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cartridge: add adpcm example

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This commit is contained in:
Zack Buhman 2024-09-19 21:04:44 -05:00
parent f18944e523
commit f275732dfc
4 changed files with 410 additions and 1 deletions
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12
cartridge/Makefile
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@ -8,7 +8,7 @@ CARCH = -m2 -mb
### general flags ###
OPT ?= -O3
OPT ?= -O2
DEBUG = -g -gdwarf-4
@ -63,6 +63,12 @@ OBJDUMP = $(TARGET)objdump
--rename-section .data=.rom.$(basename $@) \
$< $@
%.adpcm.o: %.adpcm
$(OBJCOPY) \
-I binary -O elf32-sh -B sh2 \
--rename-section .data=.rom.$(basename $@) \
$< $@
### object files ###
SYS_IP_OBJ += $(LIB)/ip/sys_id.o
@ -83,6 +89,10 @@ CARTRIDGE_OBJ = main.o wc3.pcm.o
cartridge.elf: LDSCRIPT = $(LIB)/cartridge.lds
cartridge.elf: $(SYS_IP_OBJ) $(COMMON_OBJ) $(CARTRIDGE_OBJ)
ADPCM_OBJ = adpcm.o ecclesia.adpcm.o
adpcm.elf: LDSCRIPT = $(LIB)/cartridge.lds
adpcm.elf: $(SYS_IP_OBJ) $(COMMON_OBJ) $(ADPCM_OBJ)
.SUFFIXES:
.INTERMEDIATE:
.SECONDARY:

220
cartridge/adpcm.cpp Normal file
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@ -0,0 +1,220 @@
#include <stdint.h>
#include "vdp1.h"
#include "vdp2.h"
#include "scsp.h"
#include "smpc.h"
#include "../common/copy.hpp"
extern void * _ecclesia_adpcm_start __asm("_binary_ecclesia_adpcm_start");
extern void * _ecclesia_adpcm_size __asm("_binary_ecclesia_adpcm_size");
// table of index changes
static const int8_t index_table[16] = {
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8
};
// quantizer lookup table
static const int16_t step_size_table[89] = {
7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ,
16 , 17 , 19 , 21 , 23 , 25 , 28 , 31 ,
34 , 37 , 41 , 45 , 50 , 55 , 60 , 66 ,
73 , 80 , 88 , 97 , 107 , 118 , 130 , 143 ,
157 , 173 , 190 , 209 , 230 , 253 , 279 , 307 ,
337 , 371 , 408 , 449 , 494 , 544 , 598 , 658 ,
724 , 796 , 876 , 963 , 1060 , 1166 , 1282 , 1411 ,
1552 , 1707 , 1878 , 2066 , 2272 , 2499 , 2749 , 3024 ,
3327 , 3660 , 4026 , 4428 , 4871 , 5358 , 5894 , 6484 ,
7132 , 7845 , 8630 , 9493 , 10442 , 11487 , 12635 , 13899 ,
15289 , 16818 , 18500 , 20350 , 22385 , 24623 , 27086 , 29794 ,
32767
};
struct adpcm_state {
int32_t predicted_sample;
int32_t index;
int32_t step_size;
};
static struct adpcm_state state;
void __attribute__ ((noinline)) init_state()
{
state.predicted_sample = 0;
state.index = 0;
state.step_size = 7;
}
int16_t decode_sample(int sample)
{
int difference = 0;
if (sample & 0b100)
difference += state.step_size;
if (sample & 0b010)
difference += state.step_size >> 1;
if (sample & 0b001)
difference += state.step_size >> 2;
difference += state.step_size >> 3;
if (sample & 0b1000) {
difference = -difference;
}
state.predicted_sample += difference;
if (state.predicted_sample > 32767)
state.predicted_sample = 32767;
if (state.predicted_sample < -32768)
state.predicted_sample = -32768;
state.index += index_table[sample];
if (state.index < 0)
state.index = 0;
if (state.index > 88)
state.index = 88;
state.step_size = step_size_table[state.index];
return state.predicted_sample;
}
void snd_init()
{
while ((smpc.reg.SF & 1) != 0);
smpc.reg.SF = 1;
smpc.reg.COMREG = COMREG__SNDOFF;
while (smpc.reg.OREG[31].val != OREG31__SNDOFF);
scsp.reg.ctrl.MIXER = MIXER__MEM4MB;
volatile uint32_t * dsp_steps = reinterpret_cast<volatile uint32_t *>(&(scsp.reg.dsp.STEP[0].MPRO[0]));
fill<volatile uint32_t>(dsp_steps, 0, (sizeof (scsp.reg.dsp.STEP)));
for (int i = 0; i < 32; i++) {
scsp.reg.slot[i].SA = 0;
scsp.reg.slot[i].MIXER = 0;
}
scsp.reg.ctrl.MIXER = MIXER__MEM4MB | MIXER__MVOL(0xf);
}
void __attribute__ ((noinline)) decode_chunk(volatile uint16_t * dst, const uint8_t * src, int samples)
{
for (int i = 0; i < samples / 2; i++) {
uint8_t b = src[i];
int nib0 = (b >> 0) & 0xf;
int nib1 = (b >> 4) & 0xf;
dst[i * 2 + 0] = decode_sample(nib0);
dst[i * 2 + 1] = decode_sample(nib1);
}
}
void snd_step()
{
const uint8_t * buf = reinterpret_cast<uint8_t*>(&_ecclesia_adpcm_start);
const uint32_t size = reinterpret_cast<uint32_t>(&_ecclesia_adpcm_size);
constexpr uint32_t chunk_samples = 16384 / 2;
decode_chunk(&scsp.ram.u16[0], buf, chunk_samples);
scsp_slot& slot = scsp.reg.slot[0];
// start address (bytes)
slot.SA = SA__KYONB | SA__LPCTL__NORMAL | SA__SA(0); // kx kb sbctl[1:0] ssctl[1:0] lpctl[1:0] 8b sa[19:0]
slot.LSA = 0; // loop start address (samples)
slot.LEA = chunk_samples * 2; // loop end address (samples)
//slot.EG = EG__EGHOLD; // d2r d1r ho ar krs dl rr
slot.EG = EG__AR(0x1F) | EG__D1R(0x00) | EG__D2R(0x00) | EG__RR(0x1F);
slot.FM = 0; // stwinh sdir tl mdl mdxsl mdysl
slot.PITCH = PITCH__OCT(-1) | PITCH__FNS(0); // oct fns
slot.LFO = 0; // lfof plfows
slot.MIXER = MIXER__DISDL(0b110); // disdl dipan efsdl efpan
slot.LOOP |= LOOP__KYONEX;
uint32_t offset = 1;
uint32_t chunk = 1;
constexpr uint32_t timer_a_interrupt = (1 << 6);
scsp.reg.ctrl.TIMA = TIMA__TACTL(7)
| TIMA__TIMA(128);
scsp.reg.ctrl.SCIRE = timer_a_interrupt;
while (1) {
decode_chunk(&scsp.ram.u16[chunk_samples * chunk],
&buf[(chunk_samples * offset) / 2],
chunk_samples);
chunk = !chunk;
offset = offset + 1;
if (chunk_samples * offset > size * 2) {
offset = 0;
}
/*
uint32_t sample = 0;
const uint32_t target = chunk_samples * 2;
constexpr uint32_t sample_interval = (1 << 10);
while (sample < target) {
scsp.reg.ctrl.SCIRE = sample_interval;
while (!(scsp.reg.ctrl.SCIPD & sample_interval));
sample++;
}
*/
while (!(scsp.reg.ctrl.SCIPD & timer_a_interrupt));
scsp.reg.ctrl.TIMA = TIMA__TACTL(7)
| TIMA__TIMA(128);
scsp.reg.ctrl.SCIRE = timer_a_interrupt;
}
}
extern "C"
void main() __attribute__((section(".text.main")));
void main()
{
// DISP: Please make sure to change this bit from 0 to 1 during V blank.
vdp2.reg.TVMD = ( TVMD__DISP | TVMD__LSMD__NON_INTERLACE
| TVMD__VRESO__240 | TVMD__HRESO__NORMAL_320);
// VDP2 User's Manual:
// "When sprite data is in an RGB format, sprite register 0 is selected"
// "When the value of a priority number is 0h, it is read as transparent"
//
// The power-on value of PRISA is zero. Set the priority for sprite register 0
// to some number greater than zero, so that the color data is not interpreted
// as "transparent".
vdp2.reg.PRISA = PRISA__S0PRIN(1); // Sprite register 0 Priority Number
/* TVM settings must be performed from the second H-blank IN interrupt after the
V-blank IN interrupt to the H-blank IN interrupt immediately after the V-blank
OUT interrupt. */
// "normal" display resolution, 16 bits per pixel, 512x256 framebuffer
vdp1.reg.TVMR = TVMR__TVM__NORMAL;
// swap framebuffers every 1 cycle; non-interlace
vdp1.reg.FBCR = 0;
// erase upper-left coordinate
vdp1.reg.EWLR = EWLR__16BPP_X1(0) | EWLR__Y1(0);
// erase lower-right coordinate
vdp1.reg.EWRR = EWRR__16BPP_X3(319) | EWRR__Y3(239);
// during a framebuffer erase cycle, write the color "black" to each pixel
const uint16_t black = 1 << 15 | 0x00ff;
vdp1.reg.EWDR = black;
vdp1.vram.cmd[0].CTRL = CTRL__END;
init_state();
snd_init();
snd_step();
const uint16_t blue = 1 << 15 | 0x7f00;
vdp1.reg.EWDR = blue;
vdp2.reg.BGON = 0;
// start drawing (execute the command list) on every frame
vdp1.reg.PTMR = PTMR__PTM__FRAME_CHANGE;
while (1);
}

179
cartridge/adpcm.py Normal file
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@ -0,0 +1,179 @@
from dataclasses import dataclass
import struct
# Table of index changes
index_table = [
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8
]
assert len(index_table) == 16
# quantizer lookup table
step_size_table = [
7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ,
16 , 17 , 19 , 21 , 23 , 25 , 28 , 31 ,
34 , 37 , 41 , 45 , 50 , 55 , 60 , 66 ,
73 , 80 , 88 , 97 , 107 , 118 , 130 , 143 ,
157 , 173 , 190 , 209 , 230 , 253 , 279 , 307 ,
337 , 371 , 408 , 449 , 494 , 544 , 598 , 658 ,
724 , 796 , 876 , 963 , 1060 , 1166 , 1282 , 1411 ,
1552 , 1707 , 1878 , 2066 , 2272 , 2499 , 2749 , 3024 ,
3327 , 3660 , 4026 , 4428 , 4871 , 5358 , 5894 , 6484 ,
7132 , 7845 , 8630 , 9493 , 10442 , 11487 , 12635 , 13899 ,
15289 , 16818 , 18500 , 20350 , 22385 , 24623 , 27086 , 29794 ,
32767
]
assert len(step_size_table) == 89
@dataclass
class ADPCMState:
predicted_sample: int
index: int
step_size: int
def encode_sample(state, sample):
assert sample >= -32768 and sample <= 32767
difference = sample - state.predicted_sample
if difference >= 0:
new_sample = 0b0000
else:
new_sample = 0b1000
difference = -difference
mask = 0b100
temp_step_size = state.step_size
# division through repeated subtraction
for i in range(3):
if difference >= temp_step_size:
new_sample |= mask
difference -= temp_step_size
temp_step_size >>= 1
mask >>= 1
difference = 0
if new_sample & 0b100:
difference += state.step_size
if new_sample & 0b010:
difference += state.step_size >> 1
if new_sample & 0b001:
difference += state.step_size >> 2
difference += state.step_size >> 3
if new_sample & 0b1000:
difference = -difference
state.predicted_sample += difference
if state.predicted_sample > 32767:
state.predicted_sample = 32767
elif state.predicted_sample < -32768:
state.predicted_sample = -32768
state.index += index_table[new_sample]
if state.index < 0:
state.index = 0
elif state.index > 88:
state.index = 88
state.step_size = step_size_table[state.index]
return new_sample
def sign_extend(value, bits):
sign_bit = 1 << (bits - 1)
return (value & (sign_bit - 1)) - (value & sign_bit)
def test_encode_sample():
sample = sign_extend(0x873f, 16)
state = ADPCMState(
predicted_sample = sign_extend(0x8700, 16),
index = 24,
step_size = 73
)
new_sample = encode_sample(state, sample)
assert new_sample == 3
assert (state.predicted_sample & 0xffff) == 0x873f, hex(state.predicted_sample)
assert state.index == 23
assert state.step_size == step_size_table[23]
test_encode_sample()
def decode_sample(state, sample):
difference = 0
if sample & 0b100:
difference += state.step_size
if sample & 0b010:
difference += state.step_size >> 1
if sample & 0b001:
difference += state.step_size >> 2
difference += state.step_size >> 3
if sample & 0b1000:
difference = -difference
state.predicted_sample += difference
if state.predicted_sample > 32767:
state.predicted_sample = 32767
elif state.predicted_sample < -32768:
state.predicted_sample = -32768
state.index += index_table[sample]
if state.index < 0:
state.index = 0
elif state.index > 88:
state.index = 88
state.step_size = step_size_table[state.index]
return state.predicted_sample
def test_decode_sample():
sample = 3
state = ADPCMState(
predicted_sample = sign_extend(0x8700, 16),
index = 24,
step_size = 73
)
new_sample = decode_sample(state, sample)
assert new_sample == sign_extend(0x873f, 16)
assert state.index == 23
assert state.step_size == step_size_table[23]
test_decode_sample()
with open('ecclesia.pcm', 'rb') as f:
pcm = f.read()
def nibbles(buf):
state = ADPCMState(
0, 0, 7
)
byte = 0
for i in range(len(buf) // 2):
sample, = struct.unpack('>h', buf[i * 2:i * 2+2])
new_sample = encode_sample(state, sample)
assert new_sample >= 0 and new_sample <= 15
if i % 2 == 0:
byte = new_sample
else:
byte |= (new_sample << 4)
yield byte
with open('ecclesia.adpcm', 'wb') as f:
f.write(bytes(nibbles(pcm)))
with open('ecclesia.adpcm', 'rb') as f:
adpcm = f.read()
def unnibbles(buf):
state = ADPCMState(
0, 0, 7
)
for i in range(len(buf) * 2):
nib = (buf[i // 2] >> (4 * (i % 2))) & 0xf
new_sample = decode_sample(state, nib)
yield struct.pack('>h', new_sample)
with open('ecclesia.adpcm.pcm', 'wb') as f:
for b in unnibbles(adpcm):
f.write(b)

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cartridge/ecclesia.adpcm Normal file
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