DOOM-3-BFG/neo/idlib/DataQueue.h

#ifndef DATAQUEUE_H
#define DATAQUEUE_H

template< int maxItems, int maxBuffer >
class idDataQueue {
public:
	idDataQueue() {
		dataLength = 0;
	}
	bool Append( int sequence, const byte * b1, int b1Len, const byte * b2 = NULL, int b2Len = 0 );
	void RemoveOlderThan( int sequence );

	int GetDataLength() const { return dataLength; }

	int Num() const { return items.Num(); }
	int ItemSequence( int i ) const { return items[i].sequence; }
	int ItemLength( int i ) const { return items[i].length; }
	const byte * ItemData( int i ) const { return &data[items[i].dataOffset]; }

	void Clear() { dataLength = 0; items.Clear(); memset( data, 0, sizeof( data ) ); }

private:
	struct msgItem_t {
		int		sequence;
		int		length;
		int		dataOffset;
	};
	idStaticList<msgItem_t, maxItems > items;
	int		dataLength;
	byte	data[ maxBuffer ];
};

/*
========================
idDataQueue::RemoveOlderThan
========================
*/
template< int maxItems, int maxBuffer >
void idDataQueue< maxItems, maxBuffer >::RemoveOlderThan( int sequence ) {
	int length = 0;
	while ( items.Num() > 0 && items[0].sequence < sequence ) {
		length += items[0].length;
		items.RemoveIndex( 0 );
	}
	if ( length >= dataLength ) {
		assert( items.Num() == 0 );
		assert( dataLength == length );
		dataLength = 0;
	} else if ( length > 0 ) {
		memmove( data, data + length, dataLength - length );
		dataLength -= length;
	}
	length = 0;
	for ( int i = 0; i < items.Num(); i++ ) {
		items[i].dataOffset = length;
		length += items[i].length;
	}
	assert( length == dataLength );
}

/*
========================
idDataQueue::Append
========================
*/
template< int maxItems, int maxBuffer >
bool idDataQueue< maxItems, maxBuffer >::Append( int sequence, const byte * b1, int b1Len, const byte * b2, int b2Len ) {
	if ( items.Num() == items.Max() ) {
		return false;
	}
	if ( dataLength + b1Len + b2Len >= maxBuffer ) {
		return false;
	}
	msgItem_t & item = *items.Alloc();
	item.length = b1Len + b2Len;
	item.sequence = sequence;
	item.dataOffset = dataLength;
	memcpy( data + dataLength, b1, b1Len );	dataLength += b1Len;
	memcpy( data + dataLength, b2, b2Len );	dataLength += b2Len;
	return true;
}

#endif // DATAQUEUE_H