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
|
;===========================================================================
; Copyright (c) 1990-2005 Info-ZIP. All rights reserved.
;
; See the accompanying file LICENSE, version 2004-May-22 or later
; (the contents of which are also included in zip.h) for terms of use.
; If, for some reason, all these files are missing, the Info-ZIP license
; also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
;===========================================================================
; crc_i386.asm, optimized CRC calculation function for Zip and UnZip,
; created by Paul Kienitz and Christian Spieler.
;
; Revised 06-Oct-96, Scott Field (sfield@microsoft.com)
; fixed to assemble with masm by not using .model directive which makes
; assumptions about segment alignment. Also,
; avoid using loop, and j[e]cxz where possible. Use mov + inc, rather
; than lodsb, and other misc. changes resulting in the following performance
; increases:
;
; unrolled loops NO_UNROLLED_LOOPS
; *8 >8 <8 *8 >8 <8
;
; +54% +42% +35% +82% +52% +25%
;
; first item in each table is input buffer length, even multiple of 8
; second item in each table is input buffer length, > 8
; third item in each table is input buffer length, < 8
;
; Revised 02-Apr-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au)
; Incorporated Rodney Brown's 32-bit-reads optimization as found in the
; UNIX AS source crc_i386.S. This new code can be disabled by defining
; the macro symbol NO_32_BIT_LOADS.
;
; Revised 12-Oct-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au)
; Incorporated Rodney Brown's additional tweaks for 32-bit-optimized CPUs
; (like the Pentium Pro, Pentium II, and probably some Pentium clones).
; This optimization is controlled by the macro symbol __686 and is disabled
; by default. (This default is based on the assumption that most users
; do not yet work on a Pentium Pro or Pentium II machine ...)
;
; Revised 25-Mar-98, Cosmin Truta (cosmint@cs.ubbcluj.ro)
; Working without .model directive caused tasm32 version 5.0 to produce
; bad object code. The optimized alignments can be optionally disabled
; by defining NO_ALIGN, thus allowing to use .model flat. There is no need
; to define this macro if using other versions of tasm.
;
; Revised 16-Jan-2005, Cosmin Truta (cosmint@cs.ubbcluj.ro)
; Enabled the 686 build by default, because there are hardly any pre-686 CPUs
; in serious use nowadays. (See the 12-Oct-97 note above.)
;
; FLAT memory model assumed.
;
; Loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
; This results in shorter code at the expense of reduced performance.
;
;==============================================================================
;
; Do NOT assemble this source if external crc32 routine from zlib gets used.
;
IFNDEF USE_ZLIB
;
.386p
name crc_i386
IFDEF NO_ALIGN
.model flat
ENDIF
IFNDEF PRE_686
IFNDEF __686
__686 EQU 1 ; optimize for Pentium Pro, Pentium II and compatible CPUs
ENDIF
ENDIF
extrn _get_crc_table:near ; ZCONST ulg near *get_crc_table(void);
;
IFNDEF NO_STD_STACKFRAME
; Use a `standard' stack frame setup on routine entry and exit.
; Actually, this option is set as default, because it results
; in smaller code !!
STD_ENTRY MACRO
push ebp
mov ebp,esp
ENDM
Arg1 EQU 08H[ebp]
Arg2 EQU 0CH[ebp]
Arg3 EQU 10H[ebp]
STD_LEAVE MACRO
pop ebp
ENDM
ELSE ; NO_STD_STACKFRAME
STD_ENTRY MACRO
ENDM
Arg1 EQU 18H[esp]
Arg2 EQU 1CH[esp]
Arg3 EQU 20H[esp]
STD_LEAVE MACRO
ENDM
ENDIF ; ?NO_STD_STACKFRAME
; These two (three) macros make up the loop body of the CRC32 cruncher.
; registers modified:
; eax : crc value "c"
; esi : pointer to next data byte (or dword) "buf++"
; registers read:
; edi : pointer to base of crc_table array
; scratch registers:
; ebx : index into crc_table array
; (requires upper three bytes = 0 when __686 is undefined)
IFNDEF __686 ; optimize for 386, 486, Pentium
Do_CRC MACRO
mov bl,al ; tmp = c & 0xFF
shr eax,8 ; c = (c >> 8)
xor eax,[edi+ebx*4] ; ^ table[tmp]
ENDM
ELSE ; __686 : optimize for Pentium Pro, Pentium II and compatible CPUs
Do_CRC MACRO
movzx ebx,al ; tmp = c & 0xFF
shr eax,8 ; c = (c >> 8)
xor eax,[edi+ebx*4] ; ^ table[tmp]
ENDM
ENDIF ; ?__686
Do_CRC_byte MACRO
xor al, byte ptr [esi] ; c ^= *buf
inc esi ; buf++
Do_CRC ; c = (c >> 8) ^ table[c & 0xFF]
ENDM
IFNDEF NO_32_BIT_LOADS
Do_CRC_dword MACRO
xor eax, dword ptr [esi] ; c ^= *(ulg *)buf
add esi, 4 ; ((ulg *)buf)++
Do_CRC
Do_CRC
Do_CRC
Do_CRC
ENDM
ENDIF ; !NO_32_BIT_LOADS
IFNDEF NO_ALIGN
_TEXT segment use32 para public 'CODE'
ELSE
_TEXT segment use32
ENDIF
assume CS: _TEXT
public _crc32
_crc32 proc near ; ulg crc32(ulg crc, ZCONST uch *buf, extent len)
STD_ENTRY
push edi
push esi
push ebx
push edx
push ecx
mov esi,Arg2 ; 2nd arg: uch *buf
sub eax,eax ;> if (!buf)
test esi,esi ;> return 0;
jz fine ;> else {
call _get_crc_table
mov edi,eax
mov eax,Arg1 ; 1st arg: ulg crc
IFNDEF __686
sub ebx,ebx ; ebx=0; make bl usable as a dword
ENDIF
mov ecx,Arg3 ; 3rd arg: extent len
not eax ;> c = ~crc;
test ecx,ecx
IFNDEF NO_UNROLLED_LOOPS
jz bail
IFNDEF NO_32_BIT_LOADS
align_loop:
test esi,3 ; align buf pointer on next
jz SHORT aligned_now ; dword boundary
Do_CRC_byte
dec ecx
jnz align_loop
aligned_now:
ENDIF ; !NO_32_BIT_LOADS
mov edx,ecx ; save len in edx
shr ecx,3 ; ecx = len / 8
jz SHORT No_Eights
IFNDEF NO_ALIGN
; align loop head at start of 486 internal cache line !!
align 16
ENDIF
Next_Eight:
IFNDEF NO_32_BIT_LOADS
Do_CRC_dword
Do_CRC_dword
ELSE ; NO_32_BIT_LOADS
Do_CRC_byte
Do_CRC_byte
Do_CRC_byte
Do_CRC_byte
Do_CRC_byte
Do_CRC_byte
Do_CRC_byte
Do_CRC_byte
ENDIF ; ?NO_32_BIT_LOADS
dec ecx
jnz Next_Eight
No_Eights:
mov ecx,edx
and ecx,000000007H ; ecx = len % 8
ENDIF ; !NO_UNROLLED_LOOPS
jz SHORT bail ;> if (len)
IFNDEF NO_ALIGN
; align loop head at start of 486 internal cache line !!
align 16
ENDIF
loupe: ;> do {
Do_CRC_byte ; c = CRC32(c, *buf++);
dec ecx ;> } while (--len);
jnz loupe
bail: ;> }
not eax ;> return ~c;
fine:
pop ecx
pop edx
pop ebx
pop esi
pop edi
STD_LEAVE
ret
_crc32 endp
_TEXT ends
;
ENDIF ; !USE_ZLIB
;
end
|
