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|
//! Test the u256 implementation. the ops already get exercised reasonably well through the `f128`
//! routines, so this only does a few million fuzz iterations against GMP.
#![cfg(feature = "build-mpfr")]
use std::sync::LazyLock;
use libm::support::{HInt, u256};
type BigInt = rug::Integer;
use libm_test::bigint_fuzz_iteration_count;
use libm_test::generate::random::SEED;
use rand::{Rng, SeedableRng};
use rand_chacha::ChaCha8Rng;
use rug::Assign;
use rug::integer::Order;
use rug::ops::NotAssign;
static BIGINT_U256_MAX: LazyLock<BigInt> =
LazyLock::new(|| BigInt::from_digits(&[u128::MAX, u128::MAX], Order::Lsf));
/// Copied from the test module.
fn hexu(v: u256) -> String {
format!("0x{:032x}{:032x}", v.hi, v.lo)
}
fn random_u256(rng: &mut ChaCha8Rng) -> u256 {
let lo: u128 = rng.random();
let hi: u128 = rng.random();
u256 { lo, hi }
}
fn assign_bigint(bx: &mut BigInt, x: u256) {
bx.assign_digits(&[x.lo, x.hi], Order::Lsf);
}
fn from_bigint(bx: &mut BigInt) -> u256 {
// Truncate so the result fits into `[u128; 2]`. This makes all ops overflowing.
*bx &= &*BIGINT_U256_MAX;
let mut bres = [0u128, 0];
bx.write_digits(&mut bres, Order::Lsf);
bx.assign(0);
u256 {
lo: bres[0],
hi: bres[1],
}
}
fn check_one(
x: impl FnOnce() -> String,
y: impl FnOnce() -> Option<String>,
actual: u256,
expected: &mut BigInt,
) {
let expected = from_bigint(expected);
if actual != expected {
let xmsg = x();
let ymsg = y().map(|y| format!("y: {y}\n")).unwrap_or_default();
panic!(
"Results do not match\n\
input: {xmsg}\n\
{ymsg}\
actual: {}\n\
expected: {}\
",
hexu(actual),
hexu(expected),
)
}
}
#[test]
fn mp_u256_bitor() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
let mut by = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x = random_u256(&mut rng);
let y = random_u256(&mut rng);
assign_bigint(&mut bx, x);
assign_bigint(&mut by, y);
let actual = x | y;
bx |= &by;
check_one(|| hexu(x), || Some(hexu(y)), actual, &mut bx);
}
}
#[test]
fn mp_u256_not() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x = random_u256(&mut rng);
assign_bigint(&mut bx, x);
let actual = !x;
bx.not_assign();
check_one(|| hexu(x), || None, actual, &mut bx);
}
}
#[test]
fn mp_u256_add() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
let mut by = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x = random_u256(&mut rng);
let y = random_u256(&mut rng);
assign_bigint(&mut bx, x);
assign_bigint(&mut by, y);
let actual = if u256::MAX - x >= y {
x + y
} else {
// otherwise (u256::MAX - x) < y, so the wrapped result is
// (x + y) - (u256::MAX + 1) == y - (u256::MAX - x) - 1
y - (u256::MAX - x) - 1_u128.widen()
};
bx += &by;
check_one(|| hexu(x), || Some(hexu(y)), actual, &mut bx);
}
}
#[test]
fn mp_u256_sub() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
let mut by = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x = random_u256(&mut rng);
let y = random_u256(&mut rng);
assign_bigint(&mut bx, x);
assign_bigint(&mut by, y);
// since the operators (may) panic on overflow,
// we should test something that doesn't
let actual = if x >= y { x - y } else { y - x };
bx -= &by;
bx.abs_mut();
check_one(|| hexu(x), || Some(hexu(y)), actual, &mut bx);
}
}
#[test]
fn mp_u256_shl() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x = random_u256(&mut rng);
let shift: u32 = rng.random_range(0..256);
assign_bigint(&mut bx, x);
let actual = x << shift;
bx <<= shift;
check_one(|| hexu(x), || Some(shift.to_string()), actual, &mut bx);
}
}
#[test]
fn mp_u256_shr() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x = random_u256(&mut rng);
let shift: u32 = rng.random_range(0..256);
assign_bigint(&mut bx, x);
let actual = x >> shift;
bx >>= shift;
check_one(|| hexu(x), || Some(shift.to_string()), actual, &mut bx);
}
}
#[test]
fn mp_u256_widen_mul() {
let mut rng = ChaCha8Rng::from_seed(*SEED);
let mut bx = BigInt::new();
let mut by = BigInt::new();
for _ in 0..bigint_fuzz_iteration_count() {
let x: u128 = rng.random();
let y: u128 = rng.random();
bx.assign(x);
by.assign(y);
let actual = x.widen_mul(y);
bx *= &by;
check_one(
|| format!("{x:#034x}"),
|| Some(format!("{y:#034x}")),
actual,
&mut bx,
);
}
}
|
