Merge rust-lang/libm#77

77: adding ceilf and floorf  r=japaric a=jackmott

Finishes issues rust-lang/libm#56  and rust-lang/libm#54 

Co-authored-by: Jack Mott <jack.mott@gmail.com>

library/compiler-builtins/libm/src/lib.rs

@@ -34,10 +34,8 @@ pub fn _eq(a: u64, b: u64) -> bool {
 ///
 /// This trait is sealed and cannot be implemented outside of `libm`.
 pub trait F32Ext: private::Sealed {
-    #[cfg(todo)]
     fn floor(self) -> Self;
 
-    #[cfg(todo)]
     fn ceil(self) -> Self;
 
     fn round(self) -> Self;
@@ -141,13 +139,11 @@ pub trait F32Ext: private::Sealed {
 }
 
 impl F32Ext for f32 {
-    #[cfg(todo)]
     #[inline]
     fn floor(self) -> Self {
         floorf(self)
     }
 
-    #[cfg(todo)]
     #[inline]
     fn ceil(self) -> Self {
         ceilf(self)

library/compiler-builtins/libm/src/math/ceilf.rs

@@ -0,0 +1,29 @@
+use core::f32;
+
+pub fn ceilf(x: f32) -> f32 {
+    let mut ui = x.to_bits();
+    let e = (((ui >> 23) & 0xff) - 0x7f) as i32;
+
+    if e >= 23 {
+        return x;
+    }
+    if e >= 0 {
+        let m = 0x007fffff >> e;
+        if (ui & m) == 0 {
+            return x;
+        }
+        force_eval!(x + f32::from_bits(0x7b800000));
+        if ui >> 31 == 0 {
+            ui += m;
+        }
+        ui &= !m;
+    } else {
+        force_eval!(x + f32::from_bits(0x7b800000));
+        if ui >> 31 != 0 {
+            return -0.0;
+        } else if ui << 1 != 0 {
+            return 1.0;
+        }
+    }
+    return f32::from_bits(ui);
+}

library/compiler-builtins/libm/src/math/floorf.rs

@@ -0,0 +1,30 @@
+use core::f32;
+
+#[inline]
+pub fn floorf(x: f32) -> f32 {
+    let mut ui = x.to_bits();
+    let e = (((ui >> 23) & 0xff) - 0x7f) as i32;
+
+    if e >= 23 {
+        return x;
+    }
+    if e >= 0 {
+        let m: u32 = 0x007fffff >> e;
+        if (ui & m) == 0 {
+            return x;
+        }
+        force_eval!(x + f32::from_bits(0x7b800000));
+        if ui >> 31 != 0 {
+            ui += m;
+        }
+        ui &= !m;
+    } else {
+        force_eval!(x + f32::from_bits(0x7b800000));
+        if ui >> 31 == 0 {
+            ui = 0;
+        } else if ui << 1 != 0 {
+            return -1.0;
+        }
+    }
+    return f32::from_bits(ui);
+}

library/compiler-builtins/libm/src/math/mod.rs

@@ -6,8 +6,10 @@ macro_rules! force_eval {
     };
 }
 
+mod ceilf;
 mod fabs;
 mod fabsf;
+mod floorf;
 mod fmodf;
 mod powf;
 mod round;
@@ -27,8 +29,10 @@ mod hypotf;
 //mod service;
 
 pub use self::{
+    ceilf::ceilf,
     fabs::fabs,
     fabsf::fabsf,
+    floorf::floorf,
     fmodf::fmodf,
     powf::powf,
     round::round,

library/compiler-builtins/libm/test-generator/src/main.rs

@@ -652,12 +652,12 @@ fn main() -> Result<(), Box<Error>> {
 // With signature `fn(f32) -> f32`
 f32_f32! {
     // acosf,
-    // floorf,
+    floorf,
     truncf,
     // asinf,
     // atanf,
     // cbrtf,
-    // ceilf,
+    ceilf,
     // cosf,
     // coshf,
     // exp2f,