MSP430实现循环冗余算法

/******************************************************************************;   Code for application report slaa221 - "CRC Implementation with MSP430";;   E.Lenchak;   Texas Instruments, Inc;   March 2004;   Built with IAR Embedded Workbench Version: 3.20A;******************************************************************************; THIS PROGRAM IS PROVIDED "AS IS". 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To protect TI's; rights in the Program, you agree not to decompile, reverse; engineer, disassemble or otherwise translate any object code; versions of the Program to a human-readable form.  You agree; that in no event will you alter, remove or destroy any; copyright notice included in the Program.  TI reserves all; rights not specifically granted under this license. Except; as specifically provided herein, nothing in this agreement; shall be construed as conferring by implication, estoppel,; or otherwise, upon you, any license or other right under any; TI patents, copyrights or trade secrets.;; You may not use the Program in non-TI devices.;;******************************************************************************//**********************************************************************************FUNCTIONS: 16/32-bit CRC Algorithms, bitwsie and table methodsARGUMENTS: "bitwise algorithm function signature"   return: CRC   arg1: CRC init value   arg2: CRC generator polynomial   arg3: pointer to the message   arg4: size of message in bytes  "table-based algorithm function signature"   return: CRC   arg1: CRC init value   arg2: pointer to CRC table (specific to generator polynomial)   arg3: pointer to the message   arg4: size of message in bytes***********************************************************************************/#ifdef __ICC430__＃i nclude  "msp430x16x.h"#endif＃i nclude "..inccrc.h"/************************************** CRC MEMBERS (FUNCTIONS)**************************************/// this is an equivalent C implementation to the assembly implementationunsigned short crc16MakeBitwise(unsigned short crc, unsigned short poly,       unsigned char *pmsg, unsigned int msg_size){    unsigned int i, j, carry;    unsigned char msg;    unsigned short temp; temp = *pmsg++ << 8; temp |= *pmsg++; crc ^= temp;        for(i = 0 ; i < msg_size-2 ; i ++)    {        msg = *pmsg++;          for(j = 0 ; j < 8 ; j++)        {   carry = crc & 0x8000;   crc = (crc << 1) | (msg >> 7);   if(carry) crc ^= poly;   msg <<= 1;        }    }    for(i = 0 ; i < 2 ; i ++)    {     for(j = 0 ; j < 8 ; j++)        {   carry = crc & 0x8000;   crc <<= 1;   if(carry) crc ^= poly;        }     }    return(crc ^ CRC16_FINAL_XOR);}// this is a C-optimized implementationunsigned short crc16MakeBitwise2(unsigned short crc, unsigned short poly,      unsigned char *pmsg, unsigned int msg_size){    unsigned int i, j;    unsigned short msg;        for(i = 0 ; i < msg_size ; i ++)    {        msg = (*pmsg++ << 8);          for(j = 0 ; j < 8 ; j++)        {            if((msg ^ crc) >> 15) crc = (crc << 1) ^ poly;   else crc <<= 1;    msg <<= 1;        }    }       return(crc ^ CRC16_FINAL_XOR);}// this is an equivalent C implementation to the assembly implementationunsigned long crc32MakeBitwise(unsigned long crc, unsigned long poly,       unsigned char *pmsg, unsigned int msg_size){    unsigned int i, j, carry;    unsigned char msg;    unsigned long temp; temp = (unsigned long)(*pmsg++) << 24; temp |= (unsigned long)(*pmsg++) << 16; temp |= (unsigned long)(*pmsg++) << 8; temp |= (unsigned long)(*pmsg++); crc ^= temp;    for(i = 0 ; i < msg_size-4 ; i ++)    {        msg = *pmsg++;  for(j = 0 ; j < 8 ; j++)        {   carry = crc >> 31;   crc = (crc << 1) | (msg >> 7);   if(carry) crc ^= poly;   msg <<= 1;        }    }        for(i = 0 ; i < 4 ; i ++)    {     for(j = 0 ; j < 8 ; j++)        {   carry = crc >> 31;   crc <<= 1;   if(carry) crc ^= poly;        }     }     return(crc ^ CRC32_FINAL_XOR);}// this is a C-optimized implementationunsigned long crc32MakeBitwise2(unsigned long crc, unsigned long poly,         unsigned char *pmsg, unsigned int msg_size){    unsigned int i, j;    unsigned long msg;                for(i = 0 ; i < msg_size ; i++)    {        msg = *pmsg++;        msg <<= 24;                for(j = 0 ; j < 8 ; j++)        {            if((msg ^ crc) >> 31) crc = (crc << 1) ^ poly;   else crc <<= 1;   msg <<= 1;        }    }        return(crc ^ CRC32_FINAL_XOR);}unsigned short crc16MakeTableMethod(unsigned short crc, TBL_MEM unsigned short *table,         unsigned char *pbuffer, unsigned int length){    while(length--)         crc = table[((crc >> 8) ^ *pbuffer++)] ^ (crc << 8); // normal    return(crc ^ CRC16_FINAL_XOR);}unsigned short crc16rMakeTableMethod(unsigned short crc, TBL_MEM unsigned short *table,         unsigned char *pbuffer, unsigned int length){    while(length--)         crc = table[(crc & 0xFF) ^ *pbuffer++] ^ (crc >> 8); // reflected    return(crc ^ CRC16R_FINAL_XOR);}unsigned long crc32MakeTableMethod(unsigned long crc, TBL_MEM unsigned long *table,            unsigned char *pbuffer, unsigned int length){    while(length--)         crc = table[((crc >> 24) ^ *pbuffer++)] ^ (crc << 8); // normal    return(crc ^ CRC32_FINAL_XOR);}unsigned long crc32rMakeTableMethod(unsigned long crc, TBL_MEM unsigned long *table,            unsigned char *pbuffer, unsigned int length){    while(length--)         crc = table[(crc ^ *pbuffer++) & 0xFFL] ^ (crc >> 8); // reflected    return(crc ^ CRC32R_FINAL_XOR);}/************************************ CRC UTILITIES************************************/void crc16BuildTable(unsigned short *ptable, unsigned short poly){ unsigned int i, j;    for(i = 0; i <= 255; i++)    {        ptable[i] = i << 8;        for(j = 0; j < 8; j++)            ptable[i] = (ptable[i] << 1) ^ (ptable[i] & 0x8000 ? poly : 0);    }}void crc32BuildTable(unsigned long *ptable, unsigned long poly){ unsigned int i, j;    for(i = 0; i <= 255; i++)    {        ptable[i] = (long)i << 24;                for(j = 0; j < 8; j++)            ptable[i] = (ptable[i] << 1) ^ (ptable[i] & 0x80000000 ? poly : 0);    }}unsigned long bitReflect(unsigned long data, unsigned int width){    unsigned long result = 0; unsigned int i;    for (i = 1; i < (width + 1); i++)    {        if(data & 1) result |= 0x1L << (width - i);        data >>= 1;    }     return result;}/************************************ END ***************************************/