CSND Services

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The CSND service talks to the DSP using the DSP FIFO to negotiate what CSND channels are allocated to the DSP, and this seems to be channels 0-7 (usually). The rest are dedicated to CSND services.

CSND service "csnd:SND"[edit]

Command Header Description
0x00010140 Initialize
0x00020000 Shutdown
0x00030040 ExecuteCommands
0x00040080 PlaySoundDirectly
0x00050000 AcquireSoundChannels
0x00060000 ReleaseSoundChannels
0x00070000 AcquireCapUnit
0x00080040 ReleaseCapUnit
0x00090082 FlushDataCache
0x000A0082 StoreDataCache
0x000B0082 InvalidateDataCache
0x000C0000 Reset

A maximum of 4 service sessions can be opened at the same time for this service.

For cache operations addresses must be in 0x14000000-0x1C000000 range. Starting with 8.0.0-18 addresses in the range 0x30000000-0x40000000 are also allowed.

This service is normally used for playing CWAVs. The audio data must be located in the 0x14000000 virtual memory region, since CSND requires the physical address for playing the audio.