From 300ca4c16a45ef129a65a5520eab068f1f74c29b Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 31 May 2023 18:21:30 +0200
Subject: Add link cable sync in

---
 Makefile        |  2 +-
 src/main.c      |  4 +++-
 src/sequencer.c | 46 ++++++++++++++++++++++++++++++++++------------
 src/settings.c  | 20 ++++++++++++++++++++
 src/settings.h  |  2 ++
 5 files changed, 60 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index 5ccc725..ff4204f 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,7 @@ INC_FLAGS   := $(addprefix -I,$(INC_DIRS))
 INC_FLAGS   += -I$(LIBGBA_SRC)
 
 # Output library names and executables.
-TARGET         := STEPPER-v1.4-dev
+TARGET         := STEPPER-v1.4-dev-syncin
 ELF            := $(BUILD_DIR)/$(TARGET).elf
 BIN            := $(BUILD_DIR)/$(TARGET).gba
 
diff --git a/src/main.c b/src/main.c
index 0d4056a..ab5bccf 100644
--- a/src/main.c
+++ b/src/main.c
@@ -32,9 +32,11 @@ WITH REGARD TO THIS SOFTWARE.
 //  - Select + up/down to queue the next pattern as we move to it?
 //
 //  Advanced
-//  + Sync via CV by using the link cable.
+//  + Sync (OUT) via CV by using the link cable.
 //  + Audio sync by panning left the sound and using right as a click (or
 //    viceversa, needs to check the standard.)
+//  + Sync (IN) via CV by using the link cable.
+//  - Add tap tempo for BPM.
 //  - Allow "marking" several trigs to be able to copy/paste them and/or adjust
 //    their parameters.
 //  - Per trig note probability.
diff --git a/src/sequencer.c b/src/sequencer.c
index 2ee6b07..5120805 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -182,6 +182,9 @@ play_step(void) {
 
 void
 set_time(int bpm) {
+    if (settings.sync == SYNC_IN_LINK) {
+        return;
+    }
     // The number of ticks of a 1024 cycle clock in a step based on the BPM can
     // be calculated as:
     //     X bpm -> 60000 / 4 / bpm = Y ms = Ye-3 s
@@ -299,9 +302,8 @@ handle_channel_selection(void) {
 }
 
 void
-stop_playing(void) {
+stop_sound(void) {
     play_status = 0;
-    step_counter = 0;
     TIMER_CTRL_2 = 0;
     SOUND_SQUARE1_CTRL = 0;
     SOUND_SQUARE2_CTRL = 0;
@@ -310,10 +312,25 @@ stop_playing(void) {
     redraw_play_pause = true;
 }
 
+void
+stop_playing(void) {
+    step_counter = 0;
+    stop_sound();
+}
+
 void
 toggle_playing(void) {
     play_status ^= 1;
     step_counter = 0;
+    SOUND_SQUARE1_CTRL = 0;
+    SOUND_SQUARE2_CTRL = 0;
+    SOUND_WAVE_CTRL = 0;
+    SOUND_NOISE_CTRL = 0;
+    redraw_play_pause = true;
+    if (settings.sync == SYNC_IN_LINK) {
+        return;
+    }
+
     if ((TIMER_CTRL_2 & TIMER_CTRL_ENABLE) == 0) {
         if (current_pattern != next_pattern) {
             current_pattern = next_pattern;
@@ -323,17 +340,20 @@ toggle_playing(void) {
         play_step();
     } else {
         TIMER_CTRL_2 ^= TIMER_CTRL_ENABLE;
-        SOUND_SQUARE1_CTRL = 0;
-        SOUND_SQUARE2_CTRL = 0;
-        SOUND_WAVE_CTRL = 0;
-        SOUND_NOISE_CTRL = 0;
     }
-    redraw_play_pause = true;
 }
 
 void
 pause_playing(void) {
     play_status ^= 1;
+    SOUND_SQUARE1_CTRL = 0;
+    SOUND_SQUARE2_CTRL = 0;
+    SOUND_WAVE_CTRL = 0;
+    SOUND_NOISE_CTRL = 0;
+    redraw_play_pause = true;
+    if (settings.sync == SYNC_IN_LINK) {
+        return;
+    }
     if ((TIMER_CTRL_2 & TIMER_CTRL_ENABLE) == 0) {
         if (current_pattern != next_pattern && step_counter == 0) {
             current_pattern = next_pattern;
@@ -343,12 +363,7 @@ pause_playing(void) {
         play_step();
     } else {
         TIMER_CTRL_2 ^= TIMER_CTRL_ENABLE;
-        SOUND_SQUARE1_CTRL = 0;
-        SOUND_SQUARE2_CTRL = 0;
-        SOUND_WAVE_CTRL = 0;
-        SOUND_NOISE_CTRL = 0;
     }
-    redraw_play_pause = true;
 }
 
 void
@@ -1006,6 +1021,13 @@ handle_sequencer_input(void) {
     }
 }
 
+void
+serial_irq() {
+    if (play_status) {
+        play_step();
+    }
+}
+
 void
 sequencer_init(void) {
     stop_playing();
diff --git a/src/settings.c b/src/settings.c
index b814e1a..2c698d1 100644
--- a/src/settings.c
+++ b/src/settings.c
@@ -13,8 +13,25 @@ draw_settings_cursor(void) {
     draw_line(x + 3, y + 5, x + 3, y + 5, COL_ACC_0);
 }
 
+void serial_irq(void);
+void stop_sound(void);
+void toggle_playing(void);
+
 void
 set_audio_settings(void) {
+    stop_sound();
+    if (settings.sync == SYNC_IN_LINK) {
+        irs_set(IRQ_SERIAL, serial_irq);
+        irs_set(IRQ_TIMER_2, NULL);
+        SIO_MODE = SIO_MODE_GP
+            | SIO_SC_OUT(0)
+            | SIO_SD_OUT(0)
+            | SIO_SI_OUT(0)
+            | SIO_SO_OUT(0)
+            | SIO_IRQ_ENABLE;
+    } else {
+        irs_set(IRQ_SERIAL, NULL);
+    }
     switch (settings.sync) {
         case SYNC_OUT_LINK_AUDIO_4:
         case SYNC_OUT_LINK_AUDIO_8:
@@ -121,4 +138,7 @@ handle_settings_input(void) {
     if (key_tap(KEY_A)) {
         next_scene = SCENE_SEQUENCER;
     }
+    if (key_tap(KEY_START)) {
+        toggle_playing();
+    }
 }
diff --git a/src/settings.h b/src/settings.h
index 960eabc..1a45d75 100644
--- a/src/settings.h
+++ b/src/settings.h
@@ -14,6 +14,7 @@ typedef enum SyncSetting {
     SYNC_OUT_LINK_AUDIO_16,
     SYNC_OUT_LINK_AUDIO_8,
     SYNC_OUT_LINK_AUDIO_4,
+    SYNC_IN_LINK,
     SYNC_NUM,
 } SyncSetting;
 
@@ -28,6 +29,7 @@ char * sync_setting_str[] = {
     "LINK+AUDIO OUT (16)",
     "LINK+AUDIO OUT (8)",
     "LINK+AUDIO OUT (4)",
+    "LINK IN",
 };
 
 typedef enum  ThemeSetting {
-- 
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