add 1kHz timer and music (placeholder notes)

src/game.c

@@ -58,6 +58,8 @@ enum ACCELERATION {
 };
 
 static uint8_t pause_screen(void) NONBANKED {
+    snd_music_off();
+
     uint8_t n = 0;
 
     while (1) {
@@ -118,6 +120,8 @@ static void status(uint8_t health, uint8_t power, uint8_t *hiwater) NONBANKED {
 }
 
 static void show_explosion(uint16_t power) NONBANKED {
+    snd_music_off();
+
     snd_explode();
 
     for (uint8_t n = 0; n < (4 * 4); n++) {
@@ -160,7 +164,11 @@ int32_t game(void) NONBANKED {
     DISPLAY_ON;
     enable_interrupts();
 
+    snd_music_off();
+    snd_game_music();
+
     while(1) {
+        snd_play();
         key_read();
 
         enum ACCELERATION acc = 0;

src/main.c

@@ -33,6 +33,7 @@
 #include "score.h"
 #include "sgb_border.h"
 #include "border_sgb.h"
+#include "timer.h"
 #include "main.h"
 
 #ifdef DEBUG
@@ -205,7 +206,11 @@ static void splash(void) NONBANKED {
     DISPLAY_ON;
     enable_interrupts();
 
+    snd_music_off();
+    snd_menu_music();
+
     while (1) {
+        snd_play();
         key_read();
 
         if (key_pressed(J_LEFT)) {
@@ -307,6 +312,8 @@ static uint16_t ask_name(int32_t score) NONBANKED {
     DISPLAY_ON;
     enable_interrupts();
 
+    snd_gameover_music();
+
     char name[3] = { 'a', 'a', 'a' };
     uint8_t pos = 0;
     win_name_draw(convert_name(name[0], name[1], name[2]), score < 0, pos);
@@ -384,6 +391,7 @@ void main(void) NONBANKED {
         cpu_fast();
     }
 
+    timer_init();
     spr_init();
     snd_init();
 

src/sound.c

@@ -23,11 +23,48 @@
  * See <http://www.gnu.org/licenses/>.
  */
 
-#include <gbdk/platform.h>
-
+#include "banks.h"
+#include "timer.h"
+#include "sound_menu.h"
+#include "sound_game.h"
+#include "sound_over.h"
 #include "sound.h"
 
-void snd_init(void) NONBANKED {
+BANKREF(sound)
+
+const uint16_t frequencies[SILENCE] = {
+      44,  156,  262,  363,  457,  547,  631,  710,  786,  854,  923,  986, //  0 .. 11
+    1046, 1102, 1155, 1205, 1253, 1297, 1339, 1379, 1417, 1452, 1486, 1517, // 12 .. 23
+    1546, 1575, 1602, 1627, 1650, 1673, 1694, 1714, 1732, 1750, 1767, 1783, // 24 .. 35
+    1798, 1812, 1825, 1837, 1849, 1860, 1871, 1881, 1890, 1899, 1907, 1915, // 36 .. 47
+    1923, 1930, 1936, 1943, 1949, 1954, 1959, 1964, 1969, 1974, 1978, 1982, // 48 .. 59
+    1985, 1988, 1992, 1995, 1998, 2001, 2004, 2006, 2009, 2011, 2013, 2015  // 60 .. 71
+};
+
+static struct music const * music = NULL;
+static uint8_t bank;
+static uint16_t off = 0;
+static uint16_t last_t = 0;
+
+static void play_note(enum notes note) NONBANKED {
+    if (note < SILENCE) {
+        START_ROM_BANK(BANK(sound));
+            uint16_t freq = frequencies[note];
+        END_ROM_BANK();
+
+        NR11_REG = 0x80 | 0x3F; // 50% duty, shortest initial length
+        NR12_REG = 0xF0; // max volume, no change
+        NR13_REG = freq & 0xFF; // given frequency
+        NR14_REG = 0x80 | ((freq >> 8) & 0x07); // trigger, upper freq bits
+    } else {
+        NR11_REG = 0x80 | 0x3F; // 50% duty, shortest initial length
+        NR12_REG = 0x10; // 'lowest' volume without pop, no change
+        NR13_REG = 0x00; // lowest frequency
+        NR14_REG = 0x80 | 0x40 | 0x00; // trigger, enable length, upper freq bits
+    }
+}
+
+void snd_init(void) BANKED {
     NR52_REG = 0x80; // sound on
     NR51_REG = 0xFF; // all channels on left and right
 
@@ -38,14 +75,70 @@ void snd_init(void) NONBANKED {
 #endif
 }
 
-void snd_shot(void) NONBANKED {
+void snd_music_off(void) BANKED {
+    play_note(SILENCE);
+}
+
+void snd_menu_music(void) BANKED {
+    music = &music_menu;
+    bank = BANK(sound_menu);
+    off = 0;
+    last_t = timer_get();
+
+    START_ROM_BANK(bank);
+        play_note(music->notes[off]);
+    END_ROM_BANK();
+}
+
+void snd_game_music(void) BANKED {
+    music = &music_game;
+    bank = BANK(sound_game);
+    off = 0;
+    last_t = timer_get();
+
+    START_ROM_BANK(bank);
+    play_note(music->notes[off]);
+    END_ROM_BANK();
+}
+
+void snd_gameover_music(void) BANKED {
+    music = &music_over;
+    bank = BANK(sound_over);
+    off = 0;
+    last_t = timer_get();
+
+    START_ROM_BANK(bank);
+    play_note(music->notes[off]);
+    END_ROM_BANK();
+}
+
+void snd_play(void) NONBANKED {
+    if (!music) {
+        return;
+    }
+
+    START_ROM_BANK(bank);
+        uint16_t diff = timer_get() - last_t;
+        if (diff >= music->duration) {
+            off++;
+            if (music->notes[off] != END) {
+                play_note(music->notes[off]);
+            } else {
+                off = 0xFFFF;
+            }
+            last_t = timer_get();
+        }
+    END_ROM_BANK();
+}
+
+void snd_shot(void) BANKED {
     NR41_REG = 0x2F; // length timer, higher value is shorter time (up to 0x3F)
     NR42_REG = 0xF0; // initially full volume, no volume changes over time
     NR43_REG = 0x11; // frequency distribution
     NR44_REG = 0xC0; // trigger and enable length
 }
 
-void snd_explode(void) NONBANKED {
+void snd_explode(void) BANKED {
     NR41_REG = 0x00; // length timer, higher value is shorter time (up to 0x3F)
     NR42_REG = 0xF1; // initially full volume, then fade sound out
     NR43_REG = 0x46; // frequency distribution

src/sound.h

@@ -20,8 +20,34 @@
 #ifndef __SOUND_H__
 #define __SOUND_H__
 
-void snd_init(void);
-void snd_shot(void);
-void snd_explode(void);
+#include <gbdk/platform.h>
+
+enum notes {
+    C0, Cd0, D0, Dd0, E0, F0, Fd0, G0, Gd0, A0, Ad0, B0, //  0 .. 11
+    C1, Cd1, D1, Dd1, E1, F1, Fd1, G1, Gd1, A1, Ad1, B1, // 12 .. 23
+    C2, Cd2, D2, Dd2, E2, F2, Fd2, G2, Gd2, A2, Ad2, B2, // 24 .. 35
+    C3, Cd3, D3, Dd3, E3, F3, Fd3, G3, Gd3, A3, Ad3, B3, // 36 .. 47
+    C4, Cd4, D4, Dd4, E4, F4, Fd4, G4, Gd4, A4, Ad4, B4, // 48 .. 59
+    C5, Cd5, D5, Dd5, E5, F5, Fd5, G5, Gd5, A5, Ad5, B5, // 60 .. 71
+    SILENCE, END                                         // 72 .. 73
+};
+
+struct music {
+    enum notes * const notes;
+    uint16_t duration;
+};
+
+void snd_init(void) BANKED;
+
+void snd_music_off(void) BANKED;
+void snd_menu_music(void) BANKED;
+void snd_game_music(void) BANKED;
+void snd_gameover_music(void) BANKED;
+void snd_play(void);
+
+void snd_shot(void) BANKED;
+void snd_explode(void) BANKED;
+
+BANKREF_EXTERN(sound)
 
 #endif // __SOUND_H__

src/sound_game.c

@@ -0,0 +1,44 @@
+/*
+ * sound_game.c
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * Based on examples from gbdk-2020:
+ * https://github.com/gbdk-2020/gbdk-2020/blob/develop/gbdk-lib/examples/gb/sound/sound.c
+ *
+ * And the docs for the DMG APU:
+ * https://gbdev.io/pandocs/Audio_Registers.html
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#include "banks.h"
+#include "sound_game.h"
+
+BANKREF(sound_game)
+
+const enum notes game_music[] = {
+    C3, C3, G3, G3, A3, A3, G3, SILENCE,
+    F3, F3, E3, E3, D3, D3, C3, SILENCE,
+    G3, G3, F3, F3, E3, E3, D3, D3,
+    G3, G3, F3, F3, E3, E3, D3, D3,
+    C3, C3, G3, G3, A3, A3, G3, SILENCE,
+    F3, F3, E3, E3, D3, D3, C3, SILENCE,
+    SILENCE, SILENCE, END
+};
+
+const struct music music_game = {
+    .notes = game_music,
+    .duration = 200,
+};

src/sound_game.h

@@ -0,0 +1,29 @@
+/*
+ * sound_game.h
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __SOUND_GAME_H__
+#define __SOUND_GAME_H__
+
+#include "sound.h"
+
+extern const struct music music_game;
+
+BANKREF_EXTERN(sound_game)
+
+#endif // __SOUND_GAME_H__

src/sound_menu.c

@@ -0,0 +1,44 @@
+/*
+ * sound_menu.c
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * Based on examples from gbdk-2020:
+ * https://github.com/gbdk-2020/gbdk-2020/blob/develop/gbdk-lib/examples/gb/sound/sound.c
+ *
+ * And the docs for the DMG APU:
+ * https://gbdev.io/pandocs/Audio_Registers.html
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#include "banks.h"
+#include "sound_menu.h"
+
+BANKREF(sound_menu)
+
+const enum notes menu_music[] = {
+    C3, C3, G3, G3, A3, A3, G3, SILENCE,
+    F3, F3, E3, E3, D3, D3, C3, SILENCE,
+    G3, G3, F3, F3, E3, E3, D3, D3,
+    G3, G3, F3, F3, E3, E3, D3, D3,
+    C3, C3, G3, G3, A3, A3, G3, SILENCE,
+    F3, F3, E3, E3, D3, D3, C3, SILENCE,
+    SILENCE, SILENCE, END
+};
+
+const struct music music_menu = {
+    .notes = menu_music,
+    .duration = 200,
+};

src/sound_menu.h

@@ -0,0 +1,29 @@
+/*
+ * sound_menu.h
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __SOUND_MENU_H__
+#define __SOUND_MENU_H__
+
+#include "sound.h"
+
+extern const struct music music_menu;
+
+BANKREF_EXTERN(sound_menu)
+
+#endif // __SOUND_MENU_H__

src/sound_over.c

@@ -0,0 +1,44 @@
+/*
+ * sound_over.c
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * Based on examples from gbdk-2020:
+ * https://github.com/gbdk-2020/gbdk-2020/blob/develop/gbdk-lib/examples/gb/sound/sound.c
+ *
+ * And the docs for the DMG APU:
+ * https://gbdev.io/pandocs/Audio_Registers.html
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#include "banks.h"
+#include "sound_over.h"
+
+BANKREF(sound_over)
+
+const enum notes over_music[] = {
+    C3, C3, G3, G3, A3, A3, G3, SILENCE,
+    F3, F3, E3, E3, D3, D3, C3, SILENCE,
+    G3, G3, F3, F3, E3, E3, D3, D3,
+    G3, G3, F3, F3, E3, E3, D3, D3,
+    C3, C3, G3, G3, A3, A3, G3, SILENCE,
+    F3, F3, E3, E3, D3, D3, C3, SILENCE,
+    SILENCE, SILENCE, END
+};
+
+const struct music music_over = {
+    .notes = over_music,
+    .duration = 200,
+};

src/sound_over.h

@@ -0,0 +1,29 @@
+/*
+ * sound_over.h
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __SOUND_OVER_H__
+#define __SOUND_OVER_H__
+
+#include "sound.h"
+
+extern const struct music music_over;
+
+BANKREF_EXTERN(sound_over)
+
+#endif // __SOUND_OVER_H__

src/timer.c

@@ -0,0 +1,50 @@
+/*
+ * timer.c
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#include "timer.h"
+#include "gb/gb.h"
+
+static volatile uint16_t count;
+
+static void timer_isr(void) NONBANKED {
+    count++;
+}
+
+void timer_init(void) BANKED {
+    CRITICAL {
+        count = 0;
+        add_TIM(timer_isr);
+        if (_cpu == CGB_TYPE) {
+            TMA_REG = 0x100 - 131; // 131.072kHz / 131 = ~1000Hz
+        } else {
+            TMA_REG = 0x100 - 65; // 65.536kHz / 65 = ~1008Hz
+        }
+        TAC_REG = TACF_65KHZ | TACF_START;
+
+        set_interrupts(TIM_IFLAG | VBL_IFLAG);
+    }
+}
+
+uint16_t timer_get(void) BANKED {
+    uint16_t r;
+    CRITICAL {
+        r = count;
+    }
+    return r;
+}

src/timer.h

@@ -0,0 +1,29 @@
+/*
+ * timer.h
+ * Duality
+ *
+ * Copyright (C) 2025 Thomas Buck <thomas@xythobuz.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * See <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __TIMER_H__
+#define __TIMER_H__
+
+#include <gbdk/platform.h>
+#include <stdint.h>
+
+void timer_init(void) BANKED;
+uint16_t timer_get(void) BANKED;
+
+#endif // __TIMER_H__