mirror of https://github.com/bsnes-emu/bsnes.git
1065 lines
43 KiB
C
1065 lines
43 KiB
C
#include <stdint.h>
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#include <math.h>
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#include <string.h>
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#include <assert.h>
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#include "gb.h"
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#define likely(x) __builtin_expect((x), 1)
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#define unlikely(x) __builtin_expect((x), 0)
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static const uint8_t duties[] = {
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0, 0, 0, 0, 0, 0, 0, 1,
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1, 0, 0, 0, 0, 0, 0, 1,
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1, 0, 0, 0, 0, 1, 1, 1,
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0, 1, 1, 1, 1, 1, 1, 0,
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};
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static void refresh_channel(GB_gameboy_t *gb, unsigned index, unsigned cycles_offset)
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{
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unsigned multiplier = gb->apu_output.cycles_since_render + cycles_offset - gb->apu_output.last_update[index];
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gb->apu_output.summed_samples[index].left += gb->apu_output.current_sample[index].left * multiplier;
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gb->apu_output.summed_samples[index].right += gb->apu_output.current_sample[index].right * multiplier;
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gb->apu_output.last_update[index] = gb->apu_output.cycles_since_render + cycles_offset;
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}
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bool GB_apu_is_DAC_enabled(GB_gameboy_t *gb, unsigned index)
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{
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if (gb->model >= GB_MODEL_AGB) {
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/* On the AGB, mixing is done digitally, so there are no per-channel
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DACs. Instead, all channels are summed digital regardless of
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whatever the DAC state would be on a CGB or earlier model. */
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return true;
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}
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switch (index) {
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case GB_SQUARE_1:
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return gb->io_registers[GB_IO_NR12] & 0xF8;
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case GB_SQUARE_2:
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return gb->io_registers[GB_IO_NR22] & 0xF8;
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case GB_WAVE:
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return gb->apu.wave_channel.enable;
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case GB_NOISE:
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return gb->io_registers[GB_IO_NR42] & 0xF8;
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}
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return false;
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}
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static uint8_t agb_bias_for_channel(GB_gameboy_t *gb, unsigned index)
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{
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if (!gb->apu.is_active[index]) return 0;
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switch (index) {
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case GB_SQUARE_1:
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return gb->apu.square_channels[GB_SQUARE_1].current_volume;
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case GB_SQUARE_2:
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return gb->apu.square_channels[GB_SQUARE_2].current_volume;
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case GB_WAVE:
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return 0;
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case GB_NOISE:
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return gb->apu.noise_channel.current_volume;
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}
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return 0;
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}
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static void update_sample(GB_gameboy_t *gb, unsigned index, int8_t value, unsigned cycles_offset)
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{
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if (gb->model >= GB_MODEL_AGB) {
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/* On the AGB, because no analog mixing is done, the behavior of NR51 is a bit different.
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A channel that is not connected to a terminal is idenitcal to a connected channel
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playing PCM sample 0. */
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gb->apu.samples[index] = value;
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if (gb->apu_output.sample_rate) {
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unsigned right_volume = (gb->io_registers[GB_IO_NR50] & 7) + 1;
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unsigned left_volume = ((gb->io_registers[GB_IO_NR50] >> 4) & 7) + 1;
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if (index == GB_WAVE) {
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/* For some reason, channel 3 is inverted on the AGB */
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value ^= 0xF;
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}
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GB_sample_t output;
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uint8_t bias = agb_bias_for_channel(gb, index);
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if (gb->io_registers[GB_IO_NR51] & (1 << index)) {
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output.right = (0xf - value * 2 + bias) * right_volume;
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}
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else {
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output.right = 0xf * right_volume;
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}
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if (gb->io_registers[GB_IO_NR51] & (0x10 << index)) {
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output.left = (0xf - value * 2 + bias) * left_volume;
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}
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else {
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output.left = 0xf * left_volume;
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}
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if (*(uint32_t *)&(gb->apu_output.current_sample[index]) != *(uint32_t *)&output) {
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refresh_channel(gb, index, cycles_offset);
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gb->apu_output.current_sample[index] = output;
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}
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}
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return;
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}
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if (!GB_apu_is_DAC_enabled(gb, index)) {
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value = gb->apu.samples[index];
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}
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else {
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gb->apu.samples[index] = value;
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}
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if (gb->apu_output.sample_rate) {
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unsigned right_volume = 0;
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if (gb->io_registers[GB_IO_NR51] & (1 << index)) {
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right_volume = (gb->io_registers[GB_IO_NR50] & 7) + 1;
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}
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unsigned left_volume = 0;
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if (gb->io_registers[GB_IO_NR51] & (0x10 << index)) {
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left_volume = ((gb->io_registers[GB_IO_NR50] >> 4) & 7) + 1;
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}
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GB_sample_t output = {(0xf - value * 2) * left_volume, (0xf - value * 2) * right_volume};
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if (*(uint32_t *)&(gb->apu_output.current_sample[index]) != *(uint32_t *)&output) {
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refresh_channel(gb, index, cycles_offset);
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gb->apu_output.current_sample[index] = output;
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}
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}
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}
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static double smooth(double x)
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{
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return 3*x*x - 2*x*x*x;
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}
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static void render(GB_gameboy_t *gb)
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{
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GB_sample_t output = {0, 0};
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UNROLL
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for (unsigned i = 0; i < GB_N_CHANNELS; i++) {
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double multiplier = CH_STEP;
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if (gb->model < GB_MODEL_AGB) {
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if (!GB_apu_is_DAC_enabled(gb, i)) {
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gb->apu_output.dac_discharge[i] -= ((double) DAC_DECAY_SPEED) / gb->apu_output.sample_rate;
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if (gb->apu_output.dac_discharge[i] < 0) {
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multiplier = 0;
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gb->apu_output.dac_discharge[i] = 0;
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}
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else {
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multiplier *= smooth(gb->apu_output.dac_discharge[i]);
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}
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}
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else {
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gb->apu_output.dac_discharge[i] += ((double) DAC_ATTACK_SPEED) / gb->apu_output.sample_rate;
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if (gb->apu_output.dac_discharge[i] > 1) {
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gb->apu_output.dac_discharge[i] = 1;
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}
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else {
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multiplier *= smooth(gb->apu_output.dac_discharge[i]);
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}
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}
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}
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if (likely(gb->apu_output.last_update[i] == 0)) {
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output.left += gb->apu_output.current_sample[i].left * multiplier;
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output.right += gb->apu_output.current_sample[i].right * multiplier;
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}
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else {
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refresh_channel(gb, i, 0);
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output.left += (signed long) gb->apu_output.summed_samples[i].left * multiplier
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/ gb->apu_output.cycles_since_render;
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output.right += (signed long) gb->apu_output.summed_samples[i].right * multiplier
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/ gb->apu_output.cycles_since_render;
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gb->apu_output.summed_samples[i] = (GB_sample_t){0, 0};
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}
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gb->apu_output.last_update[i] = 0;
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}
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gb->apu_output.cycles_since_render = 0;
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GB_sample_t filtered_output = gb->apu_output.highpass_mode?
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(GB_sample_t) {output.left - gb->apu_output.highpass_diff.left,
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output.right - gb->apu_output.highpass_diff.right} :
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output;
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switch (gb->apu_output.highpass_mode) {
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case GB_HIGHPASS_OFF:
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gb->apu_output.highpass_diff = (GB_double_sample_t) {0, 0};
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break;
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case GB_HIGHPASS_ACCURATE:
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gb->apu_output.highpass_diff = (GB_double_sample_t)
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{output.left - filtered_output.left * gb->apu_output.highpass_rate,
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output.right - filtered_output.right * gb->apu_output.highpass_rate};
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break;
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case GB_HIGHPASS_REMOVE_DC_OFFSET: {
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unsigned mask = gb->io_registers[GB_IO_NR51];
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unsigned left_volume = 0;
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unsigned right_volume = 0;
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UNROLL
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for (unsigned i = GB_N_CHANNELS; i--;) {
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if (gb->apu.is_active[i]) {
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if (mask & 1) {
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left_volume += (gb->io_registers[GB_IO_NR50] & 7) * CH_STEP * 0xF;
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}
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if (mask & 0x10) {
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right_volume += ((gb->io_registers[GB_IO_NR50] >> 4) & 7) * CH_STEP * 0xF;
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}
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}
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else {
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left_volume += gb->apu_output.current_sample[i].left * CH_STEP;
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right_volume += gb->apu_output.current_sample[i].right * CH_STEP;
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}
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mask >>= 1;
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}
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gb->apu_output.highpass_diff = (GB_double_sample_t)
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{left_volume * (1 - gb->apu_output.highpass_rate) + gb->apu_output.highpass_diff.left * gb->apu_output.highpass_rate,
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right_volume * (1 - gb->apu_output.highpass_rate) + gb->apu_output.highpass_diff.right * gb->apu_output.highpass_rate};
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case GB_HIGHPASS_MAX:;
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}
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}
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assert(gb->apu_output.sample_callback);
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gb->apu_output.sample_callback(gb, &filtered_output);
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}
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static uint16_t new_sweep_sample_length(GB_gameboy_t *gb)
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{
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uint16_t delta = gb->apu.shadow_sweep_sample_length >> (gb->io_registers[GB_IO_NR10] & 7);
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if (gb->io_registers[GB_IO_NR10] & 8) {
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return gb->apu.shadow_sweep_sample_length - delta;
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}
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return gb->apu.shadow_sweep_sample_length + delta;
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}
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static void update_square_sample(GB_gameboy_t *gb, unsigned index)
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{
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if (gb->apu.square_channels[index].current_sample_index & 0x80) return;
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uint8_t duty = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR11 :GB_IO_NR21] >> 6;
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update_sample(gb, index,
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duties[gb->apu.square_channels[index].current_sample_index + duty * 8]?
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gb->apu.square_channels[index].current_volume : 0,
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0);
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}
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/* the effects of NRX2 writes on current volume are not well documented and differ
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between models and variants. The exact behavior can only be verified on CGB as it
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requires the PCM12 register. The behavior implemented here was verified on *my*
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CGB, which might behave differently from other CGB revisions, as well as from the
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DMG, MGB or SGB/2 */
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static void nrx2_glitch(uint8_t *volume, uint8_t value, uint8_t old_value)
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{
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if (value & 8) {
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(*volume)++;
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}
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if (((value ^ old_value) & 8)) {
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*volume = 0x10 - *volume;
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}
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if ((value & 7) && !(old_value & 7) && *volume && !(value & 8)) {
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(*volume)--;
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}
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if ((old_value & 7) && (value & 8)) {
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(*volume)--;
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}
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(*volume) &= 0xF;
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}
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static void tick_square_envelope(GB_gameboy_t *gb, enum GB_CHANNELS index)
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{
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uint8_t nrx2 = gb->io_registers[index == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
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if (gb->apu.square_channels[index].volume_countdown || (nrx2 & 7)) {
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if (!gb->apu.square_channels[index].volume_countdown || !--gb->apu.square_channels[index].volume_countdown) {
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if (gb->cgb_double_speed) {
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if (index == GB_SQUARE_1) {
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gb->apu.pcm_mask[0] &= gb->apu.square_channels[GB_SQUARE_1].current_volume | 0xF1;
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}
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else {
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gb->apu.pcm_mask[0] &= (gb->apu.square_channels[GB_SQUARE_2].current_volume << 2) | 0x1F;
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}
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}
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if ((nrx2 & 8) && gb->apu.square_channels[index].current_volume < 0xF) {
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gb->apu.square_channels[index].current_volume++;
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}
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else if (!(nrx2 & 8) && gb->apu.square_channels[index].current_volume > 0) {
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gb->apu.square_channels[index].current_volume--;
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}
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gb->apu.square_channels[index].volume_countdown = nrx2 & 7;
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if (gb->apu.is_active[index]) {
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update_square_sample(gb, index);
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}
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}
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}
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}
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static void tick_noise_envelope(GB_gameboy_t *gb)
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{
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uint8_t nr42 = gb->io_registers[GB_IO_NR42];
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if (gb->apu.noise_channel.volume_countdown || (nr42 & 7)) {
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if (!gb->apu.noise_channel.volume_countdown || !--gb->apu.noise_channel.volume_countdown) {
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if (gb->cgb_double_speed) {
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gb->apu.pcm_mask[0] &= (gb->apu.noise_channel.current_volume << 2) | 0x1F;
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}
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if ((nr42 & 8) && gb->apu.noise_channel.current_volume < 0xF) {
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gb->apu.noise_channel.current_volume++;
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}
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else if (!(nr42 & 8) && gb->apu.noise_channel.current_volume > 0) {
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gb->apu.noise_channel.current_volume--;
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}
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gb->apu.noise_channel.volume_countdown = nr42 & 7;
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if (gb->apu.is_active[GB_NOISE]) {
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update_sample(gb, GB_NOISE,
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(gb->apu.noise_channel.lfsr & 1) ?
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gb->apu.noise_channel.current_volume : 0,
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0);
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}
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}
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}
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}
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void GB_apu_div_event(GB_gameboy_t *gb)
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{
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if (!gb->apu.global_enable) return;
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if (gb->apu.skip_div_event == GB_SKIP_DIV_EVENT_SKIP) {
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gb->apu.skip_div_event = GB_SKIP_DIV_EVENT_SKIPPED;
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return;
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}
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if (gb->apu.skip_div_event == GB_SKIP_DIV_EVENT_SKIPPED) {
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gb->apu.skip_div_event = GB_SKIP_DIV_EVENT_INACTIVE;
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}
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else {
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gb->apu.div_divider++;
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}
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if ((gb->apu.div_divider & 1) == 0) {
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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uint8_t nrx2 = gb->io_registers[i == GB_SQUARE_1? GB_IO_NR12 : GB_IO_NR22];
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if (gb->apu.is_active[i] && gb->apu.square_channels[i].volume_countdown == 0 && (nrx2 & 7)) {
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tick_square_envelope(gb, i);
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}
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}
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if (gb->apu.is_active[GB_NOISE] && gb->apu.noise_channel.volume_countdown == 0 && (gb->io_registers[GB_IO_NR42] & 7)) {
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tick_noise_envelope(gb);
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}
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}
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if ((gb->apu.div_divider & 7) == 0) {
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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tick_square_envelope(gb, i);
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}
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tick_noise_envelope(gb);
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}
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if ((gb->apu.div_divider & 1) == 1) {
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for (unsigned i = GB_SQUARE_2 + 1; i--;) {
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if (gb->apu.square_channels[i].length_enabled) {
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if (gb->apu.square_channels[i].pulse_length) {
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if (!--gb->apu.square_channels[i].pulse_length) {
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gb->apu.is_active[i] = false;
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update_sample(gb, i, 0, 0);
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}
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}
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}
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}
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if (gb->apu.wave_channel.length_enabled) {
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if (gb->apu.wave_channel.pulse_length) {
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if (!--gb->apu.wave_channel.pulse_length) {
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gb->apu.is_active[GB_WAVE] = false;
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update_sample(gb, GB_WAVE, 0, 0);
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}
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}
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}
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if (gb->apu.noise_channel.length_enabled) {
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if (gb->apu.noise_channel.pulse_length) {
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if (!--gb->apu.noise_channel.pulse_length) {
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gb->apu.is_active[GB_NOISE] = false;
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update_sample(gb, GB_NOISE, 0, 0);
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}
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}
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}
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}
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if ((gb->apu.div_divider & 3) == 3) {
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if (!gb->apu.sweep_enabled) {
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return;
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}
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if (gb->apu.square_sweep_countdown) {
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if (!--gb->apu.square_sweep_countdown) {
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if ((gb->io_registers[GB_IO_NR10] & 0x70) && (gb->io_registers[GB_IO_NR10] & 0x07)) {
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gb->apu.square_channels[GB_SQUARE_1].sample_length =
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gb->apu.shadow_sweep_sample_length =
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gb->apu.new_sweep_sample_length;
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}
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if (gb->io_registers[GB_IO_NR10] & 0x70) {
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/* Recalculation and overflow check only occurs after a delay */
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gb->apu.square_sweep_calculate_countdown = 0x13 - gb->apu.lf_div;
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}
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gb->apu.square_sweep_countdown = ((gb->io_registers[GB_IO_NR10] >> 4) & 7);
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if (!gb->apu.square_sweep_countdown) gb->apu.square_sweep_countdown = 8;
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}
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}
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}
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}
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void GB_apu_run(GB_gameboy_t *gb)
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{
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/* Convert 4MHZ to 2MHz. apu_cycles is always divisable by 4. */
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uint8_t cycles = gb->apu.apu_cycles >> 2;
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gb->apu.apu_cycles = 0;
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if (!cycles) return;
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if (likely(!gb->stopped || GB_is_cgb(gb))) {
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/* To align the square signal to 1MHz */
|
|
gb->apu.lf_div ^= cycles & 1;
|
|
gb->apu.noise_channel.alignment += cycles;
|
|
|
|
if (gb->apu.square_sweep_calculate_countdown) {
|
|
if (gb->apu.square_sweep_calculate_countdown > cycles) {
|
|
gb->apu.square_sweep_calculate_countdown -= cycles;
|
|
}
|
|
else {
|
|
/* APU bug: sweep frequency is checked after adding the sweep delta twice */
|
|
gb->apu.new_sweep_sample_length = new_sweep_sample_length(gb);
|
|
if (gb->apu.new_sweep_sample_length > 0x7ff) {
|
|
gb->apu.is_active[GB_SQUARE_1] = false;
|
|
update_sample(gb, GB_SQUARE_1, 0, gb->apu.square_sweep_calculate_countdown - cycles);
|
|
gb->apu.sweep_enabled = false;
|
|
}
|
|
gb->apu.sweep_decreasing |= gb->io_registers[GB_IO_NR10] & 8;
|
|
gb->apu.square_sweep_calculate_countdown = 0;
|
|
}
|
|
}
|
|
|
|
UNROLL
|
|
for (unsigned i = GB_SQUARE_1; i <= GB_SQUARE_2; i++) {
|
|
if (gb->apu.is_active[i]) {
|
|
uint8_t cycles_left = cycles;
|
|
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;
|
|
if (cycles_left == 0 && gb->apu.samples[i] == 0) {
|
|
gb->apu.pcm_mask[0] &= i == GB_SQUARE_1? 0xF0 : 0x0F;
|
|
}
|
|
|
|
update_square_sample(gb, i);
|
|
}
|
|
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]) {
|
|
uint8_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 =
|
|
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,
|
|
cycles - cycles_left);
|
|
gb->apu.wave_channel.wave_form_just_read = true;
|
|
}
|
|
if (cycles_left) {
|
|
gb->apu.wave_channel.sample_countdown -= cycles_left;
|
|
gb->apu.wave_channel.wave_form_just_read = false;
|
|
}
|
|
}
|
|
|
|
if (gb->apu.is_active[GB_NOISE]) {
|
|
uint8_t cycles_left = cycles;
|
|
while (unlikely(cycles_left > gb->apu.noise_channel.sample_countdown)) {
|
|
cycles_left -= gb->apu.noise_channel.sample_countdown + 1;
|
|
gb->apu.noise_channel.sample_countdown = gb->apu.noise_channel.sample_length * 4 + 3;
|
|
|
|
/* Step LFSR */
|
|
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;
|
|
}
|
|
|
|
gb->apu.current_lfsr_sample = gb->apu.noise_channel.lfsr & 1;
|
|
|
|
if (cycles_left == 0 && gb->apu.samples[GB_NOISE] == 0) {
|
|
gb->apu.pcm_mask[1] &= 0x0F;
|
|
}
|
|
|
|
update_sample(gb, GB_NOISE,
|
|
gb->apu.current_lfsr_sample ?
|
|
gb->apu.noise_channel.current_volume : 0,
|
|
0);
|
|
}
|
|
if (cycles_left) {
|
|
gb->apu.noise_channel.sample_countdown -= cycles_left;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (gb->apu_output.sample_rate) {
|
|
gb->apu_output.cycles_since_render += cycles;
|
|
|
|
if (gb->apu_output.sample_cycles >= gb->apu_output.cycles_per_sample) {
|
|
gb->apu_output.sample_cycles -= gb->apu_output.cycles_per_sample;
|
|
render(gb);
|
|
}
|
|
}
|
|
}
|
|
void GB_apu_init(GB_gameboy_t *gb)
|
|
{
|
|
memset(&gb->apu, 0, sizeof(gb->apu));
|
|
/* Restore the wave form */
|
|
for (unsigned reg = GB_IO_WAV_START; reg <= GB_IO_WAV_END; reg++) {
|
|
gb->apu.wave_channel.wave_form[(reg - GB_IO_WAV_START) * 2] = gb->io_registers[reg] >> 4;
|
|
gb->apu.wave_channel.wave_form[(reg - GB_IO_WAV_START) * 2 + 1] = gb->io_registers[reg] & 0xF;
|
|
}
|
|
gb->apu.lf_div = 1;
|
|
/* 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;
|
|
}
|
|
}
|
|
|
|
uint8_t GB_apu_read(GB_gameboy_t *gb, uint8_t reg)
|
|
{
|
|
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;
|
|
}
|
|
reg = GB_IO_WAV_START + gb->apu.wave_channel.current_sample_index / 2;
|
|
}
|
|
|
|
return gb->io_registers[reg] | read_mask[reg - GB_IO_NR10];
|
|
}
|
|
|
|
void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
|
|
{
|
|
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) {
|
|
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--;) {
|
|
update_sample(gb, i, gb->apu.samples[i], 0);
|
|
}
|
|
break;
|
|
case GB_IO_NR52: {
|
|
|
|
uint8_t old_nrx1[] = {
|
|
gb->io_registers[GB_IO_NR11],
|
|
gb->io_registers[GB_IO_NR21],
|
|
gb->io_registers[GB_IO_NR31],
|
|
gb->io_registers[GB_IO_NR41]
|
|
};
|
|
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);
|
|
old_nrx1[0] &= 0x3F;
|
|
old_nrx1[1] &= 0x3F;
|
|
|
|
gb->apu.global_enable = false;
|
|
}
|
|
|
|
if (!GB_is_cgb(gb) && (value & 0x80)) {
|
|
GB_apu_write(gb, GB_IO_NR11, old_nrx1[0]);
|
|
GB_apu_write(gb, GB_IO_NR21, old_nrx1[1]);
|
|
GB_apu_write(gb, GB_IO_NR31, old_nrx1[2]);
|
|
GB_apu_write(gb, GB_IO_NR41, old_nrx1[3]);
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* Square channels */
|
|
case GB_IO_NR10:
|
|
if (gb->apu.sweep_decreasing && !(value & 8)) {
|
|
gb->apu.is_active[GB_SQUARE_1] = false;
|
|
update_sample(gb, GB_SQUARE_1, 0, 0);
|
|
gb->apu.sweep_enabled = false;
|
|
gb->apu.square_sweep_calculate_countdown = 0;
|
|
}
|
|
if ((value & 0x70) == 0) {
|
|
/* Todo: what happens if we set period to 0 while a calculate event is scheduled, and then
|
|
re-set it to non-zero? */
|
|
gb->apu.square_sweep_calculate_countdown = 0;
|
|
}
|
|
break;
|
|
|
|
case GB_IO_NR11:
|
|
case GB_IO_NR21: {
|
|
unsigned 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: {
|
|
unsigned index = reg == GB_IO_NR22? GB_SQUARE_2: GB_SQUARE_1;
|
|
if (((value & 0x7) == 0) && ((gb->io_registers[reg] & 0x7) != 0)) {
|
|
/* Envelope disabled */
|
|
gb->apu.square_channels[index].volume_countdown = 0;
|
|
}
|
|
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->apu.square_channels[index].current_volume, value, gb->io_registers[reg]);
|
|
update_square_sample(gb, index);
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
case GB_IO_NR13:
|
|
case GB_IO_NR23: {
|
|
unsigned 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;
|
|
break;
|
|
}
|
|
|
|
case GB_IO_NR14:
|
|
case GB_IO_NR24: {
|
|
unsigned index = reg == GB_IO_NR24? GB_SQUARE_2: GB_SQUARE_1;
|
|
|
|
/* TODO: When the sample length changes right before being updated, 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]) {
|
|
/* 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].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_length &= 0xFF;
|
|
gb->apu.square_channels[index].sample_length |= (value & 7) << 8;
|
|
if (index == GB_SQUARE_1) {
|
|
gb->apu.shadow_sweep_sample_length =
|
|
gb->apu.new_sweep_sample_length =
|
|
gb->apu.square_channels[0].sample_length;
|
|
}
|
|
if (value & 0x80) {
|
|
/* Current sample index remains unchanged when restarting channels 1 or 2. It is only reset by
|
|
turning the APU off. */
|
|
if (!gb->apu.is_active[index]) {
|
|
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 6 - gb->apu.lf_div;
|
|
}
|
|
else {
|
|
/* Timing quirk: if already active, sound starts 2 (2MHz) ticks earlier.*/
|
|
gb->apu.square_channels[index].sample_countdown = (gb->apu.square_channels[index].sample_length ^ 0x7FF) * 2 + 4 - gb->apu.lf_div;
|
|
}
|
|
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 take 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);
|
|
}
|
|
|
|
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);
|
|
/* We use the highest bit in current_sample_index to mark this sample is not actually playing yet, */
|
|
gb->apu.square_channels[index].current_sample_index |= 0x80;
|
|
}
|
|
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.sweep_decreasing = false;
|
|
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 = 0x13 - gb->apu.lf_div;
|
|
}
|
|
else {
|
|
gb->apu.square_sweep_calculate_countdown = 0;
|
|
}
|
|
gb->apu.sweep_enabled = gb->io_registers[GB_IO_NR10] & 0x77;
|
|
gb->apu.square_sweep_countdown = ((gb->io_registers[GB_IO_NR10] >> 4) & 7);
|
|
if (!gb->apu.square_sweep_countdown) gb->apu.square_sweep_countdown = 8;
|
|
}
|
|
|
|
}
|
|
|
|
/* APU glitch - if length is enabled while the DIV-divider's LSB is 1, tick the length once. */
|
|
if ((value & 0x40) &&
|
|
!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.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 = (uint8_t[]){4, 0, 1, 2}[(value >> 5) & 3];
|
|
if (gb->apu.is_active[GB_WAVE]) {
|
|
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;
|
|
gb->apu.wave_channel.sample_length |= value & 0xFF;
|
|
break;
|
|
case GB_IO_NR34:
|
|
gb->apu.wave_channel.sample_length &= 0xFF;
|
|
gb->apu.wave_channel.sample_length |= (value & 7) << 8;
|
|
if ((value & 0x80)) {
|
|
/* 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 &&
|
|
gb->apu.wave_channel.enable) {
|
|
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.
|
|
|
|
Additionally, I believe DMGs, including those we behave differently than emulated,
|
|
are all deterministic. */
|
|
if (offset < 4) {
|
|
gb->io_registers[GB_IO_WAV_START] = gb->io_registers[GB_IO_WAV_START + offset];
|
|
gb->apu.wave_channel.wave_form[0] = gb->apu.wave_channel.wave_form[offset / 2];
|
|
gb->apu.wave_channel.wave_form[1] = gb->apu.wave_channel.wave_form[offset / 2 + 1];
|
|
}
|
|
else {
|
|
memcpy(gb->io_registers + GB_IO_WAV_START,
|
|
gb->io_registers + GB_IO_WAV_START + (offset & ~3),
|
|
4);
|
|
memcpy(gb->apu.wave_channel.wave_form,
|
|
gb->apu.wave_channel.wave_form + (offset & ~3) * 2,
|
|
8);
|
|
}
|
|
}
|
|
if (!gb->apu.is_active[GB_WAVE]) {
|
|
gb->apu.is_active[GB_WAVE] = true;
|
|
update_sample(gb, GB_WAVE,
|
|
gb->apu.wave_channel.current_sample >> gb->apu.wave_channel.shift,
|
|
0);
|
|
}
|
|
gb->apu.wave_channel.sample_countdown = (gb->apu.wave_channel.sample_length ^ 0x7FF) + 3;
|
|
gb->apu.wave_channel.current_sample_index = 0;
|
|
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->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;
|
|
if (gb->apu.is_active[GB_WAVE] && !gb->apu.wave_channel.enable) {
|
|
gb->apu.is_active[GB_WAVE] = false;
|
|
update_sample(gb, GB_WAVE, 0, 0);
|
|
}
|
|
|
|
break;
|
|
|
|
/* Noise Channel */
|
|
|
|
case GB_IO_NR41: {
|
|
gb->apu.noise_channel.pulse_length = (0x40 - (value & 0x3f));
|
|
break;
|
|
}
|
|
|
|
case GB_IO_NR42: {
|
|
if (((value & 0x7) == 0) && ((gb->io_registers[reg] & 0x7) != 0)) {
|
|
/* Envelope disabled */
|
|
gb->apu.noise_channel.volume_countdown = 0;
|
|
}
|
|
if ((value & 0xF8) == 0) {
|
|
/* This disables the DAC */
|
|
gb->io_registers[reg] = value;
|
|
gb->apu.is_active[GB_NOISE] = false;
|
|
update_sample(gb, GB_NOISE, 0, 0);
|
|
}
|
|
else if (gb->apu.is_active[GB_NOISE]) {
|
|
nrx2_glitch(&gb->apu.noise_channel.current_volume, value, gb->io_registers[reg]);
|
|
update_sample(gb, GB_NOISE,
|
|
gb->apu.current_lfsr_sample ?
|
|
gb->apu.noise_channel.current_volume : 0,
|
|
0);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case GB_IO_NR43: {
|
|
gb->apu.noise_channel.narrow = value & 8;
|
|
unsigned divisor = (value & 0x07) << 1;
|
|
if (!divisor) divisor = 1;
|
|
gb->apu.noise_channel.sample_length = (divisor << (value >> 4)) - 1;
|
|
|
|
/* Todo: changing the frequency sometimes delays the next sample. This is probably
|
|
due to how the frequency is actually calculated in the noise channel, which is probably
|
|
not by calculating the effective sample length and counting simiarly to the other channels.
|
|
This is not emulated correctly. */
|
|
break;
|
|
}
|
|
|
|
case GB_IO_NR44: {
|
|
if (value & 0x80) {
|
|
gb->apu.noise_channel.sample_countdown = (gb->apu.noise_channel.sample_length) * 2 + 6 - gb->apu.lf_div;
|
|
|
|
/* I'm COMPLETELY unsure about this logic, but it passes all relevant tests.
|
|
See comment in NR43. */
|
|
if ((gb->io_registers[GB_IO_NR43] & 7) && (gb->apu.noise_channel.alignment & 2) == 0) {
|
|
if ((gb->io_registers[GB_IO_NR43] & 7) == 1) {
|
|
gb->apu.noise_channel.sample_countdown += 2;
|
|
}
|
|
else {
|
|
gb->apu.noise_channel.sample_countdown -= 2;
|
|
}
|
|
}
|
|
if (gb->apu.is_active[GB_NOISE]) {
|
|
gb->apu.noise_channel.sample_countdown += 2;
|
|
}
|
|
|
|
gb->apu.noise_channel.current_volume = gb->io_registers[GB_IO_NR42] >> 4;
|
|
|
|
/* The volume changes caused by NRX4 sound start take 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[GB_NOISE]) {
|
|
update_sample(gb, GB_NOISE,
|
|
gb->apu.current_lfsr_sample ?
|
|
gb->apu.noise_channel.current_volume : 0,
|
|
0);
|
|
}
|
|
gb->apu.noise_channel.lfsr = 0;
|
|
gb->apu.current_lfsr_sample = false;
|
|
gb->apu.noise_channel.volume_countdown = gb->io_registers[GB_IO_NR42] & 7;
|
|
|
|
if (!gb->apu.is_active[GB_NOISE] && (gb->io_registers[GB_IO_NR42] & 0xF8) != 0) {
|
|
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;
|
|
}
|
|
|
|
default:
|
|
if (reg >= GB_IO_WAV_START && reg <= GB_IO_WAV_END) {
|
|
gb->apu.wave_channel.wave_form[(reg - GB_IO_WAV_START) * 2] = value >> 4;
|
|
gb->apu.wave_channel.wave_form[(reg - GB_IO_WAV_START) * 2 + 1] = value & 0xF;
|
|
}
|
|
}
|
|
gb->io_registers[reg] = value;
|
|
}
|
|
|
|
void GB_set_sample_rate(GB_gameboy_t *gb, unsigned sample_rate)
|
|
{
|
|
|
|
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.rate_set_in_clocks = false;
|
|
GB_apu_update_cycles_per_sample(gb);
|
|
}
|
|
|
|
void GB_set_sample_rate_by_clocks(GB_gameboy_t *gb, double cycles_per_sample)
|
|
{
|
|
|
|
if (cycles_per_sample == 0) {
|
|
GB_set_sample_rate(gb, 0);
|
|
return;
|
|
}
|
|
gb->apu_output.cycles_per_sample = cycles_per_sample;
|
|
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.rate_set_in_clocks = true;
|
|
}
|
|
|
|
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_apu_update_cycles_per_sample(GB_gameboy_t *gb)
|
|
{
|
|
if (gb->apu_output.rate_set_in_clocks) return;
|
|
if (gb->apu_output.sample_rate) {
|
|
gb->apu_output.cycles_per_sample = 2 * GB_get_clock_rate(gb) / (double)gb->apu_output.sample_rate; /* 2 * because we use 8MHz units */
|
|
}
|
|
}
|