122 lines
4.0 KiB
C
122 lines
4.0 KiB
C
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#include "crc.h"
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//#include <stdio.h> //用于验证和生成CRC_Table
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//X8+X4+X3+X2+1 -> 0X1D -> POLY=B8
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static const unsigned char crc_table[] =
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{
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0x00, 0xb8, 0xc8, 0x70, 0x28, 0x90, 0xe0, 0x58, 0x50, 0xe8, 0x98, 0x20, 0x78, 0xc0, 0xb0, 0x08,
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0xa0, 0x18, 0x68, 0xd0, 0x88, 0x30, 0x40, 0xf8, 0xf0, 0x48, 0x38, 0x80, 0xd8, 0x60, 0x10, 0xa8,
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0xf8, 0x40, 0x30, 0x88, 0xd0, 0x68, 0x18, 0xa0, 0xa8, 0x10, 0x60, 0xd8, 0x80, 0x38, 0x48, 0xf0,
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0x58, 0xe0, 0x90, 0x28, 0x70, 0xc8, 0xb8, 0x00, 0x08, 0xb0, 0xc0, 0x78, 0x20, 0x98, 0xe8, 0x50,
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0x48, 0xf0, 0x80, 0x38, 0x60, 0xd8, 0xa8, 0x10, 0x18, 0xa0, 0xd0, 0x68, 0x30, 0x88, 0xf8, 0x40,
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0xe8, 0x50, 0x20, 0x98, 0xc0, 0x78, 0x08, 0xb0, 0xb8, 0x00, 0x70, 0xc8, 0x90, 0x28, 0x58, 0xe0,
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0xb0, 0x08, 0x78, 0xc0, 0x98, 0x20, 0x50, 0xe8, 0xe0, 0x58, 0x28, 0x90, 0xc8, 0x70, 0x00, 0xb8,
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0x10, 0xa8, 0xd8, 0x60, 0x38, 0x80, 0xf0, 0x48, 0x40, 0xf8, 0x88, 0x30, 0x68, 0xd0, 0xa0, 0x18,
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0x90, 0x28, 0x58, 0xe0, 0xb8, 0x00, 0x70, 0xc8, 0xc0, 0x78, 0x08, 0xb0, 0xe8, 0x50, 0x20, 0x98,
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0x30, 0x88, 0xf8, 0x40, 0x18, 0xa0, 0xd0, 0x68, 0x60, 0xd8, 0xa8, 0x10, 0x48, 0xf0, 0x80, 0x38,
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0x68, 0xd0, 0xa0, 0x18, 0x40, 0xf8, 0x88, 0x30, 0x38, 0x80, 0xf0, 0x48, 0x10, 0xa8, 0xd8, 0x60,
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0xc8, 0x70, 0x00, 0xb8, 0xe0, 0x58, 0x28, 0x90, 0x98, 0x20, 0x50, 0xe8, 0xb0, 0x08, 0x78, 0xc0,
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0xd8, 0x60, 0x10, 0xa8, 0xf0, 0x48, 0x38, 0x80, 0x88, 0x30, 0x40, 0xf8, 0xa0, 0x18, 0x68, 0xd0,
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0x78, 0xc0, 0xb0, 0x08, 0x50, 0xe8, 0x98, 0x20, 0x28, 0x90, 0xe0, 0x58, 0x00, 0xb8, 0xc8, 0x70,
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0x20, 0x98, 0xe8, 0x50, 0x08, 0xb0, 0xc0, 0x78, 0x70, 0xc8, 0xb8, 0x00, 0x58, 0xe0, 0x90, 0x28,
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0x80, 0x38, 0x48, 0xf0, 0xa8, 0x10, 0x60, 0xd8, 0xd0, 0x68, 0x18, 0xa0, 0xf8, 0x40, 0x30, 0x88,
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};
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unsigned char CRC_Calc(unsigned char * dataptr,unsigned char len)
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{
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unsigned char i;
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unsigned char crc=0xFF; // 计算的初始crc值
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while(len--)
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{
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crc ^= *dataptr++; // 每次先与需要计算的数据异或,计算完指向下一数据
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for (i=0; i<8; i++) // 下面这段计算过程与计算一个字节crc一样
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{
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if (crc & 0x80) // 判断最高位是否为1
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// 最高位为1，不需要异或，往左移一位，然后与0x31异或
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// 0x31(多项式：x8+x5+x4+1，100110001)，最高位不需要异或，直接去掉
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//X8+X4+X3+X2+1 -> 0X1D -> B8
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crc = (crc << 1) ^ 0xB8;
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else
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crc = (crc << 1);
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}
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}
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return (crc^0XFF);
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}
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unsigned char CRC_Calc_Table(unsigned char * dataptr,unsigned char len)
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{
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unsigned char crc = 0xFF;
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while (len--)
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{
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crc = crc_table[crc ^ *dataptr++];
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}
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return (crc^0XFF);
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}
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//以下程序用于验证和生成CRC_Table
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/*
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unsigned char cal_table_high_first(unsigned char value)
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{
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unsigned char i, crc;
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crc = value;
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//数据往左移了8位，需要计算8次
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for (i=0; i<8; i++)
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{
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if (crc & 0x80) //判断最高位是否为1
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{
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//最高位为1，不需要异或，往左移一位，然后与0x31异或
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//0x31(多项式：x8+x5+x4+1，100110001)，最高位不需要异或，直接去掉
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//X8+X4+X3+X2+1 -> 0X1D -> B8
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crc = (crc << 1) ^ 0xB8; }
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else
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{
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//最高位为0时，不需要异或，整体数据往左移一位
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crc = (crc << 1);
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}
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}
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return crc;
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}
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//计算crc_Table
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void create_crc_table(void)
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{
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unsigned short i;
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unsigned char j;
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for (i=0; i<=0xFF; i++)
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{
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if (0 == (i%16))
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printf("\n");
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j = i&0xFF;
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printf("0x%.2x, ", cal_table_high_first (j)); //依次计算每个字节的crc校验值
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}
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printf("\n");
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}
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int main()
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{
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unsigned char TestArr[] = {0x00,0x15,0x22,0x11,0xff,0x13,0x66};
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unsigned char crc;
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create_crc_table();
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printf("crc_data = {0x00,0x15,0x22,0x11,0xff,0x13,0x66}\n");
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crc = CRC_Calc(TestArr,7);
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printf("CRC_Calc = 0x%x \n",crc);
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crc = CRC_Calc_Table(TestArr,7);
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printf("CRC_Calc_Table = 0x%x \n",crc);
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return 0;
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}
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*/
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