rotl.rs

#![feature(asm, macro_rules)]

use std::mem;

fn rotl(val: u64, shift: u8) -> u64 {
    let sz = mem::size_of_val(&val);

    (val << shift) | (val >> (sz * 8 - shift as uint))
}

macro_rules! rotl(
    ($val: expr, $shift: expr) => (
        {
            let val = $val;
            let shift = $shift;
            let sz = mem::size_of_val(&val);
            (val << shift) | (val >> (sz * 8 - shift as uint))
        }
    );
)

fn asm_rotl(mut x: u64, a: u8) -> u64 {
    unsafe {
        asm!("rolq $2, $0"
             : "=r"(x)
             : "0"(x), "{cl}"(a));
    }

    x
}

fn main() {
    println!("rotl(32, 2) - {}", rotl(32, 2));
    println!("rotl!(32, 2) - {}", rotl!(32, 2));
    println!("asm_rotl(32, 2) - {}", asm_rotl(32, 2));
}

-> % rustc r.rs
-> % ./r
rotl(32, 2) - 128
rotl!(32, 2) - 128
asm_rotl(32, 2) - 128