fixed_decimal/
ops.rs

1// This file is part of ICU4X. For terms of use, please see the file
2// called LICENSE at the top level of the ICU4X source tree
3// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5//! Int operations that are not yet in the standard library.
6
7/// Computes `a - b` where `a` is signed and `b` is unsigned.
8///
9/// If overflow occurs, panics in debug mode and wraps in release mode.
10#[inline(always)]
11pub fn i16_sub_unsigned(a: i16, b: u16) -> i16 {
12    let c = a.wrapping_sub(b as i16);
13    debug_assert_eq!(a as i32 - b as i32, c as i32);
14    c
15}
16
17#[test]
18fn test_i16_sub_unsigned() {
19    assert_eq!(i16_sub_unsigned(5, 0), 5);
20    assert_eq!(i16_sub_unsigned(5, 4), 1);
21    assert_eq!(i16_sub_unsigned(5, 5), 0);
22    assert_eq!(i16_sub_unsigned(5, 6), -1);
23    assert_eq!(i16_sub_unsigned(0, 0), 0);
24    assert_eq!(i16_sub_unsigned(0, 1), -1);
25    assert_eq!(i16_sub_unsigned(-5, 0), -5);
26    assert_eq!(i16_sub_unsigned(-5, 1), -6);
27
28    assert_eq!(i16_sub_unsigned(i16::MAX, 0), i16::MAX);
29    assert_eq!(i16_sub_unsigned(i16::MAX, 1), i16::MAX - 1);
30    assert_eq!(i16_sub_unsigned(i16::MAX, i16::MAX as u16 - 1), 1);
31    assert_eq!(i16_sub_unsigned(i16::MAX, i16::MAX as u16), 0);
32    assert_eq!(i16_sub_unsigned(i16::MAX, i16::MAX as u16 + 1), -1);
33    assert_eq!(i16_sub_unsigned(i16::MAX, u16::MAX - 1), i16::MIN + 1);
34    assert_eq!(i16_sub_unsigned(i16::MAX, u16::MAX), i16::MIN);
35}
36
37/// Computes `a - b` where `a >= b`.
38///
39/// Overflow cannot occur because the result is unsigned.
40///
41/// This is similar to `abs_diff` but with the additional constraint that `a >= b`.
42///
43/// If `a < b`, panics in debug mode and wraps in release mode.
44#[inline(always)]
45pub fn i16_abs_sub(a: i16, b: i16) -> u16 {
46    debug_assert!(a >= b);
47    let c = (a as u16).wrapping_sub(b as u16);
48    debug_assert_eq!(a as i32 - b as i32, c as i32);
49    c
50}
51
52#[test]
53fn test_i16_abs_sub() {
54    assert_eq!(i16_abs_sub(5, -1), 6);
55    assert_eq!(i16_abs_sub(5, 0), 5);
56    assert_eq!(i16_abs_sub(5, 4), 1);
57    assert_eq!(i16_abs_sub(5, 5), 0);
58    assert_eq!(i16_abs_sub(0, -1), 1);
59    assert_eq!(i16_abs_sub(0, 0), 0);
60    assert_eq!(i16_abs_sub(-5, -5), 0);
61    assert_eq!(i16_abs_sub(-5, -6), 1);
62
63    assert_eq!(i16_abs_sub(i16::MAX, i16::MIN), u16::MAX);
64    assert_eq!(i16_abs_sub(i16::MAX, i16::MIN + 1), u16::MAX - 1);
65    assert_eq!(i16_abs_sub(i16::MAX, -1), i16::MAX as u16 + 1);
66    assert_eq!(i16_abs_sub(i16::MAX, 0), i16::MAX as u16);
67    assert_eq!(i16_abs_sub(i16::MAX, 1), i16::MAX as u16 - 1);
68    assert_eq!(i16_abs_sub(i16::MAX, i16::MAX - 1), 1);
69    assert_eq!(i16_abs_sub(i16::MAX, i16::MAX), 0);
70}
fixed_decimal/ops.rs

fixed_decimal/
ops.rs
