Method GetCacheIndex

Source/Utility/ROMFileCache.cpp:197–250

//
//*****************************************************************************
ROMFileCache::CacheIdx	ROMFileCache::GetCacheIndex( u32 address )
{
	u32		chunk_map_idx( AddressToChunkMapIndex( address ) );
	#ifdef DAEDALUS_ENABLE_ASSERTS
	DAEDALUS_ASSERT( chunk_map_idx < mChunkMapEntries, "Chunk address is out of range?" );
	#endif
	//
	//	Check if this chunk is already cached, load if necessary
	//
	CacheIdx	idx( mpChunkMap[ chunk_map_idx ] );
	if(idx == INVALID_IDX)
	{
		CacheIdx	selected_idx( 0 );
		u32			oldest_timestamp( mpChunkInfo[ 0 ].LastUseIdx );

		for(CacheIdx i = 1; i < CACHE_SIZE; ++i)
		{
			u32		timestamp( mpChunkInfo[ i ].LastUseIdx );
			if(timestamp < oldest_timestamp)
			{
				oldest_timestamp = timestamp;
				selected_idx = i;
			}
		}

		//
		//	Purge the current chunk
		//
		PurgeChunk( selected_idx );

		//
		//	And load up the new one
		//
		SChunkInfo &		chunk_info( mpChunkInfo[ selected_idx ] );
		chunk_info.StartOffset = GetChunkStartAddress( address );
		chunk_info.LastUseIdx = ++mMRUIdx;

		#ifdef DAEDALUS_ENABLE_ASSERTS
		DAEDALUS_ASSERT( chunk_map_idx < mChunkMapEntries, "Chunk address is out of range?" );
		#endif

		mpChunkMap[ chunk_map_idx ] = selected_idx;

		u32		storage_offset( selected_idx * CHUNK_SIZE );
		u8 *	p_dst( mpStorage + storage_offset );

		//DBGConsole_Msg( 0, "[CRomCache - loading %02x, %08x-%08x", selected_idx, chunk_info.StartOffset, chunk_info.StartOffset + CHUNK_SIZE );
		mpROMFile->ReadChunk( chunk_info.StartOffset, p_dst, CHUNK_SIZE );

		idx = selected_idx;
	}

	return idx;
}

//*****************************************************************************
//