X-Git-Url: https://git.dogcows.com/gitweb?a=blobdiff_plain;f=src%2Frandom.cc;fp=src%2Frandom.cc;h=22bbd4e615e2171047650c33b70c9c937065b378;hb=79b5f738f2e38acb60cda7e09f54802933a17105;hp=0000000000000000000000000000000000000000;hpb=a891a2dcbbb63d9e771da6efff00a33da614e737;p=chaz%2Fyoink

diff --git a/src/random.cc b/src/random.cc
new file mode 100644
index 0000000..22bbd4e
--- /dev/null
+++ b/src/random.cc
@@ -0,0 +1,115 @@
+
+/*******************************************************************************
+
+ Copyright (c) 2009, Charles McGarvey
+ All rights reserved.
+ 
+ Redistribution   and   use  in  source  and  binary  forms,  with  or  without
+ modification, are permitted provided that the following conditions are met:
+ 
+   * Redistributions  of  source  code  must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+   * Redistributions  in binary form must reproduce the above copyright notice,
+     this  list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+ 
+ THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES  (INCLUDING,  BUT  NOT  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES;  LOSS  OF  USE,  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*******************************************************************************/
+
+#include <cstdlib>		// srand, rand, RAND_MAX
+#include <ctime>		// time
+#include <cmath>		// log
+#include <climits>		// ULONG_MAX
+
+#include "random.hh"
+
+
+namespace rng {
+
+unsigned seed(unsigned theSeed)
+{
+	srand(theSeed);
+	return theSeed;
+}
+
+unsigned seed()
+{
+	return seed(time(0));
+}
+
+
+template <typename T>
+T get()
+{
+	const  float ln2 = 0.693147;
+	static const unsigned bitsPerPiece = std::log(float(RAND_MAX)) / ln2;
+	static const unsigned sizeOfType = sizeof(T) * 8;
+	static const unsigned pieces = sizeOfType / bitsPerPiece +
+								 ((sizeOfType % bitsPerPiece) ? 1 : 0);
+
+	T bits = 0;
+
+	// we need to call rand() multiple times if it won't provide enough random
+	// bits to fill the size of the given type
+	for (unsigned i = 0; i < pieces; i++)
+	{
+		long piece = rand();
+		bits |= piece << (i * bitsPerPiece);
+	}
+
+	return bits;
+}
+
+
+template <>
+bool get<bool>()
+{
+	return rand() % 2;
+}
+
+template <typename T>
+T get(T lower, T upper)
+{
+	unsigned short randInt = get<unsigned int>();
+	return lower + T(randInt % (upper - lower + 1));
+}
+
+template <>
+float get(float lower, float upper)
+{
+	unsigned long randInt = get<unsigned long>();
+	return (float(randInt) / float(ULONG_MAX)) * (upper - lower) + lower;
+}
+
+template <>
+double get(double lower, double upper)
+{
+	unsigned long long randInt = get<unsigned long long>();
+	return (double(randInt) / double(ULLONG_MAX)) * (upper - lower) + lower;
+}
+
+template <>
+float get()
+{
+	return get<float>(0.0, 1.0);
+}
+
+template <>
+double get()
+{
+	return get<double>(0.0, 1.0);
+}
+
+
+}; // namespace rng
+