问如何掩码比特？

EN

int x = (int)byte_value;

x = ((x << 4) | x) & 0b0000111100001111;
x = ((x << 2) | x) & 0b0011001100110011;
x = ((x << 1) | x) & 0b0101010101010101;
x = (x << 1) | x;

x = (x & 0b0101010101010101) | (~x & 0b1010101010101010);

unsigned char b = 0xff;
unsigned int result = 0x0;

for (int i=0; i<8; i++) {
    result <<= 2;  // make place for the next 2 bits

    int isSet = b & 0x80; // check highest significant bit of b
    if (isSet) {
        result |= 0x01;  // in bits: 01
    }
    else {
        result |= 0x02; // in bits: 10
    }

    b <<= 1;
}