翻转一个字节

位操作技巧：字节反转

最新推荐文章于 2022-12-23 17:28:10 发布

原创最新推荐文章于 2022-12-23 17:28:10 发布 · 762 阅读

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#翻转一个字节

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1.查表

unsigned char reverse8( unsigned char c){
    static unsigned char sta[16] ={//不多不少的静态数据
        0x00,0x08,0x04,0x0C,0x02,0x0A,0x06,0x0E,0x01,0x09,0x05,0x0D,0x03,0x0B,0x07,0x0F
    };
    unsigned char d = 0; //没有判断
    d |= (sta[c&0xF]) << 4;
    d |= sta[c>>4];
    return d;
}

2.移位(更快)

unsigned char reverse8_2(unsigned char c) {
    c = (c & 0x55) << 1 | (c & 0xAA) >> 1;
    c = (c & 0x33) << 2 | (c & 0xCC) >> 2;
    c = (c & 0x0F) << 4 | (c & 0xF0) >> 4;
    return c;
}