Use sincos instead of sine and cosine separately

jeremysalwen · Jun 5, 2011 · 21b9607 · 21b9607
1 parent e5e9b32
commit 21b9607
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Showing 2 changed files with 16 additions and 4 deletions.
diff --git a/QuickTrig.h b/QuickTrig.h
@@ -61,8 +61,19 @@ class CQuickTrig
     {
         return QuickCosQ((int)(dAngle*(kMsTableSize*kLsTableSize/(2*PI))) );
     }
+	inline void QuickSinCos(double dAngle,float * cos, float* sin) const // Returns cos with 20 bits of precision.
+    {
+        return QuickSinCosQ((int)(dAngle*(kMsTableSize*kLsTableSize/(2*PI))),cos,sin );
+    }
 
-
+	inline void QuickSinCosQ(int nIndex, float* cos, float*sin) const {
+	 // Based on the identity sin(u+v) = sinu cosv + cosu sinv
+	    // based on the identity cos(u+v) = cosu cosv + sinu sinv
+        TSinCos *pscu = mMsBitsTable +( (nIndex >> kLSBits) & (kMsTableSize-1));
+        TSinCos *pscv = mLsBitsTable + ( (nIndex) & (kLsTableSize-1));
+        *cos= pscu->mcos * pscv->mcos - pscu->msin * pscv->msin;
+        *sin= pscu->msin * pscv->mcos + pscu->mcos * pscv->msin;
+	}
 
 
 };
diff --git a/kn0ck0ut6.cpp b/kn0ck0ut6.cpp
@@ -368,9 +368,10 @@ void AKnockout::do_rebuild(long numSampsToProcess, long fftFrameSize, long osamp
 			tmp *= dFreqfactor;
 			tmp += (double)k*expct;
 
-			/* get real and imag part and re-interleave */
-			gFFTworksp[k][0] = magn*myQT.QuickCos(tmp);
-			gFFTworksp[k][1] = magn*myQT.QuickSin(tmp);
+			/* get real and imag part and re-interleave */
+			myQT.QuickSinCos(tmp,gFFTworksp[k],gFFTworksp[k]+1);
+			gFFTworksp[k][0] *=magn;
+			gFFTworksp[k][1] *=magn;
 
 		}