When the client application is ready, it sends the ICM_DECOMPRESSEX_BEGIN message to the driver. The client application uses dwParam1 to point to an ICDECOMPRESSEX structure and sets dwParam2 to its size. The lpbiSrc and lpbiDest members of the ICDECOMPRESSEX data structure describe the input and output formats. If either of the formats is incorrect, your driver should return ICERR_BADFORMAT. Your driver should create any tables and allocate any memory that it needs to decompress data efficiently. When done, return ICERR_OK.