utils/Install/sfxzip/crc_i386.c

   1 /* crc_i386.c -- Microsoft 32-bit C/C++ adaptation of crc_i386.asm
   2  * Created by Rodney Brown from crc_i386.asm, modified by Chr. Spieler.
   3  * Last revised: 22-Mai-1998
   4  *
   5  * Original coded (in crc_i386.asm) and put into the public domain
   6  * by Paul Kienitz and Christian Spieler.
   7  *
   8  * Revised 06-Oct-96, Scott Field (sfield@microsoft.com)
   9  *   fixed to assemble with masm by not using .model directive which makes
  10  *   assumptions about segment alignment.  Also,
  11  *   avoid using loop, and j[e]cxz where possible.  Use mov + inc, rather
  12  *   than lodsb, and other misc. changes resulting in the following performance
  13  *   increases:
  14  *
  15  *      unrolled loops                NO_UNROLLED_LOOPS
  16  *      *8    >8      <8              *8      >8      <8
  17  *
  18  *      +54%  +42%    +35%            +82%    +52%    +25%
  19  *
  20  *   first item in each table is input buffer length, even multiple of 8
  21  *   second item in each table is input buffer length, > 8
  22  *   third item in each table is input buffer length, < 8
  23  *
  24  * Revised 02-Apr-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au)
  25  *   Incorporated Rodney Brown's 32-bit-reads optimization as found in the
  26  *   UNIX AS source crc_i386.S. This new code can be disabled by defining
  27  *   the macro symbol NO_32_BIT_LOADS.
  28  *
  29  * Revised 12-Oct-97, Chr. Spieler, based on Rodney Brown (rdb@cmutual.com.au)
  30  *   Incorporated Rodney Brown's additional tweaks for 32-bit-optimized CPUs
  31  *   (like the Pentium Pro, Pentium II, and probably some Pentium clones).
  32  *   This optimization is controlled by the macro symbol __686 and is disabled
  33  *   by default. (This default is based on the assumption that most users
  34  *   do not yet work on a Pentium Pro or Pentium II machine ...)
  35  *
  36  * Revised 16-Nov-97, Chr. Spieler: Made code compatible with Borland C++
  37  *   32-bit, removed unneeded kludge for potentially unknown movzx mnemonic,
  38  *   confirmed correct working with MS VC++ (32-bit).
  39  *
  40  * Revised 22-Mai-98, Peter Kunath, Chr. Spieler : The 16-Nov-97 revision broke
  41  *   MSVC 5.0. Inside preprocessor macros, each instruction is enclosed in its
  42  *   own __asm {...} construct.  For MSVC, a "#pragma warning" was added to
  43  *   shut up the "no return value" warning message.
  44  *
  45  * FLAT memory model assumed.
  46  *
  47  * The loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
  48  * This results in shorter code at the expense of reduced performance.
  49  *
  50  */
  51
  52 #include "zip.h"
  53
  54 #ifndef USE_ZLIB
  55
  56 #ifndef ZCONST
  57 #  define ZCONST const
  58 #endif
  59
  60 /* Select wether the following inline-assember code is supported. */
  61 #if (defined(_MSC_VER) && _MSC_VER >= 700)
  62 #if (defined(_M_IX86) && _M_IX86 >= 300)
  63 #  define MSC_INLINE_ASM_32BIT_SUPPORT
  64    /* Disable warning for no return value, typical of asm functions */
  65 #  pragma warning( disable : 4035 )
  66 #endif
  67 #endif
  68
  69 #if (defined(__BORLANDC__) && __BORLANDC__ >= 452)
  70 #  define MSC_INLINE_ASM_32BIT_SUPPORT
  71 #endif
  72
  73 #ifdef MSC_INLINE_ASM_32BIT_SUPPORT
  74 /* This code is intended for Microsoft C/C++ (32-bit) compatible compilers. */
  75
  76 /*
  77  * These two (three) macros make up the loop body of the CRC32 cruncher.
  78  * registers modified:
  79  *   eax  : crc value "c"
  80  *   esi  : pointer to next data byte (or dword) "buf++"
  81  * registers read:
  82  *   edi  : pointer to base of crc_table array
  83  * scratch registers:
  84  *   ebx  : index into crc_table array
  85  *          (requires upper three bytes = 0 when __686 is undefined)
  86  */
  87 #ifndef __686
  88 #define Do_CRC { \
  89   __asm { mov   bl, al }; \
  90   __asm { shr   eax, 8 }; \
  91   __asm { xor   eax, [edi+ebx*4] }; }
  92 #else /* __686 */
  93 #define Do_CRC { \
  94   __asm { movzx ebx, al }; \
  95   __asm { shr   eax, 8  }; \
  96   __asm { xor   eax, [edi+ebx*4] }; }
  97 #endif /* ?__686 */
  98
  99 #define Do_CRC_byte { \
 100   __asm { xor   al, byte ptr [esi] }; \
 101   __asm { inc   esi }; \
 102   Do_CRC; }
 103
 104 #ifndef NO_32_BIT_LOADS
 105 #define Do_CRC_dword { \
 106   __asm { xor   eax, dword ptr [esi] }; \
 107   __asm { add   esi, 4 }; \
 108   Do_CRC; \
 109   Do_CRC; \
 110   Do_CRC; \
 111   Do_CRC; }
 112 #endif /* !NO_32_BIT_LOADS */
 113
 114 /* ========================================================================= */
 115 ulg crc32(crc, buf, len)
 116     ulg crc;                    /* crc shift register */
 117     ZCONST uch *buf;            /* pointer to bytes to pump through */
 118     extent len;                 /* number of bytes in buf[] */
 119 /* Run a set of bytes through the crc shift register.  If buf is a NULL
 120    pointer, then initialize the crc shift register contents instead.
 121    Return the current crc in either case. */
 122 {
 123     __asm {
 124                 push    edx
 125                 push    ecx
 126
 127                 mov     esi,buf         ;/* 2nd arg: uch *buf              */
 128                 sub     eax,eax         ;/*> if (!buf)                     */
 129                 test    esi,esi         ;/*>   return 0;                   */
 130                 jz      fine            ;/*> else {                        */
 131
 132                 call    get_crc_table
 133                 mov     edi,eax
 134                 mov     eax,crc         ;/* 1st arg: ulg crc               */
 135 #ifndef __686
 136                 sub     ebx,ebx         ;/* ebx=0; => bl usable as a dword */
 137 #endif
 138                 mov     ecx,len         ;/* 3rd arg: extent len            */
 139                 not     eax             ;/*>   c = ~crc;                   */
 140
 141 #ifndef NO_UNROLLED_LOOPS
 142 #  ifndef NO_32_BIT_LOADS
 143                 test    ecx,ecx
 144                 je      bail
 145 align_loop:
 146                 test    esi,3           ;/* align buf pointer on next      */
 147                 jz      aligned_now     ;/*  dword boundary                */
 148     }
 149                 Do_CRC_byte             ;
 150     __asm {
 151                 dec     ecx
 152                 jnz     align_loop
 153 aligned_now:
 154 #  endif /* !NO_32_BIT_LOADS */
 155                 mov     edx,ecx         ;/* save len in edx  */
 156                 and     edx,000000007H  ;/* edx = len % 8    */
 157                 shr     ecx,3           ;/* ecx = len / 8    */
 158                 jz      No_Eights
 159 ; align loop head at start of 486 internal cache line !!
 160                 align   16
 161 Next_Eight:
 162     }
 163 #  ifndef NO_32_BIT_LOADS
 164                 Do_CRC_dword ;
 165                 Do_CRC_dword ;
 166 #  else /* NO_32_BIT_LOADS */
 167                 Do_CRC_byte ;
 168                 Do_CRC_byte ;
 169                 Do_CRC_byte ;
 170                 Do_CRC_byte ;
 171                 Do_CRC_byte ;
 172                 Do_CRC_byte ;
 173                 Do_CRC_byte ;
 174                 Do_CRC_byte ;
 175 #  endif /* ?NO_32_BIT_LOADS */
 176     __asm {
 177                 dec     ecx
 178                 jnz     Next_Eight
 179 No_Eights:
 180                 mov     ecx,edx
 181
 182 #endif /* NO_UNROLLED_LOOPS */
 183 #ifndef NO_JECXZ_SUPPORT
 184                 jecxz   bail            ;/*>  if (len)                     */
 185 #else
 186                 test    ecx,ecx         ;/*>  if (len)                     */
 187                 jz      bail
 188 #endif
 189 ; align loop head at start of 486 internal cache line !!
 190                 align   16
 191 loupe:                                  ;/*>    do { */
 192     }
 193                 Do_CRC_byte             ;/*       c = CRC32(c, *buf++);    */
 194     __asm {
 195                 dec     ecx             ;/*>    } while (--len);           */
 196                 jnz     loupe
 197
 198 bail:                                   ;/*> }                             */
 199                 not     eax             ;/*> return ~c;                    */
 200 fine:
 201                 pop     ecx
 202                 pop     edx
 203     }
 204 #ifdef NEED_RETURN
 205     return _EAX;
 206 #endif
 207 }
 208 #endif /* MSC_INLINE_ASM_32BIT_SUPPORT */
 209 #if (defined(_MSC_VER) && _MSC_VER >= 700)
 210 #if (defined(_M_IX86) && _M_IX86 >= 300)
 211    /* Reenable missing return value warning */
 212 #  pragma warning( default : 4035 )
 213 #endif
 214 #endif
 215 #endif /* !USE_ZLIB */