add drums to score screen music

src/sound.c

     }
 }
 
+static void play_drum(enum drums drum) NONBANKED {
+    switch (drum) {
+        case dKick:
+            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
+            break;
+
+        case dSnare:
+            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
+            NR44_REG = 0xC0; // trigger and enable length
+            break;
+
+        default:
+            break;
+    }
+}
+
 void snd_init(void) BANKED {
     NR52_REG = 0x80; // sound on
     NR51_REG = 0xFF; // all channels on left and right
 }
 
 static void play_current_note(void) NONBANKED {
+    if (!music) {
+        return;
+    }
+
     START_ROM_BANK(bank);
-        play_note(music->notes[off]);
+    if (music->notes) {
+        if (music->notes[off] != END) {
+            play_note(music->notes[off]);
+        }
+    }
+    if (music->drums) {
+        if (music->drums[off] != dEND) {
+            play_drum(music->drums[off]);
+        }
+    }
     END_ROM_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 += music->duration;
+
+            if (music->notes) {
+                if (music->notes[off] != END) {
+                    play_note(music->notes[off]);
+                } else {
+                    off = 0xFFFF;
+                }
+            }
+
+            if (music->drums) {
+                if (music->drums[off] != dEND) {
+                    play_drum(music->drums[off]);
+                } else {
+                    off = 0xFFFF;
+                }
+            }
         }
     END_ROM_BANK();
 }

src/sound.h

 #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
-    SIL = SILENCE,
-
-    Db0 = Cd0,
-    Eb0 = Dd0, Ed0 = F0,
-    Fb0 = E0,
-    Gb0 = Fd0,
-    Ab0 = Gd0,
-    Bb0 = Ad0,
-
-    Cb1 = B0,
-    Db1 = Cd1,
-    Eb1 = Dd1, Ed1 = F1,
-    Fb1 = E1,
-    Gb1 = Fd1,
-    Ab1 = Gd1,
-    Bb1 = Ad1,
-
-    Cb2 = B1,
-    Db2 = Cd2,
-    Eb2 = Dd2, Ed2 = F2,
-    Fb2 = E2,
-    Gb2 = Fd2,
-    Ab2 = Gd2,
-    Bb2 = Ad2,
-
-    Cb3 = B2,
-    Db3 = Cd3,
-    Eb3 = Dd3, Ed3 = F3,
-    Fb3 = E3,
-    Gb3 = Fd3,
-    Ab3 = Gd3,
-    Bb3 = Ad3,
-
-    Cb4 = B3,
-    Db4 = Cd4,
-    Eb4 = Dd4, Ed4 = F4,
-    Fb4 = E4,
-    Gb4 = Fd4,
-    Ab4 = Gd4,
-    Bb4 = Ad4,
-
-    Cb5 = B4,
-    Db5 = Cd5,
-    Eb5 = Dd5, Ed5 = F5,
-    Fb5 = E5,
-    Gb5 = Fd5,
-    Ab5 = Gd5,
-    Bb5 = Ad5,
+    C0 = 0, 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, SIL = SILENCE,                             // 72 .. 73
+
+              Db0 = Cd0, Eb0 = Dd0, Ed0 = F0,
+    Fb0 = E0, Gb0 = Fd0, Ab0 = Gd0, Bb0 = Ad0,
+
+    Cb1 = B0, Db1 = Cd1, Eb1 = Dd1, Ed1 = F1,
+    Fb1 = E1, Gb1 = Fd1, Ab1 = Gd1, Bb1 = Ad1,
+
+    Cb2 = B1, Db2 = Cd2, Eb2 = Dd2, Ed2 = F2,
+    Fb2 = E2, Gb2 = Fd2, Ab2 = Gd2, Bb2 = Ad2,
+
+    Cb3 = B2, Db3 = Cd3, Eb3 = Dd3, Ed3 = F3,
+    Fb3 = E3, Gb3 = Fd3, Ab3 = Gd3, Bb3 = Ad3,
+
+    Cb4 = B3, Db4 = Cd4, Eb4 = Dd4, Ed4 = F4,
+    Fb4 = E4, Gb4 = Fd4, Ab4 = Gd4, Bb4 = Ad4,
+
+    Cb5 = B4, Db5 = Cd5, Eb5 = Dd5, Ed5 = F5,
+    Fb5 = E5, Gb5 = Fd5, Ab5 = Gd5, Bb5 = Ad5,
+};
+
+enum drums {
+    dKick = 0, dSnare,
+    dSilence,
+
+    dKi = dKick, dSn = dSnare,
+    dSI = dSilence,
+    dEND,
 };
 
 struct music {
     enum notes * const notes;
+    enum drums * const drums;
     uint16_t duration;
 };
 

src/sound_game.c

 
 const struct music music_game = {
     .notes = game_music,
+    .drums = NULL,
     .duration = 200,
 };

src/sound_menu.c

 
 const struct music music_menu = {
     .notes = menu_music,
+    .drums = NULL,
     .duration = 200,
 };

src/sound_over.c

 
 BANKREF(sound_over)
 
-const enum notes over_music[] = {
+const enum notes over_notes[] = {
     // fanfare
     /*
      C3,  C3,  C3,  C3, Ab2, Ab2, Bb2, Bb2,
     END
 };
 
+#define DRUM_LOOP \
+    dKi, dSI, dSI, dSI, dSI, dSI, dKi, dSI, \
+    dSn, dSI, dSI, dSI, dKi, dSI, dSI, dSI \
+
+const enum drums over_drums[] = {
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+    DRUM_LOOP,
+
+    dSI, dSI, dSI, dSI, dSI, dSI, dSI, dSI,
+    dSI, dSI, dSI, dSI, dSI, dSI, dSI, dSI,
+    dEND
+};
+
 const struct music music_over = {
-    .notes = over_music,
+    .notes = over_notes,
+    .drums = over_drums,
     .duration = 120,
 };