Allow exponentiation (** operator) with fp arguments

The operator is implemented by utilizing the equivalence relation of
x**y == exp(y*log(x)). This introduces a non-trivial error, which may
be reduced/eliminated at a later date by implementing a specialized
pow() function.

src/lib/C4Real.h

@@ -67,6 +67,7 @@ class C4RealBase
 
 	friend C4RealBase Sin(const C4RealBase &);
 	friend C4RealBase Cos(const C4RealBase &);
+	friend C4RealBase Pow(const C4RealBase &, const C4RealBase &);
 	friend typename C4RealImpl;
 
 public:

src/lib/C4RealImpl_FPU.h

@@ -37,6 +37,10 @@ inline C4Real_FPU_Float Cos(const C4Real_FPU_Float &real)
 {
 	return std::cos(real.value * static_cast<float>(M_PI) / 180.0f);
 }
+inline C4Real_FPU_Float Pow(const C4Real_FPU_Float &x, const C4Real_FPU_Float &y)
+{
+	return std::pow(x.value, y.value);
+}
 
 // Overload to avoid conversion warning
 template<>

src/lib/C4RealImpl_SSE.cpp

@@ -42,4 +42,11 @@ C4Real_SSE_Float Cos(const C4Real_SSE_Float &real)
 {
 	return C4RealImpl_SSE(cos_ps(_mm_mul_ps(real.value.value, deg2rad)));
 }
-
+C4Real_SSE_Float Pow(const C4Real_SSE_Float &x, const C4Real_SSE_Float &y)
+{
+	C4RealImpl_SSE val;
+	val.value = log_ps(x.value.value);
+	val *= y.value;
+	val.value = exp_ps(val.value);
+	return val;
+}

src/lib/C4RealImpl_SSE.h

@@ -30,12 +30,15 @@ class C4RealImpl_SSE
 {
 	friend C4Real_SSE_Float Sin(const C4Real_SSE_Float &);
 	friend C4Real_SSE_Float Cos(const C4Real_SSE_Float &);
+	friend C4Real_SSE_Float Pow(const C4Real_SSE_Float &, const C4Real_SSE_Float &);
 	__m128 value;
+	C4RealImpl_SSE Pow(const C4RealImpl_SSE &y) const; // power function
 
 	inline C4RealImpl_SSE(__m128 rhs)
 		: value(rhs)
 	{}
 
+
 public:
 	inline C4RealImpl_SSE()
 		: value(_mm_setzero_ps())

src/script/C4AulExec.cpp

@@ -296,7 +296,7 @@ C4Value C4AulExec::Exec(C4AulBCC *pCPos, bool fPassErrors)
 			{
 				CheckOpPars(pCPos->Par.i);
 				C4Value *pPar1 = pCurVal - 1, *pPar2 = pCurVal;
-				pPar1->SetInt(Pow(pPar1->_getInt(), pPar2->_getInt()));
+				pPar1->Set(pPar1->Pow(*pPar2));
 				PopValue();
 				break;
 			}

src/script/C4AulParse.cpp

@@ -440,7 +440,7 @@ C4ScriptOpDef C4ScriptOpMap[] =
 	{ 16, "--", AB_Dec,             AB_Inc,  1, 1, 1, C4V_Int,  C4V_Numeric,    C4V_Any},
 	
 	// postfix
-	{ 14, "**", AB_Pow,             AB_ERR,  1, 0, 0, C4V_Int,  C4V_Int,    C4V_Int},
+	{ 14, "**", AB_Pow,             AB_ERR,  1, 0, 0, C4V_Int,  C4V_Numeric,    C4V_Numeric},
 	{ 13, "/",  AB_Div,             AB_ERR,  1, 0, 0, C4V_Any,  C4V_Numeric,    C4V_Numeric},
 	{ 13, "*",  AB_Mul,             AB_ERR,  1, 0, 0, C4V_Any,  C4V_Numeric,    C4V_Numeric},
 	{ 13, "%",  AB_Mod,             AB_ERR,  1, 0, 0, C4V_Int,  C4V_Int,    C4V_Int},

src/script/C4Value.h

@@ -222,6 +222,17 @@ public:
 		operator--();
 		return nrv;
 	}
+	C4Value Pow(const C4Value &rhs) const
+	{
+		assert(ConvertTo(C4V_Numeric));
+		assert(rhs.ConvertTo(C4V_Numeric));
+		C4Value nrv;
+		if (Type == C4V_Float || rhs.Type == C4V_Float)
+			nrv.SetFloat(::Pow(getFloat(), rhs.getFloat()));
+		else
+			nrv.SetInt(::Pow(getInt(), rhs.getInt()));
+		return nrv;
+	}
 
 	// getters
 	C4V_Data GetData()    const { return Data; }