Merge remote-tracking branch 'origin/master' into llvm7

2 files changed, 27 insertions, 6 deletions

diff --git a/std/math/index.zig b/std/math/index.zig
index 83ba055329..a549a6bb61 100644
--- a/std/math/index.zig
+++ b/std/math/index.zig
@@ -558,6 +558,32 @@ test "math.floorPowerOfTwo" {
     comptime testFloorPowerOfTwo();
 }
 
+pub fn log2_int(comptime T: type, x: T) Log2Int(T) {
+    assert(x != 0);
+    return Log2Int(T)(T.bit_count - 1 - @clz(x));
+}
+
+pub fn log2_int_ceil(comptime T: type, x: T) Log2Int(T) {
+    assert(x != 0);
+    const log2_val = log2_int(T, x);
+    if (T(1) << log2_val == x)
+        return log2_val;
+    return log2_val + 1;
+}
+
+test "std.math.log2_int_ceil" {
+    assert(log2_int_ceil(u32, 1) == 0);
+    assert(log2_int_ceil(u32, 2) == 1);
+    assert(log2_int_ceil(u32, 3) == 2);
+    assert(log2_int_ceil(u32, 4) == 2);
+    assert(log2_int_ceil(u32, 5) == 3);
+    assert(log2_int_ceil(u32, 6) == 3);
+    assert(log2_int_ceil(u32, 7) == 3);
+    assert(log2_int_ceil(u32, 8) == 3);
+    assert(log2_int_ceil(u32, 9) == 4);
+    assert(log2_int_ceil(u32, 10) == 4);
+}
+
 fn testFloorPowerOfTwo() void {
     assert(floorPowerOfTwo(u32, 63) == 32);
     assert(floorPowerOfTwo(u32, 64) == 64);
diff --git a/std/math/log2.zig b/std/math/log2.zig
index 998d6d6c5e..d5bbe385c2 100644
--- a/std/math/log2.zig
+++ b/std/math/log2.zig
@@ -31,17 +31,12 @@ pub fn log2(x: var) @typeOf(x) {
             return result;
         },
         TypeId.Int => {
-            return log2_int(T, x);
+            return math.log2_int(T, x);
         },
         else => @compileError("log2 not implemented for " ++ @typeName(T)),
     }
 }
 
-pub fn log2_int(comptime T: type, x: T) T {
-    assert(x != 0);
-    return T.bit_count - 1 - T(@clz(x));
-}
-
 pub fn log2_32(x_: f32) f32 {
     const ivln2hi: f32 =  1.4428710938e+00;
     const ivln2lo: f32 = -1.7605285393e-04;