asm_att

lib.rs:

Macros that makes the assembly writing of ATT syntax more convenient.

Examples

use asm_att::{asm_att, global_asm_att, naked_asm_att};

#[cfg(target_arch = "x86_64")]
{
    fn add(left: i64, right: i64) -> i64 {
        let result: i64;
        unsafe {
            asm_att!(
                "mov {0}, {2}",
                "add {1}, {2}",
                in(reg) left,
                in(reg) right,
                out(reg) result
            );
        }
        result
    }

    fn str_compare(a: &str, b: &str) -> bool {
        if a.len() != b.len() {
            return false;
        }

        let len = a.len();
        let mut result = 0_i8;
        unsafe {
            asm_att!(
                "cld",
                "repe cmpsb",
                "sete {res}",
                in("rsi") a.as_ptr(),
                in("rdi") b.as_ptr(),
                in("rcx") len,
                res=lateout(reg_byte) result
            );
        }
        result != 0
    }

    fn counter2(number: u64) -> u64 {
        let mut counter = 0;
        unsafe {
            asm_att!(
                "cmp $0, {n}",
                "je 2f",
                "1:",
                "inc {c}",
                "cmp {n}, {c}",
                "jne 1b",
                "2:",
                c=inout(reg) counter,
                n=in(reg) number,
                options(nostack)
            );
        }
        counter
    }

    fn slice_copy2(src: &[u8], dst: &mut [u8]) {
        let (src_len, dst_len) = (src.len(), dst.len());
        if src_len != dst_len {
            panic!(
                "{}: source slice length ({}) does not match destination slice length ({}).",
                core::any::type_name_of_val(&slice_copy2),
                src_len,
                dst_len
            );
        }

        unsafe {
            asm_att!(
                "cld",
                "movq {src}, %rsi",
                "movq {dst}, %rdi",
                "movq {n}, %rcx",
                "rep movsb",
                src=in(reg) src.as_ptr(),
                dst=in(reg) dst.as_mut_ptr(),
                n=in(reg) dst_len as u64,
                out("rsi") _,
                out("rdi") _,
                out("rcx") _
            );
        }
    }

    fn add_works() {
        let result = add(2, 3);
        assert_eq!(result, 5);

        assert_eq!(add(5, 3), 8);
        assert_eq!(add(-1, 1), 0);
        assert_eq!(add(100, 200), 300);
    }

    fn str_compare_works() {
        assert!(str_compare("", ""));
        assert!(str_compare("hello", "hello"));
        assert!(!str_compare("hello", "world"));
    }

    fn counter2_works(n: u64) {
        for i in 0..n {
            assert_eq!(counter2(i), i);
        }
    }

    fn slice_copy2_works() {
        const SRC: &[u8] = b"Hello World\0";
        const SRC_LEN: usize = SRC.len();

        let mut dst = [0_u8; SRC_LEN];
        slice_copy2(&SRC, &mut dst);
        assert_eq!(SRC, dst);

        {
            let src = str::from_utf8(SRC).unwrap();
            let dst = str::from_utf8(&dst).unwrap();
            assert_eq!(src, dst);
        }
    }

    add_works();
    str_compare_works();
    counter2_works(200);
    slice_copy2_works();
}