Added most recent version of unmodified HL2 SDK for Episode 1 engine

mathlib/powsse.cpp

@@ -0,0 +1,35 @@
+// $Id$
+
+#include "mathlib/ssemath.h"
+
+__m128 PowSSE_FixedPoint_Exponent(__m128 x, int exponent)
+{
+	__m128 rslt=Four_Ones;									// x^0=1.0
+	int xp=abs(exponent);
+	if (xp & 3)												// fraction present?
+	{
+		__m128 sq_rt=_mm_sqrt_ps(x);
+		if (xp & 1)											// .25?
+			rslt=_mm_sqrt_ps(sq_rt);						// x^.25
+		if (xp & 2)
+			rslt=_mm_mul_ps(rslt,sq_rt);
+	}
+	xp>>=2;													// strip fraction
+	__m128 curpower=x;										// curpower iterates through  x,x^2,x^4,x^8,x^16...
+
+	while(1)
+	{
+		if (xp & 1)
+			rslt=_mm_mul_ps(rslt,curpower);
+		xp>>=1;
+		if (xp)
+			curpower=_mm_mul_ps(curpower,curpower);
+		else
+			break;
+	}
+	if (exponent<0)
+		return _mm_rcp_ps(rslt);							// pow(x,-b)=1/pow(x,b)
+	else
+		return rslt;
+}
+