CSND Shared Memory
This page describes the structure of the CSND shared memory.
Type0 Command Structure
| Index Byte | Size | Description |
|---|---|---|
| 0x0 | 2 | Offset in shared-memory for the command to process immediately after this one, when not 0xFFFF. |
| 0x2 | 2 | CommandID |
| 0x4 | 1 | This is initially zero when this command data is written by the user process, once the CSND module finishes processing the command this is set to 0x1. |
| 0x5 | 3 | Padding? |
| 0x8 | 4 | The low 5-bits for this field is the the channel-index. This word is used for command parameters as well. |
| 0xC | 0x14 | Command parameters |
Type0 Commands
Command 0x8
| Index Byte | Size | Description |
|---|---|---|
| 0x2 | 2 | CmdID 0x8 |
| 0xC | 4 | Value for the audio sampling frequency? |
This sets the audio sampling frequency?
Command 0xE
| Index Byte | Size | Description |
|---|---|---|
| 0x2 | 2 | CmdID 0xE |
| 0xC | 4 | Usually zero? |
| 0x10 | 4 | Usually zero? |
| 0x14 | 4 | Physical address for the audio data, for the main channel. |
| 0x18 | 4 | Physical address for the audio data, for the second channel. When this address is not 0x0, this is used for stereo audio. Otherwise when 0x0, mono audio is used via the above main address. |
| 0x1C | 4 | Total byte-size for the audio data. |
This initializes the CSND channel registers located at: 0x1EC03400 + (channel_index*0x20).