Add bitrotate module.

[gnulib.git] / lib / bitrotate.h

diff --git a/lib/bitrotate.h b/lib/bitrotate.h
new file mode 100644 (file)
index 0000000..f3b6a66
--- /dev/null
+++ b/lib/bitrotate.h
@@ -0,0 +1,60 @@
+/* bitrotate.h - Rotate bits in integers
+   Copyright (C) 2008 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Simon Josefsson <simon@josefsson.org>, 2008. */
+
+#ifndef _GL_BITROTATE_H
+#define _GL_BITROTATE_H
+
+#include <stdint.h>
+
+/* Given an unsigned 32-bit argument X, return the value corresponding
+   to rotating the bits N steps to the left.  N must be between 1 and
+   31 inclusive. */
+static inline uint32_t
+rotl32 (uint32_t x, int n)
+{
+  return ((x << n) | (x >> (32 - n))) & 0xFFFFFFFF;
+}
+
+/* Given an unsigned 32-bit argument X, return the value corresponding
+   to rotating the bits N steps to the right.  N must be between 1 to
+   31 inclusive.*/
+static inline uint32_t
+rotr32 (uint32_t x, int n)
+{
+  return ((x >> n) | (x << (32 - n))) & 0xFFFFFFFF;
+}
+
+/* Given an unsigned 16-bit argument X, return the value corresponding
+   to rotating the bits N steps to the left.  N must be between 1 to
+   15 inclusive. */
+static inline uint16_t
+rotl16 (uint16_t x, int n)
+{
+  return ((x << n) | (x >> (16 - n))) & 0xFFFFFFFF;
+}
+
+/* Given an unsigned 16-bit argument X, return the value corresponding
+   to rotating the bits N steps to the right.  N must be in 1 to 15
+   inclusive. */
+static inline uint16_t
+rotr16 (uint16_t x, int n)
+{
+  return ((x >> n) | (x << (16 - n))) & 0xFFFFFFFF;
+}
+
+#endif /* _GL_BITROTATE_H */