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/*------------------------------------------------------------------------------
* gencrc.c : generate crc table
*
* Copyright (C) 2013 by T.TAKASU, All rights reserved.
*
* version : $Revision:$ $Date:$
* history : 2013/02/28 1.0 new
*-----------------------------------------------------------------------------*/
#include <stdio.h>
#include <string.h>
static const char rcsid[]="$Id:$";
#define POLYCRC16 0x1021u /* CRC16 polynomial for BINEX,NVS */
#define POLYCRC24Q 0x1864CFBu /* CRC24Q polynomial for SBAS */
/* generate crc-16 parity table -----------------------------------------------*/
static void gen_crc16(FILE *fp)
{
unsigned short crcs[256]={0};
int i,j;
for (i=0;i<256;i++) {
crcs[i]=(unsigned short)i<<8;
for (j=0;j<8;j++) {
if (crcs[i]&0x8000) crcs[i]=(crcs[i]<<1)^POLYCRC16;
else crcs[i]<<=1;
}
}
fprintf(fp,"static const unsigned short tbl_CRC16[]={\n");
for (i=0;i<32;i++) {
fprintf(fp," ");
for (j=0;j<8;j++) {
fprintf(fp,"0x%04X%s",crcs[j+i*8],i==31&&j==7?"":",");
}
fprintf(fp,"\n");
}
fprintf(fp,"};\n");
}
/* generate crc-24q parity table ---------------------------------------------*/
static void gen_crc24(FILE *fp)
{
unsigned int crcs[256]={0};
int i,j;
for (i=0;i<256;i++) {
crcs[i]=(unsigned int)i<<16;
for (j=0;j<8;j++) if ((crcs[i]<<=1)&0x1000000) crcs[i]^=POLYCRC24Q;
}
fprintf(fp,"static const unsigned int tbl_CRC24Q[]={\n");
for (i=0;i<32;i++) {
fprintf(fp," ");
for (j=0;j<8;j++) {
fprintf(fp,"0x%06X%s",crcs[j+i*8],i==31&&j==7?"":",");
}
fprintf(fp,"\n");
}
fprintf(fp,"};\n");
}
/* main ----------------------------------------------------------------------*/
int main(int argc, char **argv)
{
FILE *fp=stdout;
int i,crc=0;
for (i=1;i<argc;i++) {
if (!strcmp(argv[i],"-16")) crc=0;
else if (!strcmp(argv[i],"-24")) crc=1;
}
switch (crc) {
case 0: gen_crc16(fp); break;
case 1: gen_crc24(fp); break;
}
return 0;
}
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