.globl npot
    .type npot, @function
    # First parameter = value to elevate to the next power of two
    # Return value = the given value elevated to the NPoT
npot:
    xor %rax, %rax
    bsr %rdi, %rcx
    jz npot_end
    movq $1, %rax
    shl %cl, %rax
    cmp %rax, %rdi
    je npot_end
    shl $1, %rax
npot_end:
    ret