# x - rax
# temp - rdx
# temp2 - rdi
    .text
    .global bitrev
    .type   bitrev, @function
bitrev:
    movq %rdi,%rax

        #(x & 0x5555555555555555) << 1
    movq %rax, %rdx
    andq $0x5555555555555555, %rdx
    shlq $1, %rdx
        #(x & 0xAAAAAAAAAAAAAAAA) >> 1;
    movq %rax, %rdi
    andq $0xAAAAAAAAAAAAAAAA, %rdi
    shrq $1, %rdi
        #x = temp | temp2;
    movq %rdx, %rax
    orq %rdi, %rax
        #
    movq %rax, %rdx
    andq $0x3333333333333333, %rdx
    shlq $2, %rdx
        #
    movq %rax, %rdi
    andq $0xCCCCCCCCCCCCCCCC, %rdi
    shrq $2, %rdi
        #
    movq %rdx, %rax
    orq %rdi, %rax

        #
    movq %rax, %rdx
    andq $0x0F0F0F0F0F0F0F0F, %rdx
    shlq $4, %rdx
        #
    movq %rax, %rdi
    andq $0xF0F0F0F0F0F0F0F0, %rdi
    shrq $4, %rdi
        #
    movq %rdx, %rax
    orq %rdi, %rax

        #
    movq %rax, %rdx
    andq $0x00FF00FF00FF00FF, %rdx
    shlq $8, %rdx
        #
    movq %rax, %rdi
    andq $0xFF00FF00FF00FF00, %rdi
    shrq $8, %rdi
        #
    movq %rdx, %rax
    orq %rdi, %rax

        #
    movq %rax, %rdx
    andq $0x0000FFFF0000FFFF, %rdx
    shlq $16, %rdx
        #
    movq %rax, %rdi
    andq $0xFFFF0000FFFF0000, %rdi
    shrq $16, %rdi
        #
    movq %rdx, %rax
    orq %rdi, %rax

        #
    movq %rax, %rdx
    shlq $32, %rdx
        #
    movq %rax, %rdi
    shrq $32, %rdi

    movq %rdx, %rax
    orq %rdi, %rax

    ret

    .size   bitrev, .-bitrev