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Diffstat (limited to '')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/remquo.rs | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/remquo.rs b/vendor/compiler_builtins/libm/src/math/remquo.rs new file mode 100644 index 000000000..0afd1f7f5 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/remquo.rs @@ -0,0 +1,110 @@ +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn remquo(mut x: f64, mut y: f64) -> (f64, i32) { + let ux: u64 = x.to_bits(); + let mut uy: u64 = y.to_bits(); + let mut ex = ((ux >> 52) & 0x7ff) as i32; + let mut ey = ((uy >> 52) & 0x7ff) as i32; + let sx = (ux >> 63) != 0; + let sy = (uy >> 63) != 0; + let mut q: u32; + let mut i: u64; + let mut uxi: u64 = ux; + + if (uy << 1) == 0 || y.is_nan() || ex == 0x7ff { + return ((x * y) / (x * y), 0); + } + if (ux << 1) == 0 { + return (x, 0); + } + + /* normalize x and y */ + if ex == 0 { + i = uxi << 12; + while (i >> 63) == 0 { + ex -= 1; + i <<= 1; + } + uxi <<= -ex + 1; + } else { + uxi &= (!0) >> 12; + uxi |= 1 << 52; + } + if ey == 0 { + i = uy << 12; + while (i >> 63) == 0 { + ey -= 1; + i <<= 1; + } + uy <<= -ey + 1; + } else { + uy &= (!0) >> 12; + uy |= 1 << 52; + } + + q = 0; + + if ex + 1 != ey { + if ex < ey { + return (x, 0); + } + /* x mod y */ + while ex > ey { + i = uxi.wrapping_sub(uy); + if (i >> 63) == 0 { + uxi = i; + q += 1; + } + uxi <<= 1; + q <<= 1; + ex -= 1; + } + i = uxi.wrapping_sub(uy); + if (i >> 63) == 0 { + uxi = i; + q += 1; + } + if uxi == 0 { + ex = -60; + } else { + while (uxi >> 52) == 0 { + uxi <<= 1; + ex -= 1; + } + } + } + + /* scale result and decide between |x| and |x|-|y| */ + if ex > 0 { + uxi -= 1 << 52; + uxi |= (ex as u64) << 52; + } else { + uxi >>= -ex + 1; + } + x = f64::from_bits(uxi); + if sy { + y = -y; + } + if ex == ey || (ex + 1 == ey && (2.0 * x > y || (2.0 * x == y && (q % 2) != 0))) { + x -= y; + // TODO: this matches musl behavior, but it is incorrect + q = q.wrapping_add(1); + } + q &= 0x7fffffff; + let quo = if sx ^ sy { -(q as i32) } else { q as i32 }; + if sx { + (-x, quo) + } else { + (x, quo) + } +} + +#[cfg(test)] +mod tests { + use super::remquo; + + #[test] + fn test_q_overflow() { + // 0xc000000000000001, 0x04c0000000000004 + let _ = remquo(-2.0000000000000004, 8.406091369059082e-286); + } +} |