From f9761247794fce2de3726f3de9871a8ec24dcef3 Mon Sep 17 00:00:00 2001
From: Alejandro Colomar <alx@nginx.com>
Date: Tue, 5 Sep 2023 02:58:10 +0200
Subject: Libunit: added bit functions.

These are based on C23's <stdbit.h>.

Signed-off-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---
 src/nxt_unit_bit.h | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 src/nxt_unit_bit.h

(limited to 'src/nxt_unit_bit.h')

diff --git a/src/nxt_unit_bit.h b/src/nxt_unit_bit.h
new file mode 100644
index 00000000..6b43b7c0
--- /dev/null
+++ b/src/nxt_unit_bit.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2022-2023, Alejandro Colomar <alx@kernel.org>
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_UNIT_BIT_H_INCLUDED_
+#define _NXT_UNIT_BIT_H_INCLUDED_
+
+
+#include <limits.h>
+
+
+/* C23 <stdbit.h> stuff */
+nxt_inline unsigned long nxt_bit_ceil_ul(unsigned long x);
+nxt_inline unsigned long nxt_bit_ceil_wrap_ul(unsigned long x);
+nxt_inline int nxt_bit_width_ul(unsigned long x);
+nxt_inline int nxt_leading_zeros_ul(unsigned long x);
+nxt_inline int nxt_trailing_zeros_ul(unsigned long x);
+
+
+nxt_inline unsigned long
+nxt_bit_ceil_ul(unsigned long x)
+{
+    return 1 + (ULONG_MAX >> nxt_leading_zeros_ul(x));
+}
+
+
+nxt_inline unsigned long
+nxt_bit_ceil_wrap_ul(unsigned long x)
+{
+    return (x == 0) ? 0 : nxt_bit_ceil_ul(x);
+}
+
+
+nxt_inline int
+nxt_bit_width_ul(unsigned long x)
+{
+    return (x == 0) ? 0 : nxt_trailing_zeros_ul(nxt_bit_ceil_ul(x));
+}
+
+
+nxt_inline int
+nxt_leading_zeros_ul(unsigned long x)
+{
+    if (x == 0) {
+        return sizeof(unsigned long) * CHAR_BIT;
+    }
+
+    return __builtin_clzl(x);
+}
+
+
+nxt_inline int
+nxt_trailing_zeros_ul(unsigned long x)
+{
+    if (x == 0) {
+        return sizeof(unsigned long) * CHAR_BIT;
+    }
+
+    return __builtin_ctzl(x);
+}
+
+
+#endif /* _NXT_UNIT_BIT_H_INCLUDED_ */
-- 
cgit