std.io.Writer: add support for non-power-of-two int sizes

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/std/math.zig b/lib/std/math.zig
index 4221118ba5..8bd7c364f9 100644
--- a/lib/std/math.zig
+++ b/lib/std/math.zig
@@ -1122,6 +1122,23 @@ pub fn isPowerOfTwo(v: anytype) bool {
     return (v & (v - 1)) == 0;
 }
 
+/// Aligns the given integer type bit width to a width divisible by 8.
+pub fn ByteAlignedInt(comptime T: type) type {
+    const info = @typeInfo(T).Int;
+    const bits = (info.bits + 7) / 8 * 8;
+    const extended_type = std.meta.Int(info.signedness, bits);
+    return extended_type;
+}
+
+test "ByteAlignedInt" {
+    try testing.expect(ByteAlignedInt(u0) == u0);
+    try testing.expect(ByteAlignedInt(i0) == i0);
+    try testing.expect(ByteAlignedInt(u3) == u8);
+    try testing.expect(ByteAlignedInt(u8) == u8);
+    try testing.expect(ByteAlignedInt(i111) == i112);
+    try testing.expect(ByteAlignedInt(u129) == u136);
+}
+
 /// Rounds the given floating point number to an integer, away from zero.
 /// Uses a dedicated hardware instruction when available.
 /// This is the same as calling the builtin @round