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bsnes/Core/sgb.c

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#include "gb.h"
#include <math.h>
#define INTRO_ANIMATION_LENGTH 200
enum {
PAL01 = 0x00,
PAL23 = 0x01,
PAL03 = 0x02,
PAL12 = 0x03,
ATTR_BLK = 0x04,
ATTR_LIN = 0x05,
ATTR_DIV = 0x06,
PAL_SET = 0x0A,
PAL_TRN = 0x0B,
DATA_SND = 0x0F,
MLT_REQ = 0x11,
CHR_TRN = 0x13,
PCT_TRN = 0x14,
ATTR_TRN = 0x15,
ATTR_SET = 0x16,
MASK_EN = 0x17,
};
typedef enum {
MASK_DISABLED,
MASK_FREEZE,
MASK_BLACK,
MASK_COLOR_0,
} mask_mode_t;
typedef enum {
TRANSFER_LOW_TILES,
TRANSFER_HIGH_TILES,
TRANSFER_BORDER_DATA,
TRANSFER_PALETTES,
TRANSFER_ATTRIBUTES,
} transfer_dest_t;
#define SGB_PACKET_SIZE 16
static inline void pal_command(GB_gameboy_t *gb, unsigned first, unsigned second)
{
gb->sgb->effective_palettes[0] = gb->sgb->effective_palettes[4] =
gb->sgb->effective_palettes[8] = gb->sgb->effective_palettes[12] =
gb->sgb->command[1] | (gb->sgb->command[2] << 8);
for (unsigned i = 0; i < 3; i++) {
gb->sgb->effective_palettes[first * 4 + i + 1] = gb->sgb->command[3 + i * 2] | (gb->sgb->command[4 + i * 2] << 8);
}
for (unsigned i = 0; i < 3; i++) {
gb->sgb->effective_palettes[second * 4 + i + 1] = gb->sgb->command[9 + i * 2] | (gb->sgb->command[10 + i * 2] << 8);
}
}
static inline void load_attribute_file(GB_gameboy_t *gb, unsigned file_index)
{
if (file_index > 0x2C) return;
uint8_t *output = gb->sgb->attribute_map;
for (unsigned i = 0; i < 90; i++) {
uint8_t byte = gb->sgb->attribute_files[file_index * 90 + i];
for (unsigned j = 4; j--;) {
*(output++) = byte >> 6;
byte <<= 2;
}
}
}
static void command_ready(GB_gameboy_t *gb)
{
/* SGB header commands are used to send the contents of the header to the SNES CPU.
A header command looks like this:
Command ID: 0b1111xxx1, where xxx is the packet index. (e.g. F1 for [0x104, 0x112), F3 for [0x112, 0x120))
Checksum: Simple one byte sum for the following content bytes
0xE content bytes. The last command, FB, is padded with zeros, so information past the header is not sent. */
if ((gb->sgb->command[0] & 0xF1) == 0xF1) {
uint8_t checksum = 0;
for (unsigned i = 2; i < 0x10; i++) {
checksum += gb->sgb->command[i];
}
if (checksum != gb->sgb->command[1]) {
GB_log(gb, "Failed checksum for SGB header command, disabling SGB features\n");
gb->sgb->disable_commands = true;
return;
}
if (gb->sgb->command[0] == 0xf9) {
if (gb->sgb->command[0xc] != 3) { // SGB Flag
gb->sgb->disable_commands = true;
}
}
else if (gb->sgb->command[0] == 0xfb) {
if (gb->sgb->command[0x3] != 0x33) { // Old licensee code
gb->sgb->disable_commands = true;
}
}
return;
}
switch (gb->sgb->command[0] >> 3) {
case PAL01:
pal_command(gb, 0, 1);
break;
case PAL23:
pal_command(gb, 2, 3);
break;
case PAL03:
pal_command(gb, 0, 3);
break;
case PAL12:
pal_command(gb, 1, 2);
break;
case ATTR_BLK: {
struct {
uint8_t count;
struct {
uint8_t control;
uint8_t palettes;
uint8_t left, top, right, bottom;
} data[];
} *command = (void *)(gb->sgb->command + 1);
if (command->count > 0x12) return;
for (unsigned i = 0; i < command->count; i++) {
bool inside = command->data[i].control & 1;
bool middle = command->data[i].control & 2;
bool outside = command->data[i].control & 4;
uint8_t inside_palette = command->data[i].palettes & 0x3;
uint8_t middle_palette = (command->data[i].palettes >> 2) & 0x3;
uint8_t outside_palette = (command->data[i].palettes >> 4) & 0x3;
if (inside && !middle && !outside) {
middle = true;
middle_palette = inside_palette;
}
else if (outside && !middle && !inside) {
middle = true;
middle_palette = outside_palette;
}
command->data[i].left &= 0x1F;
command->data[i].top &= 0x1F;
command->data[i].right &= 0x1F;
command->data[i].bottom &= 0x1F;
for (unsigned y = 0; y < 18; y++) {
for (unsigned x = 0; x < 20; x++) {
if (x < command->data[i].left || x > command->data[i].right ||
y < command->data[i].top || y > command->data[i].bottom) {
if (outside) {
gb->sgb->attribute_map[x + 20 * y] = outside_palette;
}
}
else if (x > command->data[i].left && x < command->data[i].right &&
y > command->data[i].top && y < command->data[i].bottom) {
if (inside) {
gb->sgb->attribute_map[x + 20 * y] = inside_palette;
}
}
else if(middle) {
gb->sgb->attribute_map[x + 20 * y] = middle_palette;
}
}
}
}
break;
}
case ATTR_LIN: {
struct {
uint8_t count;
uint8_t data[];
} *command = (void *)(gb->sgb->command + 1);
if (command->count > sizeof(gb->sgb->command) - 2) return;
for (unsigned i = 0; i < command->count; i++) {
bool horizontal = command->data[i] & 0x80;
uint8_t palette = (command->data[i] >> 5) & 0x3;
uint8_t line = (command->data[i]) & 0x1F;
if (horizontal) {
if (line > 18) continue;
for (unsigned x = 0; x < 20; x++) {
gb->sgb->attribute_map[x + 20 * line] = palette;
}
}
else {
if (line > 20) continue;
for (unsigned y = 0; y < 18; y++) {
gb->sgb->attribute_map[line + 20 * y] = palette;
}
}
}
break;
}
case ATTR_DIV: {
uint8_t high_palette = gb->sgb->command[1] & 3;
uint8_t low_palette = (gb->sgb->command[1] >> 2) & 3;
uint8_t middle_palette = (gb->sgb->command[1] >> 4) & 3;
bool horizontal = gb->sgb->command[1] & 0x40;
uint8_t line = gb->sgb->command[2] & 0x1F;
for (unsigned y = 0; y < 18; y++) {
for (unsigned x = 0; x < 20; x++) {
if ((horizontal? y : x) < line) {
gb->sgb->attribute_map[x + 20 * y] = low_palette;
}
else if ((horizontal? y : x) == line) {
gb->sgb->attribute_map[x + 20 * y] = middle_palette;
}
else {
gb->sgb->attribute_map[x + 20 * y] = high_palette;
}
}
}
break;
}
case PAL_SET:
memcpy(&gb->sgb->effective_palettes[0],
&gb->sgb->ram_palettes[4 * (gb->sgb->command[1] + (gb->sgb->command[2] & 1) * 0x100)],
8);
memcpy(&gb->sgb->effective_palettes[4],
&gb->sgb->ram_palettes[4 * (gb->sgb->command[3] + (gb->sgb->command[4] & 1) * 0x100)],
8);
memcpy(&gb->sgb->effective_palettes[8],
&gb->sgb->ram_palettes[4 * (gb->sgb->command[5] + (gb->sgb->command[6] & 1) * 0x100)],
8);
memcpy(&gb->sgb->effective_palettes[12],
&gb->sgb->ram_palettes[4 * (gb->sgb->command[7] + (gb->sgb->command[8] & 1) * 0x100)],
8);
gb->sgb->effective_palettes[12] = gb->sgb->effective_palettes[8] =
gb->sgb->effective_palettes[4] = gb->sgb->effective_palettes[0];
if (gb->sgb->command[9] & 0x80) {
load_attribute_file(gb, gb->sgb->command[9] & 0x3F);
}
if (gb->sgb->command[9] & 0x40) {
gb->sgb->mask_mode = MASK_DISABLED;
}
break;
case PAL_TRN:
gb->sgb->vram_transfer_countdown = 2;
gb->sgb->transfer_dest = TRANSFER_PALETTES;
break;
case DATA_SND:
// Not supported, but used by almost all SGB games for hot patching, so let's mute the warning for this
break;
case MLT_REQ:
gb->sgb->player_count = (uint8_t[]){1, 2, 1, 4}[gb->sgb->command[1] & 3];
gb->sgb->current_player = gb->sgb->player_count - 1;
break;
case CHR_TRN:
gb->sgb->vram_transfer_countdown = 2;
gb->sgb->transfer_dest = (gb->sgb->command[1] & 1)? TRANSFER_HIGH_TILES : TRANSFER_LOW_TILES;
break;
case PCT_TRN:
gb->sgb->vram_transfer_countdown = 2;
gb->sgb->transfer_dest = TRANSFER_BORDER_DATA;
break;
case ATTR_TRN:
gb->sgb->vram_transfer_countdown = 2;
gb->sgb->transfer_dest = TRANSFER_ATTRIBUTES;
break;
case ATTR_SET:
load_attribute_file(gb, gb->sgb->command[0] & 0x3F);
if (gb->sgb->command[0] & 0x40) {
gb->sgb->mask_mode = MASK_DISABLED;
}
break;
case MASK_EN:
gb->sgb->mask_mode = gb->sgb->command[1] & 3;
break;
default:
if ((gb->sgb->command[0] >> 3) == 8 &&
(gb->sgb->command[1] & ~0x80) == 0 &&
(gb->sgb->command[2] & ~0x80) == 0) {
/* Mute/dummy sound commands, ignore this command as it's used by many games at startup */
break;
}
GB_log(gb, "Unimplemented SGB command %x: ", gb->sgb->command[0] >> 3);
for (unsigned i = 0; i < gb->sgb->command_write_index / 8; i++) {
GB_log(gb, "%02x ", gb->sgb->command[i]);
}
GB_log(gb, "\n");
}
}
void GB_sgb_write(GB_gameboy_t *gb, uint8_t value)
{
if (!GB_is_sgb(gb)) return;
if (gb->sgb->disable_commands) return;
if (gb->sgb->command_write_index >= sizeof(gb->sgb->command) * 8) return;
uint16_t command_size = (gb->sgb->command[0] & 7 ?: 1) * SGB_PACKET_SIZE * 8;
if ((gb->sgb->command[0] & 0xF1) == 0xF1) {
command_size = SGB_PACKET_SIZE * 8;
}
switch ((value >> 4) & 3) {
case 3:
gb->sgb->ready_for_pulse = true;
/* TODO: This is the logic used by BGB which *should* work for most/all games, but a proper test ROM is needed */
if (gb->sgb->player_count > 1 && (gb->io_registers[GB_IO_JOYP] & 0x30) == 0x10) {
gb->sgb->current_player++;
gb->sgb->current_player &= gb->sgb->player_count - 1;
}
break;
case 2: // Zero
if (!gb->sgb->ready_for_pulse || !gb->sgb->ready_for_write) return;
if (gb->sgb->ready_for_stop) {
if (gb->sgb->command_write_index == command_size) {
command_ready(gb);
gb->sgb->command_write_index = 0;
memset(gb->sgb->command, 0, sizeof(gb->sgb->command));
}
gb->sgb->ready_for_pulse = false;
gb->sgb->ready_for_write = false;
gb->sgb->ready_for_stop = false;
}
else {
gb->sgb->command_write_index++;
gb->sgb->ready_for_pulse = false;
if (((gb->sgb->command_write_index) & (SGB_PACKET_SIZE * 8 - 1)) == 0) {
gb->sgb->ready_for_stop = true;
}
}
break;
case 1: // One
if (!gb->sgb->ready_for_pulse || !gb->sgb->ready_for_write) return;
if (gb->sgb->ready_for_stop) {
GB_log(gb, "Corrupt SGB command.\n");
gb->sgb->ready_for_pulse = false;
gb->sgb->ready_for_write = false;
gb->sgb->command_write_index = 0;
memset(gb->sgb->command, 0, sizeof(gb->sgb->command));
}
else {
gb->sgb->command[gb->sgb->command_write_index / 8] |= 1 << (gb->sgb->command_write_index & 7);
gb->sgb->command_write_index++;
gb->sgb->ready_for_pulse = false;
if (((gb->sgb->command_write_index) & (SGB_PACKET_SIZE * 8 - 1)) == 0) {
gb->sgb->ready_for_stop = true;
}
}
break;
case 0:
if (!gb->sgb->ready_for_pulse) return;
gb->sgb->ready_for_write = true;
gb->sgb->ready_for_pulse = false;
if (((gb->sgb->command_write_index) & (SGB_PACKET_SIZE * 8 - 1)) != 0 ||
gb->sgb->command_write_index == 0 ||
gb->sgb->ready_for_stop) {
gb->sgb->command_write_index = 0;
memset(gb->sgb->command, 0, sizeof(gb->sgb->command));
gb->sgb->ready_for_stop = false;
}
break;
default:
break;
}
}
static inline uint8_t scale_channel(uint8_t x)
{
return (x << 3) | (x >> 2);
}
static uint32_t convert_rgb15(GB_gameboy_t *gb, uint16_t color)
{
uint8_t r = (color) & 0x1F;
uint8_t g = (color >> 5) & 0x1F;
uint8_t b = (color >> 10) & 0x1F;
r = scale_channel(r);
g = scale_channel(g);
b = scale_channel(b);
return gb->rgb_encode_callback(gb, r, g, b);
}
static uint32_t convert_rgb15_with_fade(GB_gameboy_t *gb, uint16_t color, uint8_t fade)
{
uint8_t r = ((color) & 0x1F) - fade;
uint8_t g = ((color >> 5) & 0x1F) - fade;
uint8_t b = ((color >> 10) & 0x1F) - fade;
if (r >= 0x20) r = 0;
if (g >= 0x20) g = 0;
if (b >= 0x20) b = 0;
r = scale_channel(r);
g = scale_channel(g);
b = scale_channel(b);
return gb->rgb_encode_callback(gb, r, g, b);
}
#include <stdio.h>
static void render_boot_animation (GB_gameboy_t *gb)
{
#include "sgb_animation_logo.inc"
uint32_t *output = &gb->screen[48 + 40 * 256];
uint8_t *input = animation_logo;
unsigned fade_blue = 0;
unsigned fade_red = 0;
if (gb->sgb->intro_animation < 80 - 32) {
fade_blue = 32;
}
else if (gb->sgb->intro_animation < 80) {
fade_blue = 80 - gb->sgb->intro_animation;
}
else if (gb->sgb->intro_animation > INTRO_ANIMATION_LENGTH - 32) {
fade_red = fade_blue = gb->sgb->intro_animation - INTRO_ANIMATION_LENGTH + 32;
}
uint32_t colors[] = {
convert_rgb15(gb, 0),
convert_rgb15_with_fade(gb, 0x14A5, fade_blue),
convert_rgb15_with_fade(gb, 0x54E0, fade_blue),
convert_rgb15_with_fade(gb, 0x0019, fade_red),
convert_rgb15(gb, 0x0011),
convert_rgb15(gb, 0x0009),
};
unsigned y_min = (144 - animation_logo_height) / 2;
unsigned y_max = y_min + animation_logo_height;
for (unsigned y = 0; y < 144; y++) {
for (unsigned x = 0; x < 160; x++) {
if (y < y_min || y >= y_max) {
*(output++) = colors[0];
}
else {
uint8_t color = *input;
if (color >= 3) {
if (color == gb->sgb->intro_animation / 2 - 3) {
color = 5;
}
else if (color == gb->sgb->intro_animation / 2 - 4) {
color = 4;
}
else if (color < gb->sgb->intro_animation / 2 - 4) {
color = 3;
}
else {
color = 0;
}
}
*(output++) = colors[color];
input++;
}
}
output += 256 - 160;
}
}
void GB_sgb_render(GB_gameboy_t *gb)
{
if (gb->sgb->intro_animation < INTRO_ANIMATION_LENGTH) gb->sgb->intro_animation++;
if (!gb->screen || !gb->rgb_encode_callback) return;
if (gb->sgb->mask_mode != MASK_FREEZE) {
memcpy(gb->sgb->effective_screen_buffer,
gb->sgb->screen_buffer,
sizeof(gb->sgb->effective_screen_buffer));
}
if (gb->sgb->vram_transfer_countdown) {
if (--gb->sgb->vram_transfer_countdown == 0) {
if (gb->sgb->transfer_dest == TRANSFER_LOW_TILES || gb->sgb->transfer_dest == TRANSFER_HIGH_TILES) {
uint8_t *base = &gb->sgb->pending_border.tiles[gb->sgb->transfer_dest == TRANSFER_HIGH_TILES ? 0x80 * 8 * 8 : 0];
for (unsigned tile = 0; tile < 0x80; tile++) {
unsigned tile_x = (tile % 10) * 16;
unsigned tile_y = (tile / 10) * 8;
for (unsigned y = 0; y < 0x8; y++) {
for (unsigned x = 0; x < 0x8; x++) {
base[tile * 8 * 8 + y * 8 + x] = gb->sgb->screen_buffer[(tile_x + x) + (tile_y + y) * 160] +
gb->sgb->screen_buffer[(tile_x + x + 8) + (tile_y + y) * 160] * 4;
}
}
}
}
else {
unsigned size = 0;
uint16_t *data = NULL;
switch (gb->sgb->transfer_dest) {
case TRANSFER_PALETTES:
size = 0x100;
data = gb->sgb->ram_palettes;
break;
case TRANSFER_BORDER_DATA:
size = 0x88;
data = gb->sgb->pending_border.raw_data;
break;
case TRANSFER_ATTRIBUTES:
size = 0xFE;
data = (uint16_t *)gb->sgb->attribute_files;
break;
default:
return; // Corrupt state?
}
for (unsigned tile = 0; tile < size; tile++) {
unsigned tile_x = (tile % 20) * 8;
unsigned tile_y = (tile / 20) * 8;
for (unsigned y = 0; y < 0x8; y++) {
static const uint16_t pixel_to_bits[4] = {0x0000, 0x0080, 0x8000, 0x8080};
*data = 0;
for (unsigned x = 0; x < 8; x++) {
*data |= pixel_to_bits[gb->sgb->screen_buffer[(tile_x + x) + (tile_y + y) * 160] & 3] >> x;
}
#ifdef GB_BIG_ENDIAN
if (gb->sgb->transfer_dest == TRANSFER_ATTRIBUTES) {
*data = __builtin_bswap16(*data);
}
#endif
data++;
}
}
if (gb->sgb->transfer_dest == TRANSFER_BORDER_DATA) {
gb->sgb->border_animation = 64;
}
}
}
}
uint32_t colors[4 * 4];
for (unsigned i = 0; i < 4 * 4; i++) {
colors[i] = convert_rgb15(gb, gb->sgb->effective_palettes[i]);
}
if (gb->sgb->intro_animation < INTRO_ANIMATION_LENGTH) {
render_boot_animation(gb);
}
else {
uint32_t *output = &gb->screen[48 + 40 * 256];
uint8_t *input = gb->sgb->effective_screen_buffer;
switch ((mask_mode_t) gb->sgb->mask_mode) {
case MASK_DISABLED:
case MASK_FREEZE: {
for (unsigned y = 0; y < 144; y++) {
for (unsigned x = 0; x < 160; x++) {
uint8_t palette = gb->sgb->attribute_map[x / 8 + y / 8 * 20] & 3;
*(output++) = colors[(*(input++) & 3) + palette * 4];
}
output += 256 - 160;
}
break;
}
case MASK_BLACK:
{
uint32_t black = convert_rgb15(gb, 0);
for (unsigned y = 0; y < 144; y++) {
for (unsigned x = 0; x < 160; x++) {
*(output++) = black;
}
output += 256 - 160;
}
break;
}
case MASK_COLOR_0:
{
for (unsigned y = 0; y < 144; y++) {
for (unsigned x = 0; x < 160; x++) {
*(output++) = colors[0];
}
output += 256 - 160;
}
break;
}
}
}
uint32_t border_colors[16 * 4];
if (gb->sgb->border_animation == 0 || gb->sgb->intro_animation < INTRO_ANIMATION_LENGTH) {
for (unsigned i = 0; i < 16 * 4; i++) {
border_colors[i] = convert_rgb15(gb, gb->sgb->border.palette[i]);
}
}
else if (gb->sgb->border_animation > 32) {
gb->sgb->border_animation--;
for (unsigned i = 0; i < 16 * 4; i++) {
border_colors[i] = convert_rgb15_with_fade(gb, gb->sgb->border.palette[i], 64 - gb->sgb->border_animation);
}
}
else {
gb->sgb->border_animation--;
for (unsigned i = 0; i < 16 * 4; i++) {
border_colors[i] = convert_rgb15_with_fade(gb, gb->sgb->border.palette[i], gb->sgb->border_animation);
}
}
if (gb->sgb->border_animation == 32) {
memcpy(&gb->sgb->border, &gb->sgb->pending_border, sizeof(gb->sgb->border));
}
for (unsigned tile_y = 0; tile_y < 28; tile_y++) {
for (unsigned tile_x = 0; tile_x < 32; tile_x++) {
bool gb_area = false;
if (tile_x >= 6 && tile_x < 26 && tile_y >= 5 && tile_y < 23) {
gb_area = true;
}
uint16_t tile = gb->sgb->border.map[tile_x + tile_y * 32];
uint8_t flip_x = (tile & 0x4000)? 0x7 : 0;
uint8_t flip_y = (tile & 0x8000)? 0x7 : 0;
uint8_t palette = (tile >> 10) & 3;
for (unsigned y = 0; y < 8; y++) {
for (unsigned x = 0; x < 8; x++) {
uint8_t color = gb->sgb->border.tiles[(tile & 0xFF) * 64 + (x ^ flip_x) + (y ^ flip_y) * 8] & 0xF;
if (color == 0) {
if (gb_area) continue;
gb->screen[tile_x * 8 + x + (tile_y * 8 + y) * 0x100] = colors[0];
}
else {
gb->screen[tile_x * 8 + x + (tile_y * 8 + y) * 0x100] = border_colors[color + palette * 16];
}
}
}
}
}
}
void GB_sgb_load_default_data(GB_gameboy_t *gb)
{
#include "sgb_border.inc"
memcpy(gb->sgb->border.map, tilemap, sizeof(tilemap));
memcpy(gb->sgb->border.palette, palette, sizeof(palette));
/* Expend tileset */
for (unsigned tile = 0; tile < sizeof(tiles) / 32; tile++) {
for (unsigned y = 0; y < 8; y++) {
for (unsigned x = 0; x < 8; x++) {
gb->sgb->border.tiles[tile * 8 * 8 + y * 8 + x] =
(tiles[tile * 32 + y * 2 + 0] & (1 << (7 ^ x)) ? 1 : 0) |
(tiles[tile * 32 + y * 2 + 1] & (1 << (7 ^ x)) ? 2 : 0) |
(tiles[tile * 32 + y * 2 + 16] & (1 << (7 ^ x)) ? 4 : 0) |
(tiles[tile * 32 + y * 2 + 17] & (1 << (7 ^ x)) ? 8 : 0);
}
}
}
if (gb->model != GB_MODEL_SGB2) {
/* Delete the "2" */
gb->sgb->border.map[25 * 32 + 25] = gb->sgb->border.map[25 * 32 + 26] =
gb->sgb->border.map[26 * 32 + 25] = gb->sgb->border.map[26 * 32 + 26] =
gb->sgb->border.map[27 * 32 + 25] = gb->sgb->border.map[27 * 32 + 26] =
gb->sgb->border.map[0];
/* Re-center */
memmove(&gb->sgb->border.map[25 * 32 + 1], &gb->sgb->border.map[25 * 32], (32 * 3 - 1) * sizeof(gb->sgb->border.map[0]));
}
gb->sgb->effective_palettes[0] = 0x639E;
gb->sgb->effective_palettes[1] = 0x263A;
gb->sgb->effective_palettes[2] = 0x10D4;
gb->sgb->effective_palettes[3] = 0x2866;
}
static double fm_synth(double phase)
{
return (sin(phase * M_PI * 2) +
sin(phase * M_PI * 2 + sin(phase * M_PI * 2)) +
sin(phase * M_PI * 2 + sin(phase * M_PI * 3)) +
sin(phase * M_PI * 2 + sin(phase * M_PI * 4))) / 4;
}
static double fm_sweep(double phase)
{
double ret = 0;
for (unsigned i = 0; i < 8; i++) {
ret += sin((phase * M_PI * 2 + sin(phase * M_PI * 8) / 4) * pow(1.25, i)) * (8 - i) / 36;
}
return ret;
}
static double random_double(void)
{
return ((random() % 0x10001) - 0x8000) / (double) 0x8000;
}
bool GB_sgb_render_jingle(GB_gameboy_t *gb, GB_sample_t *dest, size_t count)
{
const double frequencies[7] = {
466.16, // Bb4
587.33, // D5
698.46, // F5
830.61, // Ab5
1046.50, // C6
1244.51, // Eb6
1567.98, // G6
};
if (gb->sgb->intro_animation < 0) {
for (unsigned i = 0; i < count; i++) {
dest->left = dest->right = 0;
dest++;
}
return true;
}
if (gb->sgb->intro_animation >= INTRO_ANIMATION_LENGTH) return false;
signed jingle_stage = (gb->sgb->intro_animation - 64) / 3;
double sweep_cutoff_ratio = 2000.0 * pow(2, gb->sgb->intro_animation / 20.0) / gb->apu_output.sample_rate;
double sweep_phase_shift = 1000.0 * pow(2, gb->sgb->intro_animation / 40.0) / gb->apu_output.sample_rate;
if (sweep_cutoff_ratio > 1) {
sweep_cutoff_ratio = 1;
}
for (unsigned i = 0; i < count; i++) {
double sample = 0;
for (signed f = 0; f < 7 && f < jingle_stage; f++) {
sample += fm_synth(gb->sgb_intro_jingle_phases[f]) *
(0.75 * pow(0.5, jingle_stage - f) + 0.25) / 5.0;
gb->sgb_intro_jingle_phases[f] += frequencies[f] / gb->apu_output.sample_rate;
}
if (gb->sgb->intro_animation > 100) {
sample *= pow((INTRO_ANIMATION_LENGTH - gb->sgb->intro_animation) / (INTRO_ANIMATION_LENGTH - 100.0), 3);
}
if (gb->sgb->intro_animation < 120) {
double next = fm_sweep(gb->sgb_intro_sweep_phase) * 0.3 + random_double() * 0.7;
gb->sgb_intro_sweep_phase += sweep_phase_shift;
gb->sgb_intro_sweep_previous_sample = next * (sweep_cutoff_ratio) +
gb->sgb_intro_sweep_previous_sample * (1 - sweep_cutoff_ratio);
sample += gb->sgb_intro_sweep_previous_sample * pow((120 - gb->sgb->intro_animation) / 120.0, 2) * 0.8;
}
dest->left = dest->right = sample * 0x7000;
dest++;
}
return true;
}
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