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03631bf235bc1e23d79c25cfc95ad6986e4a8744
gameboy/APU.cpp
Raimon Zamora 03631bf235 - [NEW] audio viewer 
- [FIX] Sampling rate pujat a 44100Hz, el aliasing quasi desapareix
- [NEW] Canals 2 i 3 implementats
- [FIX] El control de duració en els canals 1 i 2 era incorrecte
2025-01-29 19:33:13 +01:00

379 lines
13 KiB
C++
Raw Blame History

#include "APU.h"
#include <SDL2/SDL.h>
#include "audio_viewer.h"
namespace APU
{
#define SAMPLING_FREQ 44100
#define AUDIO_BUFFER_SIZE 8192
const float cycles_per_sample = 4194304.0f / SAMPLING_FREQ;
SDL_AudioDeviceID sdlAudioDevice;
uint8_t sound_buffer[AUDIO_BUFFER_SIZE];
uint16_t sound_pos=0;
uint16_t sound_start=0;
float t_sound = 0.0f;
uint32_t samples_generated=0;
uint32_t samples_time =0;
uint32_t samples_t=0;
#define CH1 channels[0]
#define CH2 channels[1]
#define CH3 channels[2]
#define CH4 channels[3]
#define apu_enabled (NR52&0x80)
#define DAC1_enabled ((NR12&0xf8)!=0)
#define DAC2_enabled ((NR22&0xf8)!=0)
#define DAC3_enabled ((NR30&0x80)!=0)
uint8_t duty_cycles[4][8] = {
{1, 1, 1, 1, 1, 1, 1, 0},
{1, 1, 1, 1, 1, 1, 0, 0},
{1, 1, 1, 1, 0, 0, 0, 0},
{1, 1, 0, 0, 0, 0, 0, 0},
};
struct channel_t
{
bool enabled = false;
uint8_t length_timer = 0;
bool length_enable = false;
uint16_t period_divider = 0;
uint8_t duty_cycle=0;
uint8_t duty_step = 0;
uint8_t volume = 0;
uint8_t envelope_sweep_timer=0;
};
channel_t channels[4];
uint8_t DIVAPU = 0;
uint8_t NR10 = 0; // 0xff10 - Sound channel 1 sweep
uint8_t NR11 = 0; // 0xff11 - Sound channel 1 length timer & duty cycle
uint8_t NR12 = 0; // 0xff12 - Sound channel 1 volume & envelope
uint8_t NR13 = 0; // 0xff13 - Sound channel 1 period low
uint8_t NR14 = 0; // 0xff14 - Sound channel 1 period high & control
// 0xff15 - Not used?
uint8_t NR21 = 0; // 0xff16 - Sound channel 2 length timer & duty cycle
uint8_t NR22 = 0; // 0xff17 - Sound channel 2 volume & envelope
uint8_t NR23 = 0; // 0xff18 - Sound channel 2 period low
uint8_t NR24 = 0; // 0xff19 - Sound channel 2 period high & control
uint8_t NR30 = 0; // 0xff1a - Sound channel 3 DAC enable
uint8_t NR31 = 0; // 0xff1b - Sound channel 3 length timer
uint8_t NR32 = 0; // 0xff1c - Sound channel 3 output level
uint8_t NR33 = 0; // 0xff1d - Sound channel 3 period low
uint8_t NR34 = 0; // 0xff1e - Sound channel 3 period high & control
// 0xff1f - Not used?
uint8_t NR41 = 0; // 0xff20 - Sound channel 4 length timer
uint8_t NR42 = 0; // 0xff21 - Sound channel 4 volume & envelope
uint8_t NR43 = 0; // 0xff22 - Sound channel 4 frequency & randomness
uint8_t NR44 = 0; // 0xff23 - Sound channel 4 control
uint8_t NR50 = 0; // 0xff24 - Master volume & VIN panning
uint8_t NR51 = 0; // 0xff25 - Sound panning
uint8_t NR52 = 0; // 0xff26 - Sound on/off
// 0xff27-0xff2f - Not used?
uint8_t WaveRAM[16]; // 0xff30-0xff3f
void audioCallback(void * userdata, uint8_t * stream, int len)
{
for (int i=0;i<len;++i)
{
stream[i] = sound_buffer[(sound_start++)&(AUDIO_BUFFER_SIZE-1)];
}
}
void silence()
{
SDL_PauseAudioDevice(sdlAudioDevice, 1);
}
void resume()
{
SDL_PauseAudioDevice(sdlAudioDevice, 0);
}
void init()
{
SDL_AudioSpec audioSpec{SAMPLING_FREQ, AUDIO_U8, 1, 0, AUDIO_BUFFER_SIZE>>2, 0, 0, &audioCallback, NULL};
sdlAudioDevice = SDL_OpenAudioDevice(NULL, 0, &audioSpec, NULL, 0);
resume();
//samples_time=SDL_GetTicks();
audio_viewer::init();
}
void reset()
{
NR10 = 0;
NR11 = 0;
NR12 = 0;
NR13 = 0;
NR14 = 0;
NR21 = 0;
NR22 = 0;
NR23 = 0;
NR24 = 0;
NR30 = 0;
NR31 = 0;
NR32 = 0;
NR33 = 0;
NR34 = 0;
NR41 = 0;
NR42 = 0;
NR43 = 0;
NR44 = 0;
NR50 = 0;
NR51 = 0;
NR52 = 0;
CH1.duty_cycle = 0;
}
void triggerCH1()
{
CH1.enabled = true;
CH1.length_timer=NR11&0x3f;
CH1.period_divider = NR13 | ((NR14 &0x7)<<8);
// envelope timer is reset
CH1.volume = NR12>>4;
// sweep does several things (check documentation)
}
void triggerCH2()
{
CH2.enabled = true;
CH2.length_timer=NR21&0x3f;
CH2.period_divider = NR23 | ((NR24 &0x7)<<8);
// envelope timer is reset
CH2.volume = NR22>>4;
// sweep does several things (check documentation)
}
void triggerCH3()
{
CH3.enabled = true;
CH3.length_timer=NR31;
CH3.period_divider = NR33 | ((NR34 &0x7)<<8);
// envelope timer is reset
CH3.volume = (NR32>>5)&0x3;
// sweep does several things (check documentation)
}
uint8_t readRegister(uint16_t address)
{
switch(address)
{
case 0xff10: return NR10; break;
case 0xff11: return NR11 & 0xc0; break;
case 0xff12: return NR12; break;
case 0xff13: return 0x00; break;
case 0xff14: return NR14 & 0x40; break;
case 0xff16: return NR21 & 0xc0; break;
case 0xff17: return NR22; break;
case 0xff18: return 0x00; break;
case 0xff19: return NR24 & 0x40; break;
case 0xff1a: return NR30; break;
case 0xff1b: return 0x00; break;
case 0xff1c: return NR32; break;
case 0xff1d: return 0x00; break;
case 0xff1e: return NR34 & 0x40; break;
case 0xff24: return NR50; break;
case 0xff25: return NR51; break;
case 0xff26: return NR52; break;
case 0xff30: return WaveRAM[0]; break;
case 0xff31: return WaveRAM[1]; break;
case 0xff32: return WaveRAM[2]; break;
case 0xff33: return WaveRAM[3]; break;
case 0xff34: return WaveRAM[4]; break;
case 0xff35: return WaveRAM[5]; break;
case 0xff36: return WaveRAM[6]; break;
case 0xff37: return WaveRAM[7]; break;
case 0xff38: return WaveRAM[8]; break;
case 0xff39: return WaveRAM[9]; break;
case 0xff3a: return WaveRAM[10]; break;
case 0xff3b: return WaveRAM[11]; break;
case 0xff3c: return WaveRAM[12]; break;
case 0xff3d: return WaveRAM[13]; break;
case 0xff3e: return WaveRAM[14]; break;
case 0xff3f: return WaveRAM[15]; break;
}
return 0x00;
}
void writeRegister(uint16_t address, uint8_t value)
{
if (!apu_enabled && (address!=0xff26)) return;
switch(address)
{
case 0xff10: NR10 = value; break;
case 0xff11: NR11 = value; CH1.length_timer=NR11&0x3f; CH1.duty_cycle = NR11>>6; break;
case 0xff12: NR12 = value; break;
case 0xff13: NR13 = value; break;
case 0xff14: NR14 = value; CH1.length_enable=(value&0x40); if (value&0x80) triggerCH1(); break;
case 0xff16: NR21 = value; CH2.length_timer=NR21&0x3f; CH2.duty_cycle = NR21>>6; break;
case 0xff17: NR22 = value; break;
case 0xff18: NR23 = value; break;
case 0xff19: NR24 = value; CH2.length_enable=(value&0x40); if (value&0x80) triggerCH2(); break;
case 0xff1a: NR30 = value; break;
case 0xff1b: NR31 = value; CH3.length_timer=NR31; break;
case 0xff1c: NR32 = value; break;
case 0xff1d: NR33 = value; break;
case 0xff1e: NR34 = value; CH3.length_enable=(value&0x40); if (value&0x80) triggerCH3(); break;
case 0xff24: NR50 = value; break;
case 0xff25: NR51 = value; break;
case 0xff26: if (value&0x80) reset(); NR52 = (value&0x80) | (NR52 & 0x0f); break;
case 0xff30: WaveRAM[0] = value; break;
case 0xff31: WaveRAM[1] = value; break;
case 0xff32: WaveRAM[2] = value; break;
case 0xff33: WaveRAM[3] = value; break;
case 0xff34: WaveRAM[4] = value; break;
case 0xff35: WaveRAM[5] = value; break;
case 0xff36: WaveRAM[6] = value; break;
case 0xff37: WaveRAM[7] = value; break;
case 0xff38: WaveRAM[8] = value; break;
case 0xff39: WaveRAM[9] = value; break;
case 0xff3a: WaveRAM[10] = value; break;
case 0xff3b: WaveRAM[11] = value; break;
case 0xff3c: WaveRAM[12] = value; break;
case 0xff3d: WaveRAM[13] = value; break;
case 0xff3e: WaveRAM[14] = value; break;
case 0xff3f: WaveRAM[15] = value; break;
}
}
uint8_t DIVAPU_envelope_sweep = 0;
uint8_t DIVAPU_length = 0;
uint8_t DIVAPU_CH1_freq_sweep = 0;
void incDIVAPU()
{
DIVAPU++;
DIVAPU_length++;
if (DIVAPU_length==2) {
DIVAPU_length=0;
if (CH1.enabled && CH1.length_enable) {
if (CH1.length_timer==63) {
CH1.enabled = false;
CH1.length_timer=0;
} else {
CH1.length_timer++;
}
}
if (CH2.enabled && CH2.length_enable) {
if (CH2.length_timer==63) {
CH2.enabled = false;
CH2.length_timer=0;
} else {
CH2.length_timer++;
}
}
if (CH3.enabled && CH3.length_enable) {
if (CH3.length_timer==255) {
CH3.enabled = false;
CH3.length_timer = 0;
} else {
CH3.length_timer++;
}
}
}
DIVAPU_CH1_freq_sweep++;
if (DIVAPU_CH1_freq_sweep==4) {
DIVAPU_CH1_freq_sweep=0;
// Do the freq sweep thing
}
DIVAPU_envelope_sweep++;
if (DIVAPU_envelope_sweep==8) {
DIVAPU_envelope_sweep=0;
if ( CH1.enabled && (NR12&0x7) ) { // If sweep pace != 0, envelope sweep is enabled
CH1.envelope_sweep_timer++;
if ( CH1.envelope_sweep_timer == (NR12&0x07) ) { // if timer == envelope sweep, increase or decrease volume
CH1.envelope_sweep_timer=0;
if (NR12&0x8) { // bit set increases, reset decreases
if (CH1.volume<0x0f) CH1.volume++;
} else {
if (CH1.volume>0) CH1.volume--;
}
}
}
if ( CH2.enabled && (NR22&0x7) ) { // If sweep pace != 0, envelope sweep is enabled
CH2.envelope_sweep_timer++;
if ( CH2.envelope_sweep_timer == (NR22&0x07) ) { // if timer == envelope sweep, increase or decrease volume
CH2.envelope_sweep_timer=0;
if (NR22&0x8) { // bit set increases, reset decreases
if (CH2.volume<0x0f) CH2.volume++;
} else {
if (CH2.volume>0) CH2.volume--;
}
}
}
// Do the envelope sweep thing
}
}
uint32_t dots = 0;
uint32_t dotsCH3 = 0;
void update(uint32_t dt)
{
dots += dt;
while (dots>=4) {
dots -= 4;
CH1.period_divider++;
if (CH1.period_divider==2048) {
CH1.period_divider = NR13 | ((NR14 &0x7)<<8);
CH1.duty_step++;
if (CH1.duty_step==8) CH1.duty_step=0;
}
CH2.period_divider++;
if (CH2.period_divider==2048) {
CH2.period_divider = NR23 | ((NR24 &0x7)<<8);
CH2.duty_step++;
if (CH2.duty_step==8) CH2.duty_step=0;
}
}
dotsCH3 += dt;
while (dotsCH3>=2) {
dotsCH3 -= 2;
CH3.period_divider++;
if (CH3.period_divider==2048) {
CH3.period_divider = NR33 | ((NR34 &0x7)<<8);
CH3.duty_step++;
if (CH3.duty_step==32) CH3.duty_step=0;
}
}
t_sound += dt;
samples_t += dt;
if (t_sound>=cycles_per_sample) {
t_sound-=cycles_per_sample;
uint16_t sampleCH1 = 0;
if (apu_enabled && DAC1_enabled) sampleCH1 = (duty_cycles[CH1.duty_cycle][CH1.duty_step]*CH1.volume)<<2;
uint16_t sampleCH2 = 0;
if (apu_enabled && DAC2_enabled) sampleCH2 = (duty_cycles[CH2.duty_cycle][CH2.duty_step]*CH2.volume)<<2;
uint16_t sampleCH3 = 0;
if (apu_enabled && DAC3_enabled) {
uint8_t step = CH3.duty_step>>1;
uint8_t actual_sample = (CH3.duty_step&1 ? WaveRAM[step]&0x0f : WaveRAM[step]>>4)<<2;
sampleCH3 = CH3.volume==0 ? 0 : CH3.volume==1 ? actual_sample : CH3.volume==2 ? actual_sample>>1 : actual_sample>>2;
}
uint8_t sample = (sampleCH1+sampleCH2+sampleCH3)&0xff;
sound_buffer[(sound_pos++)&(AUDIO_BUFFER_SIZE-1)] = sample;
audio_viewer::addsample(sample);
//if (ear) last_1 = sound_pos;
}
}
}
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