https://gist.github.com/janek2012/7493983/raw/0ede6a37f321a7478f4094506cc80700bf42ea99/crc-129.c

/* generate crc table crc-ccitt */
/* crc-ccitt is based on the polynomial x^16+x^12+x^5+1 */
/* The prescription for determining the mask to use for a given polynomial
	is as follows:
		1.  Represent the polynomial by a 17-bit number
		2.  Assume that the most and least significant bits are 1
		3.  Place the right 16 bits into an integer
*/

#include	<stdio.h>
#include	<stdlib.h>
#include	<string.h>


#define		MTT	0x1021		/* crc-ccitt mask */

/* function declarations */
unsigned long long updcrc(unsigned long long,int,unsigned long long);
void perr(char *);

/* driver */
int main()
{
	int i,j;
	printf("\n\t");
	for(i=0;i<32;i++)
	{
		for(j=0;j<8;j++) printf("0x%04X, ",updcrc(0,8*i+j,MTT));
		printf("\n\t");
	}
	return 0;
}

/* update crc */
unsigned long long updcrc(crc,c,mask)
unsigned long long crc,mask; int c;
{
	int i;
	c<<=8;
	for(i=0;i<64;i++)
	{
		if((crc ^ c) & 0x8000) crc=(crc<<1)^mask;
		else crc<<=1;
		c<<=1;
	}
	return crc;
}




/* error abort */
void perr(s)
char *s;
{
	printf("\n%s",s); exit(1);
}


/* compute crc's */
/* crc-ccitt is based on the polynomial x^16+x^12+x^5+1 */
/* The prescription for determining the mask to use for a given polynomial
	is as follows:
		1.  Represent the polynomial by a 17-bit number
		2.  Assume that the most and least significant bits are 1
		3.  Place the right 16 bits into an integer
*/
/* Usage : ccittf [filename] */

#include	<stdio.h>
#include	<stdlib.h>
#include	<string.h>
#include	<time.h>


#define		MTT	0x1021		/* crc-ccitt mask */
#define     CLK_TCK CLOCKS_PER_SEC

/* function declarations */
unsigned short int updcrc(unsigned short int,int);
void perr(char *);

/* variables */
char filename[100];
unsigned short int crctt;
int ch;
unsigned long num;
FILE *fp;
unsigned short int crctttab[256] =
{
	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
	0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
	0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
	0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
	0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
	0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
	0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
	0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
	0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
	0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
	0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
	0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
	0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
	0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
	0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
	0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
	0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
	0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
	0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
	0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
	0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
	0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
	0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
	0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
	0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
	0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
	0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
	0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
	0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
	0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
	0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
	0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};

/* driver */
int main(argc,argv)
int argc; char **argv;
{
 clock_t start,end;
	if(argc>2) perr("Usage:  ccittf [filename]");
	if(argc==2) strcpy(filename,argv[1]);
	else
	{
		printf("\nEnter filename:  "); gets(filename);
	}
	if((fp=fopen(filename,"rb"))==NULL) perr("Can't open file");
	num=0L; crctt=0;
	start=clock();
	while((ch=fgetc(fp))!=EOF)
	{
		//if (ch == '\n')
		//	continue;
		num++;
		//int i; for (i=0;i<10000;i++){
		crctt=updcrc(crctt,ch);
		//}
	}
	end=clock();
	fclose(fp);
	printf("\nNumber of bytes = %lu\nCRCTT = %04X\n",
		num,crctt);
	printf("Czas trwania: %f\n",(double)(end-start)/CLK_TCK);
	return 0;
}

/* update crc */
unsigned long long updcrc(crc,c)
unsigned long long  crc; int c;
{
	int tmp;
	tmp=(crc>>64)^c;
	crc=(crc<<64)^crctttab[tmp];
	return crc;
}

/* error abort */
void perr(s)
char *s;
{
	printf("\n%s",s); exit(1);
}