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Commit | Line | Data |
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8faf50e0 XL |
1 | use core::f32; |
2 | ||
48663c56 | 3 | #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
8faf50e0 | 4 | pub fn truncf(x: f32) -> f32 { |
a1dfa0c6 XL |
5 | // On wasm32 we know that LLVM's intrinsic will compile to an optimized |
6 | // `f32.trunc` native instruction, so we can leverage this for both code size | |
7 | // and speed. | |
8 | llvm_intrinsically_optimized! { | |
9 | #[cfg(target_arch = "wasm32")] { | |
10 | return unsafe { ::core::intrinsics::truncf32(x) } | |
11 | } | |
12 | } | |
8faf50e0 XL |
13 | let x1p120 = f32::from_bits(0x7b800000); // 0x1p120f === 2 ^ 120 |
14 | ||
15 | let mut i: u32 = x.to_bits(); | |
16 | let mut e: i32 = (i >> 23 & 0xff) as i32 - 0x7f + 9; | |
17 | let m: u32; | |
18 | ||
19 | if e >= 23 + 9 { | |
20 | return x; | |
21 | } | |
22 | if e < 9 { | |
23 | e = 1; | |
24 | } | |
25 | m = -1i32 as u32 >> e; | |
26 | if (i & m) == 0 { | |
27 | return x; | |
28 | } | |
29 | force_eval!(x + x1p120); | |
30 | i &= !m; | |
31 | f32::from_bits(i) | |
32 | } | |
33 | ||
34 | #[cfg(test)] | |
35 | mod tests { | |
36 | #[test] | |
37 | fn sanity_check() { | |
38 | assert_eq!(super::truncf(1.1), 1.0); | |
39 | } | |
40 | } |