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/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)
This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
**********/
// "liveMedia"
// Copyright (c) 1996-2005 Live Networks, Inc. All rights reserved.
// Abstract class for parsing a byte stream
// Implementation
#include "StreamParser.hh"
#include <string.h>
#include <stdlib.h>
#define BANK_SIZE 150000
StreamParser::StreamParser(FramedSource* inputSource,
FramedSource::onCloseFunc* onInputCloseFunc,
void* onInputCloseClientData,
clientContinueFunc* clientContinueFunc,
void* clientContinueClientData)
: fInputSource(inputSource), fOnInputCloseFunc(onInputCloseFunc),
fOnInputCloseClientData(onInputCloseClientData),
fClientContinueFunc(clientContinueFunc),
fClientContinueClientData(clientContinueClientData),
fSavedParserIndex(0), fSavedRemainingUnparsedBits(0),
fCurParserIndex(0), fRemainingUnparsedBits(0),
fTotNumValidBytes(0) {
fBank[0] = new unsigned char[BANK_SIZE];
fBank[1] = new unsigned char[BANK_SIZE];
fCurBankNum = 0;
fCurBank = fBank[fCurBankNum];
}
StreamParser::~StreamParser() {
delete[] fBank[0]; delete[] fBank[1];
}
#define NO_MORE_BUFFERED_INPUT 1
void StreamParser::ensureValidBytes1(unsigned numBytesNeeded) {
// We need to read some more bytes from the input source.
// First, clarify how much data to ask for:
unsigned maxInputFrameSize = fInputSource->maxFrameSize();
if (maxInputFrameSize > numBytesNeeded) numBytesNeeded = maxInputFrameSize;
// First, check whether these new bytes would overflow the current
// bank. If so, start using a new bank now.
if (fCurParserIndex + numBytesNeeded > BANK_SIZE) {
// Swap banks, but save any still-needed bytes from the old bank:
unsigned numBytesToSave = fTotNumValidBytes - fSavedParserIndex;
unsigned char const* from = &curBank()[fSavedParserIndex];
fCurBankNum = (fCurBankNum + 1)%2;
fCurBank = fBank[fCurBankNum];
memmove(curBank(), from, numBytesToSave);
fCurParserIndex = fCurParserIndex - fSavedParserIndex;
fSavedParserIndex = 0;
fTotNumValidBytes = numBytesToSave;
}
// ASSERT: fCurParserIndex + numBytesNeeded > fTotNumValidBytes
// && fCurParserIndex + numBytesNeeded <= BANK_SIZE
if (fCurParserIndex + numBytesNeeded > BANK_SIZE) {
// If this happens, it means that we have too much saved parser state.
// To fix this, increase BANK_SIZE as appropriate.
fInputSource->envir() << "StreamParser internal error ("
<< fCurParserIndex << "+ "
<< numBytesNeeded << " > "
<< BANK_SIZE << ")\n";
exit(1);
}
// Try to read as many new bytes as will fit in the current bank:
unsigned maxNumBytesToRead = BANK_SIZE - fTotNumValidBytes;
fInputSource->getNextFrame(&curBank()[fTotNumValidBytes],
maxNumBytesToRead,
afterGettingBytes, this,
fOnInputCloseFunc, fOnInputCloseClientData);
throw NO_MORE_BUFFERED_INPUT;
}
void StreamParser::afterGettingBytes(void* clientData,
unsigned numBytesRead,
unsigned /*numTruncatedBytes*/,
struct timeval presentationTime,
unsigned /*durationInMicroseconds*/){
StreamParser* buffer = (StreamParser*)clientData;
// Sanity check: Make sure we didn't get too many bytes for our bank:
if (buffer->fTotNumValidBytes + numBytesRead > BANK_SIZE) {
buffer->fInputSource->envir()
<< "StreamParser::afterGettingBytes() warning: read "
<< numBytesRead << " bytes; expected no more than "
<< BANK_SIZE - buffer->fTotNumValidBytes << "\n";
}
unsigned char* ptr = &buffer->curBank()[buffer->fTotNumValidBytes];
buffer->fTotNumValidBytes += numBytesRead;
// Continue our original calling source where it left off:
buffer->restoreSavedParserState();
// Sigh... this is a crock; things would have been a lot simpler
// here if we were using threads, with synchronous I/O...
buffer->fClientContinueFunc(buffer->fClientContinueClientData,
ptr, numBytesRead, presentationTime);
}
void StreamParser::saveParserState() {
fSavedParserIndex = fCurParserIndex;
fSavedRemainingUnparsedBits = fRemainingUnparsedBits;
}
void StreamParser::restoreSavedParserState() {
fCurParserIndex = fSavedParserIndex;
fRemainingUnparsedBits = fSavedRemainingUnparsedBits;
}
void StreamParser::skipBits(unsigned numBits) {
if (numBits <= fRemainingUnparsedBits) {
fRemainingUnparsedBits -= numBits;
} else {
numBits -= fRemainingUnparsedBits;
unsigned numBytesToExamine = (numBits+7)/8; // round up
ensureValidBytes(numBytesToExamine);
fCurParserIndex += numBytesToExamine;
fRemainingUnparsedBits = 8*numBytesToExamine - numBits;
}
}
unsigned StreamParser::getBits(unsigned numBits) {
if (numBits <= fRemainingUnparsedBits) {
unsigned char lastByte = *lastParsed();
lastByte >>= (fRemainingUnparsedBits - numBits);
fRemainingUnparsedBits -= numBits;
return (unsigned)lastByte &~ ((~0)<<numBits);
} else {
unsigned char lastByte;
if (fRemainingUnparsedBits > 0) {
lastByte = *lastParsed();
} else {
lastByte = 0;
}
unsigned remainingBits = numBits - fRemainingUnparsedBits; // > 0
// For simplicity, read the next 4 bytes, even though we might not
// need all of them here:
unsigned result = test4Bytes();
result >>= (32 - remainingBits);
result |= (lastByte << remainingBits);
if (numBits < 32) result &=~ ((~0)<<numBits);
unsigned const numRemainingBytes = (remainingBits+7)/8;
fCurParserIndex += numRemainingBytes;
fRemainingUnparsedBits = 8*numRemainingBytes - remainingBits;
return result;
}
}
void StreamParser::flushInput() {
fCurParserIndex = fSavedParserIndex = 0;
fSavedRemainingUnparsedBits = fRemainingUnparsedBits = 0;
fTotNumValidBytes = 0;
}
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