saturating_scale: add test

This commit is contained in:
Robert Jördens 2021-06-10 10:24:43 +02:00
parent b0052128e0
commit 45bbfe186f
1 changed files with 39 additions and 1 deletions

View File

@ -70,7 +70,7 @@ impl Unwrapper {
mod tests {
use super::*;
#[test]
fn mini() {
fn overflowing_sub_correctness() {
for (x0, x1, v) in [
(0i32, 0i32, 0i8),
(0, 1, 0),
@ -101,4 +101,42 @@ mod tests {
assert_eq!(dx, dx0);
}
}
#[test]
fn saturating_scale_correctness() {
let shift = 8;
for (lo, hi, res) in [
(0i32, 0i32, 0i32),
(0, 1, 0x0100_0000),
(0, -1, -0x0100_0000),
(0x100, 0, 1),
(-1 << 31, 0, -1 << 23),
(0x7fffffff, 0, 0x007f_ffff),
(0x7fffffff, 1, 0x0017f_ffff),
(-0x7fffffff, -1, -0x0180_0000),
(0x1234_5600, 0x7f, 0x7f12_3456),
(0x1234_5600, -0x7f, -0x7f00_0000 + 0x12_3456),
(0, 0x7f, 0x7f00_0000),
(0, 0x80, 0x7fff_ff80),
(0, -0x7f, -0x7f00_0000),
(0, -0x80, -0x7fff_ff80),
(0x7fff_ffff, 0x7f, 0x7f7f_ffff),
(-0x8000_0000, 0x7f, 0x7e80_0000),
(-0x8000_0000, -0x7f, -0x7f80_0000),
(0x7fff_ffff, -0x7f, -0x7e80_0001),
(0x100, 0x7f, 0x7f00_0001),
(0, -0x80, -0x7fff_ff80),
(-1 << 31, 0x80, 0x7fff_ff80),
(-1 << 31, -0x80, -0x7fff_ff80),
]
.iter()
{
let s = saturating_scale(*lo, *hi, shift);
assert_eq!(
*res, s,
"{:#x} != {:#x} = saturating_scale({:#x}, {:#x}, {:#x})",
*res, s, *lo, *hi, shift
);
}
}
}