Added original SDK code for Alien Swarm.

public/mathlib/math_pfns.h

@@ -0,0 +1,110 @@
+//========= Copyright <20> 1996-2005, Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=====================================================================================//
+
+#ifndef _MATH_PFNS_H_
+#define _MATH_PFNS_H_
+
+#include <limits>
+
+#if defined( _X360 )
+#include <xboxmath.h>
+#endif
+
+#if !defined( _X360 )
+
+#include <xmmintrin.h>
+
+// These globals are initialized by mathlib and redirected based on available fpu features
+
+// The following are not declared as macros because they are often used in limiting situations,
+// and sometimes the compiler simply refuses to inline them for some reason
+FORCEINLINE float FastSqrt( float x )
+{
+	__m128 root = _mm_sqrt_ss( _mm_load_ss( &x ) );
+	return *( reinterpret_cast<float *>( &root ) );
+}
+
+FORCEINLINE float FastRSqrtFast( float x )
+{
+	// use intrinsics
+	__m128 rroot = _mm_rsqrt_ss( _mm_load_ss( &x ) );
+	return *( reinterpret_cast<float *>( &rroot ) );
+}
+// Single iteration NewtonRaphson reciprocal square root:
+// 0.5 * rsqrtps * (3 - x * rsqrtps(x) * rsqrtps(x)) 	
+// Very low error, and fine to use in place of 1.f / sqrtf(x).	
+FORCEINLINE float FastRSqrt( float x )
+{
+	float rroot = FastRSqrtFast( x );
+	return (0.5f * rroot) * (3.f - (x * rroot) * rroot);
+}
+
+void FastSinCos( float x, float* s, float* c );  // any x
+float FastCos( float x );
+
+
+
+inline float FastRecip(float x) {return 1.0f / x;}
+// Simple SSE rsqrt.  Usually accurate to around 6 (relative) decimal places 
+// or so, so ok for closed transforms.  (ie, computing lighting normals)
+inline float FastSqrtEst(float x) { return FastRSqrtFast(x) * x; }
+
+
+#endif // !_X360
+
+#if defined( _X360 )
+
+FORCEINLINE float _VMX_Sqrt( float x )
+{
+	return __fsqrts( x );
+}
+
+FORCEINLINE float _VMX_RSqrt( float x )
+{
+	float rroot = __frsqrte( x );
+
+	// Single iteration NewtonRaphson on reciprocal square root estimate
+	return (0.5f * rroot) * (3.0f - (x * rroot) * rroot);
+}
+
+FORCEINLINE float _VMX_RSqrtFast( float x )
+{
+	return __frsqrte( x );
+}
+
+FORCEINLINE void _VMX_SinCos( float a, float *pS, float *pC )
+{
+	XMScalarSinCos( pS, pC, a );
+}
+
+FORCEINLINE float _VMX_Cos( float a )
+{
+	return XMScalarCos( a );
+}
+
+// the 360 has fixed hw and calls directly
+#define FastSqrt(x)			_VMX_Sqrt(x)
+#define	FastRSqrt(x)		_VMX_RSqrt(x)
+#define FastRSqrtFast(x)	_VMX_RSqrtFast(x)
+#define FastSinCos(x,s,c)	_VMX_SinCos(x,s,c)
+#define FastCos(x)			_VMX_Cos(x)
+
+inline float FastRecip(float x) {return __fres(x);}
+inline float FastSqrtEst(float x) { return __frsqrte(x) * x; }
+
+#endif // _X360
+
+// if x is infinite, return FLT_MAX
+inline float FastClampInfinity( float x )
+{
+#ifdef _X360
+	return fsel( std::numeric_limits<float>::infinity() - x, x, FLT_MAX );
+#else
+	return ( x > FLT_MAX ? FLT_MAX : x );
+#endif
+}
+
+#endif // _MATH_PFNS_H_