arne
/
cryptopp
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

speed up DEFLATE decompression

pull/2/head
weidai 2004-04-08 01:28:03 +00:00
parent c2f6c37e6d
commit 391a032791
2 changed files with 24 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
zinflate.cpp
View File

@ -223,7 +223,7 @@ void Inflator::IsolatedInitialize(const NameValuePairs &parameters)
m_reader.SkipBits(m_reader.BitsBuffered()); m_reader.SkipBits(m_reader.BitsBuffered());
} }
inline void Inflator::OutputByte(byte b) void Inflator::OutputByte(byte b)
{ {
m_window[m_current++] = b; m_window[m_current++] = b;
if (m_current == m_window.size()) if (m_current == m_window.size())
@ -231,26 +231,38 @@ inline void Inflator::OutputByte(byte b)
ProcessDecompressedData(m_window + m_lastFlush, m_window.size() - m_lastFlush); ProcessDecompressedData(m_window + m_lastFlush, m_window.size() - m_lastFlush);
m_lastFlush = 0; m_lastFlush = 0;
m_current = 0; m_current = 0;
m_wrappedAround = true;
} }
if (m_maxDistance < m_window.size())
m_maxDistance++;
} }
void Inflator::OutputString(const byte *string, unsigned int length) void Inflator::OutputString(const byte *string, unsigned int length)
{ {
while (length--) while (length)
OutputByte(*string++); {
unsigned int len = STDMIN(length, m_window.size() - m_current);
memcpy(m_window + m_current, string, len);
m_current += len;
if (m_current == m_window.size())
{
ProcessDecompressedData(m_window + m_lastFlush, m_window.size() - m_lastFlush);
m_lastFlush = 0;
m_current = 0;
m_wrappedAround = true;
}
string += len;
length -= len;
}
} }
void Inflator::OutputPast(unsigned int length, unsigned int distance) void Inflator::OutputPast(unsigned int length, unsigned int distance)
{ {
if (distance > m_maxDistance)
throw BadBlockErr();
unsigned int start; unsigned int start;
if (m_current > distance) if (distance <= m_current)
start = m_current - distance; start = m_current - distance;
else else if (m_wrappedAround && distance <= m_window.size())
start = m_current + m_window.size() - distance; start = m_current + m_window.size() - distance;
else
throw BadBlockErr();
if (start + length > m_window.size()) if (start + length > m_window.size())
{ {
@ -268,7 +280,6 @@ void Inflator::OutputPast(unsigned int length, unsigned int distance)
{ {
memcpy(m_window + m_current, m_window + start, length); memcpy(m_window + m_current, m_window + start, length);
m_current += length; m_current += length;
m_maxDistance = STDMIN((unsigned int)m_window.size(), m_maxDistance + length);
} }
} }
@ -311,7 +322,7 @@ void Inflator::ProcessInput(bool flush)
return; return;
ProcessPrestreamHeader(); ProcessPrestreamHeader();
m_state = WAIT_HEADER; m_state = WAIT_HEADER;
m_maxDistance = 0; m_wrappedAround = false;
m_current = 0; m_current = 0;
m_lastFlush = 0; m_lastFlush = 0;
m_window.New(1 << GetLog2WindowSize()); m_window.New(1 << GetLog2WindowSize());

4
zinflate.h
View File

@ -132,7 +132,7 @@ private:
enum State {PRE_STREAM, WAIT_HEADER, DECODING_BODY, POST_STREAM, AFTER_END}; enum State {PRE_STREAM, WAIT_HEADER, DECODING_BODY, POST_STREAM, AFTER_END};
State m_state; State m_state;
bool m_repeat, m_eof; bool m_repeat, m_eof, m_wrappedAround;
byte m_blockType; byte m_blockType;
word16 m_storedLen; word16 m_storedLen;
enum NextDecode {LITERAL, LENGTH_BITS, DISTANCE, DISTANCE_BITS}; enum NextDecode {LITERAL, LENGTH_BITS, DISTANCE, DISTANCE_BITS};
@ -141,7 +141,7 @@ private:
HuffmanDecoder m_dynamicLiteralDecoder, m_dynamicDistanceDecoder; HuffmanDecoder m_dynamicLiteralDecoder, m_dynamicDistanceDecoder;
LowFirstBitReader m_reader; LowFirstBitReader m_reader;
SecByteBlock m_window; SecByteBlock m_window;
unsigned int m_maxDistance, m_current, m_lastFlush; unsigned int m_current, m_lastFlush;
}; };
NAMESPACE_END NAMESPACE_END