initial check in for structure used to decode Huffman encoded TIFF images

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3064 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/translators/tifftranslator/DecodeTree.cpp

@@ -0,0 +1,132 @@
+/*****************************************************************************/
+// DecodeTree
+// Written by Michael Wilber, OBOS Translation Kit Team
+//
+// DecodeTree.cpp
+//
+// This object is used for fast decoding of Huffman encoded data
+//
+//
+// Copyright (c) 2003 OpenBeOS Project
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
+// and/or sell copies of the Software, and to permit persons to whom the 
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included 
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+/*****************************************************************************/
+
+#include "DecodeTree.h"
+
+DecodeTree::DecodeTree()
+{
+	fptop = new DecodeNode;
+	if (fptop) {		
+		fptop->value = -1;
+		fptop->branches[0] = NULL;
+		fptop->branches[1] = NULL;
+	}
+}
+
+void
+destroy_node(DecodeNode *pnode)
+{
+	if (pnode->branches[0])
+		destroy_node(pnode->branches[0]);
+	if (pnode->branches[1])
+		destroy_node(pnode->branches[1]);
+
+	delete pnode;
+}
+DecodeTree::~DecodeTree()
+{
+	if (fptop) {
+		destroy_node(fptop);
+		fptop = NULL;
+	}
+}
+
+status_t
+DecodeTree::AddEncoding(uint16 encoding, uint8 length, uint16 value)
+{
+	if (!fptop)
+		return B_NO_MEMORY;
+	if (!length || length > 16)
+		return B_BAD_VALUE;
+		
+	DecodeNode *pcurrent = fptop, *pnext = NULL;
+	uint8 bitsleft = length;
+		
+	while (bitsleft > 0) {
+		uint32 branch = (encoding >> (bitsleft - 1)) & 1;
+	
+		// if a new node needs to be allocated
+		if (!pcurrent->branches[branch]) {
+			pcurrent->branches[branch] = new DecodeNode;
+			pnext = pcurrent->branches[branch];
+			if (!pnext)
+				return B_NO_MEMORY;
+
+			pnext->value = -1;	
+			pnext->branches[0] = NULL;
+			pnext->branches[1] = NULL;
+		
+		} else
+			// if a node exists
+			pnext = pcurrent->branches[branch];
+	
+		if (bitsleft == 1) {
+			pnext->value = value;
+			return B_OK;
+		
+		} else {
+			pcurrent = pnext;
+			bitsleft--;
+		}
+	}
+	
+	return B_ERROR;
+}
+
+status_t
+DecodeTree::GetValue(uint16 encdata, uint8 nbits, uint8 &bitsread) const
+{
+	if (!fptop)
+		return B_NO_MEMORY;
+	if (!nbits || nbits > 16)
+		return B_BAD_VALUE;
+
+	uint32 branch;
+	DecodeNode *pnode = fptop;
+	bitsread = 0;
+	while (bitsread < nbits) {
+	
+		branch = (encdata >> (16 - (bitsread + 1))) & 1;
+		if (!pnode->branches[branch])
+			// if I can't go any further, I've either successfully
+			// decoded some bits or I'm returning -1
+			return pnode->value;
+		else {
+			pnode = pnode->branches[branch];
+			bitsread++;
+			if (bitsread == nbits)
+				return pnode->value;
+		}
+	}
+	
+	return B_ERROR;
+}
+
+

src/add-ons/translators/tifftranslator/DecodeTree.h

@@ -0,0 +1,53 @@
+/*****************************************************************************/
+// DecodeTree
+// Written by Michael Wilber, OBOS Translation Kit Team
+//
+// DecodeTree.h
+//
+// This object is used for fast decoding of Huffman encoded data
+//
+//
+// Copyright (c) 2003 OpenBeOS Project
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
+// and/or sell copies of the Software, and to permit persons to whom the 
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included 
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+/*****************************************************************************/
+
+#ifndef DECODE_TREE_H
+#define DECODE_TREE_H
+
+#include <SupportDefs.h>
+
+struct DecodeNode {
+	int16 value;
+	DecodeNode *branches[2];
+};
+
+class DecodeTree {
+public:
+	DecodeTree();
+	~DecodeTree();
+	
+	status_t AddEncoding(uint16 encoding, uint8 length, uint16 value);
+	status_t GetValue(uint16 encdata, uint8 nbits, uint8 &bitsread) const;
+
+private:	
+	DecodeNode *fptop;
+};
+
+#endif