Merge rust-lang#69

69: implement hypotf r=japaric a=erikdesjardins

closes rust-lang#48

Co-authored-by: Erik <[email protected]>

Author: bors[bot]

src/lib.rs

@@ -88,7 +88,6 @@ pub trait F32Ext {
     #[cfg(todo)]
     fn cbrt(self) -> Self;
 
-    #[cfg(todo)]
     fn hypot(self, other: Self) -> Self;
 
     #[cfg(todo)]
@@ -254,7 +253,6 @@ impl F32Ext for f32 {
         cbrtf(self)
     }
 
-    #[cfg(todo)]
     #[inline]
     fn hypot(self, other: Self) -> Self {
         hypotf(self, other)

src/math/hypotf.rs

@@ -0,0 +1,43 @@
+use core::f32;
+
+use super::sqrtf;
+
+#[inline]
+pub fn hypotf(mut x: f32, mut y: f32) -> f32 {
+    let x1p90 = f32::from_bits(0x6c800000); // 0x1p90f === 2 ^ 90
+    let x1p_90 = f32::from_bits(0x12800000); // 0x1p-90f === 2 ^ -90
+
+    let mut uxi = x.to_bits();
+    let mut uyi = y.to_bits();
+    let uti;
+    let mut z: f32;
+
+    uxi &= -1i32 as u32 >> 1;
+    uyi &= -1i32 as u32 >> 1;
+    if uxi < uyi {
+        uti = uxi;
+        uxi = uyi;
+        uyi = uti;
+    }
+
+    x = f32::from_bits(uxi);
+    y = f32::from_bits(uyi);
+    if uyi == 0xff<<23 {
+        return y;
+    }
+    if uxi >= 0xff<<23 || uyi == 0 || uxi - uyi >= 25<<23 {
+        return x + y;
+    }
+
+    z = 1.;
+    if uxi >= (0x7f+60)<<23 {
+        z = x1p90;
+        x *= x1p_90;
+        y *= x1p_90;
+    } else if uyi < (0x7f-60)<<23 {
+        z = x1p_90;
+        x *= x1p90;
+        y *= x1p90;
+    }
+    z*sqrtf((x as f64 * x as f64 + y as f64 * y as f64) as f32)
+}

src/math/mod.rs

@@ -17,6 +17,7 @@ mod expf;
 mod floor;
 mod trunc;
 mod truncf;
+mod hypotf;
 
 //mod service;
 
@@ -34,6 +35,7 @@ pub use self::{
     floor::floor,
     trunc::trunc,
     truncf::truncf,
+    hypotf::hypotf,
 };
 
 fn isnanf(x: f32) -> bool {

test-generator/src/main.rs

@@ -678,7 +678,7 @@ f32_f32! {
 // With signature `fn(f32, f32) -> f32`
 f32f32_f32! {
     // atan2f,
-    // hypotf,
+    hypotf,
     fmodf,
     powf,
 }