/build/cargo-vendor-dir/libm-0.2.8/src/math/floor.rs
Line | Count | Source (jump to first uncovered line) |
1 | | #![allow(unreachable_code)] |
2 | | use core::f64; |
3 | | |
4 | | const TOINT: f64 = 1. / f64::EPSILON; |
5 | | |
6 | | /// Floor (f64) |
7 | | /// |
8 | | /// Finds the nearest integer less than or equal to `x`. |
9 | | #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
10 | 3 | pub fn floor(x: f64) -> f64 { |
11 | 3 | // On wasm32 we know that LLVM's intrinsic will compile to an optimized |
12 | 3 | // `f64.floor` native instruction, so we can leverage this for both code size |
13 | 3 | // and speed. |
14 | 3 | llvm_intrinsically_optimized! { |
15 | 3 | #[cfg(target_arch = "wasm32")] { |
16 | 3 | return unsafe { ::core::intrinsics::floorf64(x) } |
17 | 3 | } |
18 | 3 | } |
19 | 3 | #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] |
20 | 3 | { |
21 | 3 | //use an alternative implementation on x86, because the |
22 | 3 | //main implementation fails with the x87 FPU used by |
23 | 3 | //debian i386, probablly due to excess precision issues. |
24 | 3 | //basic implementation taken from https://github.com/rust-lang/libm/issues/219 |
25 | 3 | use super::fabs; |
26 | 3 | if fabs(x).to_bits() < 4503599627370496.0_f64.to_bits() { |
27 | 3 | let truncated = x as i64 as f64; |
28 | 3 | if truncated > x { |
29 | 3 | return truncated - 1.0; |
30 | 3 | } else { |
31 | 3 | return truncated; |
32 | 3 | } |
33 | 3 | } else { |
34 | 3 | return x; |
35 | 3 | } |
36 | 3 | } |
37 | 3 | let ui = x.to_bits(); |
38 | 3 | let e = ((ui >> 52) & 0x7ff) as i32; |
39 | 3 | |
40 | 3 | if (e >= 0x3ff + 52) || (x == 0.) { |
41 | 0 | return x; |
42 | 3 | } |
43 | | /* y = int(x) - x, where int(x) is an integer neighbor of x */ |
44 | 3 | let y = if (ui >> 63) != 0 { |
45 | 2 | x - TOINT + TOINT - x |
46 | | } else { |
47 | 1 | x + TOINT - TOINT - x |
48 | | }; |
49 | | /* special case because of non-nearest rounding modes */ |
50 | 3 | if e < 0x3ff { |
51 | 1 | force_eval!(y); |
52 | 1 | return if (ui >> 63) != 0 { -1. } else { 0.0 }; |
53 | 2 | } |
54 | 2 | if y > 0. { |
55 | 1 | x + y - 1. |
56 | | } else { |
57 | 1 | x + y |
58 | | } |
59 | 3 | } |
60 | | |
61 | | #[cfg(test)] |
62 | | mod tests { |
63 | | use super::*; |
64 | | use core::f64::*; |
65 | | |
66 | | #[test] |
67 | | fn sanity_check() { |
68 | | assert_eq!(floor(1.1), 1.0); |
69 | | assert_eq!(floor(2.9), 2.0); |
70 | | } |
71 | | |
72 | | /// The spec: https://en.cppreference.com/w/cpp/numeric/math/floor |
73 | | #[test] |
74 | | fn spec_tests() { |
75 | | // Not Asserted: that the current rounding mode has no effect. |
76 | | assert!(floor(NAN).is_nan()); |
77 | | for f in [0.0, -0.0, INFINITY, NEG_INFINITY].iter().copied() { |
78 | | assert_eq!(floor(f), f); |
79 | | } |
80 | | } |
81 | | } |