curlywas/random.cwa

import "env.memory" memory(4);

global mut randomState: i32 = 37;

fn random() -> i32 {
    let state: i32;
    randomState = (state := (
                          state := randomState ^ (randomState << 13)
                      ) ^ (state >> 17)
                  ) ^ (state << 5);
    randomState * 625341585
}

fn seed(s: i32) {
    randomState = (((s + !(s >> 31)) as i64 * 8445297036689579347i64) >> 31i64) as i32;
}

export fn tic(time: i32) {
    let i: i32;
    loop pixels {
        seed(i + (time / 100) * 320);
        i?120 = random();
        branch_if (i := i + 1) < 320*256: pixels
    }
}