Merge pull request #5 from WinampDesktop/community

Merge to main

1 files changed, 66 insertions, 0 deletions

diff --git a/Src/f263/idctref.cpp b/Src/f263/idctref.cpp
new file mode 100644
index 00000000..6bab912f
--- /dev/null
+++ b/Src/f263/idctref.cpp
@@ -0,0 +1,66 @@
+#include "idctref.h"
+#include <math.h>
+#ifndef PI
+# ifdef M_PI
+#  define PI M_PI
+# else
+#  define PI 3.14159265358979323846
+# endif
+#endif
+
+	bool IDCTRef::initted = false;
+	double IDCTRef::c[8][8]; /* cosine transform matrix for 8x1 IDCT */
+
+
+	/* initialize DCT coefficient matrix */
+
+	void IDCTRef::init()
+	{
+		if (!initted)
+		{
+			int freq, time;
+
+			for (freq=0; freq < 8; freq++)
+			{
+				double scale = (freq == 0) ? sqrt(0.125) : 0.5;
+				for (time=0; time<8; time++)
+					c[freq][time] = scale*cos((PI/8.0)*freq*(time + 0.5));
+			}
+			initted=true;
+		}
+	}
+
+	/* perform IDCT matrix multiply for 8x8 coefficient block */
+
+	void IDCTRef::idct(short *block)
+	{
+		int i, j, k, v;
+		double partial_product;
+		double tmp[64];
+
+		for (i=0; i<8; i++)
+			for (j=0; j<8; j++)
+			{
+				partial_product = 0.0;
+
+				for (k=0; k<8; k++)
+					partial_product+= c[k][j]*block[8*i+k];
+
+				tmp[8*i+j] = partial_product;
+			}
+
+		/* Transpose operation is integrated into address mapping by switching
+		   loop order of i and j */
+
+		for (j=0; j<8; j++)
+			for (i=0; i<8; i++)
+			{
+				partial_product = 0.0;
+
+				for (k=0; k<8; k++)
+					partial_product+= c[k][i]*tmp[8*k+j];
+
+				v = (int)floor(partial_product+0.5);
+				block[8*i+j] = (v<-256) ? -256 : ((v>255) ? 255 : v);
+			}
+	}