Raw APU (SPC700) access — IPL upload and execution. More...

#include <snes/types.h>

Functions
void	apuExecute (u16 spcAddr)
	End the upload session and start APU execution.
void	apuReset (void)
	Hot-swap: return a cooperating APU program to the IPL ROM.
void	apuUpload (const u8 *src, u16 spcAddr, u16 size)
	Upload a memory block into APU RAM via the IPL protocol.
void	apuWaitBoot (void)
	Block until the IPL ROM signals readiness ($AA/$BB).

Detailed Description

Raw APU (SPC700) access — IPL upload and execution.

The S-SMP boots into a 64-byte IPL ROM speaking a handshake protocol over the APU I/O ports ($2140-$2143). This module drives it from C: wait for boot, push a wla-spc700-assembled binary into APU RAM, and start it. It is the modern, ABI-verified alternative to the legacy snesmod path for projects that want direct DSP control.

Build side: list your APU program in the example Makefile's SPCSRC (e.g. SPCSRC := player.spc700.asm); common.mk assembles it with wla-spc700 against templates/memmap_spc700.inc into a flat player.spc700.bin you .incbin and upload.

extern u8 spc_image[], spc_image_end[];
 
apuWaitBoot();
apuUpload(spc_image, 0x0200, (u16)(spc_image_end - spc_image));
apuExecute(0x0200);

Warning: These calls BLOCK on the APU handshake. Run them at init, before enabling per-frame work. Do not mix this module with the snesmod module in one ROM — both own the APU.

Author: OpenSNES Team

Copyright: MIT License

Function Documentation

◆ apuExecute()

void apuExecute ( u16 spcAddr )

End the upload session and start APU execution.

Parameters

spcAddr Entry point in APU RAM (typically the upload base)

◆ apuReset()

void apuReset ( void )

Hot-swap: return a cooperating APU program to the IPL ROM.

Writes APU_RESET_MAGIC ($FE) to I/O port 0 and blocks until the IPL boot ROM signals ready again. The running APU program must cooperate by polling for the magic and running the APU_CHECK_RESET idiom from templates/memmap_spc700.inc (silence the DSP, ack on its output ports, jump back to the IPL at $FFC0).

On return, upload the next program with apuUpload()/apuExecute() — do NOT call apuWaitBoot() again (apuReset() already consumed the ready handshake).

Warning: Blocks forever if the APU program never polls for the magic. Only call it on programs built with APU_CHECK_RESET in their wait loops (see examples/audio/apu_switch).

◆ apuUpload()

void apuUpload	(	const u8 *	src,
		u16	spcAddr,
		u16	size )

Upload a memory block into APU RAM via the IPL protocol.

Parameters

src	Source in ROM/WRAM (far pointer — the bank byte is honoured, SUPERFREE sections are fine)
spcAddr	Destination address in APU RAM (e.g. 0x0200)
size	Byte count

◆ apuWaitBoot()

void apuWaitBoot ( void )

Block until the IPL ROM signals readiness ($AA/$BB).

Call once after reset before any upload. consoleInit() does not touch the APU.