我这几天看了下CRC具体校验原理，我看网上都没有一个通用的CRC库，都是一个函数写一种校验方式的那种，以下代码是随手写的一个通用的CRC软件模块， 支持最小单位字节的输入，有问题大家一起讨论。移植时需要修改的点可能是数据类型的重新定义。
#ifndef __CRC_H
#define __CRC_H#include "BSPTypeDef.h"typedef enum
{CRC4_ITU, CRC5_EPC, CRC5_ITU, CRC5_USB, CRC6_ITU, CRC7_MMC, CRC8, CRC8_ITU, CRC8_ROHC, CRC8_MAXIM, CRC16_IBM, CRC16_MAXIM, CRC16_USB, CRC16_MODBUS, CRC16_CCITT, CRC16_CCITT_FALSE, CRC16_X25, CRC16_XMODEM, CRC16_DNP, CRC32, CRC32_MPEG2, CRC_TYPE_NUM,
} E_CRC_TYPE;typedef struct
{E_CRC_TYPE Crc_Type; uint8 Crc_Width; uint8 Crc_InputInvert; uint8 Crc_OutputInvert; uint32 Crc_Poly; uint32 Crc_Init_Value; uint32 Crc_Xorout;
} CRC_TYPE;
uint32 calc_crc(E_CRC_TYPE crc_type, uint8 *pData, uint16 u16Len);
#endif
#include "crc.h"CRC_TYPE crc_map[] = {{CRC4_ITU, 4, TRUE, TRUE, 0x03, 0x00, 0x00},{CRC5_EPC, 5, FALSE, FALSE, 0x09, 0x09, 0x00},{CRC5_ITU, 5, TRUE, TRUE, 0x15, 0x00, 0x00},{CRC5_USB, 5, TRUE, TRUE, 0x05, 0x1F, 0x1F},{CRC6_ITU, 6, TRUE, TRUE, 0x03, 0x00, 0x00},{CRC7_MMC, 7, FALSE, FALSE, 0x09, 0x00, 0x00},{CRC8, 8, FALSE, FALSE, 0x07, 0x00, 0x00},{CRC8_ITU, 8, FALSE, FALSE, 0x07, 0x00, 0x55},{CRC8_ROHC, 8, TRUE, TRUE, 0x07, 0xFF, 0x00},{CRC8_MAXIM, 8, TRUE, TRUE, 0x31, 0x00, 0x00},{CRC16_IBM, 16, TRUE, TRUE, 0x8005, 0x0000, 0x0000},{CRC16_MAXIM, 16, TRUE, TRUE, 0x8005, 0x0000, 0xFFFF},{CRC16_USB, 16, TRUE, TRUE, 0x8005, 0xFFFF, 0xFFFF},{CRC16_MODBUS, 16, TRUE, TRUE, 0x8005, 0xFFFF, 0x0000},{CRC16_CCITT, 16, TRUE, TRUE, 0x1021, 0x0000, 0x0000},{CRC16_CCITT_FALSE, 16, FALSE, FALSE, 0x1021, 0xFFFF, 0x0000}, {CRC16_X25, 16, TRUE, TRUE, 0x1021, 0xFFFF, 0xFFFF},{CRC16_XMODEM, 16, FALSE, FALSE, 0x1021, 0x0000, 0x0000},{CRC16_DNP, 16, TRUE, TRUE, 0x3D65, 0x0000, 0xFFFF},{CRC32, 32, TRUE, TRUE, 0x04C11DB7, 0xFFFFFFFF, 0xFFFFFFFF},{CRC32_MPEG2, 32, FALSE, FALSE, 0x04C11DB7, 0xFFFFFFFF, 0x00000000},
};
static void Data_Bit_Invert(uint8_t *OutBuf, uint8_t *InBuf, uint8 Bit_Len);
static void Data_Bit_Invert(uint8_t *OutBuf, uint8_t *InBuf, uint8 Bit_Len)
{uint8 i;uint32 Intmp = 0;uint32 Outtmp = 0;if((void*)0 == OutBuf || (void*)0 == InBuf || 32 < Bit_Len){return;}for(i = 0; i < Bit_Len / 8; i++){Intmp |= (InBuf[i] << (i * 8));}if(0 != Bit_Len%8){Intmp |= ((InBuf[i] << (i * 8)) & ((0xFF >> (8 - (Bit_Len % 8))) << (i * 8)));}for(i = 0; i < Bit_Len; i++){if(Intmp & (1 << i)){Outtmp |= (1 << (Bit_Len - 1 - i));}}for(i = 0; i < Bit_Len / 8; i++){OutBuf[i] = ((Outtmp >> (i * 8)) & 0xFF);}if(0 != Bit_Len % 8){OutBuf[i] &= (~(0xFF >> (8 - (Bit_Len % 8))));OutBuf[i] |= ((Outtmp >> (i * 8)) & (0xFF >> (8 - (Bit_Len % 8))));}
}
uint32 calc_crc(E_CRC_TYPE crc_type, uint8 *pData, uint16 u16Len)
{uint8 tmpdata = 0;uint8 Crc_Width = crc_map[crc_type].Crc_Width; uint8 Crc_InputInvert = crc_map[crc_type].Crc_InputInvert; uint8 Crc_OutputInvert = crc_map[crc_type].Crc_OutputInvert; uint32 Crc_Poly = crc_map[crc_type].Crc_Poly; uint32 Crc_Init_Value = crc_map[crc_type].Crc_Init_Value; uint32 Crc_Xorout = crc_map[crc_type].Crc_Xorout; uint32 u32CrcVal = 0;if ((void*)0 == pData || 0 == u16Len || CRC_TYPE_NUM <= crc_type) {return u32CrcVal;}u32CrcVal = Crc_Init_Value; while(u16Len--){if(TRUE == Crc_InputInvert) {Data_Bit_Invert(&tmpdata, pData, 8);}else{tmpdata = *pData;}if(Crc_Width >= 8) {u32CrcVal ^= (tmpdata << (Crc_Width - 8));}else {u32CrcVal <<= (8 - Crc_Width); u32CrcVal ^= tmpdata;}for (uint8 i = 0; i < 8; i++){if(Crc_Width >= 8) {if (u32CrcVal & (0x00000001 << (Crc_Width - 1))){ u32CrcVal <<= 1; u32CrcVal ^= Crc_Poly;}else{u32CrcVal <<= 1;}}else {if (u32CrcVal & (0x00000001 << 7)){ u32CrcVal <<= 1;u32CrcVal ^= (Crc_Poly << (8 - Crc_Width));}else{u32CrcVal <<= 1;}} }if(Crc_Width >= 8){}else {u32CrcVal >>= (8 - Crc_Width);} u32CrcVal &= (0xFFFFFFFF >> (8 * sizeof(uint32) - Crc_Width)); pData++;}if(TRUE == Crc_OutputInvert) {Data_Bit_Invert((uint8*)&u32CrcVal, (uint8*)&u32CrcVal, Crc_Width);} u32CrcVal ^= Crc_Xorout; return u32CrcVal;
}
