1 files changed, 37 insertions, 0 deletions
diff --git a/include/c/bit/clz.h b/include/c/bit/clz.h
new file mode 100644
index 0000000..ee217f1
--- /dev/null
+++ b/include/c/bit/clz.h
@@ -0,0 +1,37 @@
+// Copyright 2023 Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier:  LGPL-3.0-or-later WITH LGPL-3.0-linking-exception
+
+
+#ifndef INCLUDE_C_BIT_CLZ_H_
+#define INCLUDE_C_BIT_CLZ_H_
+
+
+#include <assert.h>
+#include <stdint.h>
+
+
+#pragma clang assume_nonnull begin
+inline int c_leading_zeros_32(uint32_t x);
+inline int c_leading_zeros_64(uint64_t x);
+
+
+inline int
+c_leading_zeros_32(uint32_t x)
+{
+	static_assert(sizeof(int) == sizeof(uint32_t));
+
+	return (x == 0) ? UINT32_WIDTH : __builtin_clz(x);
+}
+
+
+inline int
+c_leading_zeros_64(uint64_t x)
+{
+	static_assert(sizeof(long) == sizeof(uint64_t));
+
+	return (x == 0) ? UINT64_WIDTH : __builtin_clzl(x);
+}
+#pragma clang assume_nonnull end
+
+
+#endif  // Header guard