libm/math/
truncf.rs

1use core::f32;
2
3#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
4pub fn truncf(x: f32) -> f32 {
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    }
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// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
35#[cfg(not(target_arch = "powerpc64"))]
36#[cfg(test)]
37mod tests {
38    #[test]
39    fn sanity_check() {
40        assert_eq!(super::truncf(1.1), 1.0);
41    }
42}
libm/math/truncf.rs

libm/math/
truncf.rs
