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SameBoy/Core/apu.c
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#include <stdint.h>
#include <math.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include "gb.h"
/* Band limited synthesis loosely based on: http://www.slack.net/~ant/bl-synth/ */
static int32_t band_limited_steps[GB_BAND_LIMITED_PHASES][GB_BAND_LIMITED_WIDTH];
static void __attribute__((constructor)) band_limited_init(void)
{
const unsigned master_size = GB_BAND_LIMITED_WIDTH * GB_BAND_LIMITED_PHASES;
double *master = malloc(master_size * sizeof(*master));
memset(master, 0, master_size * sizeof(*master));
const double lowpass = 15.0 / 16.0; // 1.0 means using Nyquist as the exact cutoff
const double to_angle = M_PI / GB_BAND_LIMITED_PHASES * lowpass;
double sum = 0;
nounroll for (signed i = 0; i < master_size; i++) {
// Exact Blackman window
const double a0 = 7938 / 18608.0;
const double a1 = 9240 / 18608.0;
const double a2 = 1430 / 18608.0;
double window_angle = (2.0 * M_PI * i) / (master_size);
double window = a0 - a1 * cos(window_angle) + a2 * cos(2 * window_angle);
double angle = (i - (signed)master_size / 2) * to_angle;
sum += master[i] = (angle == 0? 1 : sin(angle) / angle) * window;
}
nounroll for (signed i = 0; i < master_size; i++) {
master[i] /= sum;
}
nounroll for (signed phase = 0; phase < GB_BAND_LIMITED_PHASES; phase++) {
int32_t error = GB_BAND_LIMITED_ONE;
nounroll for (signed i = 0; i < GB_BAND_LIMITED_WIDTH; i++) {
double sum = 0;
nounroll for (signed j = 0; j < GB_BAND_LIMITED_PHASES; j++) {
signed index = i * GB_BAND_LIMITED_PHASES - phase + j;
if (index >= 0) {
sum += master[index];
}
}
int32_t cur = sum * GB_BAND_LIMITED_ONE;
error -= cur;
band_limited_steps[phase][i] = cur;
}
// Make sure the deltas sum to 1.0
band_limited_steps[phase][GB_BAND_LIMITED_WIDTH / 2] += error;
}
free(master);
}
static void band_limited_update(GB_band_limited_t *band_limited, const GB_sample_t *input, unsigned phase)
{
if (input->packed == band_limited->input.packed) return;
unsigned delay = phase / GB_BAND_LIMITED_PHASES;
phase = phase & (GB_BAND_LIMITED_PHASES - 1);
struct {
signed left, right;
} delta = {
.left = input->left - band_limited->input.left,
.right = input->right - band_limited->input.right,
};
band_limited->input.packed = input->packed;
for (unsigned i = 0; i < GB_BAND_LIMITED_WIDTH; i++) {
unsigned offset = (i + band_limited->pos + delay) & (sizeof(band_limited->buffer) / sizeof(band_limited->buffer[0]) - 1);
band_limited->buffer[offset].left += delta.left * band_limited_steps[phase][i];
band_limited->buffer[offset].right += delta.right * band_limited_steps[phase][i];
}
}
static void band_limited_update_unfiltered(GB_band_limited_t *band_limited, const GB_sample_t *input, unsigned delay)
{
if (input->packed == band_limited->input.packed) return;
struct {
signed left, right;
} delta = {
.left = input->left - band_limited->input.left,
.right = input->right - band_limited->input.right,
};
band_limited->input.packed = input->packed;
unsigned offset = (band_limited->pos + delay) & (sizeof(band_limited->buffer) / sizeof(band_limited->buffer[0]) - 1);
band_limited->buffer[offset].left += delta.left * GB_BAND_LIMITED_ONE;
band_limited->buffer[offset].right += delta.right * GB_BAND_LIMITED_ONE;
}
static void band_limited_read(GB_band_limited_t *band_limited, GB_sample_t *output, uint32_t multiplier)
{
band_limited->output.left += band_limited->buffer[band_limited->pos].left;
band_limited->output.right += band_limited->buffer[band_limited->pos].right;
band_limited->buffer[band_limited->pos].left = band_limited->buffer[band_limited->pos].right = 0;
band_limited->pos = (band_limited->pos + 1) & (sizeof(band_limited->buffer) / sizeof(band_limited->buffer[0]) - 1);
output->left = band_limited->output.left * multiplier / GB_BAND_LIMITED_ONE;
output->right = band_limited->output.right * multiplier / GB_BAND_LIMITED_ONE;
/* This hueristic will mute the channel if it's only playing an amplitude of 1 or 2 units, usually
caused by rounding errors when the channel is playing a single frequency above Nyquist. */
unsigned diff = abs(output->left - band_limited->last_output.left);
if (diff > 4) {
band_limited->silence_detection = 0;
band_limited->last_output.packed = output->packed;
return;
}
diff = abs(output->right - band_limited->last_output.right);
if (diff > 4) {
band_limited->silence_detection = 0;
band_limited->last_output.packed = output->packed;
return;
}
if (band_limited->silence_detection == 4000) {
output->packed = band_limited->last_output.packed;
}
else {
band_limited->silence_detection++;
}
}
static inline uint32_t sample_fraction_multiply(GB_gameboy_t *gb, unsigned multiplier)
{
if (unlikely(multiplier == 0)) return 0;
if (likely(multiplier < GB_QUICK_MULTIPLY_COUNT + 1)) {
return gb->apu_output.quick_fraction_multiply_cache[multiplier - 1];
}
return gb->apu_output.quick_fraction_multiply_cache[0] * multiplier;
}
static const uint8_t duties[] = {
0, 0, 0, 0, 0, 0, 0, 1,
1, 0, 0, 0, 0, 0, 0, 1,
1, 0, 0, 0, 0, 1, 1, 1,
0, 1, 1, 1, 1, 1, 1, 0,
};
bool GB_apu_is_DAC_enabled(GB_gameboy_t *gb, GB_channel_t index)
{
if (gb->model > GB_MODEL_CGB_E) {
/* On the AGB, mixing is done digitally, so there are no per-channel
DACs. Instead, all channels are summed digital regardless of
whatever the DAC state would be on a CGB or earlier model. */
return true;
}
switch (index) {
case GB_SQUARE_1:
return gb->io_registers[GB_IO_NR12] & 0xF8;
case GB_SQUARE_2:
return gb->io_registers[GB_IO_NR22] & 0xF8;
case GB_WAVE:
return gb->apu.wave_channel.enable;
case GB_NOISE:
return gb->io_registers[GB_IO_NR42] & 0xF8;
nodefault;
}
return false;
}
static uint8_t agb_bias_for_channel(GB_gameboy_t *gb, GB_channel_t index)
{
if (!gb->apu.is_active[index]) return 0;
switch (index) {
case GB_SQUARE_1:
return gb->apu.square_channels[GB_SQUARE_1].current_volume;
case GB_SQUARE_2:
return gb->apu.square_channels[GB_SQUARE_2].current_volume;
case GB_WAVE:
return 0;
case GB_NOISE:
return gb->apu.noise_channel.current_volume;
nodefault;
}
}
static void update_sample(GB_gameboy_t *gb, GB_channel_t index, int8_t value, unsigned cycles_offset)
{
if (gb->model > GB_MODEL_CGB_E) {
/* On the AGB, because no analog mixing is done, the behavior of NR51 is a bit different.
A channel that is not connected to a terminal is idenitcal to a connected channel
playing PCM sample 0. */
gb->apu.samples[index] = value;
if (gb->apu_output.sample_rate) {
unsigned right_volume = (gb->io_registers[GB_IO_NR50] & 7) + 1;
unsigned left_volume = ((gb->io_registers[GB_IO_NR50] >> 4) & 7) + 1;
int8_t silence = 0;
if (index == GB_WAVE) {
/* For some reason, channel 3 is inverted on the AGB, and has a different "silence" value */
value ^= 0xF;
silence = 7 * 2;
}
uint8_t bias = agb_bias_for_channel(gb, index);
bool left = gb->io_registers[GB_IO_NR51] & (0x10 << index);
bool right = gb->io_registers[GB_IO_NR51] & (1 << index);
GB_sample_t output = {
.left = (0xF - (left? value * 2 + bias : silence)) * left_volume,
.right = (0xF - (right? value * 2 + bias : silence)) * right_volume
};
if (unlikely(gb->apu_output.channel_muted[index])) {
output.left = output.right = 0;
}
if (unlikely(gb->apu_output.max_cycles_per_sample == 1)) {
band_limited_update_unfiltered(&gb->apu_output.band_limited[index], &output, cycles_offset);
}
else {
band_limited_update(&gb->apu_output.band_limited[index],
&output,
(((gb->apu_output.sample_fraction + sample_fraction_multiply(gb, cycles_offset)) >> 8) * GB_BAND_LIMITED_PHASES) >> 20);
}
}
return;
}
if (value == 0 && gb->apu.samples[index] == 0) return;
if (!GB_apu_is_DAC_enabled(gb, index)) {
value = gb->apu.samples[index];
}
else {
gb->apu.samples[index] = value;
}
if (gb->apu_output.sample_rate) {
unsigned right_volume = 0;
if (gb->io_registers[GB_IO_NR51] & (1 << index)) {
right_volume = (gb->io_registers[GB_IO_NR50] & 7) + 1;
}
unsigned left_volume = 0;
if (gb->io_registers[GB_IO_NR51] & (0x10 << index)) {
left_volume = ((gb->io_registers[GB_IO_NR50] >> 4) & 7) + 1;
}
GB_sample_t output = {0, 0};
if (likely(!gb->apu_output.channel_muted[index])) {
output = (GB_sample_t){(0xF - value * 2) * left_volume, (0xF - value * 2) * right_volume};
}
if (unlikely(gb->apu_output.max_cycles_per_sample == 1)) {
band_limited_update_unfiltered(&gb->apu_output.band_limited[index], &output, cycles_offset);
}
else {
band_limited_update(&gb->apu_output.band_limited[index],
&output,
(((gb->apu_output.sample_fraction + sample_fraction_multiply(gb, cycles_offset)) >> 8) * GB_BAND_LIMITED_PHASES) >> 20);
}
}
}
static double smooth(double x)
{
return 3*x*x - 2*x*x*x;
}
static signed interference(GB_gameboy_t *gb)
{
/* These aren't scientifically measured, but based on ear based on several recordings */
signed ret = 0;
if (gb->halted) {
if (gb->model <= GB_MODEL_CGB_E) {
ret -= MAX_CH_AMP / 5;
}
else {
ret -= MAX_CH_AMP / 12;
}
}
if (gb->io_registers[GB_IO_LCDC] & GB_LCDC_ENABLE) {
ret += MAX_CH_AMP / 7;
if ((gb->io_registers[GB_IO_STAT] & 3) == 3 && gb->model <= GB_MODEL_CGB_E) {
ret += MAX_CH_AMP / 14;
}
else if ((gb->io_registers[GB_IO_STAT] & 3) == 1) {
ret -= MAX_CH_AMP / 7;
}
}
if (gb->apu.global_enable) {
ret += MAX_CH_AMP / 10;
}
if (GB_is_cgb(gb) && gb->model <= GB_MODEL_CGB_E && (gb->io_registers[GB_IO_RP] & 1)) {
ret += MAX_CH_AMP / 10;
}
if (!GB_is_cgb(gb)) {
ret /= 4;
}
ret += rand() % (MAX_CH_AMP / 12);
return ret;
}
static void render(GB_gameboy_t *gb)
{
GB_sample_t output = {0, 0};
unrolled for (unsigned i = 0; i < GB_N_CHANNELS; i++) {
double multiplier = CH_STEP;
if (gb->model <= GB_MODEL_CGB_E) {
if (!GB_apu_is_DAC_enabled(gb, i)) {
gb->apu_output.dac_discharge[i] -= ((double) DAC_DECAY_SPEED) / gb->apu_output.sample_rate;
if (gb->apu_output.dac_discharge[i] < 0) {
multiplier = 0;
gb->apu_output.dac_discharge[i] = 0;
}
else {
multiplier *= smooth(gb->apu_output.dac_discharge[i]);
}
}
else {
gb->apu_output.dac_discharge[i] += ((double) DAC_ATTACK_SPEED) / gb->apu_output.sample_rate;
if (gb->apu_output.dac_discharge[i] > 1) {
gb->apu_output.dac_discharge[i] = 1;
}
else {
multiplier *= smooth(gb->apu_output.dac_discharge[i]);
}
}
}
GB_sample_t channel_output;
band_limited_read(&gb->apu_output.band_limited[i], &channel_output, multiplier);
output.left += channel_output.left;
output.right += channel_output.right;
}
gb->apu_output.cycles_since_render = 0;
if (unlikely(gb->apu_output.sample_fraction < (1 << 28))) {
gb->apu_output.sample_fraction = 0;
}
else {
gb->apu_output.sample_fraction -= 1 << 28;
}
if (gb->sgb && gb->sgb->intro_animation < GB_SGB_INTRO_ANIMATION_LENGTH) return;
GB_sample_t filtered_output = gb->apu_output.highpass_mode?
(GB_sample_t) {output.left - (int16_t)gb->apu_output.highpass_diff.left,
output.right - (int16_t)gb->apu_output.highpass_diff.right} :
output;
switch (gb->apu_output.highpass_mode) {
case GB_HIGHPASS_OFF:
gb->apu_output.highpass_diff = (GB_double_sample_t) {0, 0};
break;
case GB_HIGHPASS_ACCURATE:
gb->apu_output.highpass_diff = (GB_double_sample_t) {
output.left - (output.left - gb->apu_output.highpass_diff.left) * gb->apu_output.highpass_rate,
output.right - (output.right - gb->apu_output.highpass_diff.right) * gb->apu_output.highpass_rate
};
break;
case GB_HIGHPASS_REMOVE_DC_OFFSET: {
unsigned mask = gb->io_registers[GB_IO_NR51];
unsigned left_volume = 0;
unsigned right_volume = 0;
unrolled for (unsigned i = GB_N_CHANNELS; i--;) {
if (GB_apu_is_DAC_enabled(gb, i)) {
if (mask & 1) {
left_volume += ((gb->io_registers[GB_IO_NR50] & 7) + 1) * CH_STEP * 0xF;
}
if (mask & 0x10) {
right_volume += (((gb->io_registers[GB_IO_NR50] >> 4) & 7) + 1) * CH_STEP * 0xF;
}
}
mask >>= 1;
}
gb->apu_output.highpass_diff = (GB_double_sample_t) {
left_volume * (1 - gb->apu_output.highpass_rate) + gb->apu_output.highpass_diff.left * gb->apu_output.highpass_rate,
right_volume * (1 - gb->apu_output.highpass_rate) + gb->apu_output.highpass_diff.right * gb->apu_output.highpass_rate
};
case GB_HIGHPASS_MAX:;
}
}
if (gb->apu_output.interference_volume) {
signed interference_bias = interference(gb);
int16_t interference_sample = (interference_bias - gb->apu_output.interference_highpass);
gb->apu_output.interference_highpass = gb->apu_output.interference_highpass * gb->apu_output.highpass_rate +
(1 - gb->apu_output.highpass_rate) * interference_sample;
interference_bias *= gb->apu_output.interference_volume;
filtered_output.left = MAX(MIN(filtered_output.left + interference_bias, 0x7FFF), -0x8000);
filtered_output.right = MAX(MIN(filtered_output.right + interference_bias, 0x7FFF), -0x8000);
}
assert(gb->apu_output.sample_callback);
gb->apu_output.sample_callback(gb, &filtered_output);
if (unlikely(gb->apu_output.output_file && gb->apu_output.output_format != GB_AUDIO_FORMAT_VGM)) {
#ifdef GB_BIG_ENDIAN
if (gb->apu_output.output_format == GB_AUDIO_FORMAT_WAV) {
filtered_output.left = LE16(filtered_output.left);
filtered_output.right = LE16(filtered_output.right);
}
#endif
if (fwrite(&filtered_output, sizeof(filtered_output), 1, gb->apu_output.output_file) != 1) {
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
gb->apu_output.output_error = errno;
}
}
}
static void update_square_sample(GB_gameboy_t *gb, GB_channel_t index, unsigned cycles)
{
if (gb->apu.square_channels[index].sample_surpressed) {
if (gb->model > GB_MODEL_CGB_E) {
update_sample(gb, index, gb->apu.samples[index], 0);
}
return;
}
uint8_t duty = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR11 :GB_IO_NR21] >> 6;
update_sample(gb, index,
duties[gb->apu.square_channels[index].current_sample_index + duty * 8]?
gb->apu.square_channels[index].current_volume : 0,
cycles);
}
static inline void update_wave_sample(GB_gameboy_t *gb, unsigned cycles)
{
if (gb->apu.wave_channel.current_sample_index & 1) {
update_sample(gb, GB_WAVE,
(gb->apu.wave_channel.current_sample_byte & 0xF) >> gb->apu.wave_channel.shift,
cycles);
}
else {
update_sample(gb, GB_WAVE,
(gb->apu.wave_channel.current_sample_byte >> 4) >> gb->apu.wave_channel.shift,
cycles);
}
}
static inline void set_envelope_clock(GB_envelope_clock_t *clock, bool value, bool direction, uint8_t volume)
{
if (clock->clock == value) return;
if (value) {
clock->clock = true;
clock->should_lock = (volume == 0xF && direction) || (volume == 0x0 && !direction);
}
else {
clock->clock = false;
clock->locked |= clock->should_lock;
}
}
static void _nrx2_glitch(uint8_t *volume, uint8_t value, uint8_t old_value, uint8_t *countdown, GB_envelope_clock_t *lock)
{
if (lock->clock) {
*countdown = value & 7;
}
bool should_tick = (value & 7) && !(old_value & 7) && !lock->locked;
bool should_invert = (value & 8) ^ (old_value & 8);
if ((value & 0xF) == 8 && (old_value & 0xF) == 8 && !lock->locked) {
should_tick = true;
}
if (should_invert) {
// The weird and over-the-top way clocks for this counter are connected cause
// some weird ways for it to invert
if (value & 8) {
if (!(old_value & 7) && !lock->locked) {
*volume ^= 0xF;
}
else {
*volume = 0xE - *volume;
*volume &= 0xF;
}
should_tick = false; // Somehow prevents ticking?
}
else {
*volume = 0x10 - *volume;
*volume &= 0xF;
}
}
if (should_tick) {
if (value & 8) {
(*volume)++;
}
else {
(*volume)--;
}
*volume &= 0xF;
}
else if (!(value & 7) && lock->clock) {
set_envelope_clock(lock, false, 0, 0);
}
}
static void nrx2_glitch(GB_gameboy_t *gb, uint8_t *volume, uint8_t value, uint8_t old_value, uint8_t *countdown, GB_envelope_clock_t *lock)
{
/* Note: on pre-CGB models *some* of these are non-deterministic. Specifically,
$x0 writes seem to be non-deterministic while $x8 always work as expected.
TODO: Might be useful to find which cases are non-deterministic, and allow
the debugger to issue warnings when they're used. I suspect writes to/from
$xF are guaranteed to be deterministic. */
if (gb->model <= GB_MODEL_CGB_C) {
_nrx2_glitch(volume, 0xFF, old_value, countdown, lock);
_nrx2_glitch(volume, value, 0xFF, countdown, lock);
}
else {
_nrx2_glitch(volume, value, old_value, countdown, lock);
}
}
static void tick_square_envelope(GB_gameboy_t *gb, GB_channel_t index)
{
set_envelope_clock(&gb->apu.square_channels[index].envelope_clock, false, 0, 0);
if (gb->apu.square_channels[index].envelope_clock.locked) return;
uint8_t nrx2 = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
if (!(nrx2 & 7)) return;
if (gb->cgb_double_speed) {
if (index == GB_SQUARE_1) {
gb->apu.pcm_mask[0] &= gb->apu.square_channels[GB_SQUARE_1].current_volume | 0xF1;
}
else {
/* Note: CGB-0 behavior is instance specific and non-deterministic. Emulated behavior follows my CGB-0,
except that my CGB-0 sometimes yields "1" for 8->7 and 4->3 transitions. */
uint8_t mask;
if (unlikely(gb->model == GB_MODEL_CGB_0)) {
if (gb->apu.square_channels[GB_SQUARE_2].current_volume == 1 && (gb->io_registers[GB_IO_NR22] & 8)) {
mask = 0x1F;
}
else {
mask = 0x3F;
}
}
else {
mask = 0x3F;
}
gb->apu.pcm_mask[0] &= (gb->apu.square_channels[GB_SQUARE_2].current_volume << 4) | mask;
}
}
set_envelope_clock(&gb->apu.square_channels[index].envelope_clock, false, 0, 0);
if (nrx2 & 8) {
gb->apu.square_channels[index].current_volume++;
}
else {
gb->apu.square_channels[index].current_volume--;
}
if (gb->apu.is_active[index]) {
update_square_sample(gb, index, 0);
}
}
static void tick_noise_envelope(GB_gameboy_t *gb)
{
set_envelope_clock(&gb->apu.noise_channel.envelope_clock, false, 0, 0);
if (gb->apu.noise_channel.envelope_clock.locked) return;
uint8_t nr42 = gb->io_registers[GB_IO_NR42];
if (!(nr42 & 7)) return;
if (gb->cgb_double_speed) {
gb->apu.pcm_mask[1] &= (gb->apu.noise_channel.current_volume << 4) | 0x1F;
}
if (nr42 & 8) {
gb->apu.noise_channel.current_volume++;
}
else {
gb->apu.noise_channel.current_volume--;
}
if (gb->apu.is_active[GB_NOISE]) {
update_sample(gb, GB_NOISE,
(gb->apu.noise_channel.lfsr & 1) ?
gb->apu.noise_channel.current_volume : 0,
0);
}
}
static void sweep_calculation_done(GB_gameboy_t *gb, unsigned cycles)
{
/* APU bug: sweep frequency is checked after adding the sweep delta twice */
if (gb->apu.channel_1_restart_hold == 0) {
gb->apu.shadow_sweep_sample_length = gb->apu.square_channels[GB_SQUARE_1].sample_length;
}
if (gb->io_registers[GB_IO_NR10] & 8) {
gb->apu.sweep_length_addend ^= 0x7FF;
}
if (gb->apu.shadow_sweep_sample_length + gb->apu.sweep_length_addend > 0x7FF && !(gb->io_registers[GB_IO_NR10] & 8)) {
gb->apu.is_active[GB_SQUARE_1] = false;
update_sample(gb, GB_SQUARE_1, 0, gb->apu.square_sweep_calculate_countdown * 2 - cycles);
}
gb->apu.channel1_completed_addend = gb->apu.sweep_length_addend;
}
static void trigger_sweep_calculation(GB_gameboy_t *gb)
{
if ((gb->io_registers[GB_IO_NR10] & 0x70) && gb->apu.square_sweep_countdown == 7) {
if (gb->io_registers[GB_IO_NR10] & 0x07) {
gb->apu.square_channels[GB_SQUARE_1].sample_length =
gb->apu.sweep_length_addend + gb->apu.shadow_sweep_sample_length + !!(gb->io_registers[GB_IO_NR10] & 0x8);
gb->apu.square_channels[GB_SQUARE_1].sample_length &= 0x7FF;
}
if (gb->apu.channel_1_restart_hold == 0) {
gb->apu.sweep_length_addend = gb->apu.square_channels[GB_SQUARE_1].sample_length;
gb->apu.sweep_length_addend >>= (gb->io_registers[GB_IO_NR10] & 7);
}
/* Recalculation and overflow check only occurs after a delay */
gb->apu.square_sweep_calculate_countdown = gb->io_registers[GB_IO_NR10] & 0x7;
// TODO: this is a hack because DIV write timing is inaccurate. Will probably break on odd mode.
gb->apu.square_sweep_calculate_countdown_reload_timer = 1 + gb->apu.lf_div;
if (!gb->cgb_double_speed && gb->during_div_write) {
gb->apu.square_sweep_calculate_countdown_reload_timer = 1;
}
gb->apu.unshifted_sweep = !(gb->io_registers[GB_IO_NR10] & 0x7);
gb->apu.square_sweep_countdown = ((gb->io_registers[GB_IO_NR10] >> 4) & 7) ^ 7;
if (gb->apu.square_sweep_calculate_countdown == 0) {
gb->apu.square_sweep_instant_calculation_done = true;
}
}
}
noinline void GB_apu_delayed_envelope_tick(GB_gameboy_t *gb)
{
gb->apu.pending_envelope_tick = false;
if (!gb->apu.global_enable) return;
GB_apu_run(gb, true);
gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF;
unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (gb->apu.square_channels[i].envelope_clock.clock) {
tick_square_envelope(gb, i);
}
}
if (gb->apu.noise_channel.envelope_clock.clock) {
tick_noise_envelope(gb);
}
}
noinline void GB_apu_div_event(GB_gameboy_t *gb)
{
GB_apu_run(gb, true);
gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF;
if (!gb->apu.global_enable) return;
if (gb->apu.skip_div_event == GB_SKIP_DIV_EVENT_SKIP) {
gb->apu.skip_div_event = GB_SKIP_DIV_EVENT_SKIPPED;
return;
}
if (gb->apu.skip_div_event == GB_SKIP_DIV_EVENT_SKIPPED) {
gb->apu.skip_div_event = GB_SKIP_DIV_EVENT_INACTIVE;
}
else {
gb->apu.div_divider++;
}
if ((gb->apu.div_divider & 7) == 7) {
unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (!gb->apu.square_channels[i].envelope_clock.clock) {
gb->apu.square_channels[i].volume_countdown--;
gb->apu.square_channels[i].volume_countdown &= 7;
}
}
if (!gb->apu.noise_channel.envelope_clock.clock) {
gb->apu.noise_channel.volume_countdown--;
gb->apu.noise_channel.volume_countdown &= 7;
}
}
if (gb->cgb_double_speed && (gb->model == GB_MODEL_CGB_D || gb->model == GB_MODEL_CGB_E)) {
gb->apu.pending_envelope_tick = true;
}
else {
unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (gb->apu.square_channels[i].envelope_clock.clock) {
tick_square_envelope(gb, i);
}
}
if (gb->apu.noise_channel.envelope_clock.clock) {
tick_noise_envelope(gb);
}
}
if ((gb->apu.div_divider & 1) == 1) {
unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (gb->apu.square_channels[i].length_enabled) {
if (gb->apu.square_channels[i].pulse_length) {
if (!--gb->apu.square_channels[i].pulse_length) {
gb->apu.is_active[i] = false;
update_sample(gb, i, 0, 0);
}
}
}
}
if (gb->apu.wave_channel.length_enabled) {
if (gb->apu.wave_channel.pulse_length) {
if (!--gb->apu.wave_channel.pulse_length) {
if (gb->apu.is_active[GB_WAVE] && gb->model > GB_MODEL_CGB_E) {
if (gb->apu.wave_channel.sample_countdown == 0) {
gb->apu.wave_channel.current_sample_byte =
gb->io_registers[GB_IO_WAV_START + (((gb->apu.wave_channel.current_sample_index + 1) & 0xF) >> 1)];
}
else if (gb->apu.wave_channel.sample_countdown == 9) {
// TODO: wtf?
gb->apu.wave_channel.current_sample_byte = gb->io_registers[GB_IO_WAV_START];
}
}
gb->apu.is_active[GB_WAVE] = false;
update_sample(gb, GB_WAVE, 0, 0);
}
}
}
if (gb->apu.noise_channel.length_enabled) {
if (gb->apu.noise_channel.pulse_length) {
if (!--gb->apu.noise_channel.pulse_length) {
gb->apu.is_active[GB_NOISE] = false;
update_sample(gb, GB_NOISE, 0, 0);
}
}
}
}
if ((gb->apu.div_divider & 3) == 3) {
gb->apu.square_sweep_countdown++;
gb->apu.square_sweep_countdown &= 7;
trigger_sweep_calculation(gb);
}
}
noinline void GB_apu_div_secondary_event(GB_gameboy_t *gb)
{
GB_apu_run(gb, true);
gb->apu.pcm_mask[0] = gb->apu.pcm_mask[1] = 0xFF;
if (!gb->apu.global_enable) return;
unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
uint8_t nrx2 = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
if (gb->apu.is_active[i] && gb->apu.square_channels[i].volume_countdown == 0) {
set_envelope_clock(&gb->apu.square_channels[i].envelope_clock,
(gb->apu.square_channels[i].volume_countdown = nrx2 & 7),
nrx2 & 8,
gb->apu.square_channels[i].current_volume);
}
}
if (gb->apu.is_active[GB_NOISE] && gb->apu.noise_channel.volume_countdown == 0) {
set_envelope_clock(&gb->apu.noise_channel.envelope_clock,
(gb->apu.noise_channel.volume_countdown = gb->io_registers[GB_IO_NR42] & 7),
gb->io_registers[GB_IO_NR42] & 8,
gb->apu.noise_channel.current_volume);
}
}
static void update_lfsr(GB_gameboy_t *gb, unsigned cycles_offset)
{
gb->apu.noise_channel.current_lfsr_sample = gb->apu.noise_channel.lfsr & 1;
if (gb->apu.is_active[GB_NOISE]) {
update_sample(gb, GB_NOISE,
gb->apu.noise_channel.current_lfsr_sample ?
gb->apu.noise_channel.current_volume : 0,
cycles_offset);
}
}
static void step_lfsr(GB_gameboy_t *gb, unsigned cycles_offset)
{
gb->apu.lfsr_bit_7_before_step = gb->apu.noise_channel.lfsr & 0x80;
unsigned high_bit_mask = gb->apu.noise_channel.narrow ? 0x4040 : 0x4000;
bool new_high_bit = (gb->apu.noise_channel.lfsr ^ (gb->apu.noise_channel.lfsr >> 1) ^ 1) & 1;
gb->apu.noise_channel.lfsr >>= 1;
if (new_high_bit) {
gb->apu.noise_channel.lfsr |= high_bit_mask;
}
else {
/* This code is not redundent, it's relevant when switching LFSR widths */
gb->apu.noise_channel.lfsr &= ~high_bit_mask;
}
update_lfsr(gb, cycles_offset);
gb->apu.lfsr_stepped_in_narrow = gb->apu.noise_channel.narrow;
}
void GB_apu_run(GB_gameboy_t *gb, bool force)
{
uint32_t clock_rate = GB_get_clock_rate(gb);
bool orig_force = force;
restart:;
uint16_t cycles = gb->apu.apu_cycles;
if (force ||
(cycles + gb->apu_output.cycles_since_render >= gb->apu_output.max_cycles_per_sample) ||
(gb->apu_output.sample_cycles >= clock_rate) ||
(gb->apu.square_sweep_calculate_countdown || gb->apu.channel_1_restart_hold || gb->apu.square_sweep_calculate_countdown_reload_timer) ||
(gb->model <= GB_MODEL_CGB_E && (gb->apu.wave_channel.bugged_read_countdown || (gb->apu.wave_channel.enable && gb->apu.wave_channel.pulsed)))) {
force = true;
}
if (!force) {
return;
}
/* Force renders to never be more than max_cycles_per_sample apart by spliting runs. */
while (cycles + gb->apu_output.cycles_since_render > gb->apu_output.max_cycles_per_sample) {
/* We're already past max_cycles_per_sample. This can happen when changing clock rates, etc.
Let this sample render normally. */
if (unlikely(gb->apu_output.cycles_since_render > gb->apu_output.max_cycles_per_sample)) break;
gb->apu.apu_cycles = gb->apu_output.max_cycles_per_sample - gb->apu_output.cycles_since_render;
if (gb->apu.apu_cycles) {
// Run for just enough cycles to reach max_cycles_per_sample
cycles -= gb->apu.apu_cycles;
GB_apu_run(gb, true);
// Re-evaluate force if needed
if (!orig_force) {
force = false;
gb->apu.apu_cycles = cycles;
goto restart;
}
// Check if we need another batch
continue;
}
// Render if needed
if (gb->apu_output.sample_cycles >= clock_rate) {
gb->apu_output.sample_cycles -= clock_rate;
render(gb);
}
break;
}
gb->apu.apu_cycles = 0;
if (!cycles) {
/* This can happen in pre-CGB stop mode */
while (unlikely(gb->apu_output.sample_cycles >= clock_rate)) {
gb->apu_output.sample_cycles -= clock_rate;
render(gb);
}
return;
}
if (unlikely(gb->apu.wave_channel.bugged_read_countdown)) {
uint16_t cycles_left = cycles;
while (cycles_left) {
cycles_left--;
if (--gb->apu.wave_channel.bugged_read_countdown == 0) {
gb->apu.wave_channel.current_sample_byte =
gb->io_registers[GB_IO_WAV_START + (gb->address_bus & 0xF)];
if (gb->apu.is_active[GB_WAVE]) {
update_wave_sample(gb, 0);
}
break;
}
}
}
bool start_ch4 = false;
if (likely(!gb->stopped || GB_is_cgb(gb))) {
if (gb->apu.noise_channel.dmg_delayed_start) {
if (gb->apu.noise_channel.dmg_delayed_start == cycles) {
gb->apu.noise_channel.dmg_delayed_start = 0;
start_ch4 = true;
}
else if (gb->apu.noise_channel.dmg_delayed_start > cycles) {
gb->apu.noise_channel.dmg_delayed_start -= cycles;
}
else {
/* Split it into two */
cycles -= gb->apu.noise_channel.dmg_delayed_start;
gb->apu.apu_cycles = gb->apu.noise_channel.dmg_delayed_start;
GB_apu_run(gb, true);
}
}
/* To align the square signal to 1MHz */
gb->apu.lf_div ^= cycles & 1;
gb->apu.noise_channel.alignment += cycles;
unsigned sweep_cycles = cycles / 2;
if ((cycles & 1) && !gb->apu.lf_div) {
sweep_cycles++;
}
if (gb->apu.square_sweep_calculate_countdown_reload_timer > sweep_cycles) {
gb->apu.square_sweep_calculate_countdown_reload_timer -= sweep_cycles;
sweep_cycles = 0;
}
else {
if (gb->apu.square_sweep_calculate_countdown_reload_timer && !gb->apu.square_sweep_calculate_countdown && gb->apu.square_sweep_instant_calculation_done) {
sweep_calculation_done(gb, cycles);
}
gb->apu.square_sweep_instant_calculation_done = false;
sweep_cycles -= gb->apu.square_sweep_calculate_countdown_reload_timer;
gb->apu.square_sweep_calculate_countdown_reload_timer = 0;
}
if (gb->apu.square_sweep_calculate_countdown &&
(((gb->io_registers[GB_IO_NR10] & 7) || gb->apu.unshifted_sweep))) { // Calculation is paused if the lower bits are 0
if (gb->apu.square_sweep_calculate_countdown > sweep_cycles) {
gb->apu.square_sweep_calculate_countdown -= sweep_cycles;
}
else {
gb->apu.square_sweep_calculate_countdown = 0;
sweep_calculation_done(gb, cycles);
}
}
if (gb->apu.channel_1_restart_hold) {
if (gb->apu.channel_1_restart_hold > cycles) {
gb->apu.channel_1_restart_hold -= cycles;
}
else {
gb->apu.channel_1_restart_hold = 0;
}
}
unrolled for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
if (gb->apu.is_active[i]) {
uint16_t cycles_left = cycles;
if (unlikely(gb->apu.square_channels[i].delay)) {
if (gb->apu.square_channels[i].delay < cycles_left) {
gb->apu.square_channels[i].delay = 0;
}
else {
gb->apu.square_channels[i].delay -= cycles_left;
}
}
while (unlikely(cycles_left > gb->apu.square_channels[i].sample_countdown)) {
cycles_left -= gb->apu.square_channels[i].sample_countdown + 1;
gb->apu.square_channels[i].sample_countdown = (gb->apu.square_channels[i].sample_length ^ 0x7FF) * 2 + 1;
gb->apu.square_channels[i].current_sample_index++;
gb->apu.square_channels[i].current_sample_index &= 0x7;
gb->apu.square_channels[i].sample_surpressed = false;
if (cycles_left == 0 && gb->apu.samples[i] == 0) {
gb->apu.pcm_mask[0] &= i == GB_SQUARE_1? 0xF0 : 0x0F;
}
gb->apu.square_channels[i].did_tick = true;
update_square_sample(gb, i, cycles - cycles_left);
uint8_t duty = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR11 :GB_IO_NR21] >> 6;
uint8_t edge_sample_index = inline_const(uint8_t[], {7, 7, 5, 1})[duty];
if (gb->apu.square_channels[i].current_sample_index == edge_sample_index) {
gb->apu_output.edge_triggered[i] = true;
}
}
gb->apu.square_channels[i].just_reloaded = cycles_left == 0;
if (cycles_left) {
gb->apu.square_channels[i].sample_countdown -= cycles_left;
}
}
}
gb->apu.wave_channel.wave_form_just_read = false;
if (gb->apu.is_active[GB_WAVE]) {
uint16_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.wave_channel.sample_countdown)) {
cycles_left -= gb->apu.wave_channel.sample_countdown + 1;
gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length ^ 0x7FF;
gb->apu.wave_channel.current_sample_index++;
gb->apu.wave_channel.current_sample_index &= 0x1F;
gb->apu.wave_channel.current_sample_byte =
gb->io_registers[GB_IO_WAV_START + (gb->apu.wave_channel.current_sample_index >> 1)];
update_wave_sample(gb, cycles - cycles_left);
gb->apu.wave_channel.wave_form_just_read = true;
if (gb->apu.wave_channel.current_sample_index == 0) {
gb->apu_output.edge_triggered[GB_WAVE] = true;
}
}
if (cycles_left) {
gb->apu.wave_channel.sample_countdown -= cycles_left;
gb->apu.wave_channel.wave_form_just_read = false;
}
}
else if (gb->apu.wave_channel.enable && gb->apu.wave_channel.pulsed && gb->model <= GB_MODEL_CGB_E) {
uint16_t cycles_left = cycles;
while (unlikely(cycles_left > gb->apu.wave_channel.sample_countdown)) {
cycles_left -= gb->apu.wave_channel.sample_countdown + 1;
gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length ^ 0x7FF;
if (cycles_left) {
gb->apu.wave_channel.current_sample_byte =
gb->io_registers[GB_IO_WAV_START + (gb->address_bus & 0xF)];
}
else {
gb->apu.wave_channel.bugged_read_countdown = 1;
}
}
if (cycles_left) {
gb->apu.wave_channel.sample_countdown -= cycles_left;
}
if (gb->apu.wave_channel.sample_countdown == 0) {
gb->apu.wave_channel.bugged_read_countdown = 2;
}
}
// TODO: verify these conditions one a DMG somehow
if (gb->apu.noise_counter_active || gb->apu.noise_background_counter_active) {
uint16_t cycles_left = cycles;
unsigned divisor = (gb->io_registers[GB_IO_NR43] & 0x07) << 2;
if (!divisor) divisor = 2;
if (gb->apu.noise_channel.counter_countdown == 0) {
gb->apu.noise_channel.counter_countdown = divisor;
}
// This while doesn't get an unlikely because the noise channel steps frequently enough
while (cycles_left >= gb->apu.noise_channel.counter_countdown) {
cycles_left -= gb->apu.noise_channel.counter_countdown;
gb->apu.noise_channel.counter_countdown = divisor;
uint16_t mask = 1 << (gb->io_registers[GB_IO_NR43] >> 4);
bool old_bit = gb->apu.noise_channel.counter & mask;
gb->apu.noise_channel.counter++;
gb->apu.noise_channel.counter &= 0x3FFF;
gb->apu.noise_channel.did_step_counter = true;
bool new_bit = gb->apu.noise_channel.counter & mask;
/* Step LFSR */
if (new_bit && !old_bit && gb->apu.is_active[GB_NOISE]) {
if (cycles_left == 0 && gb->apu.samples[GB_NOISE] == 0 && !gb->cgb_double_speed) {
gb->apu.pcm_mask[1] &= 0x0F;
}
step_lfsr(gb, cycles - cycles_left);
}
}
if (cycles_left) {
if (likely(gb->apu.noise_counter_active || gb->apu.noise_background_counter_active)) {
gb->apu.noise_channel.counter_countdown -= cycles_left;
gb->apu.noise_channel.countdown_reloaded = false;
}
}
else {
gb->apu.noise_channel.countdown_reloaded = true;
gb->apu_output.edge_triggered[GB_NOISE] = true;
}
}
}
if (gb->apu_output.sample_rate) {
gb->apu_output.cycles_since_render += cycles;
gb->apu_output.sample_fraction += sample_fraction_multiply(gb, cycles);
assert(gb->apu_output.sample_fraction < (4 << 28));
if (gb->apu_output.sample_cycles >= clock_rate) {
gb->apu_output.sample_cycles -= clock_rate;
render(gb);
}
}
if (start_ch4) {
GB_apu_write(gb, GB_IO_NR44, gb->io_registers[GB_IO_NR44] | 0x80);
}
}
void GB_apu_init(GB_gameboy_t *gb)
{
memset(&gb->apu, 0, sizeof(gb->apu));
gb->apu.apu_cycles_in_2mhz = true;
gb->apu.lf_div = 1;
gb->apu.wave_channel.shift = 4;
/* APU glitch: When turning the APU on while DIV's bit 4 (or 5 in double speed mode) is on,
the first DIV/APU event is skipped. */
if (gb->div_counter & (gb->cgb_double_speed? 0x2000 : 0x1000)) {
gb->apu.skip_div_event = GB_SKIP_DIV_EVENT_SKIP;
gb->apu.div_divider = 1;
}
gb->apu.square_channels[GB_SQUARE_1].sample_countdown = -1;
gb->apu.square_channels[GB_SQUARE_2].sample_countdown = -1;
}
uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg)
{
GB_apu_run(gb, true);
if (reg == GB_IO_NR52) {
uint8_t value = 0;
for (unsigned i = 0; i < GB_N_CHANNELS; i++) {
value >>= 1;
if (gb->apu.is_active[i]) {
value |= 0x8;
}
}
if (gb->apu.global_enable) {
value |= 0x80;
}
value |= 0x70;
return value;
}
static const char read_mask[GB_IO_WAV_END - GB_IO_NR10 + 1] = {
/* NRX0 NRX1 NRX2 NRX3 NRX4 */
0x80, 0x3F, 0x00, 0xFF, 0xBF, // NR1X
0xFF, 0x3F, 0x00, 0xFF, 0xBF, // NR2X
0x7F, 0xFF, 0x9F, 0xFF, 0xBF, // NR3X
0xFF, 0xFF, 0x00, 0x00, 0xBF, // NR4X
0x00, 0x00, 0x70, 0xFF, 0xFF, // NR5X
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // Unused
// Wave RAM
0, /* ... */
};
if (reg >= GB_IO_WAV_START && reg <= GB_IO_WAV_END && gb->apu.is_active[GB_WAVE]) {
if (!GB_is_cgb(gb) && !gb->apu.wave_channel.wave_form_just_read) {
return 0xFF;
}
if (gb->model > GB_MODEL_CGB_E) {
return 0xFF;
}
reg = GB_IO_WAV_START + gb->apu.wave_channel.current_sample_index / 2;
}
return gb->io_registers[reg] | read_mask[reg - GB_IO_NR10];
}
static noinline void nr10_write_glitch(GB_gameboy_t *gb, uint8_t value)
{
// TODO: Check all of these in APU odd mode
if (gb->model <= GB_MODEL_CGB_C) {
if (gb->apu.square_sweep_calculate_countdown_reload_timer == 1 && !gb->apu.lf_div) {
if (gb->cgb_double_speed) {
/* This is some instance-specific data corruption. It might also be affect by revision.
At least for my CGB-0 (haven't tested any other CGB-0s), the '3' case is non-deterministic. */
static const uint8_t corruption[8] = {7, 7, 5, 7, 3, 3, 5, 7}; // Two of my CGB-Cs, CGB-A
// static const uint8_t corruption[8] = {7, 7, 1, 3, 3, 3, 5, 7}; // My other CGB-C, Coffee Bat's CGB-C
// static const uint8_t corruption[8] = {7, 1, 1, 3, 3, 5, 5, 7}; // My CGB-B
// static const uint8_t corruption[8] = {7, 7, 1, *, 3, 3, 5, 7}; // My CGB-0
// static const uint8_t corruption[8] = {7, 5, 1, 3, 3, 1, 5, 7}; // PinoBatch's CGB-B
// static const uint8_t corruption[8] = {7, 5, 1, 3, 3, *, 5, 7}; // GenericHeroGuy CGB-C
// TODO: How does this affect actual frequency calculation?
gb->apu.square_sweep_calculate_countdown = corruption[gb->apu.square_sweep_calculate_countdown & 7];
/* TODO: the value of 1 needs special handling, but it doesn't occur with the instance I'm emulating here */
}
}
else if (gb->apu.square_sweep_calculate_countdown_reload_timer > 1) {
if (gb->cgb_double_speed) {
// TODO: How does this affect actual frequency calculation?
gb->apu.square_sweep_calculate_countdown = value & 7;
}
}
else if (gb->apu.square_sweep_calculate_countdown) {
// No clue why 1 is a special case here
bool should_zombie_step = false;
if (!(gb->io_registers[GB_IO_NR10] & 7)) {
should_zombie_step = gb->apu.lf_div ^ gb->cgb_double_speed;
}
else if (gb->cgb_double_speed && gb->apu.square_sweep_calculate_countdown == 1) {
should_zombie_step = true;
}
if (should_zombie_step) {
gb->apu.square_sweep_calculate_countdown--;
if (gb->apu.square_sweep_calculate_countdown <= 1) {
gb->apu.square_sweep_calculate_countdown = 0;
sweep_calculation_done(gb, 0);
}
}
}
}
else {
if (gb->apu.square_sweep_calculate_countdown_reload_timer == 2) {
// Countdown just reloaded, re-reload it
gb->apu.square_sweep_calculate_countdown = value & 0x7;
if (!gb->apu.square_sweep_calculate_countdown) {
gb->apu.square_sweep_calculate_countdown_reload_timer = 0;
}
else {
// TODO: How does this affect actual frequency calculation?
}
}
if ((value & 7) && !(gb->io_registers[GB_IO_NR10] & 7) && !gb->apu.lf_div && gb->apu.square_sweep_calculate_countdown > 1) {
// TODO: Another odd glitch? Ditto
gb->apu.square_sweep_calculate_countdown--;
if (!gb->apu.square_sweep_calculate_countdown) {
sweep_calculation_done(gb, 0);
}
}
}
}
static void prepare_noise_start(GB_gameboy_t *gb)
{
/*
TODO: When restarting a channel right after starting it, before it has the chance to tick the counter, things
behave differently. Only certain behaviors of this edge case are emulated.
*/
/*
TODO: Restarting a channel in double speed mode under CGB-C and older is not accurate if the divisor is 0 or 1.
Specifically in the 0 case, the initial LFSR value seems to be deterministic, but dependant on various
parameters. It is neither 0 or the equaly unexplained 0x0055.
*/
gb->apu.noise_counter_active = gb->io_registers[GB_IO_NR42] & 0xF8; // Resets on APU off and DAC disable
bool was_started_with_dac_disabled = gb->apu.noise_started_with_dac_disabled;
gb->apu.noise_started_with_dac_disabled = !gb->apu.noise_counter_active;
unsigned divisor = (gb->io_registers[GB_IO_NR43] & 0x07);
bool was_background_counting = gb->apu.noise_background_counter_active;
gb->apu.noise_background_counter_active = true;
bool instant_step = false;
bool div_1_glitch = false;
if (divisor > 1 && gb->apu.noise_channel.counter_countdown == 1) {
gb->apu.noise_channel.counter++;
gb->apu.noise_channel.counter &= 0x3FFF;
}
else if (divisor > 1 && gb->apu.noise_channel.counter_countdown == 2 && gb->apu.is_active[GB_NOISE] && gb->model <= GB_MODEL_CGB_C && gb->cgb_double_speed) {
gb->apu.noise_channel.counter++;
gb->apu.noise_channel.counter &= 0x3FFF;
}
else if (gb->apu.noise_channel.counter_countdown == 2 &&
(gb->apu.noise_channel.alignment & 3) == 0 &&
gb->apu.is_active[GB_NOISE]) {
if (divisor == 0) {
divisor = 8;
}
else if (divisor == 1) {
if (!gb->apu.noise_channel.did_step_counter) {
div_1_glitch = true;
}
uint16_t mask = 1 << (gb->io_registers[GB_IO_NR43] >> 4);
bool old_bit = gb->apu.noise_channel.counter & mask;
gb->apu.noise_channel.counter++;
gb->apu.noise_channel.counter &= 0x3FFF;
bool new_bit = gb->apu.noise_channel.counter & mask;
if ((new_bit && !old_bit)) {
instant_step = true;
}
}
}
gb->apu.noise_channel.counter_countdown = divisor == 0? 6 : divisor * 4 + 6;
if (gb->apu.noise_channel.alignment & 1) {
if (!divisor) {
if (gb->model <= GB_MODEL_CGB_C) {
gb->apu.noise_channel.counter_countdown++;
}
else if (was_background_counting) {
gb->apu.noise_channel.counter_countdown--;
}
else {
gb->apu.noise_channel.counter_countdown++;
}
}
else {
if (gb->apu.noise_channel.alignment & 2) {
if (divisor == 1 && !gb->apu.is_active[GB_NOISE]) {
gb->apu.noise_channel.counter_countdown++;
}
else {
gb->apu.noise_channel.counter_countdown -= 3;
}
}
else {
gb->apu.noise_channel.counter_countdown--;
if (divisor == 1 && gb->apu.is_active[GB_NOISE]) {
gb->apu.noise_channel.counter_countdown -= 4;
}
}
}
}
else {
if (divisor) {
if (gb->apu.noise_channel.alignment & 2) {
if (gb->cgb_double_speed && gb->model <= GB_MODEL_CGB_C && divisor == 1) {
gb->apu.noise_channel.counter_countdown += 2;
}
else {
gb->apu.noise_channel.counter_countdown -= 2;
}
}
else if (divisor > 1 && (!gb->cgb_double_speed || gb->model > GB_MODEL_CGB_C)) {
gb->apu.noise_channel.counter_countdown -= 4;
}
/* TODO: This quirk seems way too specific */
else if (divisor == 1 && gb->apu.is_active[GB_NOISE] && !(gb->io_registers[GB_IO_NR43] & 0xf0)) {
gb->apu.noise_channel.counter_countdown -= 4;
}
}
else if (gb->cgb_double_speed && gb->model <= GB_MODEL_CGB_C) {
gb->apu.noise_channel.counter_countdown += 2;
}
}
/* Background counting glitches */
/* TODO: Double speed mode not tested */
if (divisor > 1) {
if (!gb->apu.noise_counter_active && !(gb->apu.noise_channel.alignment & 3)) {
gb->apu.noise_channel.counter_countdown += 4;
}
}
else {
if (was_background_counting && !gb->apu.is_active[GB_NOISE] && !(gb->apu.noise_channel.alignment & 3)) {
if (divisor == 0) {
if (was_started_with_dac_disabled) { // TODO: Why is it different?
gb->apu.noise_channel.counter_countdown += 28;
}
}
else {
gb->apu.noise_channel.counter_countdown -= 4;
}
}
}
/* TODO: This is weird, is the clock going out of sync? */
if (!divisor && gb->model <= GB_MODEL_CGB_C && was_background_counting && !gb->apu.is_active[GB_NOISE] && gb->cgb_double_speed) {
gb->apu.noise_channel.counter_countdown--;
}
if (div_1_glitch) {
gb->apu.noise_channel.counter_countdown -= 4;
}
if (!divisor && gb->apu.is_active[GB_NOISE] && (gb->apu.noise_channel.alignment & 3) == 3) {
/* TODO: I have no clue where this number comes from, but this number is confirmed for this edge case even for
side LFSR, despite being seemingly arbitrary. */
gb->apu.noise_channel.lfsr = 0x0055;
}
else {
gb->apu.noise_channel.lfsr = 0;
}
if (instant_step) {
step_lfsr(gb, 0);
}
}
static void nr43_write(GB_gameboy_t *gb, uint8_t new)
{
/*
NR43 writes cause glitch signals to the LFSR. They are often non-deterministic, and
they're revision and instance specific. This implementation is trying to emulate a
simplified and deterministic "variant" of specific instances of revisions I own.
For more details:
https://github.com/LIJI32/SameBoy/issues/397#issuecomment-3733625631
*/
/*
TODO: Non-determinism aside, this is currently only 100% accurate in CGB-E mode, where
my specific CGB-E is currently emulated. My CGB-D, under rare cases, samples a second
intermediate value, and this is not currently emulated. AGB revisions are extremely
glitchy, and are hard to research.
Due to FF-write glitches in pre-CGB-D revisions, all writes (even no-change writes) go
through 3 intermediate values by definition. Also, the effective counter value used is
ORed with the next (or previous, timing needs to be verified) value.
*/
bool old_narrow = gb->apu.noise_channel.narrow;
gb->apu.noise_channel.narrow = new & 8;
uint8_t old = gb->io_registers[GB_IO_NR43];
gb->io_registers[GB_IO_NR43] = new;
if ((old & 0xF0) == (new & 0xF0)) return;
uint16_t effective_counter = gb->apu.noise_channel.counter;
if (gb->model <= GB_MODEL_CGB_C && gb->apu.noise_channel.countdown_reloaded) {
effective_counter |= (effective_counter - 1) & 0x3FFF;
}
bool old_bit = (effective_counter >> (old >> 4)) & 1;
uint8_t glitch_value = (old & 0x7F) | (new & 0x80);
bool glitch_bit = (effective_counter >> (glitch_value >> 4)) & 1;
bool new_bit = (effective_counter >> (new >> 4)) & 1;
bool force_glitch = false;
if (gb->model == GB_MODEL_CGB_D) {
if (new_bit && glitch_bit && old_bit) {
if ((old ^ new) & 0x70) {
force_glitch = true;
}
}
}
if (gb->model > GB_MODEL_CGB_E) {
/* AGB behavior is very glitchy and incosistent. It can have 2 intermediate values for
NR43, and sometimes even 3, and the pattern isn't very consistent. This is a *very*
rough approximation of the behavior.
Due to having so up to 3 intermediate value, glitch behavior is complicated to look
into, so currently CGB-E behavior is arbitrarily used if a glitch occurs. */
uint8_t glitch_value2 = 0;
if (new >= 0x80 && old >= 0x80) {
glitch_value = (old & 0xCF) | (new & 0x30);
glitch_value2 = (old & 0x8F) | (new & 0x70);
}
else {
glitch_value = (old & 0xDF) | (new & 0x20);
glitch_value2 = (old & 0xCF) | (new & 0x30);
}
glitch_bit = (gb->apu.noise_channel.counter >> (glitch_value >> 4)) & 1;
uint8_t glitch_bit2 = (gb->apu.noise_channel.counter >> (glitch_value2 >> 4)) & 1;
if (glitch_bit != glitch_bit2) {
if (new_bit == old_bit) {
glitch_bit = !new_bit;
}
else if (!glitch_bit && old_bit) {
force_glitch = true;
}
}
}
/* Step LFSR */
if ((old_bit == new_bit && new_bit != glitch_bit) || force_glitch) {
/* Glitching write. Has two categories, both have non-deterministic
variants. These are the most common variants of the two categories,
which are deterministic. */
if (new_bit) {
/* Category 1 */
if (gb->model >= GB_MODEL_CGB_E) {
if (!(new & 0x80)) {
step_lfsr(gb, 0);
}
else {
/* Only happens under this odd condition */
uint8_t t1 = (old >> 4) & 7;
uint8_t t2 = (new >> 4) & 7;
if ((t1 ^ 7) + t2 > 7 || ((t1 ^ 7) & t2)) {
/* Copy bit 8 to bit 7 */
gb->apu.noise_channel.lfsr &= ~0x80;
gb->apu.noise_channel.lfsr |= (gb->apu.noise_channel.lfsr >> 1) & 0x80;
/* All specific cases have non-deterministic behaviors involved */
if ((t1 == 0 || t1 == 4) && t2 == 3) {
gb->apu.noise_channel.lfsr &= (gb->apu.noise_channel.lfsr >> 1) | 0x545;
update_lfsr(gb, 0);
}
else if (t1 == 2 && t2 == 3) {
uint16_t mask = 0x555;
if ((gb->apu.noise_channel.lfsr & 0xC) == 0xC) {
mask |= 8;
}
if ((gb->apu.noise_channel.lfsr & 0xC00) == 0xC00) {
mask |= 0x800;
}
gb->apu.noise_channel.lfsr &= (gb->apu.noise_channel.lfsr >> 1) | mask;
update_lfsr(gb, 0);
}
if (!gb->apu.noise_channel.narrow && old_narrow && gb->apu.lfsr_stepped_in_narrow) {
/* TODO: Behaves weirder in non-deterministic t1 == 0/4 scenarios? */
if (gb->apu.lfsr_bit_7_before_step) {
gb->apu.noise_channel.lfsr |= 0x40;
}
else {
gb->apu.noise_channel.lfsr &= ~0x40;
}
}
gb->apu.noise_channel.lfsr |= gb->apu.noise_channel.narrow ? 0x4040 : 0x4000;
/* TODO: verify */
gb->apu.lfsr_stepped_in_narrow = gb->apu.noise_channel.narrow;
}
}
}
else if (gb->model == GB_MODEL_CGB_D) {
static const uint8_t glitch_map_l2h[8 * 8] = {
[000] = 0x00, 0x01, 0x01, 0x21, 0x02, 0x21,
[010] = 0x03, 0x00, 0x21, 0x01, 0x04, 0x04,
[020] = 0x05, 0x01, 0x00, 0x01, 0x04, 0x21,
[030] = 0x03, 0x05, 0x05, 0x00, 0x01, 0x01,
[040] = 0x05, 0x01, 0x01, 0x21, 0x00, 0x01,
[050] = 0x05, 0x05, 0x21, 0x01, 0x05, 0x00,
[060] = 0x05, 0x01, 0x05, 0x01, 0x05, 0x01,
[070] = 0x03, 0x05, 0x05, 0x05, 0x05, 0x05,
};
/* The following transitions are a bit non-deterministic (except under forced glitched):
1 -> c, 2 -> c, 3 -> c, 3 -> d */
static const uint8_t glitch_map_h2l[8 * 8] = {
[000] = 0x00, 0x27, 0x26, 0x37, 0x21, 0x38, 0x01, 0x01,
[010] = 0x01, 0x00, 0x38, 0x21, 0x21, 0x21, 0x01, 0x01,
[020] = 0x01, 0x27, 0x00, 0x28, 0x21, 0x38, 0x01, 0x01,
[030] = 0x01, 0x02, 0x01, 0x00, 0x31, 0x21, 0x01, 0x01,
[040] = 0x06, 0x28, 0x28, 0x38, 0x00, 0x27, 0x01, 0x01,
[050] = 0x01, 0x03, 0x38, 0x21, 0x01, 0x00, 0x01, 0x01,
};
/* The following transitions are a bit non-deterministic (except under forced glitched):
8 -> 5, 2 -> 9, a -> 3, c -> 3 */
const uint8_t *glitch_map = old & 0x80? &glitch_map_h2l[0] : &glitch_map_l2h[0];
unsigned glitch = glitch_map[((old & 0x70) >> 1) | ((new & 0x70) >> 4)];
if (force_glitch) {
if (!((new ^ old) & 0x80)) {
glitch = glitch & 0x20? 5 : 0;
}
else if (!(new & 0x80)) {
glitch = glitch & 0x10? 5 : 0;
}
else if ((glitch & 0xF) == 1 || (glitch & 0xF) == 4) {
glitch = 5;
}
else {
glitch = 0;
}
}
else {
glitch &= 0xF;
}
uint16_t old_lfsr = gb->apu.noise_channel.lfsr;
uint16_t lfsr_mask = gb->apu.noise_channel.narrow ? 0x4040 : 0x4000;
switch (glitch) {
case 6: // Like 2, but conditional
case 4: // Like 2, but conditional
if ((gb->apu.noise_channel.lfsr & (glitch == 4? 0x60 : 0x40)) != 0x40) { // Todo check wide mode
case 2: // And bit 1 with bit 0 before doing glitch 1
if (!(gb->apu.noise_channel.lfsr & 1)) {
gb->apu.noise_channel.lfsr &= ~2;
}
}
case 1: // Step and set the LFSR bit
case 8: // Step and set the LFSR bit conditionally
step_lfsr(gb, 0);
case 5: // Just set LFSR
if ((glitch != 8) || (old_lfsr & 3) != 2) {
gb->apu.noise_channel.lfsr |= lfsr_mask;
}
else {
gb->apu.noise_channel.lfsr |= old_lfsr & lfsr_mask;
}
break;
case 7: // Step and OR the LFSR bit with its old value
step_lfsr(gb, 0);
gb->apu.noise_channel.lfsr |= old_lfsr & lfsr_mask;
break;
case 3: // A bit of a mess
step_lfsr(gb, 0);
gb->apu.noise_channel.lfsr &= old_lfsr;
gb->apu.noise_channel.lfsr |= old_lfsr & 1;
gb->apu.noise_channel.lfsr |= lfsr_mask;
update_lfsr(gb, 0);
break;
default: break;
}
}
}
else {
/* Category 2 */
if (gb->model >= GB_MODEL_CGB_E) {
static const uint8_t glitch_map[8 * 8] = {
/* 8 9 A B C D */
[002] = 4, [003] = 2, [004] = 2, [005] = 2, // 0
[012] = 2, [013] = 4, [014] = 2, [015] = 2, // 1
[020] = 1, [021] = 2, [023] = 1, [024] = 5, [025] = 3, // 2
[034] = 2, [035] = 2, // 3
[041] = 2, [042] = 2, [043] = 2, // 4
[050] = 6, [052] = 2, [053] = 2, // 5
};
/* The following transitions are a bit non-deterministic:
2 -> 8, 0 -> A, 2 -> C */
unsigned glitch = new & 0x80? glitch_map[((old & 0x70) >> 1) | ((new & 0x70) >> 4)] : 0;
switch (glitch) {
case 1: /* Step, followed by bit 1 &= bit 0 */
case 6: /* Variant of type 1: LFSR bit - 1 glitched by LFSR bit, LFSR bit - 2, and bit 0 */
step_lfsr(gb, 0);
if (glitch == 6) {
/* TODO: Verify wide mode */
if ((gb->apu.noise_channel.narrow &&
((gb->apu.noise_channel.lfsr & 0x71) == 0x20)) ||
(gb->apu.noise_channel.lfsr & 0x71) == 0x61) {
gb->apu.noise_channel.lfsr &= ~0x20;
}
if ((gb->apu.noise_channel.lfsr & 0x7001) == 0x2000 ||
(gb->apu.noise_channel.lfsr & 0x7001) == 0x6001) {
gb->apu.noise_channel.lfsr &= ~0x2000;
}
}
if ((gb->apu.noise_channel.lfsr & 0x3) == 2) {
gb->apu.noise_channel.lfsr &= ~2;
}
break;
case 2: { /* Step, bitwise AND with previous, except for bit 0 */
uint16_t prev = gb->apu.noise_channel.lfsr;
step_lfsr(gb, 0);
gb->apu.noise_channel.lfsr &= prev | 1;
break;
}
case 5:; /* Non deterministic variant of type 3:
The LFSR is unset if bit 0 & 1 are 0b10.
Bit 3 is complex and non-deterministic (TODO: wide mode) */
if ((gb->apu.noise_channel.lfsr & 0x3) == 2) {
gb->apu.noise_channel.lfsr &= gb->apu.noise_channel.narrow? ~0x4040 : ~0x4000;
}
if ((gb->apu.noise_channel.lfsr & 0x19) == 8) {
gb->apu.noise_channel.lfsr &= ~8;
}
case 3: /* No step, bit 0 = bit 1, some other bits have AND glitches with next*/
gb->apu.noise_channel.lfsr &= ~1;
gb->apu.noise_channel.lfsr |= (gb->apu.noise_channel.lfsr >> 1) & 1;
update_lfsr(gb, 0);
/* TODO: verify */
gb->apu.lfsr_stepped_in_narrow = gb->apu.noise_channel.narrow;
break;
case 4: { /* Step, bit 1 &= bit 0, LFSR bit -1 &= LFSR bit */
uint16_t prev = gb->apu.noise_channel.lfsr;
step_lfsr(gb, 0);
gb->apu.noise_channel.lfsr &= prev | (gb->apu.noise_channel.narrow? ~0x2022 : ~0x2002);
break;
}
default: /* No glitch, plain step*/
step_lfsr(gb, 0);
break;
}
}
else {
step_lfsr(gb, 0);
}
}
}
else if (!old_bit && new_bit) {
if (gb->model <= GB_MODEL_CGB_C) {
bool previous_narrow = gb->apu.noise_channel.narrow;
gb->apu.noise_channel.narrow = true;
step_lfsr(gb, 0);
gb->apu.noise_channel.narrow = previous_narrow;
if ((new & 0xf0) <= 0x20 && glitch_bit && !(effective_counter & 8)) { // No clue why that specific bit is tested
// Non-deterministic, not fully tested for revision differences and wide mode
// Step twice?
step_lfsr(gb, 0);
gb->apu.noise_channel.lfsr &= ~(gb->apu.noise_channel.narrow? 0x4040 : 0x4000);
gb->apu.noise_channel.lfsr |= (gb->apu.noise_channel.lfsr & (gb->apu.noise_channel.narrow? 0x2020 : 0x2000)) << 1;
}
}
else {
step_lfsr(gb, 0);
}
}
else if (gb->model <= GB_MODEL_CGB_C) {
if ((new & 0xf0) <= 0x20 && !glitch_bit && !new_bit && !old_bit && (effective_counter & 8)) { // No clue why that specific bit is tested
// Step twice?
step_lfsr(gb, 0);
}
}
}
void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
{
GB_apu_run(gb, true);
if (!gb->apu.global_enable && reg != GB_IO_NR52 && reg < GB_IO_WAV_START && (GB_is_cgb(gb) ||
(
reg != GB_IO_NR11 &&
reg != GB_IO_NR21 &&
reg != GB_IO_NR31 &&
reg != GB_IO_NR41
)
)) {
return;
}
if (reg >= GB_IO_WAV_START && reg <= GB_IO_WAV_END && gb->apu.is_active[GB_WAVE]) {
if ((!GB_is_cgb(gb) && !gb->apu.wave_channel.wave_form_just_read) || gb->model > GB_MODEL_CGB_E) {
return;
}
reg = GB_IO_WAV_START + gb->apu.wave_channel.current_sample_index / 2;
}
/* Todo: this can and should be rewritten with a function table. */
switch (reg) {
/* Globals */
case GB_IO_NR50:
case GB_IO_NR51:
gb->io_registers[reg] = value;
/* These registers affect the output of all 4 channels (but not the output of the PCM registers).*/
/* We call update_samples with the current value so the APU output is updated with the new outputs */
for (unsigned i = GB_N_CHANNELS; i--;) {
int8_t sample = gb->apu.samples[i];
gb->apu.samples[i] = 0x10; // Invalidate to force update
update_sample(gb, i, sample, 0);
}
break;
case GB_IO_NR52: {
uint8_t old_pulse_lengths[] = {
gb->apu.square_channels[0].pulse_length,
gb->apu.square_channels[1].pulse_length,
gb->apu.wave_channel.pulse_length,
gb->apu.noise_channel.pulse_length
};
if ((value & 0x80) && !gb->apu.global_enable) {
GB_apu_init(gb);
gb->apu.global_enable = true;
}
else if (!(value & 0x80) && gb->apu.global_enable) {
for (unsigned i = GB_N_CHANNELS; i--;) {
update_sample(gb, i, 0, 0);
}
memset(&gb->apu, 0, sizeof(gb->apu));
memset(gb->io_registers + GB_IO_NR10, 0, GB_IO_WAV_START - GB_IO_NR10);
gb->apu.global_enable = false;
gb->apu.apu_cycles_in_2mhz = true;
}
if (!GB_is_cgb(gb) && (value & 0x80)) {
gb->apu.square_channels[0].pulse_length = old_pulse_lengths[0];
gb->apu.square_channels[1].pulse_length = old_pulse_lengths[1];
gb->apu.wave_channel.pulse_length = old_pulse_lengths[2];
gb->apu.noise_channel.pulse_length = old_pulse_lengths[3];
}
}
break;
/* Square channels */
case GB_IO_NR10: {
if (unlikely(gb->apu.square_sweep_calculate_countdown || gb->apu.square_sweep_calculate_countdown_reload_timer)) {
nr10_write_glitch(gb, value);
}
bool old_negate = gb->io_registers[GB_IO_NR10] & 8;
gb->io_registers[GB_IO_NR10] = value;
if (gb->model <= GB_MODEL_CGB_C) {
old_negate = true;
}
if (gb->apu.shadow_sweep_sample_length + gb->apu.channel1_completed_addend + old_negate > 0x7FF &&
!(value & 8)) {
gb->apu.is_active[GB_SQUARE_1] = false;
update_sample(gb, GB_SQUARE_1, 0, 0);
}
trigger_sweep_calculation(gb);
break;
}
case GB_IO_NR11:
case GB_IO_NR21: {
GB_channel_t index = reg == GB_IO_NR21? GB_SQUARE_2: GB_SQUARE_1;
gb->apu.square_channels[index].pulse_length = (0x40 - (value & 0x3F));
if (!gb->apu.global_enable) {
value &= 0x3F;
}
break;
}
case GB_IO_NR12:
case GB_IO_NR22: {
GB_channel_t index = reg == GB_IO_NR22? GB_SQUARE_2: GB_SQUARE_1;
if ((value & 0xF8) == 0) {
/* This disables the DAC */
gb->io_registers[reg] = value;
gb->apu.is_active[index] = false;
update_sample(gb, index, 0, 0);
}
else if (gb->apu.is_active[index]) {
nrx2_glitch(gb, &gb->apu.square_channels[index].current_volume,
value, gb->io_registers[reg], &gb->apu.square_channels[index].volume_countdown,
&gb->apu.square_channels[index].envelope_clock);
update_square_sample(gb, index, 0);
}
break;
}
case GB_IO_NR13:
case GB_IO_NR23: {
GB_channel_t index = reg == GB_IO_NR23? GB_SQUARE_2: GB_SQUARE_1;
gb->apu.square_channels[index].sample_length &= ~0xFF;
gb->apu.square_channels[index].sample_length |= value & 0xFF;
if (gb->apu.square_channels[index].just_reloaded) {
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 1;
}
break;
}
case GB_IO_NR14:
case GB_IO_NR24: {
GB_channel_t index = reg == GB_IO_NR24? GB_SQUARE_2: GB_SQUARE_1;
bool was_active = gb->apu.is_active[index];
/* TODO: When the sample length changes right before being updated from ≥$700 to <$700, the countdown
should change to the old length, but the current sample should not change. Because our write
timing isn't accurate to the T-cycle, we hack around it by stepping the sample index backwards. */
if ((value & 0x80) == 0 && gb->apu.is_active[index] && (gb->io_registers[reg] & 0x7) == 7 && (value & 7) != 7) {
/* On an AGB, as well as on CGB C and earlier (TODO: Tested: 0, B and C), it behaves slightly different on
double speed. */
if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D || gb->apu.square_channels[index].sample_countdown & 1) {
if (gb->apu.square_channels[index].did_tick &&
gb->apu.square_channels[index].sample_countdown >> 1 == (gb->apu.square_channels[index].sample_length ^ 0x7FF)) {
gb->apu.square_channels[index].current_sample_index--;
gb->apu.square_channels[index].current_sample_index &= 7;
gb->apu.square_channels[index].sample_surpressed = false;
}
}
}
uint16_t old_sample_length = gb->apu.square_channels[index].sample_length;
gb->apu.square_channels[index].sample_length &= 0xFF;
gb->apu.square_channels[index].sample_length |= (value & 7) << 8;
if (gb->apu.square_channels[index].just_reloaded) {
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 1;
}
if (value & 0x80) {
/* Current sample index remains unchanged when restarting channels 1 or 2. It is only reset by
turning the APU off. */
gb->apu.square_channels[index].envelope_clock.locked = false;
gb->apu.square_channels[index].envelope_clock.clock = false;
gb->apu.square_channels[index].did_tick = false;
bool force_unsurpressed = false;
if (!gb->apu.is_active[index]) {
if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D) {
if (!(value & 4) && !(((gb->apu.square_channels[index].sample_countdown - gb->apu.square_channels[index].delay) / 2) & 0x400)) {
gb->apu.square_channels[index].current_sample_index++;
gb->apu.square_channels[index].current_sample_index &= 0x7;
force_unsurpressed = true;
}
}
gb->apu.square_channels[index].delay = 6 + gb->apu.lf_div * (gb->model < GB_MODEL_CGB_D && gb->cgb_double_speed? 1 : -1);
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + gb->apu.square_channels[index].delay;
}
else {
unsigned extra_delay = 0;
if (gb->model == GB_MODEL_CGB_E || gb->model == GB_MODEL_CGB_D) {
if (!gb->apu.square_channels[index].just_reloaded && !(value & 4) && !(((gb->apu.square_channels[index].sample_countdown - 1 - gb->apu.square_channels[index].delay) / 2) & 0x400)) {
gb->apu.square_channels[index].current_sample_index++;
gb->apu.square_channels[index].current_sample_index &= 0x7;
gb->apu.square_channels[index].sample_surpressed = false;
}
/* Todo: verify with the schematics what's going on in here */
else if (gb->apu.square_channels[index].sample_length == 0x7FF &&
old_sample_length != 0x7FF &&
(gb->apu.square_channels[index].sample_surpressed)) {
extra_delay += 2;
}
}
/* Timing quirk: if already active, sound starts 2 (2MHz) ticks earlier.*/
gb->apu.square_channels[index].delay = 4 - gb->apu.lf_div + extra_delay;
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + gb->apu.square_channels[index].delay;
}
gb->apu.square_channels[index].current_volume = gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] >> 4;
/* The volume changes caused by NRx4 sound start takes effect instantly (i.e. the effect the previously
started sound). The playback itself is not instant which is why we don't update the sample for other
cases. */
if (gb->apu.is_active[index]) {
update_square_sample(gb, index, 0);
}
gb->apu.square_channels[index].volume_countdown = gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] & 7;
if ((gb->io_registers[index == GB_SQUARE_1 ? GB_IO_NR12 : GB_IO_NR22] & 0xF8) != 0 && !gb->apu.is_active[index]) {
gb->apu.is_active[index] = true;
update_sample(gb, index, 0, 0);
gb->apu.square_channels[index].sample_surpressed = true && !force_unsurpressed;
}
if (gb->apu.square_channels[index].pulse_length == 0) {
gb->apu.square_channels[index].pulse_length = 0x40;
gb->apu.square_channels[index].length_enabled = false;
}
if (index == GB_SQUARE_1) {
gb->apu.square_sweep_instant_calculation_done = false;
gb->apu.shadow_sweep_sample_length = 0;
gb->apu.channel1_completed_addend = 0;
if (gb->io_registers[GB_IO_NR10] & 7) {
/* APU bug: if shift is nonzero, overflow check also occurs on trigger */
gb->apu.square_sweep_calculate_countdown = gb->io_registers[GB_IO_NR10] & 0x7;
if ((gb->apu.lf_div ^ !gb->cgb_double_speed) && gb->model <= GB_MODEL_CGB_C) {
gb->apu.square_sweep_calculate_countdown_reload_timer = 3;
}
else {
gb->apu.square_sweep_calculate_countdown_reload_timer = 2;
}
gb->apu.unshifted_sweep = false;
if (!was_active) {
gb->apu.square_sweep_calculate_countdown_reload_timer++;
}
gb->apu.sweep_length_addend = gb->apu.square_channels[GB_SQUARE_1].sample_length;
gb->apu.sweep_length_addend >>= (gb->io_registers[GB_IO_NR10] & 7);
}
else {
gb->apu.sweep_length_addend = 0;
}
gb->apu.channel_1_restart_hold = 2 - gb->apu.lf_div + (GB_is_cgb(gb) && gb->model != GB_MODEL_CGB_D) * 2;
gb->apu.square_sweep_countdown = ((gb->io_registers[GB_IO_NR10] >> 4) & 7) ^ 7;
}
}
/* APU glitch - if length is enabled while the DIV-divider's LSB is 1, tick the length once. */
if (((value & 0x40) || (GB_is_cgb(gb) && gb->model <= GB_MODEL_CGB_B)) && // Current value is irrelevant on CGB-B and older
!gb->apu.square_channels[index].length_enabled &&
(gb->apu.div_divider & 1) &&
gb->apu.square_channels[index].pulse_length) {
gb->apu.square_channels[index].pulse_length--;
if (gb->apu.square_channels[index].pulse_length == 0) {
if (value & 0x80) {
gb->apu.square_channels[index].pulse_length = 0x3F;
}
else {
gb->apu.is_active[index] = false;
update_sample(gb, index, 0, 0);
}
}
}
gb->apu.square_channels[index].length_enabled = value & 0x40;
break;
}
/* Wave channel */
case GB_IO_NR30:
gb->apu.wave_channel.enable = value & 0x80;
if (!gb->apu.wave_channel.enable) {
gb->apu.wave_channel.pulsed = false;
if (gb->apu.is_active[GB_WAVE]) {
// Todo: I assume this happens on pre-CGB models; test this with an audible test
if (gb->apu.wave_channel.sample_countdown == 0 && gb->model <= GB_MODEL_CGB_E) {
gb->apu.wave_channel.current_sample_byte = gb->io_registers[GB_IO_WAV_START + (gb->pc & 0xF)];
}
else if (gb->apu.wave_channel.wave_form_just_read && gb->model <= GB_MODEL_CGB_C) {
gb->apu.wave_channel.current_sample_byte = gb->io_registers[GB_IO_WAV_START + (GB_IO_NR30 & 0xF)];
}
}
gb->apu.is_active[GB_WAVE] = false;
update_sample(gb, GB_WAVE, 0, 0);
}
break;
case GB_IO_NR31:
gb->apu.wave_channel.pulse_length = (0x100 - value);
break;
case GB_IO_NR32:
gb->apu.wave_channel.shift = inline_const(uint8_t[], {4, 0, 1, 2})[(value >> 5) & 3];
if (gb->apu.is_active[GB_WAVE]) {
update_wave_sample(gb, 0);
}
break;
case GB_IO_NR33:
gb->apu.wave_channel.sample_length &= ~0xFF;
gb->apu.wave_channel.sample_length |= value & 0xFF;
if (gb->apu.wave_channel.bugged_read_countdown == 1) { // Just reloaded countdown
/* TODO: not verified with a test ROM yet */
gb->apu.wave_channel.sample_countdown = gb->apu.wave_channel.sample_length ^ 0x7FF;
}
break;
case GB_IO_NR34:
gb->apu.wave_channel.sample_length &= 0xFF;
gb->apu.wave_channel.sample_length |= (value & 7) << 8;
if (value & 0x80) {
gb->apu.wave_channel.pulsed = true;
/* DMG bug: wave RAM gets corrupted if the channel is retriggerred 1 cycle before the APU
reads from it. */
if (!GB_is_cgb(gb) &&
gb->apu.is_active[GB_WAVE] &&
gb->apu.wave_channel.sample_countdown == 0) {
unsigned offset = ((gb->apu.wave_channel.current_sample_index + 1) >> 1) & 0xF;
/* This glitch varies between models and even specific instances:
DMG-B: Most of them behave as emulated. A few behave differently.
SGB: As far as I know, all tested instances behave as emulated.
MGB, SGB2: Most instances behave non-deterministically, a few behave as emulated.
For DMG-B emulation I emulate the most common behavior, which blargg's tests expect (not my own DMG-B, which fails it)
For MGB emulation, I emulate my Game Boy Light, which happens to be deterministic.
Additionally, I believe DMGs, including those we behave differently than emulated,
are all deterministic. */
if (offset < 4 && gb->model != GB_MODEL_MGB) {
gb->io_registers[GB_IO_WAV_START] = gb->io_registers[GB_IO_WAV_START + offset];
}
else {
memcpy(gb->io_registers + GB_IO_WAV_START,
gb->io_registers + GB_IO_WAV_START + (offset & ~3),
4);
}
}
gb->apu.wave_channel.current_sample_index = 0;
if (gb->apu.is_active[GB_WAVE] && gb->apu.wave_channel.sample_countdown == 0) {
gb->apu.wave_channel.current_sample_byte = gb->io_registers[GB_IO_WAV_START];
}
if (gb->apu.wave_channel.enable) {
gb->apu.is_active[GB_WAVE] = true;
update_sample(gb, GB_WAVE,
(gb->apu.wave_channel.current_sample_byte >> 4) >> gb->apu.wave_channel.shift,
0);
}
gb->apu.wave_channel.sample_countdown = (gb->apu.wave_channel.sample_length ^ 0x7FF) + 3;
if (gb->apu.wave_channel.pulse_length == 0) {
gb->apu.wave_channel.pulse_length = 0x100;
gb->apu.wave_channel.length_enabled = false;
}
/* Note that we don't change the sample just yet! This was verified on hardware. */
}
/* APU glitch - if length is enabled while the DIV-divider's LSB is 1, tick the length once. */
if (((value & 0x40) || (GB_is_cgb(gb) && gb->model <= GB_MODEL_CGB_B)) && // Current value is irrelevant on CGB-B and older
!gb->apu.wave_channel.length_enabled &&
(gb->apu.div_divider & 1) &&
gb->apu.wave_channel.pulse_length) {
gb->apu.wave_channel.pulse_length--;
if (gb->apu.wave_channel.pulse_length == 0) {
if (value & 0x80) {
gb->apu.wave_channel.pulse_length = 0xFF;
}
else {
gb->apu.is_active[GB_WAVE] = false;
update_sample(gb, GB_WAVE, 0, 0);
}
}
}
gb->apu.wave_channel.length_enabled = value & 0x40;
break;
/* Noise Channel */
case GB_IO_NR41: {
gb->apu.noise_channel.pulse_length = (0x40 - (value & 0x3F));
break;
}
case GB_IO_NR42: {
if ((value & 0xF8) == 0) {
/* This disables the DAC */
if (gb->apu.is_active[GB_NOISE] && gb->io_registers[GB_IO_NR43] & 7) {
if (gb->apu.noise_channel.counter_countdown <= 2) {
gb->apu.noise_channel.counter++;
}
gb->apu.noise_background_counter_active = false;
}
gb->io_registers[reg] = value;
gb->apu.is_active[GB_NOISE] = false;
update_sample(gb, GB_NOISE, 0, 0);
gb->apu.noise_counter_active = false;
}
else if (gb->apu.is_active[GB_NOISE]) {
nrx2_glitch(gb, &gb->apu.noise_channel.current_volume,
value, gb->io_registers[reg], &gb->apu.noise_channel.volume_countdown,
&gb->apu.noise_channel.envelope_clock);
update_sample(gb, GB_NOISE,
gb->apu.noise_channel.current_lfsr_sample ?
gb->apu.noise_channel.current_volume : 0,
0);
}
break;
}
case GB_IO_NR43: {
if (gb->apu.noise_channel.countdown_reloaded) {
unsigned divisor = (value & 0x07) << 2;
if (!divisor) divisor = 2;
if (gb->model > GB_MODEL_CGB_C) {
gb->apu.noise_channel.counter_countdown =
divisor + (divisor == 2? 0 : inline_const(uint8_t[], {2, 1, 0, 3})[(gb->apu.noise_channel.alignment) & 3]);
}
else {
gb->apu.noise_channel.counter_countdown =
divisor + (divisor == 2? 0 : inline_const(uint8_t[], {2, 1, 4, 3})[(gb->apu.noise_channel.alignment) & 3]);
}
}
if (gb->model <= GB_MODEL_CGB_C) {
/* TODO: CGB≤C (and DMG) have various unemulated quirks when you write to NR43 just as the counter reloads */
if (gb->apu.noise_channel.countdown_reloaded) {
bool old_bit = (gb->apu.noise_channel.counter >> (gb->io_registers[GB_IO_NR43] >> 4)) & 1;
bool glitch_bit = (gb->apu.noise_channel.counter >> 7) & 1;
bool new_bit = (gb->apu.noise_channel.counter >> (value >> 4)) & 1;
if (!old_bit && new_bit && glitch_bit) {
uint16_t previous_counter = (gb->apu.noise_channel.counter - 1) & 0x3FFF;
bool old_bit = (previous_counter >> (gb->io_registers[GB_IO_NR43] >> 4)) & 1;
bool glitch_bit = (previous_counter >> 7) & 1;
bool new_bit = (previous_counter >> (value >> 4)) & 1;
if (old_bit && !new_bit && glitch_bit) {
step_lfsr(gb, 0);
}
}
}
nr43_write(gb, 0xff);
}
nr43_write(gb, value);
break;
}
case GB_IO_NR44: {
if (value & 0x80) {
gb->apu.noise_channel.envelope_clock.locked = false;
gb->apu.noise_channel.envelope_clock.clock = false;
if (!GB_is_cgb(gb) && (gb->apu.noise_channel.alignment & 3) != 0) {
gb->apu.noise_channel.dmg_delayed_start = 6;
}
else {
gb->apu.noise_channel.lfsr = 0;
prepare_noise_start(gb);
gb->apu.noise_channel.current_volume = gb->io_registers[GB_IO_NR42] >> 4;
gb->apu.noise_channel.current_lfsr_sample = false;
gb->apu.noise_channel.volume_countdown = gb->io_registers[GB_IO_NR42] & 7;
gb->apu.noise_channel.did_step_counter = (gb->apu.noise_channel.alignment & 3) == 2;
if (gb->io_registers[GB_IO_NR42] & 0xF8) {
gb->apu.is_active[GB_NOISE] = true;
update_sample(gb, GB_NOISE, 0, 0);
}
if (gb->apu.noise_channel.pulse_length == 0) {
gb->apu.noise_channel.pulse_length = 0x40;
gb->apu.noise_channel.length_enabled = false;
}
}
}
/* APU glitch - if length is enabled while the DIV-divider's LSB is 1, tick the length once. */
if ((value & 0x40) &&
!gb->apu.noise_channel.length_enabled &&
(gb->apu.div_divider & 1) &&
gb->apu.noise_channel.pulse_length) {
gb->apu.noise_channel.pulse_length--;
if (gb->apu.noise_channel.pulse_length == 0) {
if (value & 0x80) {
gb->apu.noise_channel.pulse_length = 0x3F;
}
else {
gb->apu.is_active[GB_NOISE] = false;
update_sample(gb, GB_NOISE, 0, 0);
}
}
}
gb->apu.noise_channel.length_enabled = value & 0x40;
break;
}
}
gb->io_registers[reg] = value;
}
void GB_set_sample_rate(GB_gameboy_t *gb, unsigned sample_rate)
{
if (gb->apu_output.sample_rate != sample_rate) {
GB_ASSERT_NOT_RUNNING_OTHER_THREAD(gb)
}
gb->apu_output.sample_rate = sample_rate;
if (sample_rate) {
gb->apu_output.highpass_rate = pow(0.999958, GB_get_clock_rate(gb) / (double)sample_rate);
gb->apu_output.max_cycles_per_sample = ceil(GB_get_clock_rate(gb) / 2.0 / sample_rate);
gb->apu_output.quick_fraction_multiply_cache[0] = round(sample_rate * 2.0 / GB_get_clock_rate(gb) * (1 << 28));
for (unsigned i = 1; i < GB_QUICK_MULTIPLY_COUNT; i++) {
gb->apu_output.quick_fraction_multiply_cache[i] = gb->apu_output.quick_fraction_multiply_cache[0] * (i + 1);
}
}
else {
gb->apu_output.max_cycles_per_sample = 0x400;
}
}
void GB_set_sample_rate_by_clocks(GB_gameboy_t *gb, double cycles_per_sample)
{
GB_ASSERT_NOT_RUNNING_OTHER_THREAD(gb)
if (cycles_per_sample == 0) {
GB_set_sample_rate(gb, 0);
return;
}
gb->apu_output.sample_rate = GB_get_clock_rate(gb) / cycles_per_sample * 2;
gb->apu_output.highpass_rate = pow(0.999958, cycles_per_sample);
gb->apu_output.max_cycles_per_sample = ceil(cycles_per_sample / 4);
gb->apu_output.quick_fraction_multiply_cache[0] = round(gb->apu_output.sample_rate * 2.0 / GB_get_clock_rate(gb) * (1 << 28));
for (unsigned i = 1; i < GB_QUICK_MULTIPLY_COUNT; i++) {
gb->apu_output.quick_fraction_multiply_cache[i] = gb->apu_output.quick_fraction_multiply_cache[0] * (i + 1);
}
}
unsigned GB_get_sample_rate(GB_gameboy_t *gb)
{
return gb->apu_output.sample_rate;
}
void GB_apu_set_sample_callback(GB_gameboy_t *gb, GB_sample_callback_t callback)
{
gb->apu_output.sample_callback = callback;
}
void GB_set_highpass_filter_mode(GB_gameboy_t *gb, GB_highpass_mode_t mode)
{
gb->apu_output.highpass_mode = mode;
}
void GB_set_interference_volume(GB_gameboy_t *gb, double volume)
{
gb->apu_output.interference_volume = volume;
}
typedef struct __attribute__((packed)) {
uint32_t format_chunk; // = BE32('FORM')
uint32_t size; // = BE32(file size - 8)
uint32_t format; // = BE32('AIFC')
uint32_t fver_chunk; // = BE32('FVER')
uint32_t fver_size; // = BE32(4)
uint32_t fver;
uint32_t comm_chunk; // = BE32('COMM')
uint32_t comm_size; // = BE32(0x18)
uint16_t channels; // = BE16(2)
uint32_t samples_per_channel; // = BE32(total number of samples / 2)
uint16_t bit_depth; // = BE16(16)
uint16_t frequency_exponent;
uint64_t frequency_significand;
uint32_t compression_type; // = 'NONE' (BE) or 'twos' (LE)
uint16_t compression_name; // = 0
uint32_t ssnd_chunk; // = BE32('SSND')
uint32_t ssnd_size; // = BE32(length of samples - 8)
uint32_t ssnd_offset; // = 0
uint32_t ssnd_block; // = 0
} aiff_header_t;
typedef struct __attribute__((packed)) {
uint32_t marker; // = BE32('RIFF')
uint32_t size; // = LE32(file size - 8)
uint32_t type; // = BE32('WAVE')
uint32_t fmt_chunk; // = BE32('fmt ')
uint32_t fmt_size; // = LE16(16)
uint16_t format; // = LE16(1)
uint16_t channels; // = LE16(2)
uint32_t sample_rate; // = LE32(sample_rate)
uint32_t byte_rate; // = LE32(sample_rate * 4)
uint16_t frame_size; // = LE32(4)
uint16_t bit_depth; // = LE16(16)
uint32_t data_chunk; // = BE32('data')
uint32_t data_size; // = LE32(length of samples)
} wav_header_t;
#define VGM_HEADER_SIZE 0xC0
#define VGM_DATA_OFFSET (VGM_HEADER_SIZE - 0x34)
#define VGM_SAMPLE_RATE 44100
static void vgm_set_le32(uint8_t *header, size_t offset, uint32_t value)
{
value = LE32(value);
memcpy(header + offset, &value, sizeof(value));
}
static void vgm_get_header(GB_gameboy_t *gb, uint8_t header[VGM_HEADER_SIZE], uint32_t eof_offset)
{
memset(header, 0, VGM_HEADER_SIZE);
header[0] = 'V';
header[1] = 'g';
header[2] = 'm';
header[3] = ' ';
vgm_set_le32(header, 0x04, eof_offset);
vgm_set_le32(header, 0x08, 0x00000161);
vgm_set_le32(header, 0x18, gb->apu_output.vgm_total_samples);
vgm_set_le32(header, 0x34, VGM_DATA_OFFSET);
vgm_set_le32(header, 0x80, gb->apu_output.vgm_clock_rate | (GB_is_cgb(gb) ? 0x80000000u : 0));
}
static bool vgm_write_data(GB_gameboy_t *gb, const void *data, size_t size)
{
if (!gb->apu_output.output_file) return false;
if (fwrite(data, size, 1, gb->apu_output.output_file) != 1) {
gb->apu_output.output_error = errno ?: EIO;
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
return false;
}
return true;
}
static bool vgm_flush_wait(GB_gameboy_t *gb)
{
while (gb->apu_output.vgm_pending_samples) {
if (gb->apu_output.vgm_pending_samples <= 16) {
uint8_t command = 0x70 + gb->apu_output.vgm_pending_samples - 1;
gb->apu_output.vgm_pending_samples = 0;
if (!vgm_write_data(gb, &command, sizeof(command))) return false;
}
else {
uint16_t samples = MIN(gb->apu_output.vgm_pending_samples, 0xFFFF);
uint8_t command[] = {0x61, samples & 0xFF, samples >> 8};
gb->apu_output.vgm_pending_samples -= samples;
if (!vgm_write_data(gb, command, sizeof(command))) return false;
}
}
return true;
}
static bool vgm_write_register(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
{
if (!vgm_flush_wait(gb)) return false;
uint8_t command[] = {0xB3, reg - GB_IO_NR10, value};
return vgm_write_data(gb, command, sizeof(command));
}
static uint8_t vgm_get_trigger_register(GB_gameboy_t *gb, uint8_t reg, GB_channel_t channel)
{
uint8_t value = gb->io_registers[reg] & 0x7F;
if (gb->apu.is_active[channel]) {
value |= 0x80;
}
return value;
}
static bool vgm_write_apu_snapshot(GB_gameboy_t *gb)
{
if (!vgm_write_register(gb, GB_IO_NR52, gb->apu.global_enable ? 0x80 : 0)) return false;
/* Wave RAM is preserved even when the APU is disabled. */
for (unsigned i = GB_IO_WAV_START; i <= GB_IO_WAV_END; i++) {
if (!vgm_write_register(gb, i, gb->io_registers[i])) return false;
}
if (!gb->apu.global_enable) return true;
static const uint8_t registers[] = {
GB_IO_NR50, GB_IO_NR51,
GB_IO_NR10, GB_IO_NR11, GB_IO_NR12, GB_IO_NR13,
GB_IO_NR21, GB_IO_NR22, GB_IO_NR23,
GB_IO_NR30, GB_IO_NR31, GB_IO_NR32, GB_IO_NR33,
GB_IO_NR41, GB_IO_NR42, GB_IO_NR43,
};
for (unsigned i = 0; i < sizeof(registers) / sizeof(registers[0]); i++) {
if (!vgm_write_register(gb, registers[i], gb->io_registers[registers[i]])) return false;
}
if (!vgm_write_register(gb, GB_IO_NR14,
vgm_get_trigger_register(gb, GB_IO_NR14, GB_SQUARE_1))) return false;
if (!vgm_write_register(gb, GB_IO_NR24,
vgm_get_trigger_register(gb, GB_IO_NR24, GB_SQUARE_2))) return false;
if (!vgm_write_register(gb, GB_IO_NR34,
vgm_get_trigger_register(gb, GB_IO_NR34, GB_WAVE))) return false;
if (!vgm_write_register(gb, GB_IO_NR44,
vgm_get_trigger_register(gb, GB_IO_NR44, GB_NOISE))) return false;
return true;
}
static void noinline vgm_advance(GB_gameboy_t *gb, uint8_t cycles)
{
uint64_t clock_rate = (uint64_t)gb->apu_output.vgm_clock_rate * 2;
if (!clock_rate) return;
uint64_t sample_fraction = gb->apu_output.vgm_sample_fraction + (uint64_t)cycles * VGM_SAMPLE_RATE;
uint32_t samples = sample_fraction / clock_rate;
gb->apu_output.vgm_sample_fraction = sample_fraction % clock_rate;
gb->apu_output.vgm_pending_samples += samples;
gb->apu_output.vgm_total_samples += samples;
}
void GB_apu_vgm_advance(GB_gameboy_t *gb, uint8_t cycles)
{
if (likely(!gb->apu_output.output_file)) return;
if (likely(gb->apu_output.output_format != GB_AUDIO_FORMAT_VGM)) return;
vgm_advance(gb, cycles);
}
void GB_apu_vgm_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
{
if (unlikely(gb->apu_output.output_file && gb->apu_output.output_format == GB_AUDIO_FORMAT_VGM)) {
vgm_write_register(gb, reg, value);
}
}
int GB_start_audio_recording(GB_gameboy_t *gb, const char *path, GB_audio_format_t format)
{
if (format != GB_AUDIO_FORMAT_VGM && gb->apu_output.sample_rate == 0) {
return EINVAL;
}
if (gb->apu_output.output_file) {
GB_stop_audio_recording(gb);
}
gb->apu_output.output_file = fopen(path, "wb");
if (!gb->apu_output.output_file) return errno;
gb->apu_output.output_format = format;
switch (format) {
case GB_AUDIO_FORMAT_RAW:
return 0;
case GB_AUDIO_FORMAT_VGM: {
gb->apu_output.vgm_pending_samples = 0;
gb->apu_output.vgm_total_samples = 0;
gb->apu_output.vgm_sample_fraction = 0;
gb->apu_output.vgm_clock_rate = GB_get_clock_rate(gb) ?: CPU_FREQUENCY;
uint8_t header[VGM_HEADER_SIZE];
vgm_get_header(gb, header, 0);
if (fwrite(header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
int ret = errno ?: EIO;
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
return ret;
}
if (!vgm_write_apu_snapshot(gb)) {
int ret = gb->apu_output.output_error ?: EIO;
if (gb->apu_output.output_file) {
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
}
gb->apu_output.output_error = 0;
return ret;
}
return 0;
}
case GB_AUDIO_FORMAT_AIFF: {
aiff_header_t header = {0,};
if (fwrite(&header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
int ret = errno ?: EIO;
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
return ret;
}
return 0;
}
case GB_AUDIO_FORMAT_WAV: {
wav_header_t header = {0,};
if (fwrite(&header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
int ret = errno ?: EIO;
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
return ret;
}
return 0;
}
default:
fclose(gb->apu_output.output_file);
gb->apu_output.output_file = NULL;
return EINVAL;
}
}
int GB_stop_audio_recording(GB_gameboy_t *gb)
{
if (!gb->apu_output.output_file) {
int ret = gb->apu_output.output_error ?: -1;
gb->apu_output.output_error = 0;
return ret;
}
gb->apu_output.output_error = 0;
switch (gb->apu_output.output_format) {
case GB_AUDIO_FORMAT_RAW:
break;
case GB_AUDIO_FORMAT_VGM: {
if (!vgm_flush_wait(gb)) break;
uint8_t end_command = 0x66;
if (!vgm_write_data(gb, &end_command, sizeof(end_command))) break;
long file_size = ftell(gb->apu_output.output_file);
if (file_size < 0) {
gb->apu_output.output_error = errno ?: EIO;
break;
}
uint8_t header[VGM_HEADER_SIZE];
vgm_get_header(gb, header, file_size - 4);
if (fseek(gb->apu_output.output_file, 0, SEEK_SET) != 0 ||
fwrite(header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
gb->apu_output.output_error = errno ?: EIO;
}
break;
}
case GB_AUDIO_FORMAT_AIFF: {
size_t file_size = ftell(gb->apu_output.output_file);
size_t frames = (file_size - sizeof(aiff_header_t)) / sizeof(GB_sample_t);
aiff_header_t header = {
.format_chunk = BE32('FORM'),
.size = BE32(file_size - 8),
.format = BE32('AIFC'),
.fver_chunk = BE32('FVER'),
.fver_size = BE32(4),
.fver = BE32(0xA2805140),
.comm_chunk = BE32('COMM'),
.comm_size = BE32(0x18),
.channels = BE16(2),
.samples_per_channel = BE32(frames),
.bit_depth = BE16(16),
#ifdef GB_BIG_ENDIAN
.compression_type = 'NONE',
#else
.compression_type = 'twos',
#endif
.compression_name = 0,
.ssnd_chunk = BE32('SSND'),
.ssnd_size = BE32(frames * sizeof(GB_sample_t) - 8),
.ssnd_offset = 0,
.ssnd_block = 0,
};
uint64_t significand = gb->apu_output.sample_rate;
uint16_t exponent = 0x403E;
while ((int64_t)significand > 0) {
significand <<= 1;
exponent--;
}
header.frequency_exponent = BE16(exponent);
header.frequency_significand = BE64(significand);
fseek(gb->apu_output.output_file, 0, SEEK_SET);
if (fwrite(&header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
gb->apu_output.output_error = errno;
}
break;
}
case GB_AUDIO_FORMAT_WAV: {
size_t file_size = ftell(gb->apu_output.output_file);
size_t frames = (file_size - sizeof(wav_header_t)) / sizeof(GB_sample_t);
wav_header_t header = {
.marker = BE32('RIFF'),
.size = LE32(file_size - 8),
.type = BE32('WAVE'),
.fmt_chunk = BE32('fmt '),
.fmt_size = LE16(16),
.format = LE16(1),
.channels = LE16(2),
.sample_rate = LE32(gb->apu_output.sample_rate),
.byte_rate = LE32(gb->apu_output.sample_rate * 4),
.frame_size = LE32(4),
.bit_depth = LE16(16),
.data_chunk = BE32('data'),
.data_size = LE32(frames * sizeof(GB_sample_t)),
};
fseek(gb->apu_output.output_file, 0, SEEK_SET);
if (fwrite(&header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
gb->apu_output.output_error = errno;
}
break;
}
}
if (gb->apu_output.output_file) {
if (fclose(gb->apu_output.output_file) != 0 && !gb->apu_output.output_error) {
gb->apu_output.output_error = errno ?: EIO;
}
gb->apu_output.output_file = NULL;
}
int ret = gb->apu_output.output_error;
gb->apu_output.output_error = 0;
return ret;
}
void GB_set_channel_muted(GB_gameboy_t *gb, GB_channel_t channel, bool muted)
{
assert(channel < GB_N_CHANNELS);
gb->apu_output.channel_muted[channel] = muted;
}
bool GB_is_channel_muted(GB_gameboy_t *gb, GB_channel_t channel)
{
return gb->apu_output.channel_muted[channel];
}
// Note: this intentionally does not check to see if the channel is muted.
uint8_t GB_get_channel_volume(GB_gameboy_t *gb, GB_channel_t channel)
{
switch (channel) {
case GB_SQUARE_1:
case GB_SQUARE_2:
return gb->apu.square_channels[channel].current_volume;
case GB_WAVE:
return inline_const(uint8_t[], {0xF, 8, 4, 0, 0})[gb->apu.wave_channel.shift];
case GB_NOISE:
return gb->apu.noise_channel.current_volume;
default:
return 0;
}
}
uint8_t GB_get_channel_amplitude(GB_gameboy_t *gb, GB_channel_t channel)
{
return gb->apu.is_active[channel] ? gb->apu.samples[channel] : 0;
}
uint16_t GB_get_channel_period(GB_gameboy_t *gb, GB_channel_t channel)
{
switch (channel) {
case GB_SQUARE_1:
case GB_SQUARE_2:
return gb->apu.square_channels[channel].sample_length;
case GB_WAVE:
return gb->apu.wave_channel.sample_length;
case GB_NOISE:
return (gb->io_registers[GB_IO_NR43] & 7) << (gb->io_registers[GB_IO_NR43] >> 4);
default:
return 0;
}
}
// wave_table is a user allocated uint8_t[32] array
void GB_get_apu_wave_table(GB_gameboy_t *gb, uint8_t *wave_table)
{
for (unsigned i = GB_IO_WAV_START; i <= GB_IO_WAV_END; i++) {
wave_table[2 * (i - GB_IO_WAV_START)] = gb->io_registers[i] >> 4;
wave_table[2 * (i - GB_IO_WAV_START) + 1] = gb->io_registers[i] & 0xF;
}
}
bool GB_get_channel_edge_triggered(GB_gameboy_t *gb, GB_channel_t channel)
{
bool edge_triggered = gb->apu_output.edge_triggered[channel];
gb->apu_output.edge_triggered[channel] = false;
return edge_triggered;
}
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