From 39ed87570bdb2f86969d4be821c94b722dc71179 Mon Sep 17 00:00:00 2001
From: Joe Ludwig <joe@valvesoftware.com>
Date: Wed, 26 Jun 2013 15:22:04 -0700
Subject: First version of the SOurce SDK 2013

---
 mp/src/mathlib/powsse.cpp | 96 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 mp/src/mathlib/powsse.cpp

(limited to 'mp/src/mathlib/powsse.cpp')

diff --git a/mp/src/mathlib/powsse.cpp b/mp/src/mathlib/powsse.cpp
new file mode 100644
index 00000000..111f8d24
--- /dev/null
+++ b/mp/src/mathlib/powsse.cpp
@@ -0,0 +1,96 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=====================================================================================//
+
+#include "mathlib/ssemath.h"
+
+// NOTE: This has to be the last file included!
+#include "tier0/memdbgon.h"
+
+
+fltx4 Pow_FixedPoint_Exponent_SIMD( const fltx4 & x, int exponent)
+{
+	fltx4 rslt=Four_Ones;									// x^0=1.0
+	int xp=abs(exponent);
+	if (xp & 3)												// fraction present?
+	{
+		fltx4 sq_rt=SqrtEstSIMD(x);
+		if (xp & 1)											// .25?
+			rslt=SqrtEstSIMD(sq_rt);						// x^.25
+		if (xp & 2)
+			rslt=MulSIMD(rslt,sq_rt);
+	}
+	xp>>=2;													// strip fraction
+	fltx4 curpower=x;										// curpower iterates through  x,x^2,x^4,x^8,x^16...
+
+	while(1)
+	{
+		if (xp & 1)
+			rslt=MulSIMD(rslt,curpower);
+		xp>>=1;
+		if (xp)
+			curpower=MulSIMD(curpower,curpower);
+		else
+			break;
+	}
+	if (exponent<0)
+		return ReciprocalEstSaturateSIMD(rslt);				// pow(x,-b)=1/pow(x,b)
+	else
+		return rslt;
+}
+
+
+
+
+/*
+ * (c) Ian Stephenson
+ *
+ * ian@dctsystems.co.uk
+ *
+ * Fast pow() reference implementation
+ */
+
+
+static float shift23=(1<<23);
+static float OOshift23=1.0/(1<<23);
+
+float FastLog2(float i)
+{
+	float LogBodge=0.346607f;
+	float x;
+	float y;
+	x=*(int *)&i;
+	x*= OOshift23; //1/pow(2,23);
+	x=x-127;
+
+	y=x-floorf(x);
+	y=(y-y*y)*LogBodge;
+	return x+y;
+}
+float FastPow2(float i)
+{
+	float PowBodge=0.33971f;
+	float x;
+	float y=i-floorf(i);
+	y=(y-y*y)*PowBodge;
+
+	x=i+127-y;
+	x*= shift23; //pow(2,23);
+	*(int*)&x=(int)x;
+	return x;
+}
+float FastPow(float a, float b)
+{
+	if (a <= OOshift23)
+	{
+		return 0.0f;
+	}
+	return FastPow2(b*FastLog2(a));
+}
+float FastPow10( float i )
+{
+	return FastPow2( i * 3.321928f );
+}
+
-- 
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