imgtools/imglib/e32image/deflate/deflate.cpp
changeset 0 044383f39525
child 590 360bd6b35136
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imgtools/imglib/e32image/deflate/deflate.cpp	Tue Oct 27 16:36:35 2009 +0000
@@ -0,0 +1,327 @@
+/*
+* Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).
+* All rights reserved.
+* This component and the accompanying materials are made available
+* under the terms of the License "Eclipse Public License v1.0"
+* which accompanies this distribution, and is available
+* at the URL "http://www.eclipse.org/legal/epl-v10.html".
+*
+* Initial Contributors:
+* Nokia Corporation - initial contribution.
+*
+* Contributors:
+*
+* Description: 
+* e32tools\petran\Szip\deflate.cpp
+*
+*/
+
+
+#include "deflate.h"
+#include "h_utl.h"
+#include "panic.h"
+
+class HDeflateHash
+	{
+public:
+	inline static HDeflateHash* NewLC(TInt aLinks);
+//
+	inline TInt First(const TUint8* aPtr,TInt aPos);
+	inline TInt Next(TInt aPos,TInt aOffset) const;
+private:
+	inline HDeflateHash();
+	inline static TInt Hash(const TUint8* aPtr);
+private:
+	typedef TUint16 TOffset;
+private:
+	TInt iHash[256];
+	TOffset iOffset[1];	// or more
+	};
+
+class MDeflater
+	{
+public:
+	void DeflateL(const TUint8* aBase,TInt aLength);
+	inline virtual ~MDeflater() { }; 
+private:
+	const TUint8* DoDeflateL(const TUint8* aBase,const TUint8* aEnd,HDeflateHash& aHash);
+	static TInt Match(const TUint8* aPtr,const TUint8* aEnd,TInt aPos,HDeflateHash& aHas);
+	void SegmentL(TInt aLength,TInt aDistance);
+	virtual void LitLenL(TInt aCode) =0;
+	virtual void OffsetL(TInt aCode) =0;
+	virtual void ExtraL(TInt aLen,TUint aBits) =0;
+	};
+
+class TDeflateStats : public MDeflater
+	{
+public:
+	inline TDeflateStats(TEncoding& aEncoding);
+	inline virtual ~TDeflateStats() { } 
+private:
+// from MDeflater
+	void LitLenL(TInt aCode);
+	void OffsetL(TInt aCode);
+	void ExtraL(TInt aLen,TUint aBits);
+private:
+	TEncoding& iEncoding;
+	};
+
+class TDeflater : public MDeflater
+	{
+public:
+	inline TDeflater(TBitOutput& aOutput,const TEncoding& aEncoding);
+	inline virtual ~TDeflater() { }; 
+private:
+// from MDeflater
+	void LitLenL(TInt aCode);
+	void OffsetL(TInt aCode);
+	void ExtraL(TInt aLen,TUint aBits);
+private:
+	TBitOutput& iOutput;
+	const TEncoding& iEncoding;
+	};
+
+
+// Class HDeflateHash
+
+inline HDeflateHash::HDeflateHash()
+	{TInt* p=iHash+256;do *--p=-KDeflateMaxDistance-1; while (p>iHash);}
+
+inline HDeflateHash* HDeflateHash::NewLC(TInt aLinks)
+	{
+	return new(HMem::Alloc(0,_FOFF(HDeflateHash,iOffset[Min(aLinks,KDeflateMaxDistance)]))) HDeflateHash;
+	}
+
+inline TInt HDeflateHash::Hash(const TUint8* aPtr)
+	{
+	TUint x=aPtr[0]|(aPtr[1]<<8)|(aPtr[2]<<16);
+	return (x*KDeflateHashMultiplier)>>KDeflateHashShift;
+	}
+
+inline TInt HDeflateHash::First(const TUint8* aPtr,TInt aPos)
+	{
+	TInt h=Hash(aPtr);
+	TInt offset=Min(aPos-iHash[h],KDeflateMaxDistance<<1);
+	iHash[h]=aPos;
+	iOffset[aPos&(KDeflateMaxDistance-1)]=TOffset(offset);
+	return offset;
+	}
+
+inline TInt HDeflateHash::Next(TInt aPos,TInt aOffset) const
+	{return aOffset+iOffset[(aPos-aOffset)&(KDeflateMaxDistance-1)];}
+
+
+// Class TDeflater
+//
+// generic deflation algorithm, can do either statistics and the encoder
+
+TInt MDeflater::Match(const TUint8* aPtr,const TUint8* aEnd,TInt aPos,HDeflateHash& aHash)
+	{
+	TInt offset=aHash.First(aPtr,aPos);
+	if (offset>KDeflateMaxDistance)
+		return 0;
+	TInt match=0;
+	aEnd=Min(aEnd,aPtr+KDeflateMaxLength);
+	TUint8 c=*aPtr;
+	do
+		{
+		const TUint8* p=aPtr-offset;
+		if (p[match>>16]==c)
+			{	// might be a better match
+			const TUint8* m=aPtr;
+			for (;;)
+				{
+				if (*p++!=*m++)
+					break;
+				if (m<aEnd)
+					continue;
+				return ((m-aPtr)<<16)|offset;
+				}
+			TInt l=m-aPtr-1;
+			if (l>match>>16)
+				{
+				match=(l<<16)|offset;
+				c=m[-1];
+				}
+			}
+		offset=aHash.Next(aPos,offset);
+		} while (offset<=KDeflateMaxDistance);
+	return match;
+	}
+
+const TUint8* MDeflater::DoDeflateL(const TUint8* aBase,const TUint8* aEnd,HDeflateHash& aHash)
+//
+// Apply the deflation algorithm to the data [aBase,aEnd)
+// Return a pointer after the last byte that was deflated (which may not be aEnd)
+//
+	{
+	const TUint8* ptr=aBase;
+	TInt prev=0;		// the previous deflation match
+	do
+		{
+		TInt match=Match(ptr,aEnd,ptr-aBase,aHash);
+// Extra deflation applies two optimisations which double the time taken
+// 1. If we have a match at p, then test for a better match at p+1 before using it
+// 2. When we have a match, add the hash links for all the data which will be skipped 
+		if (match>>16 < prev>>16)
+			{	// use the previous match--it was better
+			TInt len=prev>>16;
+			SegmentL(len,prev-(len<<16));
+			// fill in missing hash entries for better compression
+			const TUint8* e=ptr+len-2;
+			do 
+				{
+				++ptr;
+				if (ptr + 2 < aEnd)
+					aHash.First(ptr,ptr-aBase);
+				} while (ptr<e);
+			prev=0;
+			}
+		else if (match<=(KDeflateMinLength<<16))
+			LitLenL(*ptr);			// no deflation match here
+		else
+			{	// save this match and test the next position
+			if (prev)	// we had a match at ptr-1, but this is better
+				LitLenL(ptr[-1]);
+			prev=match;
+			}
+		++ptr;
+		} while (ptr+KDeflateMinLength-1<aEnd);
+	if (prev)
+		{		// emit the stored match
+		TInt len=prev>>16;
+		SegmentL(len,prev-(len<<16));
+		ptr+=len-1;
+		}
+	return ptr;
+	}
+
+void MDeflater::DeflateL(const TUint8* aBase,TInt aLength)
+//
+// The generic deflation algorithm
+//
+	{
+	const TUint8* end=aBase+aLength;
+	if (aLength>KDeflateMinLength)
+		{	// deflation kicks in if there is enough data
+		HDeflateHash* hash=HDeflateHash::NewLC(aLength);
+		if(hash==NULL)
+			Panic(EHuffmanOutOfMemory);
+
+		aBase=DoDeflateL(aBase,end,*hash);
+		delete hash;
+		}
+	while (aBase<end)					// emit remaining bytes
+		LitLenL(*aBase++);
+	LitLenL(TEncoding::EEos);	// eos marker
+	}
+
+void MDeflater::SegmentL(TInt aLength,TInt aDistance)
+//
+// Turn a (length,offset) pair into the deflation codes+extra bits before calling
+// the specific LitLen(), Offset() and Extra() functions.
+//
+	{
+	aLength-=KDeflateMinLength;
+	TInt extralen=0;
+	TUint len=aLength;
+	while (len>=8)
+		{
+		++extralen;
+		len>>=1;
+		}
+	LitLenL((extralen<<2)+len+TEncoding::ELiterals);
+	if (extralen)
+		ExtraL(extralen,aLength);
+//
+	aDistance--;
+	extralen=0;
+	TUint dist=aDistance;
+	while (dist>=8)
+		{
+		++extralen;
+		dist>>=1;
+		}
+	OffsetL((extralen<<2)+dist);
+	if (extralen)
+		ExtraL(extralen,aDistance);
+	}
+
+// Class TDeflateStats
+//
+// This class analyses the data stream to generate the frequency tables 
+// for the deflation algorithm
+
+inline TDeflateStats::TDeflateStats(TEncoding& aEncoding)
+	:iEncoding(aEncoding)
+	{}
+
+void TDeflateStats::LitLenL(TInt aCode)
+	{
+	++iEncoding.iLitLen[aCode];
+	}
+
+void TDeflateStats::OffsetL(TInt aCode)
+	{
+	++iEncoding.iDistance[aCode];
+	}
+
+void TDeflateStats::ExtraL(TInt,TUint)
+	{}
+
+// Class TDeflater
+//
+// Extends MDeflater to provide huffman encoding of the output
+
+inline TDeflater::TDeflater(TBitOutput& aOutput,const TEncoding& aEncoding)
+//
+// construct for encoding
+//
+	:iOutput(aOutput),iEncoding(aEncoding)
+	{}
+
+void TDeflater::LitLenL(TInt aCode)
+	{
+	iOutput.HuffmanL(iEncoding.iLitLen[aCode]);
+	}
+
+void TDeflater::OffsetL(TInt aCode)
+	{
+	iOutput.HuffmanL(iEncoding.iDistance[aCode]);
+	}
+
+void TDeflater::ExtraL(TInt aLen,TUint aBits)
+	{
+	iOutput.WriteL(aBits,aLen);
+	}
+
+void DoDeflateL(const TUint8* aBuf,TInt aLength,TBitOutput& aOutput,TEncoding& aEncoding)
+	{
+// analyse the data for symbol frequency 
+	TDeflateStats analyser(aEncoding);
+	analyser.DeflateL(aBuf,aLength);
+	
+// generate the required huffman encodings
+	Huffman::HuffmanL(aEncoding.iLitLen,TEncoding::ELitLens,aEncoding.iLitLen);
+	Huffman::HuffmanL(aEncoding.iDistance,TEncoding::EDistances,aEncoding.iDistance);
+
+// Store the encoding table
+	Huffman::ExternalizeL(aOutput,aEncoding.iLitLen,KDeflationCodes);
+
+// generate the tables
+	Huffman::Encoding(aEncoding.iLitLen,TEncoding::ELitLens,aEncoding.iLitLen);
+	Huffman::Encoding(aEncoding.iDistance,TEncoding::EDistances,aEncoding.iDistance);
+
+// now finally deflate the data with the generated encoding
+	TDeflater deflater(aOutput,aEncoding);
+	deflater.DeflateL(aBuf,aLength);
+	aOutput.PadL(1);
+	}
+
+void DeflateL(const TUint8* aBuf, TInt aLength, TBitOutput& aOutput)
+	{
+	TEncoding* encoding=new TEncoding;
+	HMem::FillZ(encoding,sizeof(TEncoding));
+	DoDeflateL(aBuf,aLength,aOutput,*encoding);
+	}
+