From f0ebc747d1b0d8753a1bc0f74b34a3012dd16753 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Tue, 30 May 2023 21:52:30 +0200
Subject: Properly handle audio/link sync settings

---
 src/gba/gba.h   | 12 ++++++++++--
 src/sequencer.c | 12 +++++++-----
 src/settings.c  | 31 +++++++++++++++++++++++++++++++
 src/settings.h  | 12 ++++++++++++
 4 files changed, 60 insertions(+), 7 deletions(-)

diff --git a/src/gba/gba.h b/src/gba/gba.h
index 2b28295..74b6942 100644
--- a/src/gba/gba.h
+++ b/src/gba/gba.h
@@ -510,10 +510,18 @@ typedef enum {
 } SoundChannel;
 
 inline u16
-sound_volume(SoundChannel channels, u8 volume) {
+sound_volume(SoundChannel channels, u8 volume, u8 pan) {
     volume = volume & 0x7;
     channels = channels & 0xF;
-    return volume | (volume << 0x4) | (channels << 0x8) | (channels << 0xC);
+    u16 right = volume | (channels << 0x8);
+    u16 left = (volume << 0x4) | (channels << 0xC);
+    if (pan == 1) {
+        return left;
+    }
+    if (pan == 2) {
+        return right;
+    }
+    return left | right;
 }
 
 // Sound Direct Sound master bits.
diff --git a/src/sequencer.c b/src/sequencer.c
index d8c5f3f..2ee6b07 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -45,7 +45,6 @@ gate_on(void) {
     irs_set(IRQ_TIMER_3, gate_off);
     TIMER_DATA_3 = n_ticks;
     TIMER_CTRL_3 = TIMER_CTRL_IRQ | TIMER_CTRL_ENABLE | TIMER_CTRL_FREQ_3;
-    audio_sync_click = true;
 }
 
 void
@@ -169,6 +168,12 @@ play_step(void) {
         case SYNC_OUT_LINK_16: { gate_on(); } break;
         case SYNC_OUT_LINK_8: { if (step_counter % 2 == 0) { gate_on(); } } break;
         case SYNC_OUT_LINK_4: { if (step_counter % 4 == 0) { gate_on(); } } break;
+        case SYNC_OUT_AUDIO_16: { audio_sync_click = true; } break;
+        case SYNC_OUT_AUDIO_8: { if (step_counter % 2 == 0) { audio_sync_click = true; } } break;
+        case SYNC_OUT_AUDIO_4: { if (step_counter % 4 == 0) { audio_sync_click = true; } } break;
+        case SYNC_OUT_LINK_AUDIO_16: { gate_on(); audio_sync_click = true; } break;
+        case SYNC_OUT_LINK_AUDIO_8: { if (step_counter % 2 == 0) { gate_on(); audio_sync_click = true; } } break;
+        case SYNC_OUT_LINK_AUDIO_4: { if (step_counter % 4 == 0) { gate_on(); audio_sync_click = true; } } break;
         default: break;
     }
     step_counter = (step_counter + 1) % 16;
@@ -1033,9 +1038,6 @@ sequencer_init(void) {
 
     // Initialize sound system.
     SOUND_STATUS = SOUND_ENABLE;
-    SOUND_DMG_MASTER = sound_volume(SOUND_SQUARE1
-            | SOUND_SQUARE2
-            | SOUND_WAVE
-            | SOUND_NOISE, 3);
     init_dsound();
+    set_audio_settings();
 }
diff --git a/src/settings.c b/src/settings.c
index d9d890d..b814e1a 100644
--- a/src/settings.c
+++ b/src/settings.c
@@ -13,6 +13,35 @@ draw_settings_cursor(void) {
     draw_line(x + 3, y + 5, x + 3, y + 5, COL_ACC_0);
 }
 
+void
+set_audio_settings(void) {
+    switch (settings.sync) {
+        case SYNC_OUT_LINK_AUDIO_4:
+        case SYNC_OUT_LINK_AUDIO_8:
+        case SYNC_OUT_LINK_AUDIO_16:
+        case SYNC_OUT_AUDIO_4:
+        case SYNC_OUT_AUDIO_8:
+        case SYNC_OUT_AUDIO_16: {
+            SOUND_DMG_MASTER = sound_volume(SOUND_SQUARE1
+                    | SOUND_SQUARE2
+                    | SOUND_WAVE
+                    | SOUND_NOISE, 3, 2);
+            SOUND_DSOUND_MASTER =
+                    SOUND_DMG100
+                    | SOUND_DSOUND_RATIO_A
+                    | SOUND_DSOUND_LEFT_A
+                    | SOUND_DSOUND_RESET_A;
+        } break;
+        default: {
+            SOUND_DMG_MASTER = sound_volume(SOUND_SQUARE1
+                    | SOUND_SQUARE2
+                    | SOUND_WAVE
+                    | SOUND_NOISE, 3, 0);
+            SOUND_DSOUND_MASTER = SOUND_DMG100;
+        } break;
+    }
+}
+
 void
 handle_settings_input(void) {
     if (key_tap(KEY_DOWN)) {
@@ -39,6 +68,7 @@ handle_settings_input(void) {
                 } else {
                     settings.sync++;
                 }
+                set_audio_settings();
             } break;
             case 1: {
                 if ((settings.theme + 1) >= THEME_NUM) {
@@ -67,6 +97,7 @@ handle_settings_input(void) {
                 } else {
                     settings.sync--;
                 }
+                set_audio_settings();
             } break;
             case 1: {
                 if (settings.theme == 0) {
diff --git a/src/settings.h b/src/settings.h
index 370c03c..960eabc 100644
--- a/src/settings.h
+++ b/src/settings.h
@@ -8,6 +8,12 @@ typedef enum SyncSetting {
     SYNC_OUT_LINK_16,
     SYNC_OUT_LINK_8,
     SYNC_OUT_LINK_4,
+    SYNC_OUT_AUDIO_16,
+    SYNC_OUT_AUDIO_8,
+    SYNC_OUT_AUDIO_4,
+    SYNC_OUT_LINK_AUDIO_16,
+    SYNC_OUT_LINK_AUDIO_8,
+    SYNC_OUT_LINK_AUDIO_4,
     SYNC_NUM,
 } SyncSetting;
 
@@ -16,6 +22,12 @@ char * sync_setting_str[] = {
     "LINK OUT (16)",
     "LINK OUT (8)",
     "LINK OUT (4)",
+    "AUDIO OUT (16)",
+    "AUDIO OUT (8)",
+    "AUDIO OUT (4)",
+    "LINK+AUDIO OUT (16)",
+    "LINK+AUDIO OUT (8)",
+    "LINK+AUDIO OUT (4)",
 };
 
 typedef enum  ThemeSetting {
-- 
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