16 Based on testing to date,
17 Pre-increment preferred for:
18 - PowerPC G3 (Adler)
19 - MIPS R5000 (Randers-Pehrson)
20 Post-increment preferred for:
21 - none
22 No measurable difference:
23 - Pentium III (Anderson)
24 - M68060 (Nikl)
25 */
26#ifdef POSTINC
27# define OFF 0
28# define PUP(a) *(a)++
29#else
30# define OFF 1
31# define PUP(a) *++(a)
32#endif
33
34/*
35 Decode literal, length, and distance codes and write out the resulting
36 literal and match bytes until either not enough input or output is
37 available, an end-of-block is encountered, or a data error is encountered.
38 When large enough input and output buffers are supplied to inflate(), for
39 example, a 16K input buffer and a 64K output buffer, more than 95% of the
40 inflate execution time is spent in this routine.
41
42 Entry assumptions:
43
44 state->mode == LEN
45 strm->avail_in >= 6
46 strm->avail_out >= 258
47 start >= strm->avail_out
48 state->bits < 8
49
50 On return, state->mode is one of:
51
52 LEN -- ran out of enough output space or enough available input
53 TYPE -- reached end of block code, inflate() to interpret next block
54 BAD -- error in block data
55
56 Notes:
57
58 - The maximum input bits used by a length/distance pair is 15 bits for the
59 length code, 5 bits for the length extra, 15 bits for the distance code,
60 and 13 bits for the distance extra. This totals 48 bits, or six bytes.
61 Therefore if strm->avail_in >= 6, then there is enough input to avoid
62 checking for available input while decoding.
63
64 - The maximum bytes that a single length/distance pair can output is 258
65 bytes, which is the maximum length that can be coded. inflate_fast()
66 requires strm->avail_out >= 258 for each loop to avoid checking for
67 output space.
68 */
69void inflate_fast(strm, start)
70z_streamp strm;
71unsigned start; /* inflate()'s starting value for strm->avail_out */
72{
73 struct inflate_state FAR *state;
74 unsigned char FAR *in; /* local strm->next_in */
75 unsigned char FAR *last; /* while in < last, enough input available */
76 unsigned char FAR *out; /* local strm->next_out */
77 unsigned char FAR *beg; /* inflate()'s initial strm->next_out */
78 unsigned char FAR *end; /* while out < end, enough space available */
79#ifdef INFLATE_STRICT
80 unsigned dmax; /* maximum distance from zlib header */
81#endif
82 unsigned wsize; /* window size or zero if not using window */
83 unsigned whave; /* valid bytes in the window */
84 unsigned write; /* window write index */
85 unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */
86 unsigned long hold; /* local strm->hold */
87 unsigned bits; /* local strm->bits */
88 code const FAR *lcode; /* local strm->lencode */
89 code const FAR *dcode; /* local strm->distcode */
90 unsigned lmask; /* mask for first level of length codes */
91 unsigned dmask; /* mask for first level of distance codes */
92 code this; /* retrieved table entry */
93 unsigned op; /* code bits, operation, extra bits, or */
94 /* window position, window bytes to copy */
95 unsigned len; /* match length, unused bytes */
96 unsigned dist; /* match distance */
97 unsigned char FAR *from; /* where to copy match from */
98
99 /* copy state to local variables */
100 state = (struct inflate_state FAR *)strm->state;
101 in = strm->next_in - OFF;
102 last = in + (strm->avail_in - 5);
Anatolij Gustschin92faa8b2011-10-15 06:32:52 +0000103 if (in > last && strm->avail_in > 5) {
104 /*
105 * overflow detected, limit strm->avail_in to the
106 * max. possible size and recalculate last
107 */
108 strm->avail_in = 0xffffffff - (unsigned int)in;
109 last = in + (strm->avail_in - 5);
110 }
Mike Frysingere89516f2011-04-08 12:23:30 +0000111 out = strm->next_out - OFF;
112 beg = out - (start - strm->avail_out);
113 end = out + (strm->avail_out - 257);
114#ifdef INFLATE_STRICT
115 dmax = state->dmax;
116#endif
117 wsize = state->wsize;
118 whave = state->whave;
119 write = state->write;
120 window = state->window;
121 hold = state->hold;
122 bits = state->bits;
123 lcode = state->lencode;
124 dcode = state->distcode;
125 lmask = (1U << state->lenbits) - 1;
126 dmask = (1U << state->distbits) - 1;
127
128 /* decode literals and length/distances until end-of-block or not enough
129 input data or output space */
130 do {
131 if (bits < 15) {
132 hold += (unsigned long)(PUP(in)) << bits;
133 bits += 8;
134 hold += (unsigned long)(PUP(in)) << bits;
135 bits += 8;
136 }
137 this = lcode[hold & lmask];
138 dolen:
139 op = (unsigned)(this.bits);
140 hold >>= op;
141 bits -= op;
142 op = (unsigned)(this.op);
143 if (op == 0) { /* literal */
144 Tracevv((stderr, this.val >= 0x20 && this.val < 0x7f ?
145 "inflate: literal '%c'\n" :
146 "inflate: literal 0x%02x\n", this.val));
147 PUP(out) = (unsigned char)(this.val);
148 }
149 else if (op & 16) { /* length base */
150 len = (unsigned)(this.val);
151 op &= 15; /* number of extra bits */
152 if (op) {
153 if (bits < op) {
154 hold += (unsigned long)(PUP(in)) << bits;
155 bits += 8;
156 }
157 len += (unsigned)hold & ((1U << op) - 1);
158 hold >>= op;
159 bits -= op;
160 }
161 Tracevv((stderr, "inflate: length %u\n", len));
162 if (bits < 15) {
163 hold += (unsigned long)(PUP(in)) << bits;
164 bits += 8;
165 hold += (unsigned long)(PUP(in)) << bits;
166 bits += 8;
167 }
168 this = dcode[hold & dmask];
169 dodist:
170 op = (unsigned)(this.bits);
171 hold >>= op;
172 bits -= op;
173 op = (unsigned)(this.op);
174 if (op & 16) { /* distance base */
175 dist = (unsigned)(this.val);
176 op &= 15; /* number of extra bits */
177 if (bits < op) {
178 hold += (unsigned long)(PUP(in)) << bits;
179 bits += 8;
180 if (bits < op) {
181 hold += (unsigned long)(PUP(in)) << bits;
182 bits += 8;
183 }
184 }
185 dist += (unsigned)hold & ((1U << op) - 1);
186#ifdef INFLATE_STRICT
187 if (dist > dmax) {
188 strm->msg = (char *)"invalid distance too far back";
189 state->mode = BAD;
190 break;
191 }
192#endif
193 hold >>= op;
194 bits -= op;
195 Tracevv((stderr, "inflate: distance %u\n", dist));
196 op = (unsigned)(out - beg); /* max distance in output */
197 if (dist > op) { /* see if copy from window */
198 op = dist - op; /* distance back in window */
199 if (op > whave) {
200 strm->msg = (char *)"invalid distance too far back";
201 state->mode = BAD;
202 break;
203 }
204 from = window - OFF;
205 if (write == 0) { /* very common case */
206 from += wsize - op;
207 if (op < len) { /* some from window */
208 len -= op;
209 do {
210 PUP(out) = PUP(from);
211 } while (--op);
212 from = out - dist; /* rest from output */
213 }
214 }
215 else if (write < op) { /* wrap around window */
216 from += wsize + write - op;
217 op -= write;
218 if (op < len) { /* some from end of window */
219 len -= op;
220 do {
221 PUP(out) = PUP(from);
222 } while (--op);
223 from = window - OFF;
224 if (write < len) { /* some from start of window */
225 op = write;
226 len -= op;
227 do {
228 PUP(out) = PUP(from);
229 } while (--op);
230 from = out - dist; /* rest from output */
231 }
232 }
233 }
234 else { /* contiguous in window */
235 from += write - op;
236 if (op < len) { /* some from window */
237 len -= op;
238 do {
239 PUP(out) = PUP(from);
240 } while (--op);
241 from = out - dist; /* rest from output */
242 }
243 }
244 while (len > 2) {
245 PUP(out) = PUP(from);
246 PUP(out) = PUP(from);
247 PUP(out) = PUP(from);
248 len -= 3;
249 }
250 if (len) {
251 PUP(out) = PUP(from);
252 if (len > 1)
253 PUP(out) = PUP(from);
254 }
255 }
256 else {
257 unsigned short *sout;
258 unsigned long loops;
259
260 from = out - dist; /* copy direct from output */
261 /* minimum length is three */
262 /* Align out addr */
263 if (!((long)(out - 1 + OFF) & 1)) {
264 PUP(out) = PUP(from);
265 len--;
266 }
267 sout = (unsigned short *)(out - OFF);
268 if (dist > 2 ) {
269 unsigned short *sfrom;
270
271 sfrom = (unsigned short *)(from - OFF);
272 loops = len >> 1;
273 do
274 PUP(sout) = get_unaligned(++sfrom);
275 while (--loops);
276 out = (unsigned char *)sout + OFF;
277 from = (unsigned char *)sfrom + OFF;
278 } else { /* dist == 1 or dist == 2 */
279 unsigned short pat16;
280
281 pat16 = *(sout-2+2*OFF);
282 if (dist == 1)
283#if defined(__BIG_ENDIAN)
284 pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8);
285#elif defined(__LITTLE_ENDIAN)
286 pat16 = (pat16 & 0xff00) | ((pat16 & 0xff00 ) >> 8);
287#else
288#error __BIG_ENDIAN nor __LITTLE_ENDIAN is defined
289#endif
290 loops = len >> 1;
291 do
292 PUP(sout) = pat16;
293 while (--loops);
294 out = (unsigned char *)sout + OFF;
295 }
296 if (len & 1)
297 PUP(out) = PUP(from);
298 }
299 }
300 else if ((op & 64) == 0) { /* 2nd level distance code */
301 this = dcode[this.val + (hold & ((1U << op) - 1))];
302 goto dodist;
303 }
304 else {
305 strm->msg = (char *)"invalid distance code";
306 state->mode = BAD;
307 break;
308 }
309 }
310 else if ((op & 64) == 0) { /* 2nd level length code */
311 this = lcode[this.val + (hold & ((1U << op) - 1))];
312 goto dolen;
313 }
314 else if (op & 32) { /* end-of-block */
315 Tracevv((stderr, "inflate: end of block\n"));
316 state->mode = TYPE;
317 break;
318 }
319 else {
320 strm->msg = (char *)"invalid literal/length code";
321 state->mode = BAD;
322 break;
323 }
324 } while (in < last && out < end);
325
326 /* return unused bytes (on entry, bits < 8, so in won't go too far back) */
327 len = bits >> 3;
328 in -= len;
329 bits -= len << 3;
330 hold &= (1U << bits) - 1;
331
332 /* update state and return */
333 strm->next_in = in + OFF;
334 strm->next_out = out + OFF;
335 strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
336 strm->avail_out = (unsigned)(out < end ?
337 257 + (end - out) : 257 - (out - end));
338 state->hold = hold;
339 state->bits = bits;
340 return;
341}
342
343/*
344 inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe):
345 - Using bit fields for code structure
346 - Different op definition to avoid & for extra bits (do & for table bits)
347 - Three separate decoding do-loops for direct, window, and write == 0
348 - Special case for distance > 1 copies to do overlapped load and store copy
349 - Explicit branch predictions (based on measured branch probabilities)
350 - Deferring match copy and interspersed it with decoding subsequent codes
351 - Swapping literal/length else
352 - Swapping window/direct else
353 - Larger unrolled copy loops (three is about right)
354 - Moving len -= 3 statement into middle of loop
355 */
356
357#endif /* !ASMINF */