Mercurial > hg > CbC > CbC_gcc
comparison zlib/contrib/asm586/match.S @ 51:ae3a4bfb450b
add some files of version 4.4.3 that have been forgotten.
author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
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date | Sun, 07 Feb 2010 18:27:48 +0900 |
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47:3bfb6c00c1e0 | 51:ae3a4bfb450b |
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1 /* match.s -- Pentium-optimized version of longest_match() | |
2 * Written for zlib 1.1.2 | |
3 * Copyright (C) 1998 Brian Raiter <breadbox@muppetlabs.com> | |
4 * | |
5 * This is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License. | |
7 */ | |
8 | |
9 #ifndef NO_UNDERLINE | |
10 #define match_init _match_init | |
11 #define longest_match _longest_match | |
12 #endif | |
13 | |
14 #define MAX_MATCH (258) | |
15 #define MIN_MATCH (3) | |
16 #define MIN_LOOKAHEAD (MAX_MATCH + MIN_MATCH + 1) | |
17 #define MAX_MATCH_8 ((MAX_MATCH + 7) & ~7) | |
18 | |
19 /* stack frame offsets */ | |
20 | |
21 #define wmask 0 /* local copy of s->wmask */ | |
22 #define window 4 /* local copy of s->window */ | |
23 #define windowbestlen 8 /* s->window + bestlen */ | |
24 #define chainlenscanend 12 /* high word: current chain len */ | |
25 /* low word: last bytes sought */ | |
26 #define scanstart 16 /* first two bytes of string */ | |
27 #define scanalign 20 /* dword-misalignment of string */ | |
28 #define nicematch 24 /* a good enough match size */ | |
29 #define bestlen 28 /* size of best match so far */ | |
30 #define scan 32 /* ptr to string wanting match */ | |
31 | |
32 #define LocalVarsSize (36) | |
33 /* saved ebx 36 */ | |
34 /* saved edi 40 */ | |
35 /* saved esi 44 */ | |
36 /* saved ebp 48 */ | |
37 /* return address 52 */ | |
38 #define deflatestate 56 /* the function arguments */ | |
39 #define curmatch 60 | |
40 | |
41 /* Offsets for fields in the deflate_state structure. These numbers | |
42 * are calculated from the definition of deflate_state, with the | |
43 * assumption that the compiler will dword-align the fields. (Thus, | |
44 * changing the definition of deflate_state could easily cause this | |
45 * program to crash horribly, without so much as a warning at | |
46 * compile time. Sigh.) | |
47 */ | |
48 | |
49 /* All the +zlib1222add offsets are due to the addition of fields | |
50 * in zlib in the deflate_state structure since the asm code was first written | |
51 * (if you compile with zlib 1.0.4 or older, use "zlib1222add equ (-4)"). | |
52 * (if you compile with zlib between 1.0.5 and 1.2.2.1, use "zlib1222add equ 0"). | |
53 * if you compile with zlib 1.2.2.2 or later , use "zlib1222add equ 8"). | |
54 */ | |
55 | |
56 #define zlib1222add (8) | |
57 | |
58 #define dsWSize (36+zlib1222add) | |
59 #define dsWMask (44+zlib1222add) | |
60 #define dsWindow (48+zlib1222add) | |
61 #define dsPrev (56+zlib1222add) | |
62 #define dsMatchLen (88+zlib1222add) | |
63 #define dsPrevMatch (92+zlib1222add) | |
64 #define dsStrStart (100+zlib1222add) | |
65 #define dsMatchStart (104+zlib1222add) | |
66 #define dsLookahead (108+zlib1222add) | |
67 #define dsPrevLen (112+zlib1222add) | |
68 #define dsMaxChainLen (116+zlib1222add) | |
69 #define dsGoodMatch (132+zlib1222add) | |
70 #define dsNiceMatch (136+zlib1222add) | |
71 | |
72 | |
73 .file "match.S" | |
74 | |
75 .globl match_init, longest_match | |
76 | |
77 .text | |
78 | |
79 /* uInt longest_match(deflate_state *deflatestate, IPos curmatch) */ | |
80 | |
81 longest_match: | |
82 | |
83 /* Save registers that the compiler may be using, and adjust %esp to */ | |
84 /* make room for our stack frame. */ | |
85 | |
86 pushl %ebp | |
87 pushl %edi | |
88 pushl %esi | |
89 pushl %ebx | |
90 subl $LocalVarsSize, %esp | |
91 | |
92 /* Retrieve the function arguments. %ecx will hold cur_match */ | |
93 /* throughout the entire function. %edx will hold the pointer to the */ | |
94 /* deflate_state structure during the function's setup (before */ | |
95 /* entering the main loop). */ | |
96 | |
97 movl deflatestate(%esp), %edx | |
98 movl curmatch(%esp), %ecx | |
99 | |
100 /* if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; */ | |
101 | |
102 movl dsNiceMatch(%edx), %eax | |
103 movl dsLookahead(%edx), %ebx | |
104 cmpl %eax, %ebx | |
105 jl LookaheadLess | |
106 movl %eax, %ebx | |
107 LookaheadLess: movl %ebx, nicematch(%esp) | |
108 | |
109 /* register Bytef *scan = s->window + s->strstart; */ | |
110 | |
111 movl dsWindow(%edx), %esi | |
112 movl %esi, window(%esp) | |
113 movl dsStrStart(%edx), %ebp | |
114 lea (%esi,%ebp), %edi | |
115 movl %edi, scan(%esp) | |
116 | |
117 /* Determine how many bytes the scan ptr is off from being */ | |
118 /* dword-aligned. */ | |
119 | |
120 movl %edi, %eax | |
121 negl %eax | |
122 andl $3, %eax | |
123 movl %eax, scanalign(%esp) | |
124 | |
125 /* IPos limit = s->strstart > (IPos)MAX_DIST(s) ? */ | |
126 /* s->strstart - (IPos)MAX_DIST(s) : NIL; */ | |
127 | |
128 movl dsWSize(%edx), %eax | |
129 subl $MIN_LOOKAHEAD, %eax | |
130 subl %eax, %ebp | |
131 jg LimitPositive | |
132 xorl %ebp, %ebp | |
133 LimitPositive: | |
134 | |
135 /* unsigned chain_length = s->max_chain_length; */ | |
136 /* if (s->prev_length >= s->good_match) { */ | |
137 /* chain_length >>= 2; */ | |
138 /* } */ | |
139 | |
140 movl dsPrevLen(%edx), %eax | |
141 movl dsGoodMatch(%edx), %ebx | |
142 cmpl %ebx, %eax | |
143 movl dsMaxChainLen(%edx), %ebx | |
144 jl LastMatchGood | |
145 shrl $2, %ebx | |
146 LastMatchGood: | |
147 | |
148 /* chainlen is decremented once beforehand so that the function can */ | |
149 /* use the sign flag instead of the zero flag for the exit test. */ | |
150 /* It is then shifted into the high word, to make room for the scanend */ | |
151 /* scanend value, which it will always accompany. */ | |
152 | |
153 decl %ebx | |
154 shll $16, %ebx | |
155 | |
156 /* int best_len = s->prev_length; */ | |
157 | |
158 movl dsPrevLen(%edx), %eax | |
159 movl %eax, bestlen(%esp) | |
160 | |
161 /* Store the sum of s->window + best_len in %esi locally, and in %esi. */ | |
162 | |
163 addl %eax, %esi | |
164 movl %esi, windowbestlen(%esp) | |
165 | |
166 /* register ush scan_start = *(ushf*)scan; */ | |
167 /* register ush scan_end = *(ushf*)(scan+best_len-1); */ | |
168 | |
169 movw (%edi), %bx | |
170 movw %bx, scanstart(%esp) | |
171 movw -1(%edi,%eax), %bx | |
172 movl %ebx, chainlenscanend(%esp) | |
173 | |
174 /* Posf *prev = s->prev; */ | |
175 /* uInt wmask = s->w_mask; */ | |
176 | |
177 movl dsPrev(%edx), %edi | |
178 movl dsWMask(%edx), %edx | |
179 mov %edx, wmask(%esp) | |
180 | |
181 /* Jump into the main loop. */ | |
182 | |
183 jmp LoopEntry | |
184 | |
185 .balign 16 | |
186 | |
187 /* do { | |
188 * match = s->window + cur_match; | |
189 * if (*(ushf*)(match+best_len-1) != scan_end || | |
190 * *(ushf*)match != scan_start) continue; | |
191 * [...] | |
192 * } while ((cur_match = prev[cur_match & wmask]) > limit | |
193 * && --chain_length != 0); | |
194 * | |
195 * Here is the inner loop of the function. The function will spend the | |
196 * majority of its time in this loop, and majority of that time will | |
197 * be spent in the first ten instructions. | |
198 * | |
199 * Within this loop: | |
200 * %ebx = chainlenscanend - i.e., ((chainlen << 16) | scanend) | |
201 * %ecx = curmatch | |
202 * %edx = curmatch & wmask | |
203 * %esi = windowbestlen - i.e., (window + bestlen) | |
204 * %edi = prev | |
205 * %ebp = limit | |
206 * | |
207 * Two optimization notes on the choice of instructions: | |
208 * | |
209 * The first instruction uses a 16-bit address, which costs an extra, | |
210 * unpairable cycle. This is cheaper than doing a 32-bit access and | |
211 * zeroing the high word, due to the 3-cycle misalignment penalty which | |
212 * would occur half the time. This also turns out to be cheaper than | |
213 * doing two separate 8-bit accesses, as the memory is so rarely in the | |
214 * L1 cache. | |
215 * | |
216 * The window buffer, however, apparently spends a lot of time in the | |
217 * cache, and so it is faster to retrieve the word at the end of the | |
218 * match string with two 8-bit loads. The instructions that test the | |
219 * word at the beginning of the match string, however, are executed | |
220 * much less frequently, and there it was cheaper to use 16-bit | |
221 * instructions, which avoided the necessity of saving off and | |
222 * subsequently reloading one of the other registers. | |
223 */ | |
224 LookupLoop: | |
225 /* 1 U & V */ | |
226 movw (%edi,%edx,2), %cx /* 2 U pipe */ | |
227 movl wmask(%esp), %edx /* 2 V pipe */ | |
228 cmpl %ebp, %ecx /* 3 U pipe */ | |
229 jbe LeaveNow /* 3 V pipe */ | |
230 subl $0x00010000, %ebx /* 4 U pipe */ | |
231 js LeaveNow /* 4 V pipe */ | |
232 LoopEntry: movb -1(%esi,%ecx), %al /* 5 U pipe */ | |
233 andl %ecx, %edx /* 5 V pipe */ | |
234 cmpb %bl, %al /* 6 U pipe */ | |
235 jnz LookupLoop /* 6 V pipe */ | |
236 movb (%esi,%ecx), %ah | |
237 cmpb %bh, %ah | |
238 jnz LookupLoop | |
239 movl window(%esp), %eax | |
240 movw (%eax,%ecx), %ax | |
241 cmpw scanstart(%esp), %ax | |
242 jnz LookupLoop | |
243 | |
244 /* Store the current value of chainlen. */ | |
245 | |
246 movl %ebx, chainlenscanend(%esp) | |
247 | |
248 /* Point %edi to the string under scrutiny, and %esi to the string we */ | |
249 /* are hoping to match it up with. In actuality, %esi and %edi are */ | |
250 /* both pointed (MAX_MATCH_8 - scanalign) bytes ahead, and %edx is */ | |
251 /* initialized to -(MAX_MATCH_8 - scanalign). */ | |
252 | |
253 movl window(%esp), %esi | |
254 movl scan(%esp), %edi | |
255 addl %ecx, %esi | |
256 movl scanalign(%esp), %eax | |
257 movl $(-MAX_MATCH_8), %edx | |
258 lea MAX_MATCH_8(%edi,%eax), %edi | |
259 lea MAX_MATCH_8(%esi,%eax), %esi | |
260 | |
261 /* Test the strings for equality, 8 bytes at a time. At the end, | |
262 * adjust %edx so that it is offset to the exact byte that mismatched. | |
263 * | |
264 * We already know at this point that the first three bytes of the | |
265 * strings match each other, and they can be safely passed over before | |
266 * starting the compare loop. So what this code does is skip over 0-3 | |
267 * bytes, as much as necessary in order to dword-align the %edi | |
268 * pointer. (%esi will still be misaligned three times out of four.) | |
269 * | |
270 * It should be confessed that this loop usually does not represent | |
271 * much of the total running time. Replacing it with a more | |
272 * straightforward "rep cmpsb" would not drastically degrade | |
273 * performance. | |
274 */ | |
275 LoopCmps: | |
276 movl (%esi,%edx), %eax | |
277 movl (%edi,%edx), %ebx | |
278 xorl %ebx, %eax | |
279 jnz LeaveLoopCmps | |
280 movl 4(%esi,%edx), %eax | |
281 movl 4(%edi,%edx), %ebx | |
282 xorl %ebx, %eax | |
283 jnz LeaveLoopCmps4 | |
284 addl $8, %edx | |
285 jnz LoopCmps | |
286 jmp LenMaximum | |
287 LeaveLoopCmps4: addl $4, %edx | |
288 LeaveLoopCmps: testl $0x0000FFFF, %eax | |
289 jnz LenLower | |
290 addl $2, %edx | |
291 shrl $16, %eax | |
292 LenLower: subb $1, %al | |
293 adcl $0, %edx | |
294 | |
295 /* Calculate the length of the match. If it is longer than MAX_MATCH, */ | |
296 /* then automatically accept it as the best possible match and leave. */ | |
297 | |
298 lea (%edi,%edx), %eax | |
299 movl scan(%esp), %edi | |
300 subl %edi, %eax | |
301 cmpl $MAX_MATCH, %eax | |
302 jge LenMaximum | |
303 | |
304 /* If the length of the match is not longer than the best match we */ | |
305 /* have so far, then forget it and return to the lookup loop. */ | |
306 | |
307 movl deflatestate(%esp), %edx | |
308 movl bestlen(%esp), %ebx | |
309 cmpl %ebx, %eax | |
310 jg LongerMatch | |
311 movl chainlenscanend(%esp), %ebx | |
312 movl windowbestlen(%esp), %esi | |
313 movl dsPrev(%edx), %edi | |
314 movl wmask(%esp), %edx | |
315 andl %ecx, %edx | |
316 jmp LookupLoop | |
317 | |
318 /* s->match_start = cur_match; */ | |
319 /* best_len = len; */ | |
320 /* if (len >= nice_match) break; */ | |
321 /* scan_end = *(ushf*)(scan+best_len-1); */ | |
322 | |
323 LongerMatch: movl nicematch(%esp), %ebx | |
324 movl %eax, bestlen(%esp) | |
325 movl %ecx, dsMatchStart(%edx) | |
326 cmpl %ebx, %eax | |
327 jge LeaveNow | |
328 movl window(%esp), %esi | |
329 addl %eax, %esi | |
330 movl %esi, windowbestlen(%esp) | |
331 movl chainlenscanend(%esp), %ebx | |
332 movw -1(%edi,%eax), %bx | |
333 movl dsPrev(%edx), %edi | |
334 movl %ebx, chainlenscanend(%esp) | |
335 movl wmask(%esp), %edx | |
336 andl %ecx, %edx | |
337 jmp LookupLoop | |
338 | |
339 /* Accept the current string, with the maximum possible length. */ | |
340 | |
341 LenMaximum: movl deflatestate(%esp), %edx | |
342 movl $MAX_MATCH, bestlen(%esp) | |
343 movl %ecx, dsMatchStart(%edx) | |
344 | |
345 /* if ((uInt)best_len <= s->lookahead) return (uInt)best_len; */ | |
346 /* return s->lookahead; */ | |
347 | |
348 LeaveNow: | |
349 movl deflatestate(%esp), %edx | |
350 movl bestlen(%esp), %ebx | |
351 movl dsLookahead(%edx), %eax | |
352 cmpl %eax, %ebx | |
353 jg LookaheadRet | |
354 movl %ebx, %eax | |
355 LookaheadRet: | |
356 | |
357 /* Restore the stack and return from whence we came. */ | |
358 | |
359 addl $LocalVarsSize, %esp | |
360 popl %ebx | |
361 popl %esi | |
362 popl %edi | |
363 popl %ebp | |
364 match_init: ret |