bilbo/saturn-examples
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

m68k: more reasonable stack pointer value

Browse Source 
The sound_cpu example works consistently on all emulators and real
hardware now.
This commit is contained in:
Zack Buhman 2023-05-16 22:55:26 +00:00
parent 8246b94aee
commit f2b53ee62a
4 changed files with 17 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Makefile
View File

@ -74,6 +74,11 @@ scsp/sine-44100-s16be-1ch.pcm:
scsp/slot.elf: scsp/slot.o scsp/sine-44100-s16be-1ch.pcm.o
m68k:
m68k/%.bin: m68k
$(MAKE) -C m68k $(notdir $@)
scsp/sound_cpu.elf: scsp/sound_cpu.o m68k/slot.bin.o
# clean
@ -89,3 +94,6 @@ clean-sh:
common/keyboard.cpp \
common/keyboard.hpp \
wordle/word_list.hpp
PHONY: m68k

5
m68k/main.cpp
View File

@ -1,5 +0,0 @@
extern "C"
void start(void)
{
while (1) {}
}

2
m68k/slot.cpp
View File

@ -10,7 +10,7 @@ void main()
{
for (long i = 0; i < 807; i++) { asm volatile ("nop"); } // wait for (way) more than 30µs
scsp.reg.ctrl.MIXER = MIXER__MEM4MB | MIXER__DAC18B | MIXER__MVOL(0xf);
scsp.reg.ctrl.MIXER = MIXER__MEM4MB | MIXER__MVOL(0xf);
const uint32_t sine_start = reinterpret_cast<uint32_t>(&_sine_start);

26
scsp/sound_cpu.cpp
View File

@ -2,45 +2,35 @@
#include "smpc.h"
#include "scsp.h"
#include "vdp2.h"
#include "../common/copy.hpp"
#include "../common/vdp2_func.hpp"
extern void * _binary_m68k_slot_bin_start __asm("_binary_m68k_slot_bin_start");
extern void * _binary_m68k_slot_bin_size __asm("_binary_m68k_slot_bin_size");
void main()
{
v_blank_in();
/* SEGA SATURN TECHNICAL BULLETIN # 51
/*
while ((smpc.reg.SF & 1) != 0);
smpc.reg.SF = 1;
smpc.reg.COMREG = COMREG__SNDOFF;
while (smpc.reg.oreg[31] != 0b00000111);
The document suggests that Sound RAM is (somewhat) preserved
during SNDOFF.
*/
while ((smpc.reg.SF & 1) != 0);
smpc.reg.SF = 1;
smpc.reg.COMREG = COMREG__SNDON;
while (smpc.reg.oreg[31] != 0b00000110);
*/
smpc.reg.COMREG = COMREG__SNDOFF;
while (smpc.reg.oreg[31] != OREG31__SNDOFF);
scsp.reg.ctrl.MIXER = MIXER__MEM4MB | MIXER__DAC18B | MIXER__MVOL(0xf);
scsp.reg.ctrl.MIXER = MIXER__MEM4MB;
uint32_t * m68k_main_start = (uint32_t *)&_binary_m68k_slot_bin_start;
uint32_t m68k_main_size = (uint32_t)&_binary_m68k_slot_bin_size;
copy<uint32_t>(&scsp.ram.u32[0], m68k_main_start, m68k_main_size);
while ((smpc.reg.SF & 1) != 0);
smpc.reg.SF = 1;
smpc.reg.COMREG = COMREG__SNDOFF;
while (smpc.reg.oreg[31] != 0b00000111);
while ((smpc.reg.SF & 1) != 0);
smpc.reg.SF = 1;
smpc.reg.COMREG = COMREG__SNDON;
while (smpc.reg.oreg[31] != 0b00000110);
while (smpc.reg.oreg[31] != OREG31__SNDON);
// do nothing while the sound CPU manipulates the SCSP
}