Update sequencer to use timers w/ different bpms

2 files changed, 82 insertions, 75 deletions

diff --git a/src/common.h b/src/common.h
index 4151d18..ece94cd 100644
--- a/src/common.h
+++ b/src/common.h
@@ -224,6 +224,7 @@ flip_page(void) {
 #define TIMER_CTRL_CASCADE (1 << 2)
 #define TIMER_CTRL_IRQ     (1 << 6)
 #define TIMER_CTRL_ENABLE  (1 << 7)
+#define TIMER_CTRL_DISABLE (0 << 7)
 
 // We use timers 2 and 3 to count the number of cycles since the profile_start
 // functions is called. Don't use if the code we are trying to profile make use
diff --git a/src/main.c b/src/main.c
index ac6bf66..b2cd2d2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -13,6 +13,64 @@
 // TODO: Cleanup OBJ/OAM memory copying and access.
 //
 
+typedef struct SeqTrigger {
+    bool trigger;
+    Note note;
+    // TODO: ...
+} SeqTrigger;
+
+static SeqTrigger sequence_synth_1 [] = {
+    {true, NOTE_D_4},
+    {true, NOTE_F_4},
+    {true, NOTE_A_4},
+    {true, NOTE_C_5},
+
+    {true, NOTE_D_4},
+    {false, NOTE_D_4},
+    {false, NOTE_D_4},
+    {false, NOTE_D_4},
+
+    {true, NOTE_D_4},
+    {true, NOTE_F_4},
+    {true, NOTE_A_4},
+    {true, NOTE_C_5},
+
+    {true, NOTE_D_4},
+    {false, NOTE_D_4},
+    {true, NOTE_A_4},
+    {false, NOTE_A_5},
+};
+
+int step_counter = 0;
+Note active_note;
+void
+irq_timer_0(void) {
+    active_note = sequence_synth_1[step_counter].note;
+    if (sequence_synth_1[step_counter].trigger) {
+        SOUND_SQUARE1_CTRL = SOUND_SQUARE_ENV_VOL(13) | SOUND_SQUARE_ENV_TIME(4) | SOUND_SQUARE_DUTY(2);
+        SOUND_SQUARE1_FREQ = SOUND_SQUARE_RESET | sound_rates[active_note];
+    }
+
+    step_counter = (step_counter + 1) % 16;
+}
+
+void
+set_time(int bpm) {
+    // TIMER_CTRL_0 = TIMER_CTRL_DISABLE;
+
+    // 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
+    //     Y ms  -> Ye-3 / 59.99e-9 /1024 = Z ticks
+    // We have to operate on integer values, so the numbers have been
+    // precalculated to `n_ticks = 244181 / bmp`
+    int n_ticks = -244181 / bpm;
+
+    irs_set(IRQ_TIMER_0, irq_timer_0);
+    TIMER_DATA_0 = n_ticks;
+    TIMER_CTRL_0 = TIMER_CTRL_IRQ | TIMER_CTRL_ENABLE | TIMER_CTRL_FREQ_3;
+}
+
 int main(void) {
     // Configure the display in mode 0 to show OBJs, where tile memory is
     // sequential.
@@ -35,91 +93,39 @@ int main(void) {
     SOUND_DMG_MASTER = sound_volume(SOUND_SQUARE1 | SOUND_SQUARE2, 7);
     SOUND_DSOUND_MASTER = SOUND_DMG100;
 
-    Note active_note = NOTE_C_4;
-    int octave_diff = 0;
-    bool playing = false;
-    bool new_note = false;
-    u8 interval = 7;
-    u32 sound_sequence[16] = {
-        NOTE_C_4,
-        NOTE_A_4,
-        NOTE_D_5,
-        NOTE_D_4,
-        NOTE_F_4,
-        NOTE_G_4,
-        NOTE_C_4,
-        NOTE_A_4,
-        NOTE_D_5,
-        NOTE_D_4,
-        NOTE_F_4,
-        NOTE_G_4,
-        NOTE_A_4,
-        NOTE_G_4,
-        NOTE_A_4,
-        NOTE_F_4,
-    };
-    int step_counter = 0;
-    int step_counter_2 = 0;
-    int frame_counter = 0;
-    bool trigger_1 = true;
-    bool trigger_2 = true;
+    // Initialize timer.
+    int bpm = 120;
+
     while(true) {
         bios_vblank_wait();
         poll_keys();
-
-        txt_position(0, 1);
-
-        if (frame_counter >= 7 * 4) {
-            if ((step_counter + 1) % 4 == 0) {
-                step_counter_2 = (step_counter_2 + 1) % 16;
-                trigger_2 = true;
-            }
-            trigger_1 = true;
-            frame_counter = 0;
-            step_counter = (step_counter + 1) % 16;
-        }
-
-        if (trigger_1 && playing) {
-            active_note = sound_sequence[step_counter];
-            txt_clear_line();
-            txt_printf("SYNTH 1\n\n");
-            txt_clear_line();
-            txt_printf("Step: %d\n", step_counter);
-            txt_clear_line();
-            txt_printf("Playing: %s\n\n\n\n", note_names[active_note]);
-            SOUND_SQUARE1_CTRL = SOUND_SQUARE_ENV_VOL(13) | SOUND_SQUARE_ENV_TIME(4) | SOUND_SQUARE_DUTY(1);
-            SOUND_SQUARE1_FREQ = SOUND_SQUARE_RESET | sound_rates[active_note];
-            trigger_1 = false;
+        if (key_hold(KEY_UP)) {
+            bpm += 1;
+            set_time(bpm);
         }
-
-        if (trigger_2 && playing) {
-            active_note = sound_sequence[step_counter_2];
-            txt_clear_line();
-            txt_printf("SYNTH 2\n\n");
-            txt_clear_line();
-            txt_printf("Step: %d\n", step_counter_2);
-            txt_clear_line();
-            txt_printf("Playing: %s\n", note_names[active_note]);
-            SOUND_SQUARE2_CTRL = SOUND_SQUARE_ENV_VOL(12) | SOUND_SQUARE_ENV_TIME(3) | SOUND_SQUARE_DUTY(3);
-            SOUND_SQUARE2_FREQ = SOUND_SQUARE_RESET | sound_rates[active_note];
-            trigger_2 = false;
+        if (key_hold(KEY_DOWN)) {
+            bpm -= 1;
+            set_time(bpm);
         }
 
-        if (key_pressed(KEY_B)) {
-            playing = true;
+        if (key_pressed(KEY_START)) {
             step_counter = 0;
-            step_counter_2 = 8;
-            frame_counter = 0;
-            trigger_1 = true;
-            trigger_2 = true;
+            set_time(bpm);
         }
-
-        if (key_pressed(KEY_A)) {
-            playing = false;
+        if (key_pressed(KEY_SELECT)) {
+            TIMER_CTRL_0 ^= TIMER_CTRL_ENABLE;
         }
 
-        frame_counter++;
-        // update_button_sprites();
+        txt_position(1,6);
+        txt_clear_line();
+        txt_printf(" BPM: %d\n\n", bpm);
+
+        txt_clear_line();
+        txt_printf(" Step: %d\n", step_counter);
+        txt_clear_line();
+        txt_printf(" Note: %s\n", note_names[active_note]);
+
+        update_button_sprites();
     };
 
     return 0;