问并行计算奇偶校验

EN

typedef unsigned uint;

uint parity( uint64_t x )
    {
    uint32_t v = x ^ (x >> 32);
    v ^= v >> 16;
    v ^= v >> 8;
    v ^= v >> 4;
    v ^= v >> 2;
    return (uint)(v ^ (v >> 1)) & 1;
    }

parity(unsigned long):
    mov     rax, rdi
    shr     rax, 32
    xor     eax, edi
    mov     edi, eax
    shr     edi, 16
    xor     eax, edi
    mov     edi, eax
    shr     edi, 8
    xor     eax, edi
    mov     edi, eax
    shr     edi, 4
    xor     eax, edi
    mov     edi, eax
    shr     edi, 2
    xor     eax, edi
    mov     edx, eax 
    shr     eax
    xor     eax, edx 
    and     eax, 1
    ret