224 lines
7.5 KiB
C++
224 lines
7.5 KiB
C++
#include "ay-3-8912.h"
|
|
#include "z80.h"
|
|
#include <SDL2/SDL.h>
|
|
|
|
#define MIXER_REG_A_TONE 0x01
|
|
#define MIXER_REG_B_TONE 0x02
|
|
#define MIXER_REG_C_TONE 0x04
|
|
#define MIXER_REG_A_NOISE 0x08
|
|
#define MIXER_REG_B_NOISE 0x10
|
|
#define MIXER_REG_C_NOISE 0x20
|
|
#define MIXER_REG_PORT_A 0x40
|
|
#define MIXER_REG_PORT_B 0x80
|
|
|
|
#define ENVELOPE_HOLD 0x01
|
|
#define ENVELOPE_ALTERNATE 0x02
|
|
#define ENVELOPE_ATTACK 0x04
|
|
#define ENVELOPE_CONTINUE 0x08
|
|
|
|
namespace audio
|
|
{
|
|
#define SAMPLING_FREQ 44100
|
|
#define AUDIO_BUFFER_SIZE 2048
|
|
float cycles_per_sample;
|
|
|
|
uint8_t volume_table[16] {0,2,3,4,6,8,11,16,23,32,45,64,90,128,180,255};
|
|
SDL_AudioDeviceID sdlAudioDevice;
|
|
|
|
uint8_t selected_register {0};
|
|
uint8_t registers[16];
|
|
|
|
uint16_t channel_a_tone_freq;
|
|
uint16_t channel_a_tone_freq_counter;
|
|
uint16_t channel_a_tone_level;
|
|
uint16_t channel_a_level;
|
|
uint16_t channel_b_tone_freq;
|
|
uint16_t channel_b_tone_freq_counter;
|
|
uint16_t channel_b_tone_level;
|
|
uint16_t channel_b_level;
|
|
uint16_t channel_c_tone_freq;
|
|
uint16_t channel_c_tone_freq_counter;
|
|
uint16_t channel_c_tone_level;
|
|
uint16_t channel_c_level;
|
|
|
|
uint8_t noise_freq;
|
|
uint8_t noise_freq_counter;
|
|
uint8_t noise_level;
|
|
uint32_t shiftreg;
|
|
|
|
uint16_t envelope_freq;
|
|
uint16_t envelope_freq_counter;
|
|
int8_t envelope_volume;
|
|
int8_t envelope_direction;
|
|
|
|
void select_register(int port, int val)
|
|
{
|
|
selected_register = val & 0xf;
|
|
}
|
|
|
|
int read_register(int port)
|
|
{
|
|
return registers[selected_register];
|
|
}
|
|
|
|
void write_register(int port, int val)
|
|
{
|
|
registers[selected_register] = val;
|
|
uint32_t clock = (z80::getClock() >> 5);
|
|
|
|
switch (selected_register) {
|
|
case 0:
|
|
case 1: {
|
|
uint16_t freq = registers[0] | ((registers[1] & 0xf) << 8);
|
|
channel_a_tone_freq = clock / freq;
|
|
channel_a_tone_freq_counter = 0;
|
|
break;
|
|
}
|
|
case 2:
|
|
case 3: {
|
|
uint16_t freq = registers[2] | ((registers[3] & 0xf) << 8);
|
|
channel_b_tone_freq = clock / freq;
|
|
channel_b_tone_freq_counter = 0;
|
|
break;
|
|
}
|
|
case 4:
|
|
case 5: {
|
|
uint16_t freq = registers[4] | ((registers[5] & 0xf) << 8);
|
|
channel_c_tone_freq = clock / freq;
|
|
channel_c_tone_freq_counter = 0;
|
|
break;
|
|
}
|
|
case 6: {
|
|
noise_freq = clock / (registers[6] & 0x1f);
|
|
noise_freq_counter = 0;
|
|
break;
|
|
}
|
|
case 11:
|
|
case 12: {
|
|
uint16_t freq = registers[11] | (registers[12] << 8);
|
|
envelope_freq = clock / freq;
|
|
break;
|
|
}
|
|
case 13:
|
|
if (registers[13]&ENVELOPE_ATTACK) {
|
|
envelope_volume = 0;
|
|
envelope_direction = 1;
|
|
} else {
|
|
envelope_volume = 15;
|
|
envelope_direction = -1;
|
|
}
|
|
}
|
|
}
|
|
|
|
void init()
|
|
{
|
|
SDL_AudioSpec audioSpec{SAMPLING_FREQ, AUDIO_U8, 1, 0, AUDIO_BUFFER_SIZE, 0, 0, NULL, NULL};
|
|
sdlAudioDevice = SDL_OpenAudioDevice(NULL, 0, &audioSpec, NULL, 0);
|
|
cycles_per_sample = z80::getClock() / SAMPLING_FREQ;
|
|
reset();
|
|
z80::connect_port(0xfffd, 0xffff, audio::read_register, audio::select_register);
|
|
z80::connect_port(0xbffd, 0xffff, nullptr, audio::write_register);
|
|
resume();
|
|
}
|
|
|
|
void reset()
|
|
{
|
|
selected_register = 0;
|
|
for (int i=0; i<16;++i) registers[i]=0;
|
|
}
|
|
|
|
void silence()
|
|
{
|
|
SDL_PauseAudioDevice(sdlAudioDevice, 1);
|
|
}
|
|
|
|
void resume()
|
|
{
|
|
SDL_PauseAudioDevice(sdlAudioDevice, 0);
|
|
}
|
|
|
|
void update(uint32_t dt)
|
|
{
|
|
for (int i=0;i<dt;i+=2)
|
|
{
|
|
// Oscillate (0-1) channel A tone level given its frequency
|
|
channel_a_tone_freq_counter++;
|
|
if (channel_a_tone_freq_counter == channel_a_tone_freq) {
|
|
channel_a_tone_freq_counter = 0;
|
|
channel_a_tone_level = channel_a_tone_level ^ 1;
|
|
}
|
|
|
|
// Oscillate (0-1) channel B tone level given its frequency
|
|
channel_b_tone_freq_counter++;
|
|
if (channel_b_tone_freq_counter == channel_b_tone_freq) {
|
|
channel_b_tone_freq_counter = 0;
|
|
channel_b_tone_level = channel_b_tone_level ^ 1;
|
|
}
|
|
|
|
// Oscillate (0-1) channel C tone level given its frequency
|
|
channel_c_tone_freq_counter++;
|
|
if (channel_c_tone_freq_counter == channel_c_tone_freq) {
|
|
channel_c_tone_freq_counter = 0;
|
|
channel_c_tone_level = channel_c_tone_level ^ 1;
|
|
}
|
|
|
|
// Oscillate (0-1) noise level given its frequency and shift register
|
|
noise_freq_counter++;
|
|
if (noise_freq_counter == noise_freq) {
|
|
noise_freq_counter = 0;
|
|
noise_level = noise_level ^ shiftreg;
|
|
uint32_t newbit = shiftreg ^ (shiftreg >> 3);
|
|
shiftreg = ((shiftreg >> 1) & 0xff) | ((newbit << 16) & 0x100);
|
|
}
|
|
|
|
// Mix tone and noise on channel A given register 7 values
|
|
channel_a_level = 1;
|
|
if (registers[7] & MIXER_REG_A_TONE) channel_a_level &= channel_a_tone_level;
|
|
if (registers[7] & MIXER_REG_A_NOISE) channel_a_level &= noise_level;
|
|
|
|
// Mix tone and noise on channel B given register 7 values
|
|
channel_b_level = 1;
|
|
if (registers[7] & MIXER_REG_B_TONE) channel_b_level &= channel_b_tone_level;
|
|
if (registers[7] & MIXER_REG_B_NOISE) channel_b_level &= noise_level;
|
|
|
|
// Mix tone and noise on channel C given register 7 values
|
|
channel_c_level = 1;
|
|
if (registers[7] & MIXER_REG_C_TONE) channel_c_level &= channel_c_tone_level;
|
|
if (registers[7] & MIXER_REG_C_NOISE) channel_c_level &= noise_level;
|
|
|
|
|
|
// Develop (0-15) envelope volume given its frequency and shape
|
|
envelope_freq_counter++;
|
|
if (envelope_freq_counter == envelope_freq) {
|
|
envelope_freq_counter = 0;
|
|
|
|
envelope_volume += envelope_direction;
|
|
if ( (envelope_volume > 15) || (envelope_volume < 0) ) {
|
|
switch(registers[13]&0xf) {
|
|
case 8:
|
|
case 12:
|
|
envelope_volume &= 0x0f;
|
|
break;
|
|
case 10:
|
|
case 14:
|
|
envelope_direction = -envelope_direction;
|
|
envelope_volume += envelope_direction;
|
|
case 11:
|
|
case 13:
|
|
envelope_direction = 0;
|
|
envelope_volume = 15;
|
|
default:
|
|
envelope_direction = 0;
|
|
envelope_volume = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
uint8_t channel_a_volume = (registers[8]&0x10) ? envelope_volume : registers[8]&0xf;
|
|
uint8_t channel_b_volume = (registers[9]&0x10) ? envelope_volume : registers[9]&0xf;
|
|
uint8_t channel_c_volume = (registers[10]&0x10) ? envelope_volume : registers[10]&0xf;
|
|
}
|
|
}
|
|
|
|
}
|