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libsst-random/RandomFuncTbl.h

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+/*
+	RandomFuncTbl.h
+	Author: James Russell <jcrussell@762studios.com>, Patrick Baggett <@762studios.com>
+	Created: 5/1/2012
+
+	Purpose: 
+
+	Private header for libsst-random function table
+
+	License:
+
+	This program is free software. It comes without any warranty, to
+	the extent permitted by applicable law. You can redistribute it
+	and/or modify it under the terms of the Do What The Fuck You Want
+	To Public License, Version 2, as published by Sam Hocevar. See
+	http://sam.zoy.org/wtfpl/COPYING for more details.
+*/
+
+#pragma once
+
+#ifndef _SST_RANDOMFUNCTBL_H
+#define _SST_RANDOMFUNCTBL_H
+
+#include <SST/SST_PRNG.h>
+#include <SST/SST_Build.h>
+#include <stdlib.h>		/* size_t */
+
+/*
+The following typedefs are used to set function pointer types.
+*/
+typedef void  (*SST_Random_InitFromSeedFunc)(void*, uint32_t);
+typedef void  (*SST_Random_GetFloatArrayFunc)(void*, float*, size_t, float, float);
+typedef int   (*SST_Random_GetIntFunc)(void*);
+typedef void  (*SST_Random_GetIntArrayFunc)(void*, int*, size_t, int, int);
+
+/*
+	Struct used to contain the necessary function pointers for a given PRNG.
+	See SST_PRNG.c for explanation of non-orthogonality.
+*/
+typedef struct SST_PRNG_FuncTable
+{
+	SST_Random_InitFromSeedFunc initFromSeed;
+	SST_Random_GetFloatArrayFunc getFloatArray;
+	SST_Random_GetIntFunc getInt;
+	SST_Random_GetIntArrayFunc getIntArray;
+	size_t privateSize;
+} SST_PRNG_FuncTable;
+
+
+#define SST_RAND_FLOATBITS_MAX (0x00FFFFFF)
+
+/* Takes a value in the range of [0, SST_RAND_FLOATBITS_MAX] and converts to float in the range 0.0 to 1.0 */
+static INLINE float randIntToFloat(uint32_t value)
+{
+	return (float)value / (float)SST_RAND_FLOATBITS_MAX;
+}
+
+/* Take any random integer in [INT_MIN,INT_MAX] and bound it to [min,max] */
+static INLINE int boundInt(int x, int min, int max)
+{
+	int diff;
+
+	x &= 0x7FFFFFFF; /* Ensure this number is positive. Modulus with negative numbers can be "surprising", e.g. 340 % 60 == 40, but -340 % 60 == 20  */
+	
+	/* Handle edge cases */
+	if(min == max)
+		return min;
+	if(min > max)
+	{
+		int tmp = min;
+		min = max;
+		max = tmp;
+	}
+	
+	diff = max - min;
+
+	return min + (x % diff);
+}
+
+
+
+extern const SST_PRNG_FuncTable _SST_MersenneFuncTable;
+extern const SST_PRNG_FuncTable _SST_CMWCFuncTable;
+extern const SST_PRNG_FuncTable _SST_SmallPRNGFuncTable;
+
+#endif
+