/* 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,v 1.5 1996/01/13 14:55:12 spc Exp $ */#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 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 */