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

m68k: add new "interrupt" example

Browse Source 
I don't completely understand how the scsp timers work; "8192" is a
magic number I came up with by experimentation.
This commit is contained in:
Zack Buhman 2023-05-17 10:33:40 +00:00
parent ab91778312
commit f21e1d5c78
7 changed files with 145 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Makefile
View File

@ -84,7 +84,9 @@ m68k:
m68k/%.bin: m68k
$(MAKE) -C m68k $(notdir $@)
scsp/sound_cpu.elf: scsp/sound_cpu.o m68k/slot.bin.o
scsp/sound_cpu__slot.elf: scsp/sound_cpu__slot.o m68k/slot.bin.o
scsp/sound_cpu__interrupt.elf: scsp/sound_cpu__interrupt.o m68k/interrupt.bin.o
# clean
clean: clean-sh

4
m68k/Makefile
View File

@ -9,4 +9,6 @@ include $(LIB)/m68k/common.mk
%.pcm.o: %.pcm
$(BUILD_BINARY_O)
slot.elf: $(LIB)/m68k/vectors.o slot.o sine-44100-s16be-1ch.pcm.o
slot.elf: $(LIB)/m68k/vectors.o $(LIB)/m68k/handlers.o slot.o sine-44100-s16be-1ch.pcm.o
interrupt.elf: $(LIB)/m68k/vectors.o $(LIB)/m68k/handlers.o interrupt.o jojo-11025-s16be-1ch.pcm.o

88
m68k/interrupt.cpp Normal file
View File

@ -0,0 +1,88 @@
#include <stdint.h>
#include "scsp.h"
extern void * _jojo_start __asm("_binary_jojo_11025_s16be_1ch_pcm_start");
static volatile int32_t frame = 0;
extern "C"
void auto_vector_1(void) __attribute__ ((interrupt_handler));
void auto_vector_1(void)
{
// reset TIMER_A interrupt
scsp.reg.ctrl.SCIRE = INT__TIMER_A;
frame++;
//if (frame > 3962) frame = 0;
const uint16_t * jojo_start = reinterpret_cast<uint16_t *>(&_jojo_start);
const uint32_t frame_addr = reinterpret_cast<uint32_t>(&jojo_start[frame * 8192]);
scsp_slot& slot = scsp.reg.slot[frame % 32];
slot.LOOP = 0;
slot.LOOP |= LOOP__KYONEX;
slot.LOOP = LOOP__KYONB | LOOP__SA(frame_addr); // kx kb sbctl[1:0] ssctl[1:0] lpctl[1:0] 8b sa[19:16]
slot.SA = SA__SA(frame_addr); // start address (bytes)
slot.LSA = 0; // loop start address (samples)
slot.LEA = 8192; // loop end address (samples)
slot.EG = EG__AR(0x1f) | EG__EGHOLD; // d2r d1r ho ar krs dl rr
slot.VOLUME = 0; // stwinh sdir tl
slot.FM = 0; // mdl mdxsl mdysl
slot.PITCH = PITCH__OCT(-2) | PITCH__FNS(0); // oct fns
slot.LFO = 0; // lfof plfows
slot.MIXER = MIXER__DISDL(0b101); // disdl dipan efsdl efpan
slot.LOOP |= LOOP__KYONEX;
return;
}
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__MVOL(0xf);
scsp.reg.ctrl.TIMA = TIMA__TACTL(7);
// timer A is vector 1 (0b001)
scsp.reg.ctrl.SCILV2 = 0;
scsp.reg.ctrl.SCILV1 = 0;
scsp.reg.ctrl.SCILV0 = SCILV__TIMER_A;
// enable TIMER_A
scsp.reg.ctrl.SCIRE = INT__TIMER_A;
scsp.reg.ctrl.SCIEB = INT__TIMER_A;
asm volatile ("move.w #8192,%sr");
const uint16_t * jojo_start = reinterpret_cast<uint16_t *>(&_jojo_start);
const uint32_t frame_addr = reinterpret_cast<uint32_t>(&jojo_start[frame * 128]);
scsp_slot& slot = scsp.reg.slot[0];
slot.LOOP = 0;
slot.LOOP |= LOOP__KYONEX;
slot.LOOP = LOOP__KYONB | LOOP__SA(frame_addr); // kx kb sbctl[1:0] ssctl[1:0] lpctl[1:0] 8b sa[19:16]
slot.SA = SA__SA(frame_addr); // start address (bytes)
slot.LSA = 0; // loop start address (samples)
slot.LEA = 128; // loop end address (samples)
slot.EG = EG__AR(0x1f) | EG__EGHOLD; // d2r d1r ho ar krs dl rr
slot.VOLUME = 0; // stwinh sdir tl
slot.FM = 0; // mdl mdxsl mdysl
slot.PITCH = PITCH__OCT(-2) | PITCH__FNS(0); // oct fns
slot.LFO = 0; // lfof plfows
slot.MIXER = MIXER__DISDL(0b101); // disdl dipan efsdl efpan
slot.LOOP |= LOOP__KYONEX;
}
extern "C"
void start(void)
{
main();
while (1);
}

BIN
m68k/jojo-11025-s16be-1ch.pcm Normal file
View File

Binary file not shown.

7
m68k/slot.cpp
View File

@ -1,8 +1,6 @@
#include <stdint.h>
#include "smpc.h"
#include "scsp.h"
#include "../common/copy.hpp"
#include "scsp.h"
extern void * _sine_start __asm("_binary_sine_44100_s16be_1ch_pcm_start");
@ -15,6 +13,9 @@ void main()
const uint32_t sine_start = reinterpret_cast<uint32_t>(&_sine_start);
scsp_slot& slot = scsp.reg.slot[0];
slot.LOOP = 0;
slot.LOOP |= LOOP__KYONEX;
slot.LOOP = LOOP__KYONB | LOOP__LPCTL__NORMAL | LOOP__SA(sine_start); // kx kb sbctl[1:0] ssctl[1:0] lpctl[1:0] 8b sa[19:16]
slot.SA = SA__SA(sine_start); // start address (bytes)
slot.LSA = 0; // loop start address (samples)

8
scsp/sound_cpu.cpp → scsp/sound_cpu__interrupt.cpp
View File

@ -5,8 +5,8 @@
#include "../common/copy.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");
extern void * _m68k_start __asm("_binary_m68k_interrupt_bin_start");
extern void * _m68k_size __asm("_binary_m68k_interrupt_bin_size");
void main()
{
@ -23,8 +23,8 @@ void main()
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;
uint32_t * m68k_main_start = reinterpret_cast<uint32_t*>(&_m68k_start);
uint32_t m68k_main_size = reinterpret_cast<uint32_t>(&_m68k_size);
copy<uint32_t>(&scsp.ram.u32[0], m68k_main_start, m68k_main_size);
while ((smpc.reg.SF & 1) != 0);

43
scsp/sound_cpu__slot.cpp Normal file
View File

@ -0,0 +1,43 @@
#include <stdint.h>
#include "smpc.h"
#include "scsp.h"
#include "../common/copy.hpp"
extern void * _m68k_start __asm("_binary_m68k_slot_bin_start");
extern void * _m68k_size __asm("_binary_m68k_slot_bin_size");
void main()
{
/* SEGA SATURN TECHNICAL BULLETIN # 51
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__SNDOFF;
while (smpc.reg.oreg[31] != OREG31__SNDOFF);
scsp.reg.ctrl.MIXER = MIXER__MEM4MB;
uint32_t * m68k_main_start = reinterpret_cast<uint32_t*>(&_m68k_start);
uint32_t m68k_main_size = reinterpret_cast<uint32_t>(&_m68k_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__SNDON;
while (smpc.reg.oreg[31] != OREG31__SNDON);
// do nothing while the sound CPU manipulates the SCSP
}
extern "C"
void start(void)
{
main();
while (1);
}