一种BCD码转换的算法

#include "stdio.h"

typedef unsigned char         uint8_t;
typedef unsigned short        uint16_t;
typedef unsigned int          uint32_t;
typedef unsigned long long    uint64_t;

/**
***************************************************************************************************
* @Brief     Decimal convert BCD code
* @Param     _Dec    Decimal    (Max: 2^64)
*            _Buf    BCD code buffer
*            _Num    Decimal digit
* @RetVal    None
* @Note      None
***************************************************************************************************
*/
void Dec_to_BCD(uint64_t _Dec, uint8_t* _Buf, uint8_t _Num)
{
    uint8_t i, n;
    uint8_t flag = 1;  /* BCD码高低字节存放控制标志 */

    /* 内部计算 _Dec 的位数，可省去形参 _Num */
#if 0
    uint8_t _Num;
    uint64_t temp = _Dec;
    do {
        _Num++;
        temp /= 10;
    } while(temp);
#endif

    for (i = 0; i < _Num; i++) {
        if (flag) {
            /* 低字节 */
            _Buf[i/2] = (_Dec % 10) & 0x0F;
            flag = 0;
        } else {
            /* 高字节 */
            _Buf[i/2] |= ((_Dec % 10) & 0x0F) << 4;;
            flag = 1;
        }
        _Dec /= 10;
    }
}

int main(void)
{
    uint8_t i;
    uint8_t buf[5] ={0};

    printf("This is example!\n");

    Dec_to_BCD(1234567890, buf, 10);
    for (i = 0; i < 5; i++) {
        printf("%#X\n", buf[i]);
    }

    return 0;
}