49 lines
1.2 KiB
Rust
49 lines
1.2 KiB
Rust
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
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pub fn rintf(x: f32) -> f32 {
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let one_over_e = 1.0 / f32::EPSILON;
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let as_u32: u32 = x.to_bits();
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let exponent: u32 = as_u32 >> 23 & 0xff;
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let is_positive = (as_u32 >> 31) == 0;
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if exponent >= 0x7f + 23 {
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x
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} else {
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let ans = if is_positive {
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x + one_over_e - one_over_e
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} else {
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x - one_over_e + one_over_e
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};
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if ans == 0.0 {
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if is_positive {
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0.0
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} else {
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-0.0
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}
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} else {
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ans
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}
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}
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}
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// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520
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#[cfg(not(target_arch = "powerpc64"))]
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#[cfg(test)]
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mod tests {
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use super::rintf;
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#[test]
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fn negative_zero() {
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assert_eq!(rintf(-0.0_f32).to_bits(), (-0.0_f32).to_bits());
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}
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#[test]
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fn sanity_check() {
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assert_eq!(rintf(-1.0), -1.0);
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assert_eq!(rintf(2.8), 3.0);
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assert_eq!(rintf(-0.5), -0.0);
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assert_eq!(rintf(0.5), 0.0);
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assert_eq!(rintf(-1.5), -2.0);
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assert_eq!(rintf(1.5), 2.0);
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}
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}
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