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2MHz audio downscaling support. Implemented NR50 and NR51.

This commit is contained in:
Lior Halphon 2017-07-21 23:06:02 +03:00
parent baccf336d7
commit a19ee1e5e0
5 changed files with 135 additions and 76 deletions
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146
Core/apu.c
View File

@ -3,12 +3,64 @@
#include <string.h>
#include "gb.h"
#define likely(x) __builtin_expect((x),1)
#define unlikely(x) __builtin_expect((x),0)
#define likely(x) __builtin_expect((x), 1)
#define unlikely(x) __builtin_expect((x), 0)
static void update_sample(GB_gameboy_t *gb, unsigned index, uint8_t value)
static void refresh_channel(GB_gameboy_t *gb, unsigned index, unsigned cycles_offset)
{
unsigned multiplier = gb->apu_output.cycles_since_render + cycles_offset - gb->apu_output.last_update[index];
gb->apu_output.summed_samples[index].left += gb->apu_output.current_sample[index].left * multiplier;
gb->apu_output.summed_samples[index].right += gb->apu_output.current_sample[index].right * multiplier;
gb->apu_output.last_update[index] = gb->apu_output.cycles_since_render + cycles_offset;
}
static void update_sample(GB_gameboy_t *gb, unsigned index, uint8_t value, unsigned cycles_offset)
{
gb->apu.samples[index] = value;
if (gb->apu_output.sample_rate) {
unsigned left_volume = 0;
if (gb->io_registers[GB_IO_NR51] & (1 << index)) {
left_volume = gb->io_registers[GB_IO_NR50] & 7;
}
unsigned right_volume = 0;
if (gb->io_registers[GB_IO_NR51] & (0x10 << index)) {
right_volume = (gb->io_registers[GB_IO_NR50] >> 4) & 7;;
}
GB_sample_t output = {value * left_volume, value * right_volume};
if (*(uint32_t *)&(gb->apu_output.current_sample[index]) != *(uint32_t *)&output) {
refresh_channel(gb, index, cycles_offset);
gb->apu_output.current_sample[index] = output;
}
}
}
static void render(GB_gameboy_t *gb)
{
GB_sample_t output = {0,0};
for (unsigned i = GB_N_CHANNELS; i--;) {
if (likely(gb->apu_output.last_update[i] == 0)) {
output.left += gb->apu_output.current_sample[i].left * CH_STEP;
output.right += gb->apu_output.current_sample[i].right * CH_STEP;
}
else {
refresh_channel(gb, i, 0);
output.left += (unsigned) gb->apu_output.summed_samples[i].left * CH_STEP
/ gb->apu_output.cycles_since_render;
output.right += (unsigned) gb->apu_output.summed_samples[i].right * CH_STEP
/ gb->apu_output.cycles_since_render;
gb->apu_output.summed_samples[i] = (GB_sample_t){0, 0};
}
gb->apu_output.last_update[i] = 0;
}
gb->apu_output.cycles_since_render = 0;
while (gb->apu_output.copy_in_progress);
while (!__sync_bool_compare_and_swap(&gb->apu_output.lock, false, true));
if (gb->apu_output.buffer_position < gb->apu_output.buffer_size) {
gb->apu_output.buffer[gb->apu_output.buffer_position++] = output;
}
gb->apu_output.lock = false;
}
void GB_apu_div_event(GB_gameboy_t *gb)
@ -20,36 +72,17 @@ void GB_apu_div_event(GB_gameboy_t *gb)
else {
gb->apu.is_active[GB_WAVE] = false;
gb->apu.wave_channel.current_sample = 0;
update_sample(gb, GB_WAVE, 0);
update_sample(gb, GB_WAVE, 0, 0);
}
}
}
static void render(GB_gameboy_t *gb)
{
while (gb->audio_copy_in_progress);
while (!__sync_bool_compare_and_swap(&gb->apu_lock, false, true));
if (gb->audio_position >= gb->buffer_size) {
gb->apu_lock = false;
return;
}
gb->audio_buffer[gb->audio_position++] = (GB_sample_t) {gb->apu.samples[GB_WAVE] * CH_STEP,
gb->apu.samples[GB_WAVE] * CH_STEP};
gb->apu_lock = false;
}
void GB_apu_run(GB_gameboy_t *gb, uint8_t cycles)
{
/* Convert 4MHZ to 2MHz. cycles is always even. */
cycles >>= 1;
double cycles_per_sample = gb->sample_rate ? CPU_FREQUENCY / (double)gb->sample_rate : 0; // TODO: this should be cached!
if (gb->sample_rate && gb->apu_sample_cycles > cycles_per_sample) {
gb->apu_sample_cycles -= cycles_per_sample;
render(gb);
}
gb->apu.wave_channel.wave_form_just_read = false;
if (gb->apu.is_active[GB_WAVE]) {
uint8_t cycles_left = cycles;
@ -60,7 +93,9 @@ void GB_apu_run(GB_gameboy_t *gb, uint8_t cycles)
gb->apu.wave_channel.current_sample_index &= 0x1F;
gb->apu.wave_channel.current_sample =
gb->apu.wave_channel.wave_form[gb->apu.wave_channel.current_sample_index];
update_sample(gb, GB_WAVE, gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift);
update_sample(gb, GB_WAVE,
gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift,
cycles - cycles_left);
gb->apu.wave_channel.wave_form_just_read = true;
}
if (cycles_left) {
@ -69,35 +104,44 @@ void GB_apu_run(GB_gameboy_t *gb, uint8_t cycles)
}
}
if (gb->apu_output.sample_rate) {
gb->apu_output.cycles_since_render += cycles;
double cycles_per_sample = CPU_FREQUENCY / (double)gb->apu_output.sample_rate; // TODO: this should be cached!
if (gb->apu_output.sample_cycles > cycles_per_sample) {
gb->apu_output.sample_cycles -= cycles_per_sample;
render(gb);
}
}
}
void GB_apu_copy_buffer(GB_gameboy_t *gb, GB_sample_t *dest, unsigned int count)
void GB_apu_copy_buffer(GB_gameboy_t *gb, GB_sample_t *dest, size_t count)
{
gb->audio_copy_in_progress = true;
gb->apu_output.copy_in_progress = true;
if (!gb->audio_stream_started) {
if (!gb->apu_output.stream_started) {
// Intentionally fail the first copy to sync the stream with the Gameboy.
gb->audio_stream_started = true;
gb->audio_position = 0;
gb->apu_output.stream_started = true;
gb->apu_output.buffer_position = 0;
}
if (count > gb->audio_position) {
// GB_log(gb, "Audio underflow: %d\n", count - gb->audio_position);
if (gb->audio_position != 0) {
for (unsigned i = 0; i < count - gb->audio_position; i++) {
dest[gb->audio_position + i] = gb->audio_buffer[gb->audio_position - 1];
if (count > gb->apu_output.buffer_position) {
// GB_log(gb, "Audio underflow: %d\n", count - gb->apu_output.buffer_position);
if (gb->apu_output.buffer_position != 0) {
for (unsigned i = 0; i < count - gb->apu_output.buffer_position; i++) {
dest[gb->apu_output.buffer_position + i] = gb->apu_output.buffer[gb->apu_output.buffer_position - 1];
}
}
else {
memset(dest + gb->audio_position, 0, (count - gb->audio_position) * sizeof(*gb->audio_buffer));
memset(dest + gb->apu_output.buffer_position, 0, (count - gb->apu_output.buffer_position) * sizeof(*gb->apu_output.buffer));
}
count = gb->audio_position;
count = gb->apu_output.buffer_position;
}
memcpy(dest, gb->audio_buffer, count * sizeof(*gb->audio_buffer));
memmove(gb->audio_buffer, gb->audio_buffer + count, (gb->audio_position - count) * sizeof(*gb->audio_buffer));
gb->audio_position -= count;
memcpy(dest, gb->apu_output.buffer, count * sizeof(*gb->apu_output.buffer));
memmove(gb->apu_output.buffer, gb->apu_output.buffer + count, (gb->apu_output.buffer_position - count) * sizeof(*gb->apu_output.buffer));
gb->apu_output.buffer_position -= count;
gb->audio_copy_in_progress = false;
gb->apu_output.copy_in_progress = false;
}
void GB_apu_init(GB_gameboy_t *gb)
@ -105,8 +149,7 @@ void GB_apu_init(GB_gameboy_t *gb)
memset(&gb->apu, 0, sizeof(gb->apu));
// gb->apu.wave_channels[0].duty = gb->apu.wave_channels[1].duty = 4;
// gb->apu.lfsr = 0x7FFF;
gb->apu.left_volume = 7;
gb->apu.right_volume = 7;
gb->io_registers[GB_IO_NR50] = 0x77;
for (int i = 0; i < 4; i++) {
gb->apu.left_enabled[i] = gb->apu.right_enabled[i] = true;
}
@ -171,12 +214,23 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
switch (reg) {
/* Globals */
case GB_IO_NR50:
case GB_IO_NR51:
/* These registers affect the output of all 3 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--;) {
update_sample(gb, i, gb->apu.samples[i], 0);
}
break;
case GB_IO_NR52:
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;
@ -189,14 +243,14 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
if (!gb->apu.wave_channel.enable) {
gb->apu.is_active[GB_WAVE] = false;
gb->apu.wave_channel.current_sample = 0;
update_sample(gb, GB_WAVE, 0);
update_sample(gb, GB_WAVE, 0, 0);
}
break;
case GB_IO_NR31:
break;
case GB_IO_NR32:
gb->apu.wave_channel.shift = (uint8_t[]){4, 0, 1, 2}[(value >> 5) & 3];
update_sample(gb, GB_WAVE, gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift);
update_sample(gb, GB_WAVE, gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift, 0);
break;
case GB_IO_NR33:
gb->apu.wave_channel.sample_length &= ~0xFF;
@ -246,7 +300,7 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
}
unsigned GB_apu_get_current_buffer_length(GB_gameboy_t *gb)
size_t GB_apu_get_current_buffer_length(GB_gameboy_t *gb)
{
return gb->audio_position;
return gb->apu_output.buffer_position;
}

38
Core/apu.h
View File

@ -6,9 +6,9 @@
#ifdef GB_INTERNAL
/* Divides nicely and never overflows with 4 channels */
#define MAX_CH_AMP 0x1E00
#define CH_STEP (MAX_CH_AMP/0xF)
/* Divides nicely and never overflows with 4 channels and 8 volume levels */
#define MAX_CH_AMP 0x1FFE
#define CH_STEP (MAX_CH_AMP/0xF/7)
#endif
/* Lengths are in either DIV ticks (256Hz, triggered by the DIV register) or
@ -20,12 +20,6 @@ typedef struct
int16_t right;
} GB_sample_t;
typedef struct
{
double left;
double right;
} GB_double_sample_t;
enum GB_CHANNELS {
GB_SQUARE_1,
GB_SQUARE_2,
@ -37,8 +31,6 @@ enum GB_CHANNELS {
typedef struct
{
bool global_enable;
uint8_t left_volume;
uint8_t right_volume;
uint8_t samples[GB_N_CHANNELS];
bool left_enabled[GB_N_CHANNELS];
@ -61,9 +53,29 @@ typedef struct
} wave_channel;
} GB_apu_t;
typedef struct {
unsigned sample_rate;
GB_sample_t *buffer;
size_t buffer_size;
size_t buffer_position;
bool stream_started; /* detects first copy request to minimize lag */
volatile bool copy_in_progress;
volatile bool lock;
double sample_cycles;
// Samples are NOT normalized to MAX_CH_AMP * 4 at this stage!
unsigned cycles_since_render;
unsigned last_update[GB_N_CHANNELS];
GB_sample_t current_sample[GB_N_CHANNELS];
GB_sample_t summed_samples[GB_N_CHANNELS];
} GB_apu_output_t;
void GB_set_sample_rate(GB_gameboy_t *gb, unsigned int sample_rate);
void GB_apu_copy_buffer(GB_gameboy_t *gb, GB_sample_t *dest, unsigned int count);
unsigned GB_apu_get_current_buffer_length(GB_gameboy_t *gb);
void GB_apu_copy_buffer(GB_gameboy_t *gb, GB_sample_t *dest, size_t count);
size_t GB_apu_get_current_buffer_length(GB_gameboy_t *gb);
#ifdef GB_INTERNAL
void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value);

16
Core/gb.c
View File

@ -125,8 +125,8 @@ void GB_free(GB_gameboy_t *gb)
if (gb->rom) {
free(gb->rom);
}
if (gb->audio_buffer) {
free(gb->audio_buffer);
if (gb->apu_output.buffer) {
free(gb->apu_output.buffer);
}
if (gb->breakpoints) {
free(gb->breakpoints);
@ -388,13 +388,13 @@ void GB_serial_set_data(GB_gameboy_t *gb, uint8_t data)
void GB_set_sample_rate(GB_gameboy_t *gb, unsigned int sample_rate)
{
if (gb->audio_buffer) {
free(gb->audio_buffer);
if (gb->apu_output.buffer) {
free(gb->apu_output.buffer);
}
gb->buffer_size = sample_rate / 25; // 40ms delay
gb->audio_buffer = malloc(gb->buffer_size * sizeof(*gb->audio_buffer));
gb->sample_rate = sample_rate;
gb->audio_position = 0;
gb->apu_output.buffer_size = sample_rate / 25; // 40ms delay
gb->apu_output.buffer = malloc(gb->apu_output.buffer_size * sizeof(*gb->apu_output.buffer));
gb->apu_output.sample_rate = sample_rate;
gb->apu_output.buffer_position = 0;
}
void GB_disconnect_serial(GB_gameboy_t *gb)

9
Core/gb.h
View File

@ -404,7 +404,6 @@ struct GB_gameboy_internal_s {
/* I/O */
uint32_t *screen;
GB_sample_t *audio_buffer;
bool keys[GB_KEY_MAX];
/* Timing */
@ -412,13 +411,7 @@ struct GB_gameboy_internal_s {
uint64_t cycles_since_last_sync;
/* Audio */
unsigned buffer_size;
unsigned sample_rate;
unsigned audio_position;
bool audio_stream_started; /* detects first copy request to minimize lag */
volatile bool audio_copy_in_progress;
volatile bool apu_lock;
double apu_sample_cycles;
GB_apu_output_t apu_output;
/* Callbacks */
void *user_data;

2
Core/timing.c
View File

@ -133,7 +133,7 @@ void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)
// Not affected by speed boost
gb->hdma_cycles += cycles;
gb->apu_sample_cycles += cycles;
gb->apu_output.sample_cycles += cycles;
gb->cycles_since_ir_change += cycles;
gb->cycles_since_input_ir_change += cycles;
gb->cycles_since_last_sync += cycles;