數組數據整體按位左移或右移一位

數組數據整體按位左移或右移一位

#include <stdio.h>

#define MSB        0x80
#define LSB        0x01

// 數組數據整體按位左移一位
int left_shift(unsigned char *str, int len)
{
    int i;
    
    for(i = 1; i <= len; i++)
    {
        str[i-1] = str[i-1] << 1;
        
        if(i < len && str[i] & MSB)
        {
            str[i-1] = str[i-1] | LSB;    
        }    
    }
    
    return 0;
}

// 數組數據整體按位右移一位
int right_shift(unsigned char *str, int len)
{
    int i;
    
    for(i = len-1; i >= 0; i--)
    {
        str[i] = str[i] >> 1;
        if(i > 0 && str[i-1] & LSB)
        {
            str[i] = str[i] | MSB;    
        }    
    }
    
    return 0;    
}

int main(void)
{
    int i;
    unsigned char x1[] = {0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01};
    unsigned char x2[] = {0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01};

    left_shift(x1, sizeof(x1)/sizeof(x1[0]));
    
    right_shift(x2, sizeof(x2)/sizeof(x2[0]));
    
    for(i = 0; i < sizeof(x1)/sizeof(x1[0]); i++)
        printf("%02x ", x1[i]);
    printf("\n");
    
    for(i = 0; i < sizeof(x2)/sizeof(x2[0]); i++)
        printf("%02x ", x2[i]);    
        
    
    return 0;    
}