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/*
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The OpenAirInterface Software Alliance licenses this file to You under
* the OAI Public License, Version 1.0 (the "License"); you may not use this file
* except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.openairinterface.org/?page_id=698
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*-------------------------------------------------------------------------------
* For more information about the OpenAirInterface (OAI) Software Alliance:
* contact@openairinterface.org
*/
/* file: crc_byte.c
purpose: generate 3GPP LTE CRCs. Byte-oriented implementation of CRC's
author: raymond.knopp@eurecom.fr
date: 21.10.2009
Original UMTS version by
P. Humblet
May 10, 2001
Modified in June, 2001, to include the length non multiple of 8
*/
#ifndef USER_MODE
#define __NO_VERSION__
#endif
//#include "PHY/types.h"
#include "defs.h"
/*ref 36-212 v8.6.0 , pp 8-9 */
/* the highest degree is set by default */
unsigned int poly24a = 0x864cfb00; //1000 0110 0100 1100 1111 1011 D^24 + D^23 + D^18 + D^17 + D^14 + D^11 + D^10 + D^7 + D^6 + D^5 + D^4 + D^3 + D + 1
unsigned int poly24b = 0x80006300; // 1000 0000 0000 0000 0110 0011 D^24 + D^23 + D^6 + D^5 + D + 1
unsigned int poly16 = 0x10210000; // 0001 0000 0010 0001 D^16 + D^12 + D^5 + 1
unsigned int poly12 = 0x80F00000; // 1000 0000 1111 D^12 + D^11 + D^3 + D^2 + D + 1
unsigned int poly8 = 0x9B000000; // 1001 1011 D^8 + D^7 + D^4 + D^3 + D + 1
/*********************************************************
For initialization && verification purposes,
bit by bit implementation with any polynomial
The first bit is in the MSB of each byte
*********************************************************/
unsigned int
crcbit (unsigned char * inputptr, int octetlen, unsigned int poly)
{
unsigned int i, crc = 0, c;
while (octetlen-- > 0) {
c = (*inputptr++) << 24;
for (i = 8; i != 0; i--) {
if ((1 << 31) & (c ^ crc))
crc = (crc << 1) ^ poly;
else
crc <<= 1;
c <<= 1;
}
}
return crc;
}
/*********************************************************
crc table initialization
*********************************************************/
static unsigned int crc24aTable[256];
static unsigned int crc24bTable[256];
static unsigned short crc16Table[256];
static unsigned short crc12Table[256];
static unsigned char crc8Table[256];
void crcTableInit (void)
{
unsigned char c = 0;
do {
crc24aTable[c] = crcbit (&c, 1, poly24a);
crc24bTable[c] = crcbit (&c, 1, poly24b);
crc16Table[c] = (unsigned short) (crcbit (&c, 1, poly16) >> 16);
crc12Table[c] = (unsigned short) (crcbit (&c, 1, poly12) >> 16);
crc8Table[c] = (unsigned char) (crcbit (&c, 1, poly8) >> 24);
} while (++c);
}
/*********************************************************
Byte by byte implementations,
assuming initial byte is 0 padded (in MSB) if necessary
*********************************************************/
unsigned int
crc24a (unsigned char * inptr, int bitlen)
{
int octetlen, resbit;
unsigned int crc = 0;
octetlen = bitlen / 8; /* Change in octets */
resbit = (bitlen % 8);
while (octetlen-- > 0) {
// printf("in %x => crc %x\n",crc,*inptr);
crc = (crc << 8) ^ crc24aTable[(*inptr++) ^ (crc >> 24)];
}
if (resbit > 0)
crc = (crc << resbit) ^ crc24aTable[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))];
return crc;
}
unsigned int crc24b (unsigned char * inptr, int bitlen)
{
int octetlen, resbit;
unsigned int crc = 0;
octetlen = bitlen / 8; /* Change in octets */
resbit = (bitlen % 8);
while (octetlen-- > 0) {
crc = (crc << 8) ^ crc24bTable[(*inptr++) ^ (crc >> 24)];
}
if (resbit > 0)
crc = (crc << resbit) ^ crc24bTable[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))];
return crc;
}
unsigned int
crc16 (unsigned char * inptr, int bitlen)
{
int octetlen, resbit;
unsigned int crc = 0;
octetlen = bitlen / 8; /* Change in octets */
resbit = (bitlen % 8);
while (octetlen-- > 0) {
crc = (crc << 8) ^ (crc16Table[(*inptr++) ^ (crc >> 24)] << 16);
}
if (resbit > 0)
crc = (crc << resbit) ^ (crc16Table[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))] << 16);
return crc;
}
unsigned int
crc12 (unsigned char * inptr, int bitlen)
{
int octetlen, resbit;
unsigned int crc = 0;
octetlen = bitlen / 8; /* Change in octets */
resbit = (bitlen % 8);
while (octetlen-- > 0) {
crc = (crc << 8) ^ (crc12Table[(*inptr++) ^ (crc >> 24)] << 16);
}
if (resbit > 0)
crc = (crc << resbit) ^ (crc12Table[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))] << 16);
return crc;
}
unsigned int
crc8 (unsigned char * inptr, int bitlen)
{
int octetlen, resbit;
unsigned int crc = 0;
octetlen = bitlen / 8; /* Change in octets */
resbit = (bitlen % 8);
while (octetlen-- > 0) {
crc = crc8Table[(*inptr++) ^ (crc >> 24)] << 24;
}
if (resbit > 0)
crc = (crc << resbit) ^ (crc8Table[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))] << 24);
return crc;
}
uint8_t check_crc(uint8_t *decoded_bytes, uint16_t len, uint8_t crc_type)
{
uint8_t crc_len,temp;
uint16_t oldcrc,crc;
switch (crc_type) {
case CRC24_A:
case CRC24_B:
crc_len=3;
break;
case CRC16:
crc_len=2;
break;
case CRC8:
crc_len=1;
break;
default:
crc_len=3;
}
// check the CRC
oldcrc= *((unsigned int *)(&decoded_bytes[(len>>3)-crc_len]));
switch (crc_type) {
case CRC24_A:
oldcrc&=0x00ffffff;
crc = crc24a(decoded_bytes,len-24)>>8;
temp=((uint8_t *)&crc)[2];
((uint8_t *)&crc)[2] = ((uint8_t *)&crc)[0];
((uint8_t *)&crc)[0] = temp;
break;
case CRC24_B:
oldcrc&=0x00ffffff;
crc = crc24b(decoded_bytes,len-24)>>8;
temp=((uint8_t *)&crc)[2];
((uint8_t *)&crc)[2] = ((uint8_t *)&crc)[0];
((uint8_t *)&crc)[0] = temp;
break;
case CRC16:
oldcrc&=0x0000ffff;
crc = crc16(decoded_bytes,
len-16)>>16;
break;
case CRC8:
oldcrc&=0x000000ff;
crc = crc8(decoded_bytes,
len-8)>>24;
break;
default:
printf("FATAL: Unknown CRC\n");
return(255);
break;
}
printf("old CRC %x, CRC %x \n",oldcrc,crc);
return (crc == oldcrc);
}
#ifdef DEBUG_CRC
/*******************************************************************/
/**
Test code
********************************************************************/
#include <stdio.h>
main()
{
unsigned char test[] = "Thebigredfox";
crcTableInit();
printf("%x\n", crcbit(test, sizeof(test) - 1, poly24));
printf("%x\n", crc24(test, (sizeof(test) - 1)*8));
printf("%x\n", crcbit(test, sizeof(test) - 1, poly8));
printf("%x\n", crc8(test, (sizeof(test) - 1)*8));
}
#endif