From 15318cad33835e4e2dc620d033e43cd930676cdd Mon Sep 17 00:00:00 2001
From: kergoth <kergoth>
Date: Fri, 25 Jan 2002 22:14:26 +0000
Subject: Initial revision

---
(limited to 'core/multimedia/opieplayer/libflash/adpcm.cc')

diff --git a/core/multimedia/opieplayer/libflash/adpcm.cc b/core/multimedia/opieplayer/libflash/adpcm.cc
new file mode 100644
index 0000000..a4bc435
--- a/dev/null
+++ b/core/multimedia/opieplayer/libflash/adpcm.cc
@@ -0,0 +1,235 @@
+
+#include "swf.h"
+
+#ifdef RCSID
+static char *rcsid = "$Id$";
+#endif
+
+// This file has been rearranged from the code posted
+// on news:forums.macromedia.com by Jonathan Gay.
+// Courtesy of Macromedia
+
+//
+// ADPCM tables
+//
+
+static const int indexTable2[2] = {
+    -1, 2,
+};
+
+// Is this ok?
+static const int indexTable3[4] = {
+    -1, -1, 2, 4,
+};
+
+static const int indexTable4[8] = {
+    -1, -1, -1, -1, 2, 4, 6, 8,
+};
+
+static const int indexTable5[16] = {
+ -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16,
+};
+
+static const int* indexTables[] = {
+ indexTable2,
+ indexTable3,
+ indexTable4,
+ indexTable5
+};
+
+static const int stepsizeTable[89] = {
+    7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
+    19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
+    50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
+    130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
+    337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
+    876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
+    2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
+    5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
+    15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
+};
+
+long
+Adpcm::GetBits(int n)
+{
+	if ( bitPos < n ) FillBuffer();
+
+	assert(bitPos >= n);
+
+	long v = ((unsigned long)bitBuf << (32-bitPos)) >> (32-n);
+	bitPos -= n;
+
+	return v;
+}
+
+long
+Adpcm::GetSBits(int n)
+{
+	if ( bitPos < n ) FillBuffer();
+
+	assert(bitPos >= n);
+
+	long v = ((long)bitBuf << (32-bitPos)) >> (32-n);
+	bitPos -= n;
+
+	return v;
+}
+
+//
+// The Decompressor
+//
+
+// Constructor
+Adpcm::Adpcm(unsigned char *buffer, long isStereo)
+{
+	stereo = isStereo;
+	src = buffer;
+
+	nBits = 0; // flag that it is not inited
+	nSamples = 0;
+
+	bitPos = 0;
+	bitBuf = 0;
+}
+
+void
+Adpcm::FillBuffer()
+{
+	while ( bitPos <= 24 /*&& srcSize > 0*/ ) {
+		bitBuf = (bitBuf<<8) | *src++;
+		bitPos += 8;
+	}
+}
+
+void
+Adpcm::Decompress(short *dst, long n)
+{
+	if ( nBits == 0 ) {
+		// Get the compression header
+		nBits = (int)GetBits(2)+2;
+	}
+
+	const int* indexTable = indexTables[nBits-2];
+	int k0 = 1 << (nBits-2);
+	int signmask = 1 << (nBits-1);
+
+	if ( !stereo ) {
+		// Optimize for mono
+		long		vp = valpred[0]; // maybe these can get into registers...
+		int		ind = index[0];
+		long		ns = nSamples;
+
+		while ( n-- > 0 ) {
+			ns++;
+
+			if ( (ns & 0xFFF) == 1 ) {
+				// Get a new block header
+				*dst++ = (short)(vp = GetSBits(16));
+
+				ind = (int)GetBits(6); // The first sample in a block does not have a delta
+			} else {
+				// Process a delta value
+				int delta = (int)GetBits(nBits);
+
+				// Compute difference and new predicted value
+				// Computes 'vpdiff = (delta+0.5)*step/4'
+				int step = stepsizeTable[ind];
+				long vpdiff = 0;
+				int k = k0;
+
+				do {
+					if ( delta & k )
+					vpdiff += step;
+					step >>= 1;
+					k >>= 1;
+				} while ( k );
+
+				vpdiff += step; // add 0.5
+
+				if ( delta & signmask ) // the sign bit
+					vp -= vpdiff;
+				else
+					vp += vpdiff;
+
+				// Find new index value
+				ind += indexTable[delta&(~signmask)];
+
+				if ( ind < 0 )
+					ind = 0;
+				else if ( ind > 88 )
+					ind = 88;
+
+				// clamp output value
+				if ( vp != (short)vp )
+					vp = vp < 0 ? -32768 : 32767;
+
+				/* Step 7 - Output value */
+				*dst++ = (short)vp;
+			}
+		}
+
+		valpred[0] = vp;
+		index[0] = ind;
+		nSamples = ns;
+
+	} else {
+		int sn = stereo ? 2 : 1;
+
+		// Stereo
+		while ( n-- > 0 ) {
+
+			nSamples++;
+
+			if ( (nSamples & 0xFFF) == 1 ) {
+				// Get a new block header
+				for ( int i = 0; i < sn; i++ ) {
+
+					*dst++ = (short)(valpred[i] = GetSBits(16));
+
+					// The first sample in a block does not have a delta
+					index[i] = (int)GetBits(6);
+				}
+			} else {
+				// Process a delta value
+				for ( int i = 0; i < sn; i++ ) {
+					int delta = (int)GetBits(nBits);
+
+					// Compute difference and new predicted value
+					// Computes 'vpdiff = (delta+0.5)*step/4'
+
+					int step = stepsizeTable[index[i]];
+					long vpdiff = 0;
+					int k = k0;
+
+					do {
+						if ( delta & k ) vpdiff += step;
+						step >>= 1;
+						k >>= 1;
+					} while ( k );
+					vpdiff += step; // add 0.5
+
+
+					if ( delta & signmask ) // the sign bit
+						valpred[i] -= vpdiff;
+					else
+						valpred[i] += vpdiff;
+
+					// Find new index value
+					index[i] += indexTable[delta&(~signmask)];
+
+					if ( index[i] < 0 )
+						index[i] = 0;
+					else if ( index[i] > 88 )
+						index[i] = 88;
+
+					// clamp output value
+					if ( valpred[i] != (short)valpred[i] )
+						valpred[i] = valpred[i] < 0 ? -32768 : 32767;
+
+					/* Step 7 - Output value */
+					*dst++ = (short)valpred[i];
+				}
+			}
+		}
+	}
+}
--
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