8位字节对齐算法

参考文章

//8位字节对齐算法
void testAlign(){
    for (int i = 0; i <= 10; i++) {
        int align = align8Bit(i);
        printf("the align is %d\n", align);
    }
}

unsigned int align8Bit(unsigned int n){
    return calc_alignFounction2(n, 8);
}

unsigned int calc_alignFounction1(unsigned int n,unsigned align){
    if (n / align * align == n) {
        return n;
    }
    return (n / align + 1) * align;
}

//** 此方法较好 */
/*
 算法说明:
 例如8字节对齐要求，后三位为0.
 (align-1)表示后三位111.
 size+(aling-1)会导致进位。
 &～（aling-1）去除后面多余的。
 */
unsigned int calc_alignFounction2(unsigned int n, unsigned align){
    return (n + (align - 1)) & (~(align - 1));
}