Add module `love.math`. Implements xorshift RNG.

Contains just a RNG for now, but may include other functionality (e.g.
transforms) later on.

New Functions:

-- as in the lua math library:
love.math.randomseed(number) -- set random seed
love.math.random()           -- get random number in [0:1) (uniformly distributed)
love.math.random(high)       -- get integer random number in [1:high]
love.math.random(low, high)  -- get integer random number in [low:high]

-- additional functions
love.math.randnormal()     -- get normally distributed number with zero mean
                           -- and unit variance
love.math.randnormal(o)    -- get normally distributed number with zero mean
                           -- and standard deviation `o`
love.math.randnormal(m, o) -- get normally distributed number with mean `m`
                           -- and standard deviation `o`

src/modules/love/love.cpp

@@ -103,6 +103,7 @@ extern "C"
 	extern int luaopen_love_sound(lua_State*);
 	extern int luaopen_love_timer(lua_State*);
 	extern int luaopen_love_thread(lua_State*);
+	extern int luaopen_love_math(lua_State*);
 	extern int luaopen_love_boot(lua_State*);
 }
 
@@ -120,6 +121,7 @@ static const luaL_Reg modules[] = {
 	{ "love.sound", luaopen_love_sound },
 	{ "love.timer", luaopen_love_timer },
 	{ "love.thread", luaopen_love_thread },
+	{ "love.math", luaopen_love_math },
 	{ "love.boot", luaopen_love_boot },
 	{ 0, 0 }
 };

src/modules/math/Math.cpp

@@ -0,0 +1,66 @@
+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+#include "Math.h"
+#include "common/math.h"
+
+#include <cmath>
+
+namespace love
+{
+namespace math
+{
+
+// 64 bit Xorshift implementation taken from the end of Sec. 3 (page 4) in
+// George Marsaglia, "Xorshift RNGs", Journal of Statistical Software, Vol.8 (Issue 14), 2003
+Math::Math()
+{
+	RNGState.seed = 0x0139408DCBBF7A44;
+	RNGState.last_randnormal = std::numeric_limits<double>::infinity();
+}
+
+uint32_t Math::rand()
+{
+	uint64_t &x = RNGState.seed;
+	x ^= (x << 13);
+	x ^= (x >> 7);
+	x ^= (x << 17);
+	return x;
+}
+
+// Box–Muller transform
+double Math::randnormal(double stddev)
+{
+	if (RNGState.last_randnormal != std::numeric_limits<double>::infinity())
+	{
+		double r = RNGState.last_randnormal;
+		RNGState.last_randnormal = std::numeric_limits<double>::infinity();
+		return r * stddev;
+	}
+
+	double r   = sqrt(-2.0 * log(1. - random()));
+	double phi = 2.0 * LOVE_M_PI * (1. - random());
+
+	RNGState.last_randnormal = r * cos(phi);
+	return r * sin(phi) * stddev;
+}
+
+} // math
+} // love

src/modules/math/Math.h

@@ -0,0 +1,91 @@
+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+#ifndef LOVE_MATH_MATH_H
+#define LOVE_MATH_MATH_H
+
+// LOVE
+#include "common/Module.h"
+
+// STL
+#include <limits>
+#include <stdint.h>
+
+namespace love
+{
+namespace math
+{
+
+class Math : public Module
+{
+public:
+	Math();
+	virtual ~Math() {}
+
+	/** Set pseudo random seed.
+	 *
+	 * It's up to the implementation how to use this.
+	 *
+	 * @param seed The random seed.
+	 */
+	inline void randomseed(uint64_t seed)
+	{
+		RNGState.seed = seed;
+	}
+
+	/** Return uniformly distributed pseudo random integer.
+	 *
+	 * @returns Pseudo random integer in [0,2^32).
+	 */
+	uint32_t rand();
+
+	/** Get uniformly distributed pseudo random number in [0,1).
+	 *
+	 * @returns Pseudo random number in [0,1).
+	 */
+	inline double random()
+	{
+		return double(rand()) / (double(std::numeric_limits<uint32_t>::max()) + 1.0);
+	}
+
+	/** Get normally distributed pseudo random number.
+	 *
+	 * @param stddev Standard deviation of the distribution.
+	 * @returns Normally distributed random number with mean 0 and variance (stddev)².
+	 */
+	double randnormal(double stddev);
+
+	virtual const char *getName() const
+	{
+		return "love.math";
+	}
+
+private:
+	struct
+	{
+		uint64_t seed;
+		double last_randnormal;
+	} RNGState;
+};
+
+} // math
+} // love
+
+#endif

src/modules/math/wrap_Math.cpp

@@ -0,0 +1,135 @@
+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+#include "wrap_Math.h"
+#include "Math.h"
+
+#include <cmath>
+#include <iostream>
+
+namespace
+{
+
+union SeedConverter
+{
+	double   seed_double;
+	uint64_t seed_uint;
+};
+
+} // anonymous namespace
+
+namespace love
+{
+namespace math
+{
+
+static Math *instance = 0;
+
+int w_randomseed(lua_State *L)
+{
+	SeedConverter s;
+	s.seed_double = luaL_checknumber(L, 1);
+	instance->randomseed(s.seed_uint);
+	return 0;
+}
+
+int w_random(lua_State *L)
+{
+	double r = instance->random();
+	int l, u;
+	// verbatim from lua 5.1.4 source code: lmathlib.c:185 ff.
+	switch (lua_gettop(L))
+	{
+	case 0:
+		lua_pushnumber(L, r);
+		break;
+	case 1:
+		u = luaL_checkint(L, 1);
+		luaL_argcheck(L, 1 <= u, 1, "interval is empty");
+		lua_pushnumber(L, floor(r * u) + 1);
+		break;
+	case 2:
+		l = luaL_checkint(L, 1);
+		u = luaL_checkint(L, 2);
+		luaL_argcheck(L, l <= u, 2, "interval is empty");
+		lua_pushnumber(L, floor(r * (u - l + 1)) + l);
+		break;
+	default:
+		return luaL_error(L, "wrong number of arguments");
+	}
+	return 1;
+}
+
+int w_randnormal(lua_State *L)
+{
+	double mean = 0.0, stddev = 1.0;
+	if (lua_gettop(L) > 1)
+	{
+		mean = luaL_checknumber(L, 1);
+		stddev = luaL_checknumber(L, 2);
+	}
+	else
+	{
+		stddev = luaL_optnumber(L, 1, 1.);
+	}
+
+	double r = instance->randnormal(stddev);
+	lua_pushnumber(L, r + mean);
+	return 1;
+}
+
+// List of functions to wrap.
+static const luaL_Reg functions[] =
+{
+	{ "randomseed", w_randomseed },
+	{ "random", w_random },
+	{ "randnormal", w_randnormal },
+	{ 0, 0 }
+};
+
+static const lua_CFunction types[] =
+{
+	0
+};
+
+extern "C" int luaopen_love_math(lua_State *L)
+{
+	if (instance == 0)
+		instance = new love::math::Math();
+	else
+		instance->retain();
+
+	if (instance == 0)
+		return luaL_error(L, "Could not open module math.");
+
+	WrappedModule w;
+	w.module = instance;
+	w.name = "math";
+	w.flags = MODULE_T;
+	w.functions = functions;
+	w.types = types;
+
+	int n = luax_register_module(L, w);
+
+	return n;
+}
+
+} // math
+} // love

src/modules/math/wrap_Math.h

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+#ifndef LOVE_MATH_WRAP_MATH_H
+#define LOVE_MATH_WRAP_MATH_H
+
+// LOVE
+#include "common/config.h"
+#include "common/runtime.h"
+
+namespace love
+{
+namespace math
+{
+
+int w_randomseed(lua_State *L);
+int w_random(lua_State *L);
+int w_randnormal(lua_State *L);
+extern "C" LOVE_EXPORT int luaopen_love_math(lua_State *L);
+
+} // random
+} // love
+
+#endif // LOVE_MATH_WRAP_MATH_H
+

src/scripts/boot.lua

@@ -257,6 +257,7 @@ function love.init()
 			image = true,
 			graphics = true,
 			audio = true,
+			math = true,
 			physics = true,
 			sound = true,
 			font = true,
@@ -307,6 +308,7 @@ function love.init()
 		"image",
 		"font",
 		"graphics",
+		"math",
 		"physics",
 	} do
 		if c.modules[v] then

src/scripts/boot.lua.h

@@ -429,6 +429,7 @@ const unsigned char boot_lua[] =
 	0x09, 0x09, 0x09, 0x67, 0x72, 0x61, 0x70, 0x68, 0x69, 0x63, 0x73, 0x20, 0x3d, 0x20, 0x74, 0x72, 0x75, 0x65, 
 	0x2c, 0x0a,
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+	0x09, 0x09, 0x09, 0x6d, 0x61, 0x74, 0x68, 0x20, 0x3d, 0x20, 0x74, 0x72, 0x75, 0x65, 0x2c, 0x0a,
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@@ -501,6 +502,7 @@ const unsigned char boot_lua[] =
 	0x09, 0x09, 0x22, 0x69, 0x6d, 0x61, 0x67, 0x65, 0x22, 0x2c, 0x0a,
 	0x09, 0x09, 0x22, 0x66, 0x6f, 0x6e, 0x74, 0x22, 0x2c, 0x0a,
 	0x09, 0x09, 0x22, 0x67, 0x72, 0x61, 0x70, 0x68, 0x69, 0x63, 0x73, 0x22, 0x2c, 0x0a,
+	0x09, 0x09, 0x22, 0x6d, 0x61, 0x74, 0x68, 0x22, 0x2c, 0x0a,
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