Sound_Mode 0 (changes)
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Programmer's SoundDMA Reference Manuals
» Part 15 – SWI Calls
» Sound Sound_Mode
» Sound_Mode 0Sound_Mode
» Sound_Mode 0
Sound_Mode 0
(SWI &40144)
| Entry | |
|---|---|
| R0 | 0 (reason code) |
| Exit | |
|---|---|
| R0 | 0 → only 8 bit sound is available |
| 1 → 16 bit sound available (plus emulated 8 bit sound) | |
| R1 | 0 if 16 bit sound unavailable. Otherwise: |
| Bits 0-3: Sound output format and clock control status: | |
| 1 → 16-bit linear output, 44k1, 22k05, 11k025 and selected original rates | |
| 2 → 16-bit linear output, internal clock, selected original rates only | |
| 3 → 16-bit linear output, external master clock source, custom rates only | |
| Bit 4: Oversampling mode (1 = enabled) | |
| Bit 5: Mono conversion status (1 = enabled) | |
| Bits 6-31: Reserved for future expansion (0 returned) |
Use
This SWI is used to detect the presence of the 16 bit sound system and to read its status and features.
Notes
If R0 is 1 on exit, it indicates that the following features are available:
- Sound_Mode with non-zero reason codes
- Sound_LinearHandler
- Sound_SampleRate
If R0 is 0 then the above features are unavailable and no attempt should be made to use them.
Use of bits 0-3 of R1 to determine the support sample rates is deprecated. Sound_SampleRate should be used instead.
Bit 4 of R1 reflects the desired oversampling state, as set by Sound_Mode 1. Note that even if bit 4 is set, it does not guarantee that oversampling is currently in use – for certain sound system configurations, hardware or software limits may prevent it from being used.
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