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/* This program will write six C routines for the calculation of
* the following CRC's. */
/* The CRC polynomial.
* These 4 values define the crc-polynomial.
* If you change them, you must change crctab[]'s initial value to what is
* printed by initcrctab() [see 'compile with -DMAKETAB' above].
*/
/* This tables assumes CCITT is MSB first. Swapped means LSB first. In that
* case the polynomial is also swapped
*/
/* 16 bit crc's */
/* Value used by: CCITT KERMIT ARC BINHEX */
/* the poly: 0x1021 0x8408 0xA001 0x1021 */
/* original: 0x1021 0x1021 0x8005 0x1021 */
/* init value: -1 0 0 0 */
/* swapped: no yes yes no */
/* bits in CRC: 16 16 16 16 */
/* ARC used by LHARC, ZOO, STUFFIT */
/* BINHEX used by XMODEM, PACKIT */
/* 32 bit crc's */
/* Value used by: CCITT32 ZIP */
/* the poly: 0x04c11db7 0xedb88320 */
/* original: 0x04c11db7 0x04c11db7 */
/* init value: -1 -1 */
/* swapped no yes */
/* bits in CRC: 32 32 */
/* ZIP used by COMPACTOR */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
static void initcrctab();
int main(int argc, char *argv[])
{
initcrctab("ccitt", 0x1021, 0xffff, 0, 16);
initcrctab("kermit", 0x8408, 0, 1, 16);
initcrctab("arc", 0xa001, 0, 1, 16);
initcrctab("binhex", 0x1021, 0, 0, 16);
initcrctab("ccitt32",0x04c11db7,0xffffffff,0,32);
initcrctab("zip",0xedb88320,0xffffffff,1,32);
exit(0);
/*NOTREACHED*/
}
static void initcrctab(name, poly, init, swapped, bits)
char *name;
int poly, init, swapped, bits;
{
register int b, i;
unsigned short v;
unsigned long vv;
FILE *fd;
char buf[20];
buf[0] = 0;
(void)strcat(buf, name);
(void)strcat(buf, ".c");
if((fd = fopen(buf, "w")) == NULL) {
(void)fprintf(stderr, "Cannot open %s for writing\n", buf);
exit(1);
}
(void)fprintf(fd, "unsigned long %s_crcinit = %d;\n", name, init);
(void)fprintf(fd, "\n");
if(bits == 16) {
(void)fprintf(fd, "static unsigned short crctab[256] = {\n");
} else {
(void)fprintf(fd, "static unsigned long crctab[256] = {\n");
}
(void)fprintf(fd, " ");
if(bits == 16) {
for(b = 0; b < 256; ++b) {
if(swapped) {
for(v = b, i = 8; --i >= 0;)
v = v & 1 ? (v>>1)^poly : v>>1;
} else {
for(v = b<<8, i = 8; --i >= 0;)
v = v & 0x8000 ? (v<<1)^poly : v<<1;
}
(void)fprintf(fd, "0x%.4x,", v & 0xffff);
if((b&7) == 7) {
(void)fprintf(fd, "\n");
if(b != 255) (void)fprintf(fd, " ");
} else {
(void)fprintf(fd, " ");
}
}
} else {
for(b = 0; b < 256; ++b) {
if(swapped) {
for(vv = b, i = 8; --i >= 0;)
vv = vv & 1 ? (vv>>1)^poly : vv>>1;
} else {
for(vv = b<<24, i = 8; --i >= 0;)
vv = vv & 0x80000000 ? (vv<<1)^poly : vv<<1;
}
(void)fprintf(fd, "0x%.8x,", vv & 0xffffffff);
if((b&3) == 3) {
(void)fprintf(fd, "\n");
if(b != 255) (void)fprintf(fd, " ");
} else {
(void)fprintf(fd, " ");
}
}
}
(void)fprintf(fd, "};\n");
(void)fprintf(fd, "\n");
(void)fprintf(fd, "unsigned long %s_updcrc(icrc, icp, icnt)\n", name);
(void)fprintf(fd, " unsigned long icrc;\n");
(void)fprintf(fd, " unsigned char *icp;\n");
(void)fprintf(fd, " int icnt;\n");
(void)fprintf(fd, "{\n");
if(bits == 16) {
(void)fprintf(fd, "#define M1 0xff\n");
(void)fprintf(fd, "#define M2 0xff00\n");
} else {
(void)fprintf(fd, "#define M1 0xffffff\n");
(void)fprintf(fd, "#define M2 0xffffff00\n");
}
(void)fprintf(fd, " register unsigned long crc = icrc;\n");
(void)fprintf(fd, " register unsigned char *cp = icp;\n");
(void)fprintf(fd, " register int cnt = icnt;\n");
(void)fprintf(fd, "\n");
(void)fprintf(fd, " while(cnt--) {\n");
if(bits == 16) {
if (swapped) {
(void)fprintf(fd,
"\tcrc=((crc>>8)&M1)^crctab[(crc&0xff)^*cp++];\n");
} else {
(void)fprintf(fd,
"\tcrc=((crc<<8)&M2)^crctab[((crc>>8)&0xff)^*cp++];\n");
}
} else {
if(swapped) {
(void)fprintf(fd,
"\tcrc=((crc>>8)&M1)^crctab[(crc&0xff)^*cp++];\n");
} else {
(void)fprintf(fd,
"\tcrc=((crc<<8)&M2)^crctab[((crc>>24)&0xff)^*cp++];\n");
}
}
(void)fprintf(fd, " }\n");
(void)fprintf(fd, "\n");
(void)fprintf(fd, " return(crc);\n");
(void)fprintf(fd, "}\n");
(void)fprintf(fd, "\n");
(void)fclose(fd);
}
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