C中的位域内存管理

#include <stdio.h>

int main()
{
    int a;
    typedef struct {
        int b7 : 1;
        int b6 : 1;
        int b5 : 1;
        int b4 : 1;
        int b3 : 1;
        int b2 : 1;
        int b1 : 1;
        int b0 : 1;
    } byte;

    byte ab0 = {0,1};
    a = *(int*)&ab0;
    printf("ab0 is %x \n",a);

    byte ab1 = {0,1,0};
    a = *(int*)&ab1;
    printf("ab1 is %x \n",a);

    byte ab2 = {0,0};
    a = *(int*)&ab2;
    printf("ab2 is %x \n",a);

    byte ab3 = {0,0};
    a = *(int*)&ab3;
    printf("ab3 is %x \n",a);

    byte ab4 = {0,0};
    a = *(int*)&ab4;
    printf("ab4 is %x \n",a);

    byte ab5 = {0,0};
    a = *(int*)&ab5;
    printf("ab5 is %x \n",a);

    byte ab6 = {0,0};
    a = *(int*)&ab6;
    printf("ab6 is %x \n",a);

    byte ab7 = {1,0};
    a = *(int*)&ab7;
    printf("ab7 is %x \n",a);

    return 0;
}

编译并运行

gcc -Wall test.c
./a.out 
ab0 is 80 
ab1 is 40 
ab2 is 20 
ab3 is 10 
ab4 is 8 
ab5 is 4 
ab6 is 2 
ab7 is 1

我在线运行代码时输出相同
http://codepad.org/ntqyuixp

我无法理解它的输出.

预期产出：
根据我的理解输出应该是

ab0 is 1 
ab1 is 2 
ab2 is 4 
ab3 is 8 
ab4 is 10 
ab5 is 20 
ab6 is 40 
ab7 is 80

>请让我知道我错过了什么.
> endianness是否扮演任何角色？
>如何为我预期的行为编写代码？