mirror of https://github.com/BOINC/boinc.git
223 lines
7.8 KiB
C
223 lines
7.8 KiB
C
/*
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Copyright (c) 1990-2000 Info-ZIP. All rights reserved.
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See the accompanying file LICENSE, version 2000-Apr-09 or later
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(the contents of which are also included in zip.h) for terms of use.
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If, for some reason, all these files are missing, the Info-ZIP license
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also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
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*/
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/* crc_i386.c -- Microsoft 32-bit C/C++ adaptation of crc_i386.asm
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* Created by Rodney Brown from crc_i386.asm, modified by Chr. Spieler.
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* Last revised: 24-Dec-1998
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*
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* Original coded (in crc_i386.asm) and put into the public domain
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* by Paul Kienitz and Christian Spieler.
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*
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* Revised 06-Oct-96, Scott Field (sfield@microsoft.com)
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* fixed to assemble with masm by not using .model directive which makes
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* assumptions about segment alignment. Also,
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* avoid using loop, and j[e]cxz where possible. Use mov + inc, rather
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* than lodsb, and other misc. changes resulting in the following performance
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* increases:
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*
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* unrolled loops NO_UNROLLED_LOOPS
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* *8 >8 <8 *8 >8 <8
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*
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* +54% +42% +35% +82% +52% +25%
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*
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* first item in each table is input buffer length, even multiple of 8
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* second item in each table is input buffer length, > 8
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* third item in each table is input buffer length, < 8
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*
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* Revised 02-Apr-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au)
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* Incorporated Rodney Brown's 32-bit-reads optimization as found in the
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* UNIX AS source crc_i386.S. This new code can be disabled by defining
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* the macro symbol NO_32_BIT_LOADS.
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*
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* Revised 12-Oct-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au)
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* Incorporated Rodney Brown's additional tweaks for 32-bit-optimized CPUs
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* (like the Pentium Pro, Pentium II, and probably some Pentium clones).
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* This optimization is controlled by the macro symbol __686 and is disabled
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* by default. (This default is based on the assumption that most users
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* do not yet work on a Pentium Pro or Pentium II machine ...)
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*
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* Revised 16-Nov-97, Chr. Spieler: Made code compatible with Borland C++
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* 32-bit, removed unneeded kludge for potentially unknown movzx mnemonic,
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* confirmed correct working with MS VC++ (32-bit).
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*
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* Revised 22-May-98, Peter Kunath, Chr. Spieler: The 16-Nov-97 revision broke
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* MSVC 5.0. Inside preprocessor macros, each instruction is enclosed in its
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* own __asm {...} construct. For MSVC, a "#pragma warning" was added to
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* shut up the "no return value" warning message.
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*
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* Revised 13-Dec-98, Chr. Spieler: Modified path to "zip.h" header file.
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*
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* FLAT memory model assumed.
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*
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* The loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
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* This results in shorter code at the expense of reduced performance.
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*
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*/
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#include "../zip.h"
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#ifndef USE_ZLIB
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#ifndef ZCONST
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# define ZCONST const
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#endif
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/* Select wether the following inline-assember code is supported. */
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#if (defined(_MSC_VER) && _MSC_VER >= 700)
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#if (defined(_M_IX86) && _M_IX86 >= 300)
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# define MSC_INLINE_ASM_32BIT_SUPPORT
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/* Disable warning for no return value, typical of asm functions */
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# pragma warning( disable : 4035 )
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#endif
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#endif
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#if (defined(__BORLANDC__) && __BORLANDC__ >= 452)
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# define MSC_INLINE_ASM_32BIT_SUPPORT
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#endif
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#ifdef MSC_INLINE_ASM_32BIT_SUPPORT
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/* This code is intended for Microsoft C/C++ (32-bit) compatible compilers. */
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/*
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* These two (three) macros make up the loop body of the CRC32 cruncher.
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* registers modified:
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* eax : crc value "c"
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* esi : pointer to next data byte (or dword) "buf++"
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* registers read:
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* edi : pointer to base of crc_table array
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* scratch registers:
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* ebx : index into crc_table array
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* (requires upper three bytes = 0 when __686 is undefined)
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*/
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#ifndef __686
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#define Do_CRC { \
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__asm { mov bl, al }; \
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__asm { shr eax, 8 }; \
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__asm { xor eax, [edi+ebx*4] }; }
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#else /* __686 */
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#define Do_CRC { \
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__asm { movzx ebx, al }; \
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__asm { shr eax, 8 }; \
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__asm { xor eax, [edi+ebx*4] }; }
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#endif /* ?__686 */
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#define Do_CRC_byte { \
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__asm { xor al, byte ptr [esi] }; \
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__asm { inc esi }; \
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Do_CRC; }
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#ifndef NO_32_BIT_LOADS
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#define Do_CRC_dword { \
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__asm { xor eax, dword ptr [esi] }; \
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__asm { add esi, 4 }; \
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Do_CRC; \
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Do_CRC; \
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Do_CRC; \
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Do_CRC; }
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#endif /* !NO_32_BIT_LOADS */
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/* ========================================================================= */
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ulg crc32(crc, buf, len)
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ulg crc; /* crc shift register */
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ZCONST uch *buf; /* pointer to bytes to pump through */
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extent len; /* number of bytes in buf[] */
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/* Run a set of bytes through the crc shift register. If buf is a NULL
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pointer, then initialize the crc shift register contents instead.
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Return the current crc in either case. */
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{
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__asm {
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push edx
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push ecx
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mov esi,buf ;/* 2nd arg: uch *buf */
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sub eax,eax ;/*> if (!buf) */
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test esi,esi ;/*> return 0; */
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jz fine ;/*> else { */
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call get_crc_table
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mov edi,eax
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mov eax,crc ;/* 1st arg: ulg crc */
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#ifndef __686
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sub ebx,ebx ;/* ebx=0; => bl usable as a dword */
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#endif
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mov ecx,len ;/* 3rd arg: extent len */
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not eax ;/*> c = ~crc; */
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test ecx,ecx
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#ifndef NO_UNROLLED_LOOPS
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jz bail
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# ifndef NO_32_BIT_LOADS
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align_loop:
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test esi,3 ;/* align buf pointer on next */
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jz aligned_now ;/* dword boundary */
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}
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Do_CRC_byte ;
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__asm {
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dec ecx
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jnz align_loop
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aligned_now:
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# endif /* !NO_32_BIT_LOADS */
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mov edx,ecx ;/* save len in edx */
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shr ecx,3 ;/* ecx = len / 8 */
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jz No_Eights
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; align loop head at start of 486 internal cache line !!
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align 16
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Next_Eight:
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}
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# ifndef NO_32_BIT_LOADS
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Do_CRC_dword ;
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Do_CRC_dword ;
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# else /* NO_32_BIT_LOADS */
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Do_CRC_byte ;
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Do_CRC_byte ;
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Do_CRC_byte ;
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Do_CRC_byte ;
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Do_CRC_byte ;
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Do_CRC_byte ;
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Do_CRC_byte ;
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Do_CRC_byte ;
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# endif /* ?NO_32_BIT_LOADS */
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__asm {
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dec ecx
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jnz Next_Eight
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No_Eights:
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mov ecx,edx
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and ecx,000000007H ;/* ecx = len % 8 */
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#endif /* !NO_UNROLLED_LOOPS */
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jz bail ;/*> if (len) */
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; align loop head at start of 486 internal cache line !!
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align 16
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loupe: ;/*> do { */
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}
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Do_CRC_byte ;/* c = CRC32(c, *buf++); */
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__asm {
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dec ecx ;/*> } while (--len); */
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jnz loupe
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bail: ;/*> } */
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not eax ;/*> return ~c; */
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fine:
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pop ecx
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pop edx
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}
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#ifdef NEED_RETURN
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return _EAX;
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#endif
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}
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#endif /* MSC_INLINE_ASM_32BIT_SUPPORT */
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#if (defined(_MSC_VER) && _MSC_VER >= 700)
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#if (defined(_M_IX86) && _M_IX86 >= 300)
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/* Reenable missing return value warning */
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# pragma warning( default : 4035 )
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#endif
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#endif
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#endif /* !USE_ZLIB */
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const char *BOINC_RCSID_395f9d2297 = "$Id: crc_i386.c 4979 2005-01-02 18:29:53Z ballen $";
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