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Diffstat (limited to 'win32/crc_i386.asm')
| -rw-r--r-- | win32/crc_i386.asm | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/win32/crc_i386.asm b/win32/crc_i386.asm new file mode 100644 index 0000000..7693d75 --- /dev/null +++ b/win32/crc_i386.asm @@ -0,0 +1,241 @@ +;=========================================================================== +; 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 |