initial commit

lib/glm/gtx/integer.inl

@@ -0,0 +1,182 @@
+/// @ref gtx_integer
+/// @file glm/gtx/integer.inl
+
+namespace glm
+{
+	// pow
+	GLM_FUNC_QUALIFIER int pow(int x, int y)
+	{
+		if(y == 0)
+			return 1;
+		int result = x;
+		for(int i = 1; i < y; ++i)
+			result *= x;
+		return result;
+	}
+
+	// sqrt: From Christopher J. Musial, An integer square root, Graphics Gems, 1990, page 387
+	GLM_FUNC_QUALIFIER int sqrt(int x)
+	{
+		if(x <= 1) return x;
+
+		int NextTrial = x >> 1;
+		int CurrentAnswer;
+
+		do
+		{
+			CurrentAnswer = NextTrial;
+			NextTrial = (NextTrial + x / NextTrial) >> 1;
+		} while(NextTrial < CurrentAnswer);
+
+		return CurrentAnswer;
+	}
+
+// Henry Gordon Dietz: http://aggregate.org/MAGIC/
+namespace detail
+{
+	GLM_FUNC_QUALIFIER unsigned int ones32(unsigned int x)
+	{
+		/* 32-bit recursive reduction using SWAR...
+		but first step is mapping 2-bit values
+		into sum of 2 1-bit values in sneaky way
+		*/
+		x -= ((x >> 1) & 0x55555555);
+		x = (((x >> 2) & 0x33333333) + (x & 0x33333333));
+		x = (((x >> 4) + x) & 0x0f0f0f0f);
+		x += (x >> 8);
+		x += (x >> 16);
+		return(x & 0x0000003f);
+	}
+}//namespace detail
+
+	// Henry Gordon Dietz: http://aggregate.org/MAGIC/
+/*
+	GLM_FUNC_QUALIFIER unsigned int floor_log2(unsigned int x)
+	{
+		x |= (x >> 1);
+		x |= (x >> 2);
+		x |= (x >> 4);
+		x |= (x >> 8);
+		x |= (x >> 16);
+
+		return _detail::ones32(x) >> 1;
+	}
+*/
+	// mod
+	GLM_FUNC_QUALIFIER int mod(int x, int y)
+	{
+		return x - y * (x / y);
+	}
+
+	// factorial (!12 max, integer only)
+	template <typename genType>
+	GLM_FUNC_QUALIFIER genType factorial(genType const & x)
+	{
+		genType Temp = x;
+		genType Result;
+		for(Result = 1; Temp > 1; --Temp)
+			Result *= Temp;
+		return Result;
+	}
+
+	template <typename T, precision P>
+	GLM_FUNC_QUALIFIER tvec2<T, P> factorial(
+		tvec2<T, P> const & x)
+	{
+		return tvec2<T, P>(
+			factorial(x.x),
+			factorial(x.y));
+	}
+
+	template <typename T, precision P>
+	GLM_FUNC_QUALIFIER tvec3<T, P> factorial(
+		tvec3<T, P> const & x)
+	{
+		return tvec3<T, P>(
+			factorial(x.x),
+			factorial(x.y),
+			factorial(x.z));
+	}
+
+	template <typename T, precision P>
+	GLM_FUNC_QUALIFIER tvec4<T, P> factorial(
+		tvec4<T, P> const & x)
+	{
+		return tvec4<T, P>(
+			factorial(x.x),
+			factorial(x.y),
+			factorial(x.z),
+			factorial(x.w));
+	}
+
+	GLM_FUNC_QUALIFIER uint pow(uint x, uint y)
+	{
+		uint result = x;
+		for(uint i = 1; i < y; ++i)
+			result *= x;
+		return result;
+	}
+
+	GLM_FUNC_QUALIFIER uint sqrt(uint x)
+	{
+		if(x <= 1) return x;
+
+		uint NextTrial = x >> 1;
+		uint CurrentAnswer;
+
+		do
+		{
+			CurrentAnswer = NextTrial;
+			NextTrial = (NextTrial + x / NextTrial) >> 1;
+		} while(NextTrial < CurrentAnswer);
+
+		return CurrentAnswer;
+	}
+
+	GLM_FUNC_QUALIFIER uint mod(uint x, uint y)
+	{
+		return x - y * (x / y);
+	}
+
+#if(GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_GCC))
+
+	GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x) 
+	{
+		return 31u - findMSB(x);
+	}
+
+#else
+
+	// Hackers Delight: http://www.hackersdelight.org/HDcode/nlz.c.txt
+	GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x) 
+	{
+		int y, m, n;
+
+		y = -int(x >> 16);      // If left half of x is 0,
+		m = (y >> 16) & 16;  // set n = 16.  If left half
+		n = 16 - m;          // is nonzero, set n = 0 and
+		x = x >> m;          // shift x right 16.
+							// Now x is of the form 0000xxxx.
+		y = x - 0x100;       // If positions 8-15 are 0,
+		m = (y >> 16) & 8;   // add 8 to n and shift x left 8.
+		n = n + m;
+		x = x << m;
+
+		y = x - 0x1000;      // If positions 12-15 are 0,
+		m = (y >> 16) & 4;   // add 4 to n and shift x left 4.
+		n = n + m;
+		x = x << m;
+
+		y = x - 0x4000;      // If positions 14-15 are 0,
+		m = (y >> 16) & 2;   // add 2 to n and shift x left 2.
+		n = n + m;
+		x = x << m;
+
+		y = x >> 14;         // Set y = 0, 1, 2, or 3.
+		m = y & ~(y >> 1);   // Set m = 0, 1, 2, or 2 resp.
+		return unsigned(n + 2 - m);
+	}
+
+#endif//(GLM_COMPILER)
+
+}//namespace glm