Digitized Sound I/O Programming
3-11
Sample Procedures
This section provides step by step procedures needed to perform the various DMA
modes of digitized sound operations described in the first section.
It covers the following sample procedures:
General procedures for a DMA mode transfer
Handling the DSP digitized sound I/O interrupt
8-bit mono PCM or ADPCM single-cycle DMA mode transfer
8-bit mono PCM or ADPCM auto-initialize DMA mode transfer
8-bit mono PCM high-speed single-cycle DMA mode transfer
8-bit mono PCM high-speed auto-initialize DMA mode transfer
8-bit stereo PCM high-speed single-cycle DMA mode transfer
8-bit stereo PCM high-speed auto-initialize DMA mode transfer
8-bit or 16-bit PCM single-cycle DMA mode transfer
8-bit or 16-bit PCM auto-initialize DMA mode transfer
To help you utilize the sample procedures more effectively, we have also included
simple C language I/O port instructions along with the discussions. In order to focus
on the key steps involved, the checking of the status ports before reading from and
writing to the DSP has been deliberately omitted. In your actual program, you must
check the status ports. Refer to the chapter "Introduction to DSP Programming" for
the details on reading from and writing to the DSP.
Before you continue, you should have read earlier section and have yourself familiar
with digitized sound data format and the transfer rate (time constant).