+++ /dev/null
-/* crc_i386.c -- Microsoft 32-bit C/C++ adaptation of crc_i386.asm
- * Created by Rodney Brown from crc_i386.asm, modified by Chr. Spieler.
- * Last revised: 22-Mai-1998
- *
- * Original coded (in crc_i386.asm) and put into the public domain
- * 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 16-Nov-97, Chr. Spieler: Made code compatible with Borland C++
- * 32-bit, removed unneeded kludge for potentially unknown movzx mnemonic,
- * confirmed correct working with MS VC++ (32-bit).
- *
- * Revised 22-Mai-98, Peter Kunath, Chr. Spieler : The 16-Nov-97 revision broke
- * MSVC 5.0. Inside preprocessor macros, each instruction is enclosed in its
- * own __asm {...} construct. For MSVC, a "#pragma warning" was added to
- * shut up the "no return value" warning message.
- *
- * FLAT memory model assumed.
- *
- * The loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
- * This results in shorter code at the expense of reduced performance.
- *
- */
-
-#include "zip.h"
-
-#ifndef USE_ZLIB
-
-#ifndef ZCONST
-# define ZCONST const
-#endif
-
-/* Select wether the following inline-assember code is supported. */
-#if (defined(_MSC_VER) && _MSC_VER >= 700)
-#if (defined(_M_IX86) && _M_IX86 >= 300)
-# define MSC_INLINE_ASM_32BIT_SUPPORT
- /* Disable warning for no return value, typical of asm functions */
-# pragma warning( disable : 4035 )
-#endif
-#endif
-
-#if (defined(__BORLANDC__) && __BORLANDC__ >= 452)
-# define MSC_INLINE_ASM_32BIT_SUPPORT
-#endif
-
-#ifdef MSC_INLINE_ASM_32BIT_SUPPORT
-/* This code is intended for Microsoft C/C++ (32-bit) compatible compilers. */
-
-/*
- * 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
-#define Do_CRC { \
- __asm { mov bl, al }; \
- __asm { shr eax, 8 }; \
- __asm { xor eax, [edi+ebx*4] }; }
-#else /* __686 */
-#define Do_CRC { \
- __asm { movzx ebx, al }; \
- __asm { shr eax, 8 }; \
- __asm { xor eax, [edi+ebx*4] }; }
-#endif /* ?__686 */
-
-#define Do_CRC_byte { \
- __asm { xor al, byte ptr [esi] }; \
- __asm { inc esi }; \
- Do_CRC; }
-
-#ifndef NO_32_BIT_LOADS
-#define Do_CRC_dword { \
- __asm { xor eax, dword ptr [esi] }; \
- __asm { add esi, 4 }; \
- Do_CRC; \
- Do_CRC; \
- Do_CRC; \
- Do_CRC; }
-#endif /* !NO_32_BIT_LOADS */
-
-/* ========================================================================= */
-ulg crc32(crc, buf, len)
- ulg crc; /* crc shift register */
- ZCONST uch *buf; /* pointer to bytes to pump through */
- extent len; /* number of bytes in buf[] */
-/* Run a set of bytes through the crc shift register. If buf is a NULL
- pointer, then initialize the crc shift register contents instead.
- Return the current crc in either case. */
-{
- __asm {
- push edx
- push ecx
-
- mov esi,buf ;/* 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,crc ;/* 1st arg: ulg crc */
-#ifndef __686
- sub ebx,ebx ;/* ebx=0; => bl usable as a dword */
-#endif
- mov ecx,len ;/* 3rd arg: extent len */
- not eax ;/*> c = ~crc; */
-
-#ifndef NO_UNROLLED_LOOPS
-# ifndef NO_32_BIT_LOADS
- test ecx,ecx
- je bail
-align_loop:
- test esi,3 ;/* align buf pointer on next */
- jz aligned_now ;/* dword boundary */
- }
- Do_CRC_byte ;
- __asm {
- dec ecx
- jnz align_loop
-aligned_now:
-# endif /* !NO_32_BIT_LOADS */
- mov edx,ecx ;/* save len in edx */
- and edx,000000007H ;/* edx = len % 8 */
- shr ecx,3 ;/* ecx = len / 8 */
- jz No_Eights
-; align loop head at start of 486 internal cache line !!
- align 16
-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 */
- __asm {
- dec ecx
- jnz Next_Eight
-No_Eights:
- mov ecx,edx
-
-#endif /* NO_UNROLLED_LOOPS */
-#ifndef NO_JECXZ_SUPPORT
- jecxz bail ;/*> if (len) */
-#else
- test ecx,ecx ;/*> if (len) */
- jz bail
-#endif
-; align loop head at start of 486 internal cache line !!
- align 16
-loupe: ;/*> do { */
- }
- Do_CRC_byte ;/* c = CRC32(c, *buf++); */
- __asm {
- dec ecx ;/*> } while (--len); */
- jnz loupe
-
-bail: ;/*> } */
- not eax ;/*> return ~c; */
-fine:
- pop ecx
- pop edx
- }
-#ifdef NEED_RETURN
- return _EAX;
-#endif
-}
-#endif /* MSC_INLINE_ASM_32BIT_SUPPORT */
-#if (defined(_MSC_VER) && _MSC_VER >= 700)
-#if (defined(_M_IX86) && _M_IX86 >= 300)
- /* Reenable missing return value warning */
-# pragma warning( default : 4035 )
-#endif
-#endif
-#endif /* !USE_ZLIB */
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