// `pub` functions will be exported.
//
// ```
// v -b wasm -no-builtin functions.v
// wasmer functions.wasm -i main.powi <a> <b>
// wasmer functions.wasm -i main.gcd <a> <b>
// ```

pub fn gcd(a_ i64, b_ i64) i64 {
    mut a := a_
    mut b := b_
    if a < 0 {
        a = -a
    }
    if b < 0 {
        b = -b
    }
    for b != 0 {
        a %= b
        if a == 0 {
            return b
        }
        b %= a
    }
    return a
}

pub fn powi(a i64, b i64) i64 {
    mut b_ := b
    mut p := a
    mut v := i64(1)

    if b_ < 0 { // exponent < 0
        if a == 0 {
            return -1 // division by 0
        }
        return if a * a != 1 {
            0
        } else {
            if (b_ & 1) > 0 {
                a
            } else {
                1
            }
        }
    }

    for b_ > 0 {
        if b_ & 1 > 0 {
            v *= p
        }
        p *= p
        b_ >>= 1
    }

    return v
}