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

   1 use core::u64;
   2
   3 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
   4 pub fn fmod(x: f64, y: f64) -> f64 {
   5     let mut uxi = x.to_bits();
   6     let mut uyi = y.to_bits();
   7     let mut ex = (uxi >> 52 & 0x7ff) as i64;
   8     let mut ey = (uyi >> 52 & 0x7ff) as i64;
   9     let sx = uxi >> 63;
  10     let mut i;
  11
  12     if uyi << 1 == 0 || y.is_nan() || ex == 0x7ff {
  13         return (x * y) / (x * y);
  14     }
  15     if uxi << 1 <= uyi << 1 {
  16         if uxi << 1 == uyi << 1 {
  17             return 0.0 * x;
  18         }
  19         return x;
  20     }
  21
  22     /* normalize x and y */
  23     if ex == 0 {
  24         i = uxi << 12;
  25         while i >> 63 == 0 {
  26             ex -= 1;
  27             i <<= 1;
  28         }
  29         uxi <<= -ex + 1;
  30     } else {
  31         uxi &= u64::MAX >> 12;
  32         uxi |= 1 << 52;
  33     }
  34     if ey == 0 {
  35         i = uyi << 12;
  36         while i >> 63 == 0 {
  37             ey -= 1;
  38             i <<= 1;
  39         }
  40         uyi <<= -ey + 1;
  41     } else {
  42         uyi &= u64::MAX >> 12;
  43         uyi |= 1 << 52;
  44     }
  45
  46     /* x mod y */
  47     while ex > ey {
  48         i = uxi.wrapping_sub(uyi);
  49         if i >> 63 == 0 {
  50             if i == 0 {
  51                 return 0.0 * x;
  52             }
  53             uxi = i;
  54         }
  55         uxi <<= 1;
  56         ex -= 1;
  57     }
  58     i = uxi.wrapping_sub(uyi);
  59     if i >> 63 == 0 {
  60         if i == 0 {
  61             return 0.0 * x;
  62         }
  63         uxi = i;
  64     }
  65     while uxi >> 52 == 0 {
  66         uxi <<= 1;
  67         ex -= 1;
  68     }
  69
  70     /* scale result */
  71     if ex > 0 {
  72         uxi -= 1 << 52;
  73         uxi |= (ex as u64) << 52;
  74     } else {
  75         uxi >>= -ex + 1;
  76     }
  77     uxi |= (sx as u64) << 63;
  78
  79     f64::from_bits(uxi)
  80 }