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crc4.c File Reference

#include "standard.h"
#include "bits.h"

Go to the source code of this file.

Defines

#define GENPOLY   0x0017

Functions

unsigned int makecrc4 (unsigned int b)
int checkcrc4 (unsigned int b)

Define Documentation

#define GENPOLY   0x0017
 

Definition at line 12 of file crc4.c.

Referenced by checkcrc4(), and makecrc4().

Function Documentation

int checkcrc4 (  unsigned int  b  ) 
 

Definition at line 33 of file crc4.c.

References GENPOLY, and getbitint().

00039 {
00040   int i;
00041         
00042   i=1;
00043   while (b>=16) { /* >= than 2^4, so degree(b) >= degree(genpoly) */
00044   if (getbitint(b,i) == 1)
00045     b ^= GENPOLY << (12-i); /* reduce with GENPOLY */
00046   i++;
00047   }
00048 /*  printf("b: %d\n",b); */
00049   return (b==0);
00050 }

unsigned int makecrc4 (  unsigned int  b  ) 
 

Definition at line 14 of file crc4.c.

References GENPOLY, and getbitint().

Referenced by make_backward_control(), and make_forward_control().

00021 {
00022   int i;
00023         
00024   i=1;
00025   while (b>=16) { /* >= 2^4, so degree(b) >= degree(genpoly) */
00026     if (getbitint(b,i) == 1)
00027       b ^= GENPOLY << (12-i); /* reduce with GENPOLY */
00028     i++;
00029   }
00030   return b;
00031 }

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