?? crc-32b.c
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/* CRC-32b version 1.03 by Craig Bruce, 27-Jan-94**** Based on "File Verification Using CRC" by Mark R. Nelson in Dr. Dobb's** Journal, May 1992, pp. 64-67. This program DOES generate the same CRC** values as ZMODEM and PKZIP**** v1.00: original release.** v1.01: fixed printf formats.** v1.02: fixed something else.** v1.03: replaced CRC constant table by generator function.*/#include <stdio.h>int main();unsigned long getcrc();void crcgen();unsigned long crcTable[256];/****************************************************************************/int main( argc, argv ) int argc; char *argv[];{ int i; FILE *fp; unsigned long crc; crcgen(); if (argc < 2) { crc = getcrc( stdin ); printf("crc32 = %08lx for <stdin>\n", crc); } else { for (i=1; i<argc; i++) { if ( (fp=fopen(argv[i],"rb")) == NULL ) { printf("error opening file \"%s\"!\n",argv[i]); } else { crc = getcrc( fp ); printf("crc32 = %08lx for \"%s\"\n", crc, argv[i]); fclose( fp ); } } } return( 0 );}/****************************************************************************/unsigned long getcrc( fp ) FILE *fp;{ register unsigned long crc; int c; crc = 0xFFFFFFFF; while( (c=getc(fp)) != EOF ) { crc = ((crc>>8) & 0x00FFFFFF) ^ crcTable[ (crc^c) & 0xFF ]; } return( crc^0xFFFFFFFF );}/****************************************************************************/void crcgen( ){ unsigned long crc, poly; int i, j; poly = 0xEDB88320L; for (i=0; i<256; i++) { crc = i; for (j=8; j>0; j--) { if (crc&1) { crc = (crc >> 1) ^ poly; } else { crc >>= 1; } } crcTable[i] = crc; }}?? 快捷鍵說明
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