text: /*
    Copyright (c) 1990-2000 Info-ZIP.  All rights reserved.
  
    See the accompanying file LICENSE, version 2000-Apr-09 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
  */
  /* crc32.c -- compute the CRC-32 of a data stream
   * Copyright (C) 1995 Mark Adler
   * For conditions of distribution and use, see copyright notice in zlib.h
   */
  
  /* $Id: crc32.c 1101 2002-09-21 14:54:45Z darkwyrm $ */
  
  #define __CRC32_C       /* identifies this source module */
  
  #include "zip.h"
  
  #ifndef USE_ZLIB
  #ifndef ASM_CRC
  
  #ifndef ZCONST
  #  define ZCONST const
  #endif
  
  #ifdef CRC32
  #  undef CRC32
  #endif
  #define CRC32(c, b) (crc_table[((int)(c) ^ (b)) & 0xff] ^ ((c) >> 8))
  #define DO1(buf)  crc = CRC32(crc, *buf++)
  #define DO2(buf)  DO1(buf); DO1(buf)
  #define DO4(buf)  DO2(buf); DO2(buf)
  #define DO8(buf)  DO4(buf); DO4(buf)
  
  /* ========================================================================= */
  ulg crc32(crc, buf, len)
      register ulg crc;           /* crc shift register */
      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. */
  {
    register ZCONST ulg near *crc_table;
  
    if (buf == NULL) return 0L;
  
    crc_table = get_crc_table();
  
    crc = crc ^ 0xffffffffL;
  #ifndef NO_UNROLLED_LOOPS
    while (len >= 8) {
      DO8(buf);
      len -= 8;
    }
  #endif
    if (len) do {
      DO1(buf);
    } while (--len);
    return crc ^ 0xffffffffL;     /* (instead of ~c for 64-bit machines) */
  }
  #endif /* !ASM_CRC */
  #endif /* !USE_ZLIB */
  