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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
commit698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch)
tree173a775858bd501c378080a10dca74132f05bc50 /vendor/libm/src/math/sqrtf.rs
parentInitial commit. (diff)
downloadrustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz
rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/libm/src/math/sqrtf.rs')
-rw-r--r--vendor/libm/src/math/sqrtf.rs112
1 files changed, 112 insertions, 0 deletions
diff --git a/vendor/libm/src/math/sqrtf.rs b/vendor/libm/src/math/sqrtf.rs
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+/* origin: FreeBSD /usr/src/lib/msun/src/e_sqrtf.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+const TINY: f32 = 1.0e-30;
+
+#[inline]
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn sqrtf(x: f32) -> f32 {
+ // On wasm32 we know that LLVM's intrinsic will compile to an optimized
+ // `f32.sqrt` native instruction, so we can leverage this for both code size
+ // and speed.
+ llvm_intrinsically_optimized! {
+ #[cfg(target_arch = "wasm32")] {
+ return if x < 0.0 {
+ ::core::f32::NAN
+ } else {
+ unsafe { ::core::intrinsics::sqrtf32(x) }
+ }
+ }
+ }
+ let mut z: f32;
+ let sign: i32 = 0x80000000u32 as i32;
+ let mut ix: i32;
+ let mut s: i32;
+ let mut q: i32;
+ let mut m: i32;
+ let mut t: i32;
+ let mut i: i32;
+ let mut r: u32;
+
+ ix = x.to_bits() as i32;
+
+ /* take care of Inf and NaN */
+ if (ix as u32 & 0x7f800000) == 0x7f800000 {
+ return x * x + x; /* sqrt(NaN)=NaN, sqrt(+inf)=+inf, sqrt(-inf)=sNaN */
+ }
+
+ /* take care of zero */
+ if ix <= 0 {
+ if (ix & !sign) == 0 {
+ return x; /* sqrt(+-0) = +-0 */
+ }
+ if ix < 0 {
+ return (x - x) / (x - x); /* sqrt(-ve) = sNaN */
+ }
+ }
+
+ /* normalize x */
+ m = ix >> 23;
+ if m == 0 {
+ /* subnormal x */
+ i = 0;
+ while ix & 0x00800000 == 0 {
+ ix <<= 1;
+ i = i + 1;
+ }
+ m -= i - 1;
+ }
+ m -= 127; /* unbias exponent */
+ ix = (ix & 0x007fffff) | 0x00800000;
+ if m & 1 == 1 {
+ /* odd m, double x to make it even */
+ ix += ix;
+ }
+ m >>= 1; /* m = [m/2] */
+
+ /* generate sqrt(x) bit by bit */
+ ix += ix;
+ q = 0;
+ s = 0;
+ r = 0x01000000; /* r = moving bit from right to left */
+
+ while r != 0 {
+ t = s + r as i32;
+ if t <= ix {
+ s = t + r as i32;
+ ix -= t;
+ q += r as i32;
+ }
+ ix += ix;
+ r >>= 1;
+ }
+
+ /* use floating add to find out rounding direction */
+ if ix != 0 {
+ z = 1.0 - TINY; /* raise inexact flag */
+ if z >= 1.0 {
+ z = 1.0 + TINY;
+ if z > 1.0 {
+ q += 2;
+ } else {
+ q += q & 1;
+ }
+ }
+ }
+
+ ix = (q >> 1) + 0x3f000000;
+ ix += m << 23;
+ f32::from_bits(ix as u32)
+}