215 lines
6.3 KiB
C
215 lines
6.3 KiB
C
/*
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* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The OpenAirInterface Software Alliance licenses this file to You under
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* the OAI Public License, Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.openairinterface.org/?page_id=698
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*-------------------------------------------------------------------------------
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* For more information about the OpenAirInterface (OAI) Software Alliance:
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* contact@openairinterface.org
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*/
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/* file: crc_byte.c
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purpose: generate 3GPP LTE CRCs. Byte-oriented implementation of CRC's
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author: raymond.knopp@eurecom.fr
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date: 21.10.2009
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Original UMTS version by
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P. Humblet
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May 10, 2001
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Modified in June, 2001, to include the length non multiple of 8
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*/
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#include "coding_defs.h"
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/*ref 36-212 v8.6.0 , pp 8-9 */
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/* the highest degree is set by default */
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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
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unsigned int poly24b = 0x80006300; // 1000 0000 0000 0000 0110 0011 D^24 + D^23 + D^6 + D^5 + D + 1
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unsigned int poly16 = 0x10210000; // 0001 0000 0010 0001 D^16 + D^12 + D^5 + 1
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unsigned int poly12 = 0x80F00000; // 1000 0000 1111 D^12 + D^11 + D^3 + D^2 + D + 1
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unsigned int poly8 = 0x9B000000; // 1001 1011 D^8 + D^7 + D^4 + D^3 + D + 1
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/*********************************************************
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For initialization && verification purposes,
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bit by bit implementation with any polynomial
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The first bit is in the MSB of each byte
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*********************************************************/
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unsigned int
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crcbit (unsigned char * inputptr, int octetlen, unsigned int poly)
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{
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unsigned int i, crc = 0, c;
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while (octetlen-- > 0) {
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c = (*inputptr++) << 24;
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for (i = 8; i != 0; i--) {
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if ((1 << 31) & (c ^ crc))
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crc = (crc << 1) ^ poly;
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else
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crc <<= 1;
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c <<= 1;
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}
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}
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return crc;
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}
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/*********************************************************
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crc table initialization
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*********************************************************/
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static unsigned int crc24aTable[256];
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static unsigned int crc24bTable[256];
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static unsigned short crc16Table[256];
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static unsigned short crc12Table[256];
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static unsigned char crc8Table[256];
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void crcTableInit (void)
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{
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unsigned char c = 0;
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do {
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crc24aTable[c] = crcbit (&c, 1, poly24a);
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crc24bTable[c] = crcbit (&c, 1, poly24b);
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crc16Table[c] = (unsigned short) (crcbit (&c, 1, poly16) >> 16);
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crc12Table[c] = (unsigned short) (crcbit (&c, 1, poly12) >> 16);
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crc8Table[c] = (unsigned char) (crcbit (&c, 1, poly8) >> 24);
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} while (++c);
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}
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/*********************************************************
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Byte by byte implementations,
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assuming initial byte is 0 padded (in MSB) if necessary
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*********************************************************/
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unsigned int
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crc24a (unsigned char * inptr, int bitlen)
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{
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int octetlen, resbit;
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unsigned int crc = 0;
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octetlen = bitlen / 8; /* Change in octets */
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resbit = (bitlen % 8);
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while (octetlen-- > 0) {
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// printf("crc24a: in %x => crc %x\n",crc,*inptr);
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crc = (crc << 8) ^ crc24aTable[(*inptr++) ^ (crc >> 24)];
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}
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if (resbit > 0)
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crc = (crc << resbit) ^ crc24aTable[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))];
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return crc;
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}
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unsigned int crc24b (unsigned char * inptr, int bitlen)
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{
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int octetlen, resbit;
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unsigned int crc = 0;
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octetlen = bitlen / 8; /* Change in octets */
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resbit = (bitlen % 8);
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while (octetlen-- > 0) {
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// printf("crc24b: in %x => crc %x (%x)\n",crc,*inptr,crc24bTable[(*inptr) ^ (crc >> 24)]);
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crc = (crc << 8) ^ crc24bTable[(*inptr++) ^ (crc >> 24)];
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}
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if (resbit > 0)
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crc = (crc << resbit) ^ crc24bTable[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))];
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return crc;
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}
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unsigned int
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crc16 (unsigned char * inptr, int bitlen)
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{
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int octetlen, resbit;
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unsigned int crc = 0;
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octetlen = bitlen / 8; /* Change in octets */
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resbit = (bitlen % 8);
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while (octetlen-- > 0) {
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crc = (crc << 8) ^ (crc16Table[(*inptr++) ^ (crc >> 24)] << 16);
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}
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if (resbit > 0)
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crc = (crc << resbit) ^ (crc16Table[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))] << 16);
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return crc;
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}
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unsigned int
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crc12 (unsigned char * inptr, int bitlen)
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{
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int octetlen, resbit;
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unsigned int crc = 0;
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octetlen = bitlen / 8; /* Change in octets */
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resbit = (bitlen % 8);
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while (octetlen-- > 0) {
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crc = (crc << 8) ^ (crc12Table[(*inptr++) ^ (crc >> 24)] << 16);
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}
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if (resbit > 0)
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crc = (crc << resbit) ^ (crc12Table[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))] << 16);
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return crc;
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}
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unsigned int
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crc8 (unsigned char * inptr, int bitlen)
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{
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int octetlen, resbit;
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unsigned int crc = 0;
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octetlen = bitlen / 8; /* Change in octets */
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resbit = (bitlen % 8);
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while (octetlen-- > 0) {
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crc = crc8Table[(*inptr++) ^ (crc >> 24)] << 24;
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}
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if (resbit > 0)
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crc = (crc << resbit) ^ (crc8Table[((*inptr) >> (8 - resbit)) ^ (crc >> (32 - resbit))] << 24);
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return crc;
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}
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#ifdef DEBUG_CRC
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/*******************************************************************/
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/**
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Test code
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********************************************************************/
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#include <stdio.h>
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main()
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{
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unsigned char test[] = "Thebigredfox";
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crcTableInit();
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printf("%x\n", crcbit(test, sizeof(test) - 1, poly24));
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printf("%x\n", crc24(test, (sizeof(test) - 1)*8));
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printf("%x\n", crcbit(test, sizeof(test) - 1, poly8));
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printf("%x\n", crc8(test, (sizeof(test) - 1)*8));
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}
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#endif
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