[Boost-commit] svn:boost r63205 - sandbox/SOC/2010/bits_and_ints/boost/integer

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