vendor/compiler_builtins/libm/src/math/ceilf.rs

   1 use core::f32;
   2
   3 /// Ceil (f32)
   4 ///
   5 /// Finds the nearest integer greater than or equal to `x`.
   6 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
   7 pub fn ceilf(x: f32) -> f32 {
   8     // On wasm32 we know that LLVM's intrinsic will compile to an optimized
   9     // `f32.ceil` native instruction, so we can leverage this for both code size
  10     // and speed.
  11     llvm_intrinsically_optimized! {
  12         #[cfg(target_arch = "wasm32")] {
  13             return unsafe { ::core::intrinsics::ceilf32(x) }
  14         }
  15     }
  16     let mut ui = x.to_bits();
  17     let e = (((ui >> 23) & 0xff).wrapping_sub(0x7f)) as i32;
  18
  19     if e >= 23 {
  20         return x;
  21     }
  22     if e >= 0 {
  23         let m = 0x007fffff >> e;
  24         if (ui & m) == 0 {
  25             return x;
  26         }
  27         force_eval!(x + f32::from_bits(0x7b800000));
  28         if ui >> 31 == 0 {
  29             ui += m;
  30         }
  31         ui &= !m;
  32     } else {
  33         force_eval!(x + f32::from_bits(0x7b800000));
  34         if ui >> 31 != 0 {
  35             return -0.0;
  36         } else if ui << 1 != 0 {
  37             return 1.0;
  38         }
  39     }
  40     f32::from_bits(ui)
  41 }
  42
  43 #[cfg(test)]
  44 mod tests {
  45     use super::*;
  46     use core::f32::*;
  47
  48     #[test]
  49     fn sanity_check() {
  50         assert_eq!(ceilf(1.1), 2.0);
  51         assert_eq!(ceilf(2.9), 3.0);
  52     }
  53
  54     /// The spec: https://en.cppreference.com/w/cpp/numeric/math/ceil
  55     #[test]
  56     fn spec_tests() {
  57         // Not Asserted: that the current rounding mode has no effect.
  58         assert!(ceilf(NAN).is_nan());
  59         for f in [0.0, -0.0, INFINITY, NEG_INFINITY].iter().copied() {
  60             assert_eq!(ceilf(f), f);
  61         }
  62     }
  63 }