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C语言常用的工具函数（自用一）
1、查表法计算crc
1.1、crc16
#define CRC16_WIDTH 16
#define POLYNOMIAL_16 0x1021
#define CRC16_PRELOAD 0xFFFF
//查表法计算crc16
const uint16_t crc16OffsetTable[256]= {
0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
0x1231,0x0210,0x3273,0x2252,0x52b5,0x4294,0x72f7,0x62d6,
0x9339,0x8318,0xb37b,0xa35a,0xd3bd,0xc39c,0xf3ff,0xe3de,
0x2462,0x3443,0x0420,0x1401,0x64e6,0x74c7,0x44a4,0x5485,
0xa56a,0xb54b,0x8528,0x9509,0xe5ee,0xf5cf,0xc5ac,0xd58d,
0x3653,0x2672,0x1611,0x0630,0x76d7,0x66f6,0x5695,0x46b4,
0xb75b,0xa77a,0x9719,0x8738,0xf7df,0xe7fe,0xd79d,0xc7bc,
0x48c4,0x58e5,0x6886,0x78a7,0x0840,0x1861,0x2802,0x3823,
0xc9cc,0xd9ed,0xe98e,0xf9af,0x8948,0x9969,0xa90a,0xb92b,
0x5af5,0x4ad4,0x7ab7,0x6a96,0x1a71,0x0a50,0x3a33,0x2a12,
0xdbfd,0xcbdc,0xfbbf,0xeb9e,0x9b79,0x8b58,0xbb3b,0xab1a,
0x6ca6,0x7c87,0x4ce4,0x5cc5,0x2c22,0x3c03,0x0c60,0x1c41,
0xedae,0xfd8f,0xcdec,0xddcd,0xad2a,0xbd0b,0x8d68,0x9d49,
0x7e97,0x6eb6,0x5ed5,0x4ef4,0x3e13,0x2e32,0x1e51,0x0e70,
0xff9f,0xefbe,0xdfdd,0xcffc,0xbf1b,0xaf3a,0x9f59,0x8f78,
0x9188,0x81a9,0xb1ca,0xa1eb,0xd10c,0xc12d,0xf14e,0xe16f,
0x1080,0x00a1,0x30c2,0x20e3,0x5004,0x4025,0x7046,0x6067,
0x83b9,0x9398,0xa3fb,0xb3da,0xc33d,0xd31c,0xe37f,0xf35e,
0x02b1,0x1290,0x22f3,0x32d2,0x4235,0x5214,0x6277,0x7256,
0xb5ea,0xa5cb,0x95a8,0x8589,0xf56e,0xe54f,0xd52c,0xc50d,
0x34e2,0x24c3,0x14a0,0x0481,0x7466,0x6447,0x5424,0x4405,
0xa7db,0xb7fa,0x8799,0x97b8,0xe75f,0xf77e,0xc71d,0xd73c,
0x26d3,0x36f2,0x0691,0x16b0,0x6657,0x7676,0x4615,0x5634,
0xd94c,0xc96d,0xf90e,0xe92f,0x99c8,0x89e9,0xb98a,0xa9ab,
0x5844,0x4865,0x7806,0x6827,0x18c0,0x08e1,0x3882,0x28a3,
0xcb7d,0xdb5c,0xeb3f,0xfb1e,0x8bf9,0x9bd8,0xabbb,0xbb9a,
0x4a75,0x5a54,0x6a37,0x7a16,0x0af1,0x1ad0,0x2ab3,0x3a92,
0xfd2e,0xed0f,0xdd6c,0xcd4d,0xbdaa,0xad8b,0x9de8,0x8dc9,
0x7c26,0x6c07,0x5c64,0x4c45,0x3ca2,0x2c83,0x1ce0,0x0cc1,
0xef1f,0xff3e,0xcf5d,0xdf7c,0xaf9b,0xbfba,0x8fd9,0x9ff8,
0x6e17,0x7e36,0x4e55,0x5e74,0x2e93,0x3eb2,0x0ed1,0x1ef0
};
/**
- @brief 按字节进行crc16计算.
- @note
- @param *data 要计算crc16的数组.
- len 数组中的有效计算字节数
*
- @retval 返回uint16_t类型的crc结果
- @author yangFei
- @date 20220324
- @note
*/
uint16_t crc16Bytewise(const uint8_t *data, uint16_t len)
{
uint16_t crc = CRC16_PRELOAD;
uint8_t *sbuf = (uint8_t *)data;
for (uint32_t counter=0 ; counter<len; ++counter)
{
crc = (crc<<8) ^ crc16OffsetTable[(uint8_t)((crc>>8) ^ *sbuf++)];
}
return ~crc;
}
/**
- @brief 按位进行crc16计算.
- @note
- @param *data 要计算crc16的数组.
- bits 数组中的有效计算位
*
- @retval 返回uint16_t类型的crc结果
- @author yangFei
- @date 20220324
- @note
*/
uint16_t crc16Bitwise(const uint8_t *data, uint16_t bits)
{
uint32_t nbFullBytes = bits/8;
uint16_t crc16 = crc16Bytewise(data, nbFullBytes);
uint32_t nbExtraBits = bits%8;
if (nbExtraBits) {
uint8_t buf[nbFullBytes+1];
crc16 = ~crc16;
buf[nbFullBytes] = data[nbFullBytes] & (uint8_t)(0xFF00 >> nbExtraBits);
crc16 ^= (buf[nbFullBytes] << (CRC16_WIDTH-8));
// Repeat polynomial calculation (avoid loop for best performance)
switch (nbExtraBits) {
case 7: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
case 6: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
case 5: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
case 4: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
case 3: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
case 2: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
case 1: crc16 = (crc16 & (1<<(CRC16_WIDTH-1))) ? (crc16 << 1) ^ POLYNOMIAL_16 : (crc16 << 1); // Fall through
}
crc16 = ~crc16;
}
return crc16;
}
1.2、crc5
/**
- @brief CRC-5计算.
- @note
- @param data 帧有效数据.
- bits 冗余校验比特数
*
- @retval 5位校验结果
- @author yangFei
- @date 20220324
- @note 只适用于RFID协议中的校验，不具备适用性；crc5Bitwise(0x818180,17) = 0x1d
*/
uint8_t crc5Bitwise(uint32_t data, uint16_t bits)
{
uint32_t crc;
uint32_t crc_n;
crc = (0x09 << 19); //19+5 = 24
while(bits--)
{
crc_n = (crc << 1) & 0xFFFFFFFF;
crc_n ^= ((data ^ crc) & (1<<23)) ? (0x29 << (19)) : 0;
crc = crc_n;
data = (data << 1) & 0xFFFFFFFF;
}
crc >>= 19;
crc ^= 0x0000001F;
crc = ~crc;
crc &= 0x0000001F;
return (uint8_t)crc;
}
2、字符转换
/**
* @brief 字符转换位16进制.
* @note
* @param a 传入的字符.
*
* @retval 返回字符对应的16进制
* @author yangFei
* @date 20220324
* @note 小写
*/
uint8_t char2hex(uint8_t a)
{
uint8_t temp;
if((a>='0')&(a<='9'))
return (a-'0');
else
{
switch(a)
{
case 'a':
temp = 10;
break;
case 'b':
temp = 11;
break;
case 'c':
temp = 12;
break;
case 'd':
temp = 13;
break;
case 'e':
temp = 14;
break;
case 'f':
temp = 15;
break;
}
return temp;
}
}
3、长整型和8位字节数组转换
3.1、将长整型中的某几位转为8位字节数组
/**
* @brief 将长整型中的某几位转为8位字节数组.
* @note
* @param long_bit 长整型数据
* @param *short_bit 8位字节数组
* @param bit_len 要转换的位长度
*
* @retval 0：转换成功 1：转换失败
* @author yangFei
* @date 20220328
* @note 默认高位在前
*/
uint8_t long_short_arr(uint64_t long_bit, uint8_t *short_bit, uint8_t bit_len)
{
uint8_t short_bytes;
short_bytes = bit_len / 8;
if(bit_len % 8)
{
short_bytes += 1;
}
if(short_bytes > 8)
{
return 1;
}
for(uint8_t i=0; i<short_bytes; i++)
{
short_bit[short_bytes-1-i] = (long_bit >> (i*8)) & 0xff;
}
return 0;
}
3.2、将8位字节数组转为长整型中的某几位
/**
* @brief 将某几位为8位字节数组转为长整型.
* @note
* @param *short_bit 8位字节数组
* @param bit_len 要转换的位长度
*
* @retval 转换后的长整型
* @author yangFei
* @date 20220328
* @note 默认高位在前
*/
uint64_t short_arr_long(uint8_t *short_bit, uint8_t bit_len)
{
uint8_t short_bytes;
uint64_t long_data = 0;
short_bytes = bit_len / 8;
if(bit_len % 8)
{
short_bytes += 1;
}
for(uint8_t i=0; i<short_bytes; i++)
{
long_data |= (short_bit[i] << ((short_bytes-1-i) * 8));
}
return long_data;
}
4、延时相关函数（基于stm32）
4.1、SysTick和nop延时
/**
* @brief 死循环us延时.
* @note
* @param nus 微秒数.
*
* @retval
* @author yangFei
* @date 20220324
* @note 若使用SysTick仍然有不可接受的误差，使用__NOP().
*/
void delay_us(uint32_t nus)
{
#define clock (SystemCoreClock / 1000000)
uint32_t ticks;
uint32_t told,tnow,tcnt = 0;
uint32_t reload = SysTick->LOAD; //LOAD的值
ticks = clock * nus; //需要的节拍数
// CPU_CRITICAL_ENTER(); /* close interrupt */
told = SysTick->VAL; //刚进入时的计数器值
while(1)
{
tnow = SysTick->VAL;
if(tnow != told)
{
if(tnow < told) tcnt += told - tnow; //这里注意一下SYSTICK是一个递减的计数器就可以了
else tcnt += reload - tnow + told;
told = tnow;
if(tcnt >= ticks)break; //时间超过/等于要延迟的时间,则退出.
}
};
// //CPU_CRITICAL_EXIT(); //恢复关中断前状态
// for(uint32_t i=0; i<nus; i++)//需要手动根据时钟计算需要几个__NOP() 80M情况下大概20个 是3.2us
// {
// // __NOP();
// // __NOP();
// // __NOP();
// // __NOP();
// //
// // __NOP();
// // __NOP();
// // __NOP();
// // __NOP();
//
//
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// __NOP();
// }
}
4.2、DWT ns延时
#define NS_TO_CYCLES(ns) (((ns)*2)/25)
#define INIT_DWT() { CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk; \
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk; \
RESET_DWT(); \
}
#define RESET_DWT() DWT->CYCCNT = 0
#define GET_DWT() (DWT->CYCCNT)
/**
* @brief DWT ns延时
* @note
* @param nsec ns延时.
*
* @retval
* @author yangFei
* @date 20220401
* @note 调用此函数前需调用INIT_DWT(); RESET_DWT();
*/
void nsdelay(uint32_t nsec)
{
RESET_DWT();
uint32_t cycles = NS_TO_CYCLES(nsec)-(nsec < 8000 ? 25 : 20); // -25/-20: compensate function call overhead
do
{
__NOP(); // Avoid code optimization
} while(GET_DWT() < cycles);
}
5、位循环移动
//循环左移
#define ROTATE_LEFT(x, n) ((x) << (n)) | ((x) >> ((8*sizeof(x)) - (n)))
//循环右移
#define ROTATE_RIGHT(x, n) ((x) >> (n)) | ((x) << ((8*sizeof(x)) - (n)))
