#include <nitro/snd.h>void SND_SetupChannelPcm( int chNo, SNDWaveFormat format, const void* dataAddr, SNDChannelLoop loop, int loopStart, int dataLen, int volume, SNDChannelDataShift shift, int timer, int pan );
chNo |
The channel number. Takes a value between 0 and 15. |
format |
The format of the waveform data. |
dataAddr |
The starting address of the waveform data. Must have 4-byte alignment. |
loop |
The loop playback setting. |
loopStart |
The loop-start position. Expressed in units of words. Takes a value of 0 to 0xffff. |
dataLen |
The data length. Expressed in units of words. Takes a value of 0 to 0x3fffff. |
volume |
The volume. Takes a value between 0 and 127. |
shift |
The data shift setting. |
timer |
The timer. Takes a value between 0x10 and 0xffff. |
pan |
The pan. Takes values in the range of 0 (left) to 64 (center) to 127 (right). |
This function sets up channels for PCM playback.
The function sets the parameters for the channel specified by chNo. The channel must be locked by the SND_LockChannel function before the parameters can be set. Once the parameters have been set, call the SND_StartTimer function to begin actual playback.
Choose from among these values for the waveform data format format:
Table. SNDWaveFormat
| Label | Description |
|---|---|
| SND_WAVE_FORMAT_PCM8 | 8-bit PCM |
| SND_WAVE_FORMAT_PCM16 | 16-bit PCM |
| SND_WAVE_FORMAT_ADPCM | IMA-ADPCM |
The waveform data's starting address dataAddr must have 4-byte alignment.
Choose from among these values for the loop playback setting loop:
Table. SNDChannelLoop
| Label | Description |
|---|---|
| SND_CHANNEL_LOOP_MANUAL | Continue to play tone, regardless of the setting for data length dataLen. |
| SND_CHANNEL_LOOP_REPEAT | Play to end of data length dataLen and then return to loop-start position loopStart and continue to play. |
| SND_CHANNEL_LOOP_1SHOT | Play to end of data length dataLen and then stop playback automatically. |
The loop-start position loopStart is specified in units of words. It is only meaningful when the loop playback setting loop is set to SND_CHANNEL_LOOP_REPEAT.
The data length dataLen specifies the size of the waveform data in units of words. The value is ignored when the loop playback setting loop is set to SND_CHANNEL_LOOP_MANUAL.
Choose from among these values for the data shift setting shift:
Table. SNDChannelDataShift
| Label | Description |
|---|---|
| SND_CHANNEL_DATASHIFT_NONE | Do not perform a data shift. |
| SND_CHANNEL_DATASHIFT_1BIT | Shift data 1 bit right. |
| SND_CHANNEL_DATASHIFT_2BIT | Shift data 2 bit right. |
| SND_CHANNEL_DATASHIFT_4BIT | Shift data 4 bit right. |
timer specifies the number of clock ticks for outputting one sample. The number of ticks per second is approximately 16.757 MHz with SND_TIMER_CLOCK. Thus, if you want to play the waveform data without changing the pitch and the sampling rate is rate Hz, then you calculate timer as follows:
timer= SND_TIMER_CLOCK /rate
This function is an ARM7 reserved function. After this function is called, processing occurs only after the command is issued with the SND_FlushCommand function.
When it is necessary to synchronize something with the completion of the process, first use SND_GetCurrentCommandTag to obtain the command tag immediately after calling this function. After the command is issued, use the command tag and call either the SND_IsFinishedCommandTag or SND_WaitForCommandProc function to confirm that the process has finished or to wait for it to complete.
SND_LockChannel, SND_StartTimer, SND_FlushCommand, SND_GetCurrentCommandTag, SND_IsFinishedCommandTag, SND_WaitForCommandProc
02/17/2005 Added a note about ARM7 command processing
10/07/2004 Corrected spelling: REPAET to REPEAT.
07/20/2004 Initial version.
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