Subject: [Boost-commit] svn:boost r63205 - sandbox/SOC/2010/bits_and_ints/boost/integer
From: muriloufg_at_[hidden]
Date: 2010-06-21 17:14:21
Author: murilov
Date: 2010-06-21 17:14:20 EDT (Mon, 21 Jun 2010)
New Revision: 63205
URL: http://svn.boost.org/trac/boost/changeset/63205
Log:
Added functions for round integral values to next integral that is power of 2
Added:
sandbox/SOC/2010/bits_and_ints/boost/integer/round_power_2.hpp (contents, props changed)
Added: sandbox/SOC/2010/bits_and_ints/boost/integer/round_power_2.hpp
==============================================================================
--- (empty file)
+++ sandbox/SOC/2010/bits_and_ints/boost/integer/round_power_2.hpp 2010-06-21 17:14:20 EDT (Mon, 21 Jun 2010)
@@ -0,0 +1,124 @@
+// Boost integer/round_power_2.hpp header file ------------------------------//
+
+// (C) Copyright Murilo Adriano Vasconcelos 2010.
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+// See http://www.boost.org for updates, documentation, and revision history.
+
+
+#ifndef BOOST_POWER_2_ROUND
+#define BOOST_POWER_2_ROUND
+
+/*
+ * The functions declared in this file an integra rounds up or down to
+ * the next power of 2.
+ *
+ * The functions `ceil_to_power_2()' rounds up and the functions
+ * `floor_to_power_2()' rounds down.
+ *
+ * Usage:
+ *
+ * T x = ceil_to_power_2(y); // rounds down
+ * T z = floor_to_power_2(w); // rounds up
+ */
+
+namespace boost {
+
+uint8_t ceil_to_power_2(uint8_t value)
+{
+ value = value - 1;
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+
+ return value + 1;
+}
+
+uint16_t ceil_to_power_2(uint16_t value)
+{
+ value = value - 1;
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+
+ return value + 1;
+}
+
+uint32_t ceil_to_power_2(uint32_t value)
+{
+ value = value - 1;
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+ value = value | (value >> 16);
+
+ return value + 1;
+}
+
+#ifndef BOOST_HAS_INT64_T
+uint64_t ceil_to_power_2(uint64_t value)
+{
+ value = value - 1;
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+ value = value | (value >> 16);
+ value = value | (value >> 32);
+
+ return value + 1;
+}
+#endif
+
+uint8_t floor_to_power_2(uint8_t value)
+{
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+
+ return value - (value >> 1);
+}
+
+uint16_t floor_to_power_2(uint16_t value)
+{
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+
+ return value - (value >> 1);
+}
+
+uint32_t floor_to_power_2(uint32_t value)
+{
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+ value = value | (value >> 16);
+
+ return value - (value >> 1);
+}
+
+#ifndef BOOST_HAS_INT64_T
+uint64_t floor_to_power_2(uint64_t value)
+{
+ value = value | (value >> 1);
+ value = value | (value >> 2);
+ value = value | (value >> 4);
+ value = value | (value >> 8);
+ value = value | (value >> 16);
+ value = value | (value >> 32);
+
+ return value - (value >> 1);
+}
+#endif
+
+}
+
+#endif