Sample Management

Functions
u16	audioGetFreeMemory (void)
	Get available SPC700 RAM for samples.
u8	audioGetSampleInfo (u8 id, AudioSample *info)
	Get information about a loaded sample.
u8	audioLoadSample (u8 id, const u8 *brrData, u16 size, u16 loopPoint)
	Load a BRR sample into SPC700 RAM.
void	audioUnloadSample (u8 id)
	Unload a sample from a slot.

Detailed Description

Function Documentation

audioGetFreeMemory()

u16 audioGetFreeMemory

(

void

)

Get available SPC700 RAM for samples.

The sample area starts at $0B00 of the sound CPU's 64 KB (below it: the driver and the sample directory) and ends

• at $FFC0, 62,656 bytes, as long as the game has configured no echo;
• at $C000, 46,336 bytes, from the first audioSetEcho(): the echo ring lives above. audioSetEcho() answers AUDIO_ERR_NO_MEMORY when samples already loaded reach into it, so a game that wants an echo calls audioSetEcho() before loading, or keeps its samples under 46 KB.

Returns

Free bytes available, under the limit that applies now

audioGetSampleInfo()

u8 audioGetSampleInfo	(	u8	id,
		AudioSample *	info )

Get information about a loaded sample.

Parameters

id	Sample ID
info	Pointer to AudioSample struct to fill

Returns

AUDIO_OK if loaded, AUDIO_ERR_NOT_LOADED otherwise

audioLoadSample()

u8 audioLoadSample	(	u8	id,
		const u8 *	brrData,
		u16	size,
		u16	loopPoint )

Load a BRR sample into SPC700 RAM.

Parameters

id	Sample slot (0-63)
brrData	Pointer to BRR sample data
size	Size in bytes (must be multiple of 9)
loopPoint	Loop offset in bytes from the start of the sample (a multiple of 9, one BRR block). It is where a sample that loops comes back to — 0 for a loop from the very start. WHETHER the sample loops is the loop flag of its last BRR block (opensnes-sample sets it), not this value: a one-shot sample ignores it.

Returns

AUDIO_OK on success, or error code

extern u8 explosion_brr[];
extern u8 explosion_brr_end[];
audioLoadSample(0, explosion_brr, explosion_brr_end - explosion_brr, 0);

audioUnloadSample()

void audioUnloadSample

(

u8

id

)

Unload a sample from a slot.

Parameters

id	Sample slot (0-63)

It does NOT stop a voice that is playing the sample — stop it first. The allocator is a bump pointer: SPC memory comes back only when the sample unloaded is the most recently loaded one, and loading a slot that is already loaded leaks the old block. (The "voices will be stopped" sentence that stood here was never implemented.)