Question

我试图定义一个用于在8位单字节记录上保留位标志的公共结构，以避免使用逐位操作使我的代码混乱。这就是我所拥有的：

var http = require("http");

http.createServer(function(request,response){

    response.writeHead(200, {"content-type":"text/html"});
    response.write("hello world");
    response.end();

}).listen(8080);

console.log("server is running....");

这是输出：

typedef struct
{
    uint8_t v1:1; // Bit 7
    uint8_t v2:1; // Bit 6
    uint8_t v3:1; // Bit 5
    uint8_t v4:1; // Bit 4
    uint8_t v5:1; // Bit 3
    uint8_t v6:1; // Bit 2
    uint8_t v7:1; // Bit 1
    uint8_t v8:1; // Bit 0
} record8x1_t;

typedef struct
{
    uint8_t v1:2; // Bits 7-6
    uint8_t v2:2; // Bits 5-4
    uint8_t v3:2; // Bits 3-2
    uint8_t v4:2; // Bits 1-0
} record8x2_t;

typedef struct
{
    uint8_t v1:4; // Bits 7-4
    uint8_t v2:4; // Bits 3-0
} record8x4_t;

typedef union
{
    uint8_t value;
    record8x1_t s1;
    record8x2_t s2;
    record8x4_t s4;
} record8_t;


record8_t eight_bits;
eight_bits.value = 0x0D;

std::cout << "eight_bits.s1.v1 = " << (int)eight_bits.s1.v1 << std::endl;
std::cout << "eight_bits.s1.v2 = " << (int)eight_bits.s1.v2 << std::endl;
std::cout << "eight_bits.s1.v3 = " << (int)eight_bits.s1.v3 << std::endl;
std::cout << "eight_bits.s1.v4 = " << (int)eight_bits.s1.v4 << std::endl;
std::cout << "eight_bits.s1.v5 = " << (int)eight_bits.s1.v5 << std::endl;
std::cout << "eight_bits.s1.v6 = " << (int)eight_bits.s1.v6 << std::endl;
std::cout << "eight_bits.s1.v7 = " << (int)eight_bits.s1.v7 << std::endl;
std::cout << "eight_bits.s1.v8 = " << (int)eight_bits.s1.v8 << std::endl;
std::cout << std::endl;
std::cout << "eight_bits.s2.v1 = " << (int)eight_bits.s2.v1 << std::endl;
std::cout << "eight_bits.s2.v2 = " << (int)eight_bits.s2.v2 << std::endl;
std::cout << "eight_bits.s2.v3 = " << (int)eight_bits.s2.v3 << std::endl;
std::cout << "eight_bits.s2.v4 = " << (int)eight_bits.s2.v4 << std::endl;
std::cout << std::endl;
std::cout << "eight_bits.s4.v1 = " << (int)eight_bits.s4.v1 << std::endl;
std::cout << "eight_bits.s4.v2 = " << (int)eight_bits.s4.v2 << std::endl;

我期待这些位从左到右，从高到低依次为 00001101 ，而不是相反的 1011000 。我在 CentOS 6.8 主机上使用 g ++（GCC）4.4.7 20120313（Red Hat 4.4.7-17）。

问题：这是一个大/小端的东西还是编译器依赖的？是否有某种 pragma 设置来解决这个问题？

这是我期待的输出：

eight_bits.s1.v1 = 1
eight_bits.s1.v2 = 0
eight_bits.s1.v3 = 1
eight_bits.s1.v4 = 1
eight_bits.s1.v5 = 0
eight_bits.s1.v6 = 0
eight_bits.s1.v7 = 0
eight_bits.s1.v8 = 0

eight_bits.s2.v1 = 1
eight_bits.s2.v2 = 3
eight_bits.s2.v3 = 0
eight_bits.s2.v4 = 0

eight_bits.s4.v1 = 13
eight_bits.s4.v2 = 0

位标志的C / C ++结构（位顺序）

0 个答案: