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
|
/*
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, both of these files are missing, the Info-ZIP license
also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
*/
/*
* crc_i386.S, optimized CRC calculation function for Zip and UnZip,
* created by Paul Kienitz and Christian Spieler.
*
* GRR 961110: incorporated Scott Field optimizations from win32/crc_i386.asm
* => overall 6% speedup in "unzip -tq" on 9MB zipfile (486-66)
*
* SPC 970402: revised for Rodney Brown's optimizations (32-bit-wide
* aligned reads for most of the data from buffer), can be
* disabled by defining the macro NO_32_BIT_LOADS
*
* SPC 971012: added 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
* preprocessor switch "__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 ...)
*
* COS 050116: Enabled the 686 build by default, because there are hardly any
* pre-686 CPUs in serious use nowadays. (See SPC 970402 above.)
*
* FLAT memory model assumed. Calling interface:
* - args are pushed onto the stack from right to left,
* - return value is given in the EAX register,
* - all other registers (with exception of EFLAGS) are preserved. (With
* GNU C 2.7.x, %edx and %ecx are `scratch' registers, but preserving
* them nevertheless adds only 4 single byte instructions.)
*
* This source generates the function
* ulg crc32(ulg crc, ZCONST uch *buf, extent len).
*
* Loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
* This results in shorter code at the expense of reduced performance.
*/
/* This file is NOT used in conjunction with zlib. */
#ifndef USE_ZLIB
/* Preprocess with -DNO_UNDERLINE if your C compiler does not prefix
* external symbols with an underline character '_'.
*/
#if defined(NO_UNDERLINE) || defined(__ELF__)
# define _crc32 crc32
# define _get_crc_table get_crc_table
#endif
/* Use 16-byte alignment if your assembler supports it. Warning: gas
* uses a log(x) parameter (.align 4 means 16-byte alignment). On SVR4
* the parameter is a number of bytes.
*/
#ifndef ALIGNMENT
# define ALIGNMENT .align 4,0x90
#endif
#if defined(i386) || defined(_i386) || defined(_I386) || defined(__i386)
/* This version is for 386 Unix, OS/2, MSDOS in 32 bit mode (gcc & gas).
* Warning: it uses the AT&T syntax: mov source,dest
* This file is only optional. If you want to use the C version,
* remove -DASM_CRC from CFLAGS in Makefile and set OBJA to an empty string.
*/
.file "crc_i386.S"
#if !defined(PRE_686) && !defined(__686)
/* Optimize for Pentium Pro and compatible CPUs by default. */
# define __686
#endif
#if defined(NO_STD_STACKFRAME) && defined(USE_STD_STACKFRAME)
# undef USE_STACKFRAME
#else
/* The default is to use standard stack frame entry, because it
* results in smaller code!
*/
# ifndef USE_STD_STACKFRAME
# define USE_STD_STACKFRAME
# endif
#endif
#ifdef USE_STD_STACKFRAME
# define _STD_ENTRY pushl %ebp ; movl %esp,%ebp
# define arg1 8(%ebp)
# define arg2 12(%ebp)
# define arg3 16(%ebp)
# define _STD_LEAVE popl %ebp
#else /* !USE_STD_STACKFRAME */
# define _STD_ENTRY
# define arg1 24(%esp)
# define arg2 28(%esp)
# define arg3 32(%esp)
# define _STD_LEAVE
#endif /* ?USE_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 lword) "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 */
#define Do_CRC /* c = (c >> 8) ^ table[c & 0xFF] */\
movb %al, %bl ;/* tmp = c & 0xFF */\
shrl $8, %eax ;/* c = (c >> 8) */\
xorl (%edi, %ebx, 4), %eax ;/* c ^= table[tmp] */
#else /* __686 : optimize for Pentium Pro and compatible CPUs */
#define Do_CRC /* c = (c >> 8) ^ table[c & 0xFF] */\
movzbl %al, %ebx ;/* tmp = c & 0xFF */\
shrl $8, %eax ;/* c = (c >> 8) */\
xorl (%edi, %ebx, 4), %eax ;/* c ^=table[tmp] */
#endif /* ?__686 */
#define Do_CRC_byte /* c = (c >> 8) ^ table[(c^*buf++)&0xFF] */\
xorb (%esi), %al ;/* c ^= *buf */\
incl %esi ;/* buf++ */\
Do_CRC
#ifndef NO_32_BIT_LOADS
#define Do_CRC_lword \
xorl (%esi), %eax ;/* c ^= *(ulg *)buf */\
addl $4, %esi ;/* ((ulg *)buf)++ */\
Do_CRC \
Do_CRC \
Do_CRC \
Do_CRC
#endif /* !NO_32_BIT_LOADS */
.text
.globl _crc32
_crc32: /* ulg crc32(ulg crc, uch *buf, extent len) */
_STD_ENTRY
pushl %edi
pushl %esi
pushl %ebx
pushl %edx
pushl %ecx
movl arg2, %esi /* 2nd arg: uch *buf */
subl %eax, %eax /* > if (!buf) */
testl %esi, %esi /* > return 0; */
jz .L_fine /* > else { */
call _get_crc_table
movl %eax, %edi
movl arg1, %eax /* 1st arg: ulg crc */
#ifndef __686
subl %ebx, %ebx /* ebx=0; bl usable as dword */
#endif
movl arg3, %ecx /* 3rd arg: extent len */
notl %eax /* > c = ~crc; */
testl %ecx, %ecx
#ifndef NO_UNROLLED_LOOPS
jz .L_bail
# ifndef NO_32_BIT_LOADS
/* Assert now have positive length */
.L_align_loop:
testl $3, %esi /* Align buf on lword boundary */
jz .L_aligned_now
Do_CRC_byte
decl %ecx
jnz .L_align_loop
.L_aligned_now:
# endif /* !NO_32_BIT_LOADS */
movl %ecx, %edx /* save len in edx */
shrl $3, %ecx /* ecx = len / 8 */
jz .L_No_Eights
/* align loop head at start of 486 internal cache line !! */
ALIGNMENT
.L_Next_Eight:
# ifndef NO_32_BIT_LOADS
/* Do_CRC_lword */
xorl (%esi), %eax ;/* c ^= *(ulg *)buf */
addl $4, %esi ;/* ((ulg *)buf)++ */
Do_CRC
Do_CRC
Do_CRC
Do_CRC
/* Do_CRC_lword */
xorl (%esi), %eax ;/* c ^= *(ulg *)buf */
addl $4, %esi ;/* ((ulg *)buf)++ */
Do_CRC
Do_CRC
Do_CRC
Do_CRC
# 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 */
decl %ecx
jnz .L_Next_Eight
.L_No_Eights:
movl %edx, %ecx
andl $7, %ecx /* ecx = len % 8 */
#endif /* !NO_UNROLLED_LOOPS */
jz .L_bail /* > if (len) */
/* align loop head at start of 486 internal cache line !! */
ALIGNMENT
.L_loupe: /* > do { */
Do_CRC_byte /* c = CRC32(c, *buf++); */
decl %ecx /* > } while (--len); */
jnz .L_loupe
.L_bail: /* > } */
notl %eax /* > return ~c; */
.L_fine:
popl %ecx
popl %edx
popl %ebx
popl %esi
popl %edi
_STD_LEAVE
ret
#else
error: this asm version is for 386 only
#endif /* i386 || _i386 || _I386 || __i386 */
#endif /* !USE_ZLIB */
|
