diff options
Diffstat (limited to 'vendor/compiler_builtins/libm/src/math/ceil.rs')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/ceil.rs | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/ceil.rs b/vendor/compiler_builtins/libm/src/math/ceil.rs new file mode 100644 index 000000000..22d892971 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/ceil.rs @@ -0,0 +1,82 @@ +#![allow(unreachable_code)] +use core::f64; + +const TOINT: f64 = 1. / f64::EPSILON; + +/// Ceil (f64) +/// +/// Finds the nearest integer greater than or equal to `x`. +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn ceil(x: f64) -> f64 { + // On wasm32 we know that LLVM's intrinsic will compile to an optimized + // `f64.ceil` native instruction, so we can leverage this for both code size + // and speed. + llvm_intrinsically_optimized! { + #[cfg(target_arch = "wasm32")] { + return unsafe { ::core::intrinsics::ceilf64(x) } + } + } + #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] + { + //use an alternative implementation on x86, because the + //main implementation fails with the x87 FPU used by + //debian i386, probablly due to excess precision issues. + //basic implementation taken from https://github.com/rust-lang/libm/issues/219 + use super::fabs; + if fabs(x).to_bits() < 4503599627370496.0_f64.to_bits() { + let truncated = x as i64 as f64; + if truncated < x { + return truncated + 1.0; + } else { + return truncated; + } + } else { + return x; + } + } + let u: u64 = x.to_bits(); + let e: i64 = (u >> 52 & 0x7ff) as i64; + let y: f64; + + if e >= 0x3ff + 52 || x == 0. { + return x; + } + // y = int(x) - x, where int(x) is an integer neighbor of x + y = if (u >> 63) != 0 { + x - TOINT + TOINT - x + } else { + x + TOINT - TOINT - x + }; + // special case because of non-nearest rounding modes + if e < 0x3ff { + force_eval!(y); + return if (u >> 63) != 0 { -0. } else { 1. }; + } + if y < 0. { + x + y + 1. + } else { + x + y + } +} + +#[cfg(test)] +mod tests { + use super::*; + use core::f64::*; + + #[test] + fn sanity_check() { + assert_eq!(ceil(1.1), 2.0); + assert_eq!(ceil(2.9), 3.0); + } + + /// The spec: https://en.cppreference.com/w/cpp/numeric/math/ceil + #[test] + fn spec_tests() { + // Not Asserted: that the current rounding mode has no effect. + assert!(ceil(NAN).is_nan()); + for f in [0.0, -0.0, INFINITY, NEG_INFINITY].iter().copied() { + assert_eq!(ceil(f), f); + } + } +} |