lightning-sys

Safe gnu lightning bindings for rust

Examples

a function that increments a number by one

use lightning_sys::{Jit, Reg, JitPointer};

let jit = Jit::new();
let mut js = jit.new_state();

js.prolog();
let inarg = js.arg();
js.getarg_i(Reg::R(0), &inarg);
js.addi(Reg::R(0), Reg::R(0), 1);
js.retr(Reg::R(0));

let incr = unsafe { js.emit::<extern fn(i32) -> i32>() };
js.clear();

assert_eq!(incr(5), 6);
assert_eq!(incr(6), 7);

A simple function call to printf

extern crate libc;

use std::ffi::CString;
use lightning_sys::{Jit, JitWord, Reg, JitPointer};
use std::convert::TryInto;

fn main() {
    let jit = Jit::new();
    let mut js = jit.new_state();

    // make sure this outlives any calls
    let cs = CString::new("generated %d bytes\n").unwrap();

    let start = js.note(file!(), line!());
    js.prolog();
    let inarg = js.arg();
    js.getarg_i(Reg::R(1), &inarg);
    js.prepare();
    js.pushargi(cs.as_ptr() as JitWord);
    js.ellipsis();
    js.pushargr(Reg::R(1));
    js.finishi(libc::printf as JitPointer);
    js.ret();
    js.epilog();
    let end = js.note(file!(), line!());

    let my_function = unsafe{ js.emit::<extern fn(i32)>() };
    /* call the generated code, passing its size as argument */
    my_function((js.address(&end) as u64 - js.address(&start) as u64).try_into().unwrap());
    js.clear();

    // TODO: dissasembly has not been implemented yet
    // js.dissasemble();
}

known issues:

• tests must be run like cargo test -- --test-threads=1