From b21162cf8e06f40baa1f58be6a8c17435cebc34d Mon Sep 17 00:00:00 2001
From: weidai <weidai@57ff6487-cd31-0410-9ec3-f628ee90f5f0>
Date: Fri, 4 Oct 2002 17:31:41 +0000
Subject: Initial revision

git-svn-id: svn://svn.code.sf.net/p/cryptopp/code/trunk/c5@2 57ff6487-cd31-0410-9ec3-f628ee90f5f0
---
 zlib.cpp | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 zlib.cpp

(limited to 'zlib.cpp')

diff --git a/zlib.cpp b/zlib.cpp
new file mode 100644
index 0000000..6195965
--- /dev/null
+++ b/zlib.cpp
@@ -0,0 +1,90 @@
+// zlib.cpp - written and placed in the public domain by Wei Dai
+
+// "zlib" is the name of a well known C language compression library
+// (http://www.zlib.org) and also the name of a compression format
+// (RFC 1950) that the library implements. This file is part of a
+// complete reimplementation of the zlib compression format.
+
+#include "pch.h"
+#include "zlib.h"
+#include "zdeflate.h"
+#include "zinflate.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+static const byte DEFLATE_METHOD = 8;
+static const byte FDICT_FLAG = 1 << 5;
+
+// *************************************************************
+
+void ZlibCompressor::WritePrestreamHeader()
+{
+	m_adler32.Restart();
+	byte cmf = DEFLATE_METHOD | ((GetLog2WindowSize()-8) << 4);
+	byte flags = GetCompressionLevel() << 6;
+	AttachedTransformation()->PutWord16(RoundUpToMultipleOf(cmf*256+flags, 31));
+}
+
+void ZlibCompressor::ProcessUncompressedData(const byte *inString, unsigned int length)
+{
+	m_adler32.Update(inString, length);
+}
+
+void ZlibCompressor::WritePoststreamTail()
+{
+	FixedSizeSecBlock<byte, 4> adler32;
+	m_adler32.Final(adler32);
+	AttachedTransformation()->Put(adler32, 4);
+}
+
+unsigned int ZlibCompressor::GetCompressionLevel() const
+{
+	static const unsigned int deflateToCompressionLevel[] = {0, 1, 1, 1, 2, 2, 2, 2, 2, 3};
+	return deflateToCompressionLevel[GetDeflateLevel()];
+}
+
+// *************************************************************
+
+ZlibDecompressor::ZlibDecompressor(BufferedTransformation *attachment, bool repeat, int propagation)
+	: Inflator(attachment, repeat, propagation)
+{
+}
+
+void ZlibDecompressor::ProcessPrestreamHeader()
+{
+	m_adler32.Restart();
+
+	byte cmf;
+	byte flags;
+
+	if (!m_inQueue.Get(cmf) || !m_inQueue.Get(flags))
+		throw HeaderErr();
+
+	if ((cmf*256+flags) % 31 != 0)
+		throw HeaderErr();	// if you hit this exception, you're probably trying to decompress invalid data
+
+	if ((cmf & 0xf) != DEFLATE_METHOD)
+		throw UnsupportedAlgorithm();
+
+	if (flags & FDICT_FLAG)
+		throw UnsupportedPresetDictionary();
+
+	m_log2WindowSize = 8 + (cmf >> 4);
+}
+
+void ZlibDecompressor::ProcessDecompressedData(const byte *inString, unsigned int length)
+{
+	AttachedTransformation()->Put(inString, length);
+	m_adler32.Update(inString, length);
+}
+
+void ZlibDecompressor::ProcessPoststreamTail()
+{
+	FixedSizeSecBlock<byte, 4> adler32;
+	if (m_inQueue.Get(adler32, 4) != 4)
+		throw Adler32Err();
+	if (!m_adler32.Verify(adler32))
+		throw Adler32Err();
+}
+
+NAMESPACE_END
-- 
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