/* * 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