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1; match686.asm -- Asm portion of the optimized longest_match for 32 bits x86
2; Copyright (C) 1995-1996 Jean-loup Gailly, Brian Raiter and Gilles Vollant.
3; File written by Gilles Vollant, by converting match686.S from Brian Raiter
4; for MASM. This is as assembly version of longest_match
5;  from Jean-loup Gailly in deflate.c
6;
7;         http://www.zlib.net
8;         http://www.winimage.com/zLibDll
9;         http://www.muppetlabs.com/~breadbox/software/assembly.html
10;
11; For Visual C++ 4.x and higher and ML 6.x and higher
12;   ml.exe is distributed in
13;  http://www.microsoft.com/downloads/details.aspx?FamilyID=7a1c9da0-0510-44a2-b042-7ef370530c64
14;
15; this file contain two implementation of longest_match
16;
17;  this longest_match was written by Brian raiter (1998), optimized for Pentium Pro
18;   (and the faster known version of match_init on modern Core 2 Duo and AMD Phenom)
19;
20;  for using an assembly version of longest_match, you need define ASMV in project
21;
22;    compile the asm file running
23;           ml /coff /Zi /c /Flmatch686.lst match686.asm
24;    and do not include match686.obj in your project
25;
26; note: contrib of zLib 1.2.3 and earlier contained both a deprecated version for
27;  Pentium (prior Pentium Pro) and this version for Pentium Pro and modern processor
28;  with autoselect (with cpu detection code)
29;  if you want support the old pentium optimization, you can still use these version
30;
31; this file is not optimized for old pentium, but it compatible with all x86 32 bits
32; processor (starting 80386)
33;
34;
35; see below : zlib1222add must be adjuster if you use a zlib version < 1.2.2.2
36
37;uInt longest_match(s, cur_match)
38;    deflate_state *s;
39;    IPos cur_match;                             /* current match */
40
41    NbStack         equ     76
42    cur_match       equ     dword ptr[esp+NbStack-0]
43    str_s           equ     dword ptr[esp+NbStack-4]
44; 5 dword on top (ret,ebp,esi,edi,ebx)
45    adrret          equ     dword ptr[esp+NbStack-8]
46    pushebp         equ     dword ptr[esp+NbStack-12]
47    pushedi         equ     dword ptr[esp+NbStack-16]
48    pushesi         equ     dword ptr[esp+NbStack-20]
49    pushebx         equ     dword ptr[esp+NbStack-24]
50
51    chain_length    equ     dword ptr [esp+NbStack-28]
52    limit           equ     dword ptr [esp+NbStack-32]
53    best_len        equ     dword ptr [esp+NbStack-36]
54    window          equ     dword ptr [esp+NbStack-40]
55    prev            equ     dword ptr [esp+NbStack-44]
56    scan_start      equ      word ptr [esp+NbStack-48]
57    wmask           equ     dword ptr [esp+NbStack-52]
58    match_start_ptr equ     dword ptr [esp+NbStack-56]
59    nice_match      equ     dword ptr [esp+NbStack-60]
60    scan            equ     dword ptr [esp+NbStack-64]
61
62    windowlen       equ     dword ptr [esp+NbStack-68]
63    match_start     equ     dword ptr [esp+NbStack-72]
64    strend          equ     dword ptr [esp+NbStack-76]
65    NbStackAdd      equ     (NbStack-24)
66
67    .386p
68
69    name    gvmatch
70    .MODEL  FLAT
71
72
73
74;  all the +zlib1222add offsets are due to the addition of fields
75;  in zlib in the deflate_state structure since the asm code was first written
76;  (if you compile with zlib 1.0.4 or older, use "zlib1222add equ (-4)").
77;  (if you compile with zlib between 1.0.5 and 1.2.2.1, use "zlib1222add equ 0").
78;  if you compile with zlib 1.2.2.2 or later , use "zlib1222add equ 8").
79
80    zlib1222add         equ     8
81
82;  Note : these value are good with a 8 bytes boundary pack structure
83    dep_chain_length    equ     74h+zlib1222add
84    dep_window          equ     30h+zlib1222add
85    dep_strstart        equ     64h+zlib1222add
86    dep_prev_length     equ     70h+zlib1222add
87    dep_nice_match      equ     88h+zlib1222add
88    dep_w_size          equ     24h+zlib1222add
89    dep_prev            equ     38h+zlib1222add
90    dep_w_mask          equ     2ch+zlib1222add
91    dep_good_match      equ     84h+zlib1222add
92    dep_match_start     equ     68h+zlib1222add
93    dep_lookahead       equ     6ch+zlib1222add
94
95
96_TEXT                   segment
97
98IFDEF NOUNDERLINE
99            public  longest_match
100            public  match_init
101ELSE
102            public  _longest_match
103            public  _match_init
104ENDIF
105
106    MAX_MATCH           equ     258
107    MIN_MATCH           equ     3
108    MIN_LOOKAHEAD       equ     (MAX_MATCH+MIN_MATCH+1)
109
110
111
112MAX_MATCH       equ     258
113MIN_MATCH       equ     3
114MIN_LOOKAHEAD   equ     (MAX_MATCH + MIN_MATCH + 1)
115MAX_MATCH_8_     equ     ((MAX_MATCH + 7) AND 0FFF0h)
116
117
118;;; stack frame offsets
119
120chainlenwmask   equ  esp + 0    ; high word: current chain len
121                    ; low word: s->wmask
122window      equ  esp + 4    ; local copy of s->window
123windowbestlen   equ  esp + 8    ; s->window + bestlen
124scanstart   equ  esp + 16   ; first two bytes of string
125scanend     equ  esp + 12   ; last two bytes of string
126scanalign   equ  esp + 20   ; dword-misalignment of string
127nicematch   equ  esp + 24   ; a good enough match size
128bestlen     equ  esp + 28   ; size of best match so far
129scan        equ  esp + 32   ; ptr to string wanting match
130
131LocalVarsSize   equ 36
132;   saved ebx   byte esp + 36
133;   saved edi   byte esp + 40
134;   saved esi   byte esp + 44
135;   saved ebp   byte esp + 48
136;   return address  byte esp + 52
137deflatestate    equ  esp + 56   ; the function arguments
138curmatch    equ  esp + 60
139
140;;; Offsets for fields in the deflate_state structure. These numbers
141;;; are calculated from the definition of deflate_state, with the
142;;; assumption that the compiler will dword-align the fields. (Thus,
143;;; changing the definition of deflate_state could easily cause this
144;;; program to crash horribly, without so much as a warning at
145;;; compile time. Sigh.)
146
147dsWSize     equ 36+zlib1222add
148dsWMask     equ 44+zlib1222add
149dsWindow    equ 48+zlib1222add
150dsPrev      equ 56+zlib1222add
151dsMatchLen  equ 88+zlib1222add
152dsPrevMatch equ 92+zlib1222add
153dsStrStart  equ 100+zlib1222add
154dsMatchStart    equ 104+zlib1222add
155dsLookahead equ 108+zlib1222add
156dsPrevLen   equ 112+zlib1222add
157dsMaxChainLen   equ 116+zlib1222add
158dsGoodMatch equ 132+zlib1222add
159dsNiceMatch equ 136+zlib1222add
160
161
162;;; match686.asm -- Pentium-Pro-optimized version of longest_match()
163;;; Written for zlib 1.1.2
164;;; Copyright (C) 1998 Brian Raiter <breadbox@muppetlabs.com>
165;;; You can look at http://www.muppetlabs.com/~breadbox/software/assembly.html
166;;;
167;;
168;;  This software is provided 'as-is', without any express or implied
169;;  warranty.  In no event will the authors be held liable for any damages
170;;  arising from the use of this software.
171;;
172;;  Permission is granted to anyone to use this software for any purpose,
173;;  including commercial applications, and to alter it and redistribute it
174;;  freely, subject to the following restrictions:
175;;
176;;  1. The origin of this software must not be misrepresented; you must not
177;;     claim that you wrote the original software. If you use this software
178;;     in a product, an acknowledgment in the product documentation would be
179;;     appreciated but is not required.
180;;  2. Altered source versions must be plainly marked as such, and must not be
181;;     misrepresented as being the original software
182;;  3. This notice may not be removed or altered from any source distribution.
183;;
184
185;GLOBAL _longest_match, _match_init
186
187
188;SECTION    .text
189
190;;; uInt longest_match(deflate_state *deflatestate, IPos curmatch)
191
192;_longest_match:
193    IFDEF NOUNDERLINE
194    longest_match       proc near
195    ELSE
196    _longest_match      proc near
197    ENDIF
198.FPO (9, 4, 0, 0, 1, 0)
199
200;;; Save registers that the compiler may be using, and adjust esp to
201;;; make room for our stack frame.
202
203        push    ebp
204        push    edi
205        push    esi
206        push    ebx
207        sub esp, LocalVarsSize
208
209;;; Retrieve the function arguments. ecx will hold cur_match
210;;; throughout the entire function. edx will hold the pointer to the
211;;; deflate_state structure during the function's setup (before
212;;; entering the main loop.
213
214        mov edx, [deflatestate]
215        mov ecx, [curmatch]
216
217;;; uInt wmask = s->w_mask;
218;;; unsigned chain_length = s->max_chain_length;
219;;; if (s->prev_length >= s->good_match) {
220;;;     chain_length >>= 2;
221;;; }
222
223        mov eax, [edx + dsPrevLen]
224        mov ebx, [edx + dsGoodMatch]
225        cmp eax, ebx
226        mov eax, [edx + dsWMask]
227        mov ebx, [edx + dsMaxChainLen]
228        jl  LastMatchGood
229        shr ebx, 2
230LastMatchGood:
231
232;;; chainlen is decremented once beforehand so that the function can
233;;; use the sign flag instead of the zero flag for the exit test.
234;;; It is then shifted into the high word, to make room for the wmask
235;;; value, which it will always accompany.
236
237        dec ebx
238        shl ebx, 16
239        or  ebx, eax
240        mov [chainlenwmask], ebx
241
242;;; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
243
244        mov eax, [edx + dsNiceMatch]
245        mov ebx, [edx + dsLookahead]
246        cmp ebx, eax
247        jl  LookaheadLess
248        mov ebx, eax
249LookaheadLess:  mov [nicematch], ebx
250
251;;; register Bytef *scan = s->window + s->strstart;
252
253        mov esi, [edx + dsWindow]
254        mov [window], esi
255        mov ebp, [edx + dsStrStart]
256        lea edi, [esi + ebp]
257        mov [scan], edi
258
259;;; Determine how many bytes the scan ptr is off from being
260;;; dword-aligned.
261
262        mov eax, edi
263        neg eax
264        and eax, 3
265        mov [scanalign], eax
266
267;;; IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
268;;;     s->strstart - (IPos)MAX_DIST(s) : NIL;
269
270        mov eax, [edx + dsWSize]
271        sub eax, MIN_LOOKAHEAD
272        sub ebp, eax
273        jg  LimitPositive
274        xor ebp, ebp
275LimitPositive:
276
277;;; int best_len = s->prev_length;
278
279        mov eax, [edx + dsPrevLen]
280        mov [bestlen], eax
281
282;;; Store the sum of s->window + best_len in esi locally, and in esi.
283
284        add esi, eax
285        mov [windowbestlen], esi
286
287;;; register ush scan_start = *(ushf*)scan;
288;;; register ush scan_end   = *(ushf*)(scan+best_len-1);
289;;; Posf *prev = s->prev;
290
291        movzx   ebx, word ptr [edi]
292        mov [scanstart], ebx
293        movzx   ebx, word ptr [edi + eax - 1]
294        mov [scanend], ebx
295        mov edi, [edx + dsPrev]
296
297;;; Jump into the main loop.
298
299        mov edx, [chainlenwmask]
300        jmp short LoopEntry
301
302align 4
303
304;;; do {
305;;;     match = s->window + cur_match;
306;;;     if (*(ushf*)(match+best_len-1) != scan_end ||
307;;;         *(ushf*)match != scan_start) continue;
308;;;     [...]
309;;; } while ((cur_match = prev[cur_match & wmask]) > limit
310;;;          && --chain_length != 0);
311;;;
312;;; Here is the inner loop of the function. The function will spend the
313;;; majority of its time in this loop, and majority of that time will
314;;; be spent in the first ten instructions.
315;;;
316;;; Within this loop:
317;;; ebx = scanend
318;;; ecx = curmatch
319;;; edx = chainlenwmask - i.e., ((chainlen << 16) | wmask)
320;;; esi = windowbestlen - i.e., (window + bestlen)
321;;; edi = prev
322;;; ebp = limit
323
324LookupLoop:
325        and ecx, edx
326        movzx   ecx, word ptr [edi + ecx*2]
327        cmp ecx, ebp
328        jbe LeaveNow
329        sub edx, 00010000h
330        js  LeaveNow
331LoopEntry:  movzx   eax, word ptr [esi + ecx - 1]
332        cmp eax, ebx
333        jnz LookupLoop
334        mov eax, [window]
335        movzx   eax, word ptr [eax + ecx]
336        cmp eax, [scanstart]
337        jnz LookupLoop
338
339;;; Store the current value of chainlen.
340
341        mov [chainlenwmask], edx
342
343;;; Point edi to the string under scrutiny, and esi to the string we
344;;; are hoping to match it up with. In actuality, esi and edi are
345;;; both pointed (MAX_MATCH_8 - scanalign) bytes ahead, and edx is
346;;; initialized to -(MAX_MATCH_8 - scanalign).
347
348        mov esi, [window]
349        mov edi, [scan]
350        add esi, ecx
351        mov eax, [scanalign]
352        mov edx, 0fffffef8h; -(MAX_MATCH_8)
353        lea edi, [edi + eax + 0108h] ;MAX_MATCH_8]
354        lea esi, [esi + eax + 0108h] ;MAX_MATCH_8]
355
356;;; Test the strings for equality, 8 bytes at a time. At the end,
357;;; adjust edx so that it is offset to the exact byte that mismatched.
358;;;
359;;; We already know at this point that the first three bytes of the
360;;; strings match each other, and they can be safely passed over before
361;;; starting the compare loop. So what this code does is skip over 0-3
362;;; bytes, as much as necessary in order to dword-align the edi
363;;; pointer. (esi will still be misaligned three times out of four.)
364;;;
365;;; It should be confessed that this loop usually does not represent
366;;; much of the total running time. Replacing it with a more
367;;; straightforward "rep cmpsb" would not drastically degrade
368;;; performance.
369
370LoopCmps:
371        mov eax, [esi + edx]
372        xor eax, [edi + edx]
373        jnz LeaveLoopCmps
374        mov eax, [esi + edx + 4]
375        xor eax, [edi + edx + 4]
376        jnz LeaveLoopCmps4
377        add edx, 8
378        jnz LoopCmps
379        jmp short LenMaximum
380LeaveLoopCmps4: add edx, 4
381LeaveLoopCmps:  test    eax, 0000FFFFh
382        jnz LenLower
383        add edx,  2
384        shr eax, 16
385LenLower:   sub al, 1
386        adc edx, 0
387
388;;; Calculate the length of the match. If it is longer than MAX_MATCH,
389;;; then automatically accept it as the best possible match and leave.
390
391        lea eax, [edi + edx]
392        mov edi, [scan]
393        sub eax, edi
394        cmp eax, MAX_MATCH
395        jge LenMaximum
396
397;;; If the length of the match is not longer than the best match we
398;;; have so far, then forget it and return to the lookup loop.
399
400        mov edx, [deflatestate]
401        mov ebx, [bestlen]
402        cmp eax, ebx
403        jg  LongerMatch
404        mov esi, [windowbestlen]
405        mov edi, [edx + dsPrev]
406        mov ebx, [scanend]
407        mov edx, [chainlenwmask]
408        jmp LookupLoop
409
410;;;         s->match_start = cur_match;
411;;;         best_len = len;
412;;;         if (len >= nice_match) break;
413;;;         scan_end = *(ushf*)(scan+best_len-1);
414
415LongerMatch:    mov ebx, [nicematch]
416        mov [bestlen], eax
417        mov [edx + dsMatchStart], ecx
418        cmp eax, ebx
419        jge LeaveNow
420        mov esi, [window]
421        add esi, eax
422        mov [windowbestlen], esi
423        movzx   ebx, word ptr [edi + eax - 1]
424        mov edi, [edx + dsPrev]
425        mov [scanend], ebx
426        mov edx, [chainlenwmask]
427        jmp LookupLoop
428
429;;; Accept the current string, with the maximum possible length.
430
431LenMaximum: mov edx, [deflatestate]
432        mov dword ptr [bestlen], MAX_MATCH
433        mov [edx + dsMatchStart], ecx
434
435;;; if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
436;;; return s->lookahead;
437
438LeaveNow:
439        mov edx, [deflatestate]
440        mov ebx, [bestlen]
441        mov eax, [edx + dsLookahead]
442        cmp ebx, eax
443        jg  LookaheadRet
444        mov eax, ebx
445LookaheadRet:
446
447;;; Restore the stack and return from whence we came.
448
449        add esp, LocalVarsSize
450        pop ebx
451        pop esi
452        pop edi
453        pop ebp
454
455        ret
456; please don't remove this string !
457; Your can freely use match686 in any free or commercial app if you don't remove the string in the binary!
458    db     0dh,0ah,"asm686 with masm, optimised assembly code from Brian Raiter, written 1998",0dh,0ah
459
460
461    IFDEF NOUNDERLINE
462    longest_match       endp
463    ELSE
464    _longest_match      endp
465    ENDIF
466
467    IFDEF NOUNDERLINE
468    match_init      proc near
469                    ret
470    match_init      endp
471    ELSE
472    _match_init     proc near
473                    ret
474    _match_init     endp
475    ENDIF
476
477
478_TEXT   ends
479end
480