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