projects / wxWidgets.git / blame
| Commit | Line | Data |
|---|---|---|
| f6bcfd97 BP |
1 | ; crc_i386.asm, optimized CRC calculation function for Zip and UnZip, not |
| 2 | ; copyrighted by Paul Kienitz and Christian Spieler. Last revised 25 Mar 98. | |
| 3 | ; | |
| 4 | ; Revised 06-Oct-96, Scott Field (sfield@microsoft.com) | |
| 5 | ; fixed to assemble with masm by not using .model directive which makes | |
| 6 | ; assumptions about segment alignment. Also, | |
| 7 | ; avoid using loop, and j[e]cxz where possible. Use mov + inc, rather | |
| 8 | ; than lodsb, and other misc. changes resulting in the following performance | |
| 9 | ; increases: | |
| 10 | ; | |
| 11 | ; unrolled loops NO_UNROLLED_LOOPS | |
| 12 | ; *8 >8 <8 *8 >8 <8 | |
| 13 | ; | |
| 14 | ; +54% +42% +35% +82% +52% +25% | |
| 15 | ; | |
| 16 | ; first item in each table is input buffer length, even multiple of 8 | |
| 17 | ; second item in each table is input buffer length, > 8 | |
| 18 | ; third item in each table is input buffer length, < 8 | |
| 19 | ; | |
| 20 | ; Revised 02-Apr-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au) | |
| 21 | ; Incorporated Rodney Brown's 32-bit-reads optimization as found in the | |
| 22 | ; UNIX AS source crc_i386.S. This new code can be disabled by defining | |
| 23 | ; the macro symbol NO_32_BIT_LOADS. | |
| 24 | ; | |
| 25 | ; Revised 12-Oct-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au) | |
| 26 | ; Incorporated Rodney Brown's additional tweaks for 32-bit-optimized CPUs | |
| 27 | ; (like the Pentium Pro, Pentium II, and probably some Pentium clones). | |
| 28 | ; This optimization is controlled by the macro symbol __686 and is disabled | |
| 29 | ; by default. (This default is based on the assumption that most users | |
| 30 | ; do not yet work on a Pentium Pro or Pentium II machine ...) | |
| 31 | ; | |
| 32 | ; FLAT memory model assumed. | |
| 33 | ; | |
| 34 | ; The loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS. | |
| 35 | ; This results in shorter code at the expense of reduced performance. | |
| 36 | ; | |
| 37 | ; Revised 25-Mar-98, Cosmin Truta (cosmint@cs.ubbcluj.ro) | |
| 38 | ; Working without .model directive caused tasm32 version 5.0 to produce | |
| 39 | ; bad object code. The optimized alignments can be optionally disabled | |
| 40 | ; by defining NO_ALIGN, thus allowing to use .model flat. There is no need | |
| 41 | ; to define this macro if using other version of tasm. | |
| 42 | ; | |
| 43 | ;============================================================================== | |
| 44 | ; | |
| 45 | ; Do NOT assemble this source if external crc32 routine from zlib gets used. | |
| 46 | ; | |
| 47 | IFNDEF USE_ZLIB | |
| 48 | ; | |
| 49 | .386p | |
| 50 | name crc_i386 | |
| 51 | ||
| 52 | IFDEF NO_ALIGN | |
| 53 | .model flat | |
| 54 | ENDIF | |
| 55 | ||
| 56 | extrn _get_crc_table:near ; ZCONST ulg near *get_crc_table(void); | |
| 57 | ||
| 58 | ; | |
| 59 | IFNDEF NO_STD_STACKFRAME | |
| 60 | ; Use a `standard' stack frame setup on routine entry and exit. | |
| 61 | ; Actually, this option is set as default, because it results | |
| 62 | ; in smaller code !! | |
| 63 | STD_ENTRY MACRO | |
| 64 | push ebp | |
| 65 | mov ebp,esp | |
| 66 | ENDM | |
| 67 | ||
| 68 | Arg1 EQU 08H[ebp] | |
| 69 | Arg2 EQU 0CH[ebp] | |
| 70 | Arg3 EQU 10H[ebp] | |
| 71 | ||
| 72 | STD_LEAVE MACRO | |
| 73 | pop ebp | |
| 74 | ENDM | |
| 75 | ||
| 76 | ELSE ; NO_STD_STACKFRAME | |
| 77 | ||
| 78 | STD_ENTRY MACRO | |
| 79 | ENDM | |
| 80 | ||
| 81 | Arg1 EQU 18H[esp] | |
| 82 | Arg2 EQU 1CH[esp] | |
| 83 | Arg3 EQU 20H[esp] | |
| 84 | ||
| 85 | STD_LEAVE MACRO | |
| 86 | ENDM | |
| 87 | ||
| 88 | ENDIF ; ?NO_STD_STACKFRAME | |
| 89 | ||
| 90 | ; These two (three) macros make up the loop body of the CRC32 cruncher. | |
| 91 | ; registers modified: | |
| 92 | ; eax : crc value "c" | |
| 93 | ; esi : pointer to next data byte (or dword) "buf++" | |
| 94 | ; registers read: | |
| 95 | ; edi : pointer to base of crc_table array | |
| 96 | ; scratch registers: | |
| 97 | ; ebx : index into crc_table array | |
| 98 | ; (requires upper three bytes = 0 when __686 is undefined) | |
| 99 | IFNDEF __686 ; optimize for 386, 486, Pentium | |
| 100 | Do_CRC MACRO | |
| 101 | mov bl,al ; tmp = c & 0xFF | |
| 102 | shr eax,8 ; c = (c >> 8) | |
| 103 | xor eax,[edi+ebx*4] ; ^ table[tmp] | |
| 104 | ENDM | |
| 105 | ELSE ; __686 : optimize for Pentium Pro, Pentium II and compatible CPUs | |
| 106 | Do_CRC MACRO | |
| 107 | movzx ebx,al ; tmp = c & 0xFF | |
| 108 | shr eax,8 ; c = (c >> 8) | |
| 109 | xor eax,[edi+ebx*4] ; ^ table[tmp] | |
| 110 | ENDM | |
| 111 | ENDIF ; ?__686 | |
| 112 | Do_CRC_byte MACRO | |
| 113 | xor al, byte ptr [esi] ; c ^= *buf | |
| 114 | inc esi ; buf++ | |
| 115 | Do_CRC ; c = (c >> 8) ^ table[c & 0xFF] | |
| 116 | ENDM | |
| 117 | IFNDEF NO_32_BIT_LOADS | |
| 118 | Do_CRC_dword MACRO | |
| 119 | xor eax, dword ptr [esi] ; c ^= *(ulg *)buf | |
| 120 | add esi, 4 ; ((ulg *)buf)++ | |
| 121 | Do_CRC | |
| 122 | Do_CRC | |
| 123 | Do_CRC | |
| 124 | Do_CRC | |
| 125 | ENDM | |
| 126 | ENDIF ; !NO_32_BIT_LOADS | |
| 127 | ||
| 128 | IFNDEF NO_ALIGN | |
| 129 | _TEXT segment use32 para public 'CODE' | |
| 130 | ELSE | |
| 131 | _TEXT segment use32 | |
| 132 | ENDIF | |
| 133 | assume CS: _TEXT | |
| 134 | ||
| 135 | public _crc32 | |
| 136 | _crc32 proc near ; ulg crc32(ulg crc, ZCONST uch *buf, extent len) | |
| 137 | STD_ENTRY | |
| 138 | push edi | |
| 139 | push esi | |
| 140 | push ebx | |
| 141 | push edx | |
| 142 | push ecx | |
| 143 | ||
| 144 | mov esi,Arg2 ; 2nd arg: uch *buf | |
| 145 | sub eax,eax ;> if (!buf) | |
| 146 | test esi,esi ;> return 0; | |
| 147 | jz fine ;> else { | |
| 148 | ||
| 149 | call _get_crc_table | |
| 150 | mov edi,eax | |
| 151 | mov eax,Arg1 ; 1st arg: ulg crc | |
| 152 | IFNDEF __686 | |
| 153 | sub ebx,ebx ; ebx=0; make bl usable as a dword | |
| 154 | ENDIF | |
| 155 | mov ecx,Arg3 ; 3rd arg: extent len | |
| 156 | not eax ;> c = ~crc; | |
| 157 | ||
| 158 | IFNDEF NO_UNROLLED_LOOPS | |
| 159 | IFNDEF NO_32_BIT_LOADS | |
| 160 | test ecx,ecx | |
| 161 | je bail | |
| 162 | align_loop: | |
| 163 | test esi,3 ; align buf pointer on next | |
| 164 | jz SHORT aligned_now ; dword boundary | |
| 165 | Do_CRC_byte | |
| 166 | dec ecx | |
| 167 | jnz align_loop | |
| 168 | aligned_now: | |
| 169 | ENDIF ; !NO_32_BIT_LOADS | |
| 170 | mov edx,ecx ; save len in edx | |
| 171 | and edx,000000007H ; edx = len % 8 | |
| 172 | shr ecx,3 ; ecx = len / 8 | |
| 173 | jz SHORT No_Eights | |
| 174 | IFNDEF NO_ALIGN | |
| 175 | ; align loop head at start of 486 internal cache line !! | |
| 176 | align 16 | |
| 177 | ENDIF | |
| 178 | Next_Eight: | |
| 179 | IFNDEF NO_32_BIT_LOADS | |
| 180 | Do_CRC_dword | |
| 181 | Do_CRC_dword | |
| 182 | ELSE ; NO_32_BIT_LOADS | |
| 183 | Do_CRC_byte | |
| 184 | Do_CRC_byte | |
| 185 | Do_CRC_byte | |
| 186 | Do_CRC_byte | |
| 187 | Do_CRC_byte | |
| 188 | Do_CRC_byte | |
| 189 | Do_CRC_byte | |
| 190 | Do_CRC_byte | |
| 191 | ENDIF ; ?NO_32_BIT_LOADS | |
| 192 | dec ecx | |
| 193 | jnz Next_Eight | |
| 194 | No_Eights: | |
| 195 | mov ecx,edx | |
| 196 | ||
| 197 | ENDIF ; NO_UNROLLED_LOOPS | |
| 198 | IFNDEF NO_JECXZ_SUPPORT | |
| 199 | jecxz bail ;> if (len) | |
| 200 | ELSE | |
| 201 | test ecx,ecx ;> if (len) | |
| 202 | jz SHORT bail | |
| 203 | ENDIF | |
| 204 | IFNDEF NO_ALIGN | |
| 205 | ; align loop head at start of 486 internal cache line !! | |
| 206 | align 16 | |
| 207 | ENDIF | |
| 208 | loupe: ;> do { | |
| 209 | Do_CRC_byte ; c = CRC32(c, *buf++); | |
| 210 | dec ecx ;> } while (--len); | |
| 211 | jnz loupe | |
| 212 | ||
| 213 | bail: ;> } | |
| 214 | not eax ;> return ~c; | |
| 215 | fine: | |
| 216 | pop ecx | |
| 217 | pop edx | |
| 218 | pop ebx | |
| 219 | pop esi | |
| 220 | pop edi | |
| 221 | STD_LEAVE | |
| 222 | ret | |
| 223 | _crc32 endp | |
| 224 | ||
| 225 | _TEXT ends | |
| 226 | ; | |
| 227 | ENDIF ; !USE_ZLIB | |
| 228 | ; | |
| 229 | end |