summaryrefslogtreecommitdiff
path: root/win32/zlib/contrib/amd64/amd64-match.S
blob: 81d4a1c9494b1c7a26849d2b594874918f04c700 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
/*
 * match.S -- optimized version of longest_match()
 * based on the similar work by Gilles Vollant, and Brian Raiter, written 1998
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the BSD License. Use by owners of Che Guevarra
 * parafernalia is prohibited, where possible, and highly discouraged
 * elsewhere.
 */

#ifndef NO_UNDERLINE
#	define	match_init	_match_init
#	define	longest_match	_longest_match
#endif

#define	scanend		ebx
#define	scanendw	bx
#define	chainlenwmask	edx /* high word: current chain len low word: s->wmask */
#define	curmatch	rsi
#define	curmatchd	esi
#define	windowbestlen	r8
#define	scanalign	r9
#define	scanalignd	r9d
#define	window		r10
#define	bestlen		r11
#define	bestlend	r11d
#define	scanstart	r12d
#define	scanstartw	r12w
#define scan		r13
#define nicematch	r14d
#define	limit		r15
#define	limitd		r15d
#define prev		rcx

/*
 * The 258 is a "magic number, not a parameter -- changing it
 * breaks the hell loose
 */
#define	MAX_MATCH	(258)
#define	MIN_MATCH	(3)
#define	MIN_LOOKAHEAD	(MAX_MATCH + MIN_MATCH + 1)
#define	MAX_MATCH_8	((MAX_MATCH + 7) & ~7)

/* stack frame offsets */
#define	LocalVarsSize	(112)
#define _chainlenwmask	( 8-LocalVarsSize)(%rsp)
#define _windowbestlen	(16-LocalVarsSize)(%rsp)
#define save_r14        (24-LocalVarsSize)(%rsp)
#define save_rsi        (32-LocalVarsSize)(%rsp)
#define save_rbx        (40-LocalVarsSize)(%rsp)
#define save_r12        (56-LocalVarsSize)(%rsp)
#define save_r13        (64-LocalVarsSize)(%rsp)
#define save_r15        (80-LocalVarsSize)(%rsp)


.globl	match_init, longest_match

/*
 * On AMD64 the first argument of a function (in our case -- the pointer to
 * deflate_state structure) is passed in %rdi, hence our offsets below are
 * all off of that.
 */

/* you can check the structure offset by running

#include <stdlib.h>
#include <stdio.h>
#include "deflate.h"

void print_depl()
{
deflate_state ds;
deflate_state *s=&ds;
printf("size pointer=%u\n",(int)sizeof(void*));

printf("#define dsWSize         (%3u)(%%rdi)\n",(int)(((char*)&(s->w_size))-((char*)s)));
printf("#define dsWMask         (%3u)(%%rdi)\n",(int)(((char*)&(s->w_mask))-((char*)s)));
printf("#define dsWindow        (%3u)(%%rdi)\n",(int)(((char*)&(s->window))-((char*)s)));
printf("#define dsPrev          (%3u)(%%rdi)\n",(int)(((char*)&(s->prev))-((char*)s)));
printf("#define dsMatchLen      (%3u)(%%rdi)\n",(int)(((char*)&(s->match_length))-((char*)s)));
printf("#define dsPrevMatch     (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_match))-((char*)s)));
printf("#define dsStrStart      (%3u)(%%rdi)\n",(int)(((char*)&(s->strstart))-((char*)s)));
printf("#define dsMatchStart    (%3u)(%%rdi)\n",(int)(((char*)&(s->match_start))-((char*)s)));
printf("#define dsLookahead     (%3u)(%%rdi)\n",(int)(((char*)&(s->lookahead))-((char*)s)));
printf("#define dsPrevLen       (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_length))-((char*)s)));
printf("#define dsMaxChainLen   (%3u)(%%rdi)\n",(int)(((char*)&(s->max_chain_length))-((char*)s)));
printf("#define dsGoodMatch     (%3u)(%%rdi)\n",(int)(((char*)&(s->good_match))-((char*)s)));
printf("#define dsNiceMatch     (%3u)(%%rdi)\n",(int)(((char*)&(s->nice_match))-((char*)s)));
}

*/


/*
  to compile for XCode 3.2 on MacOSX x86_64
  - run "gcc -g -c -DXCODE_MAC_X64_STRUCTURE amd64-match.S"
 */


#ifndef CURRENT_LINX_XCODE_MAC_X64_STRUCTURE
#define dsWSize		( 68)(%rdi)
#define dsWMask		( 76)(%rdi)
#define dsWindow	( 80)(%rdi)
#define dsPrev		( 96)(%rdi)
#define dsMatchLen	(144)(%rdi)
#define dsPrevMatch	(148)(%rdi)
#define dsStrStart	(156)(%rdi)
#define dsMatchStart	(160)(%rdi)
#define dsLookahead	(164)(%rdi)
#define dsPrevLen	(168)(%rdi)
#define dsMaxChainLen	(172)(%rdi)
#define dsGoodMatch	(188)(%rdi)
#define dsNiceMatch	(192)(%rdi)

#else 

#ifndef STRUCT_OFFSET
#	define STRUCT_OFFSET	(0)
#endif


#define dsWSize		( 56 + STRUCT_OFFSET)(%rdi)
#define dsWMask		( 64 + STRUCT_OFFSET)(%rdi)
#define dsWindow	( 72 + STRUCT_OFFSET)(%rdi)
#define dsPrev		( 88 + STRUCT_OFFSET)(%rdi)
#define dsMatchLen	(136 + STRUCT_OFFSET)(%rdi)
#define dsPrevMatch	(140 + STRUCT_OFFSET)(%rdi)
#define dsStrStart	(148 + STRUCT_OFFSET)(%rdi)
#define dsMatchStart	(152 + STRUCT_OFFSET)(%rdi)
#define dsLookahead	(156 + STRUCT_OFFSET)(%rdi)
#define dsPrevLen	(160 + STRUCT_OFFSET)(%rdi)
#define dsMaxChainLen	(164 + STRUCT_OFFSET)(%rdi)
#define dsGoodMatch	(180 + STRUCT_OFFSET)(%rdi)
#define dsNiceMatch	(184 + STRUCT_OFFSET)(%rdi)

#endif




.text

/* uInt longest_match(deflate_state *deflatestate, IPos curmatch) */

longest_match:
/*
 * Retrieve the function arguments. %curmatch will hold cur_match
 * throughout the entire function (passed via rsi on amd64).
 * rdi will hold the pointer to the deflate_state (first arg on amd64)
 */
		mov     %rsi, save_rsi
		mov     %rbx, save_rbx
		mov	%r12, save_r12
		mov     %r13, save_r13
		mov     %r14, save_r14
		mov     %r15, save_r15

/* uInt wmask = s->w_mask;						*/
/* unsigned chain_length = s->max_chain_length;				*/
/* if (s->prev_length >= s->good_match) {				*/
/*     chain_length >>= 2;						*/
/* }									*/

		movl	dsPrevLen, %eax
		movl	dsGoodMatch, %ebx
		cmpl	%ebx, %eax
		movl	dsWMask, %eax
		movl	dsMaxChainLen, %chainlenwmask
		jl	LastMatchGood
		shrl	$2, %chainlenwmask
LastMatchGood:

/* chainlen is decremented once beforehand so that the function can	*/
/* use the sign flag instead of the zero flag for the exit test.	*/
/* It is then shifted into the high word, to make room for the wmask	*/
/* value, which it will always accompany.				*/

		decl	%chainlenwmask
		shll	$16, %chainlenwmask
		orl	%eax, %chainlenwmask

/* if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;	*/

		movl	dsNiceMatch, %eax
		movl	dsLookahead, %ebx
		cmpl	%eax, %ebx
		jl	LookaheadLess
		movl	%eax, %ebx
LookaheadLess:	movl	%ebx, %nicematch

/* register Bytef *scan = s->window + s->strstart;			*/

		mov	dsWindow, %window
		movl	dsStrStart, %limitd
		lea	(%limit, %window), %scan

/* Determine how many bytes the scan ptr is off from being		*/
/* dword-aligned.							*/

		mov	%scan, %scanalign
		negl	%scanalignd
		andl	$3, %scanalignd

/* IPos limit = s->strstart > (IPos)MAX_DIST(s) ?			*/
/*     s->strstart - (IPos)MAX_DIST(s) : NIL;				*/

		movl	dsWSize, %eax
		subl	$MIN_LOOKAHEAD, %eax
		xorl	%ecx, %ecx
		subl	%eax, %limitd
		cmovng	%ecx, %limitd

/* int best_len = s->prev_length;					*/

		movl	dsPrevLen, %bestlend

/* Store the sum of s->window + best_len in %windowbestlen locally, and in memory.	*/

		lea	(%window, %bestlen), %windowbestlen
		mov	%windowbestlen, _windowbestlen

/* register ush scan_start = *(ushf*)scan;				*/
/* register ush scan_end   = *(ushf*)(scan+best_len-1);			*/
/* Posf *prev = s->prev;						*/

		movzwl	(%scan), %scanstart
		movzwl	-1(%scan, %bestlen), %scanend
		mov	dsPrev, %prev

/* Jump into the main loop.						*/

		movl	%chainlenwmask, _chainlenwmask
		jmp	LoopEntry

.balign 16

/* do {
 *     match = s->window + cur_match;
 *     if (*(ushf*)(match+best_len-1) != scan_end ||
 *         *(ushf*)match != scan_start) continue;
 *     [...]
 * } while ((cur_match = prev[cur_match & wmask]) > limit
 *          && --chain_length != 0);
 *
 * Here is the inner loop of the function. The function will spend the
 * majority of its time in this loop, and majority of that time will
 * be spent in the first ten instructions.
 */
LookupLoop:
		andl	%chainlenwmask, %curmatchd
		movzwl	(%prev, %curmatch, 2), %curmatchd
		cmpl	%limitd, %curmatchd
		jbe	LeaveNow
		subl	$0x00010000, %chainlenwmask
		js	LeaveNow
LoopEntry:	cmpw	-1(%windowbestlen, %curmatch), %scanendw
		jne	LookupLoop
		cmpw	%scanstartw, (%window, %curmatch)
		jne	LookupLoop

/* Store the current value of chainlen.					*/
		movl	%chainlenwmask, _chainlenwmask

/* %scan is the string under scrutiny, and %prev to the string we	*/
/* are hoping to match it up with. In actuality, %esi and %edi are	*/
/* both pointed (MAX_MATCH_8 - scanalign) bytes ahead, and %edx is	*/
/* initialized to -(MAX_MATCH_8 - scanalign).				*/

		mov	$(-MAX_MATCH_8), %rdx
		lea	(%curmatch, %window), %windowbestlen
		lea	MAX_MATCH_8(%windowbestlen, %scanalign), %windowbestlen
		lea	MAX_MATCH_8(%scan, %scanalign), %prev

/* the prefetching below makes very little difference... */
		prefetcht1	(%windowbestlen, %rdx)
		prefetcht1	(%prev, %rdx)

/*
 * Test the strings for equality, 8 bytes at a time. At the end,
 * adjust %rdx so that it is offset to the exact byte that mismatched.
 *
 * It should be confessed that this loop usually does not represent
 * much of the total running time. Replacing it with a more
 * straightforward "rep cmpsb" would not drastically degrade
 * performance -- unrolling it, for example, makes no difference.
 */

#undef USE_SSE	/* works, but is 6-7% slower, than non-SSE... */

LoopCmps:
#ifdef USE_SSE
		/* Preload the SSE registers */
		movdqu	  (%windowbestlen, %rdx), %xmm1
		movdqu	  (%prev, %rdx), %xmm2
		pcmpeqb	%xmm2, %xmm1
		movdqu	16(%windowbestlen, %rdx), %xmm3
		movdqu	16(%prev, %rdx), %xmm4
		pcmpeqb	%xmm4, %xmm3
		movdqu	32(%windowbestlen, %rdx), %xmm5
		movdqu	32(%prev, %rdx), %xmm6
		pcmpeqb	%xmm6, %xmm5
		movdqu	48(%windowbestlen, %rdx), %xmm7
		movdqu	48(%prev, %rdx), %xmm8
		pcmpeqb	%xmm8, %xmm7

		/* Check the comparisions' results */
		pmovmskb %xmm1, %rax
		notw	%ax
		bsfw	%ax, %ax
		jnz	LeaveLoopCmps
		
		/* this is the only iteration of the loop with a possibility of having
		   incremented rdx by 0x108 (each loop iteration add 16*4 = 0x40 
		   and (0x40*4)+8=0x108 */
		add	$8, %rdx
		jz LenMaximum
		add	$8, %rdx

		
		pmovmskb %xmm3, %rax
		notw	%ax
		bsfw	%ax, %ax
		jnz	LeaveLoopCmps
		
		
		add	$16, %rdx


		pmovmskb %xmm5, %rax
		notw	%ax
		bsfw	%ax, %ax
		jnz	LeaveLoopCmps
		
		add	$16, %rdx


		pmovmskb %xmm7, %rax
		notw	%ax
		bsfw	%ax, %ax
		jnz	LeaveLoopCmps
		
		add	$16, %rdx
		
		jmp	LoopCmps
LeaveLoopCmps:	add	%rax, %rdx
#else
		mov	(%windowbestlen, %rdx), %rax
		xor	(%prev, %rdx), %rax
		jnz	LeaveLoopCmps
		
		mov	8(%windowbestlen, %rdx), %rax
		xor	8(%prev, %rdx), %rax
		jnz	LeaveLoopCmps8

		mov	16(%windowbestlen, %rdx), %rax
		xor	16(%prev, %rdx), %rax
		jnz	LeaveLoopCmps16
				
		add	$24, %rdx
		jnz	LoopCmps
		jmp	LenMaximum
#	if 0
/*
 * This three-liner is tantalizingly simple, but bsf is a slow instruction,
 * and the complicated alternative down below is quite a bit faster. Sad...
 */

LeaveLoopCmps:	bsf	%rax, %rax /* find the first non-zero bit */
		shrl	$3, %eax /* divide by 8 to get the byte */
		add	%rax, %rdx
#	else
LeaveLoopCmps16:
		add	$8, %rdx
LeaveLoopCmps8:
		add	$8, %rdx
LeaveLoopCmps:	testl   $0xFFFFFFFF, %eax /* Check the first 4 bytes */
		jnz     Check16
		add     $4, %rdx
		shr     $32, %rax
Check16:        testw   $0xFFFF, %ax
		jnz     LenLower
		add	$2, %rdx
		shrl	$16, %eax
LenLower:	subb	$1, %al
		adc	$0, %rdx
#	endif
#endif

/* Calculate the length of the match. If it is longer than MAX_MATCH,	*/
/* then automatically accept it as the best possible match and leave.	*/

		lea	(%prev, %rdx), %rax
		sub	%scan, %rax
		cmpl	$MAX_MATCH, %eax
		jge	LenMaximum

/* If the length of the match is not longer than the best match we	*/
/* have so far, then forget it and return to the lookup loop.		*/

		cmpl	%bestlend, %eax
		jg	LongerMatch
		mov	_windowbestlen, %windowbestlen
		mov	dsPrev, %prev
		movl	_chainlenwmask, %edx
		jmp	LookupLoop

/*         s->match_start = cur_match;					*/
/*         best_len = len;						*/
/*         if (len >= nice_match) break;				*/
/*         scan_end = *(ushf*)(scan+best_len-1);			*/

LongerMatch:
		movl	%eax, %bestlend
		movl	%curmatchd, dsMatchStart
		cmpl	%nicematch, %eax
		jge	LeaveNow

		lea	(%window, %bestlen), %windowbestlen
		mov	%windowbestlen, _windowbestlen

		movzwl	-1(%scan, %rax), %scanend
		mov	dsPrev, %prev
		movl	_chainlenwmask, %chainlenwmask
		jmp	LookupLoop

/* Accept the current string, with the maximum possible length.		*/

LenMaximum:
		movl	$MAX_MATCH, %bestlend
		movl	%curmatchd, dsMatchStart

/* if ((uInt)best_len <= s->lookahead) return (uInt)best_len;		*/
/* return s->lookahead;							*/

LeaveNow:
		movl	dsLookahead, %eax
		cmpl	%eax, %bestlend
		cmovngl	%bestlend, %eax
LookaheadRet:

/* Restore the registers and return from whence we came.			*/

	mov	save_rsi, %rsi
	mov	save_rbx, %rbx
	mov	save_r12, %r12
	mov	save_r13, %r13
	mov	save_r14, %r14
	mov	save_r15, %r15

	ret

match_init:	ret