From be361790645971446b64dabf21c27a595a40c8fd Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Sat, 30 Jun 2018 01:44:54 +0200
Subject: [PATCH] add std.math f16 signbit support

refs #1122
---
 std/math/signbit.zig | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/std/math/signbit.zig b/std/math/signbit.zig
index a0191bed5c..8c6829dfcd 100644
--- a/std/math/signbit.zig
+++ b/std/math/signbit.zig
@@ -5,12 +5,18 @@ const assert = std.debug.assert;
 pub fn signbit(x: var) bool {
     const T = @typeOf(x);
     return switch (T) {
+        f16 => signbit16(x),
         f32 => signbit32(x),
         f64 => signbit64(x),
         else => @compileError("signbit not implemented for " ++ @typeName(T)),
     };
 }
 
+fn signbit16(x: f16) bool {
+    const bits = @bitCast(u16, x);
+    return bits >> 15 != 0;
+}
+
 fn signbit32(x: f32) bool {
     const bits = @bitCast(u32, x);
     return bits >> 31 != 0;
@@ -22,10 +28,16 @@ fn signbit64(x: f64) bool {
 }
 
 test "math.signbit" {
+    assert(signbit(f16(4.0)) == signbit16(4.0));
     assert(signbit(f32(4.0)) == signbit32(4.0));
     assert(signbit(f64(4.0)) == signbit64(4.0));
 }
 
+test "math.signbit16" {
+    assert(!signbit16(4.0));
+    assert(signbit16(-3.0));
+}
+
 test "math.signbit32" {
     assert(!signbit32(4.0));
     assert(signbit32(-3.0));