initial check in

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1084 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/translators/tgatranslator/StreamBuffer.cpp

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+/*****************************************************************************/
+// StreamBuffer
+// StreamBuffer.cpp
+//
+// The description goes here.
+//
+//
+// Copyright (c) 2002 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 "StreamBuffer.h"
+
+#define min(x,y) (((x) < (y)) ? (x) : (y))
+#define max(x,y) (((x) > (y)) ? (x) : (y))
+
+// ---------------------------------------------------------------
+// Constructor
+//
+// Initializes the StreamBuffer to read from pstream, buffering
+// nbuffersize bytes of data at a time. Note that if nbuffersize
+// is smaller than MIN_BUFFER_SIZE, MIN_BUFFER_SIZE is used
+// as the buffer size.
+//
+// Preconditions:
+//
+// Parameters: pstream,	the stream to be buffered
+//
+//             nbuffersize,	number of bytes to be read from
+//			                pstream at a time
+//
+// Postconditions:
+//
+// Returns:
+// ---------------------------------------------------------------
+StreamBuffer::StreamBuffer(BPositionIO *pstream, size_t nbuffersize)
+{
+	m_pStream = pstream;
+	m_pBuffer = NULL;
+	m_nBufferSize = 0;
+	m_nLen = 0;
+	m_nPos = 0;
+	
+	if (!pstream)
+		return;
+
+	m_nBufferSize = max(nbuffersize, MIN_BUFFER_SIZE);
+	m_pBuffer = new uint8[m_nBufferSize];
+	if (m_pBuffer)
+		ReadStream();
+			// Fill the buffer with data so that
+			// object is prepared for first call to
+			// Read()
+}
+
+// ---------------------------------------------------------------
+// Destructor
+//
+// Destroys data allocated for this object
+//
+// Preconditions:
+//
+// Parameters: 
+//
+// Postconditions:
+//
+// Returns:
+// ---------------------------------------------------------------
+StreamBuffer::~StreamBuffer()
+{
+	m_nBufferSize = 0;
+	m_nLen = 0;
+	m_nPos = 0;
+	m_pStream = NULL;
+	
+	delete[] m_pBuffer;
+	m_pBuffer = NULL;
+}
+
+// ---------------------------------------------------------------
+// InitCheck
+//
+// Determines whether the constructor failed or not
+//
+// Preconditions: 
+//
+// Parameters:	
+//
+// Postconditions:
+//
+// Returns: B_OK if object has been initialized successfully,
+// B_ERROR if not
+// ---------------------------------------------------------------
+status_t StreamBuffer::InitCheck()
+{
+	if (m_pStream && m_pBuffer)
+		return B_OK;
+	else
+		return B_ERROR;
+}
+
+// ---------------------------------------------------------------
+// Read
+//
+// Copies up to nbytes of data from the stream into pinto
+//
+// Preconditions: ReadStream() must be called once before this
+// function is called (the constructor does this)
+//
+// Parameters:	pinto,	the buffer to be copied to
+//
+//				nbytes,	the maximum number of bytes to copy
+//
+// Postconditions:
+//
+// Returns: the number of bytes successfully read or an
+// error code returned by BPositionIO::Read()
+// ---------------------------------------------------------------
+ssize_t StreamBuffer::Read(uint8 *pinto, size_t nbytes)
+{
+	ssize_t result = B_ERROR;
+	size_t rd1 = 0, rd2 = 0;
+	
+	rd1 = min(nbytes, m_nLen - m_nPos);
+	memcpy(pinto, m_pBuffer + m_nPos, rd1);
+	m_nPos += rd1;
+	
+	if (rd1 < nbytes) {
+		pinto += rd1;
+		result = ReadStream();
+		if (result > 0) {
+			rd2 = min(nbytes - rd1, m_nLen);
+			memcpy(pinto, m_pBuffer, rd2);
+			m_nPos += rd2;
+		} else
+			// return error code or zero
+			return result;
+	}
+	
+	return rd1 + rd2;
+}
+
+// ---------------------------------------------------------------
+// ReadStream
+//
+// Fills the stream buffer with data read in from the stream
+//
+// Preconditions: m_pBuffer must be allocated and m_nBufferSize
+// must be valid
+//
+// Parameters:	
+//
+// Postconditions:
+//
+// Returns: the number of bytes successfully read or an
+// error code returned by BPositionIO::Read()
+// ---------------------------------------------------------------
+ssize_t StreamBuffer::ReadStream()
+{
+	ssize_t rd;
+	rd = m_pStream->Read(m_pBuffer, m_nBufferSize);
+	if (rd >= 0) {
+		m_nLen = rd;
+		m_nPos = 0;
+	}
+	return rd;
+}
+
+