Add sweep in UI and parameter controls

3 files changed, 376 insertions, 78 deletions

diff --git a/src/common.h b/src/common.h
index b688711..d78f11a 100644
--- a/src/common.h
+++ b/src/common.h
@@ -105,7 +105,7 @@ rgb15(u32 red, u32 green, u32 blue ) {
 #define COLOR_RED   rgb15(31, 0, 12)
 #define COLOR_BLUE  rgb15(2, 15, 30)
 #define COLOR_CYAN  rgb15(0, 30, 30)
-#define COLOR_GREY  rgb15(4, 4, 4)
+#define COLOR_GREY  rgb15(12, 12, 12)
 #define COLOR_BLACK rgb15(0, 0, 0)
 #define COLOR_WHITE rgb15(28, 28, 28)
 
@@ -594,9 +594,14 @@ sound_volume(SoundChannel channels, u8 volume) {
 #define SOUND_SQUARE_LEN(N)      (N)
 #define SOUND_SQUARE_DUTY(N)     ((N) << 0x6)
 #define SOUND_SQUARE_ENV_TIME(N) ((N) << 0x8)
-#define SOUND_SQUARE_ENV_INC(N)  ((N) << 0xB)
+#define SOUND_SQUARE_ENV_DIR(N)  ((N) << 0xB)
 #define SOUND_SQUARE_ENV_VOL(N)  ((N) << 0xC)
 
+// DMG square 1 sweep control bits.
+#define SOUND_SWEEP_NUMBER(N) (N)
+#define SOUND_SWEEP_DIR(N)    ((N) << 0x3)
+#define SOUND_SWEEP_TIME(N)   ((N) << 0x4)
+
 // DMG square frequency bits.
 #define SOUND_SQUARE_TIMED (1 << 0xE)
 #define SOUND_SQUARE_RESET (1 << 0xF)
diff --git a/src/main.c b/src/main.c
index d64208e..b93abe6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,11 +20,6 @@ int main(void) {
     // sequential.
     DISP_CTRL = DISP_ENABLE_SPRITES | DISP_MODE_0 | DISP_BG_0;
 
-    // Initialize sprite button overlay.
-    init_sprite_pal(0, COLOR_WHITE);
-    init_sprite_pal(16, COLOR_CYAN);
-    init_sprite_pal(32, COLOR_RED);
-    init_sprites(0);
     init_sequencer_sprites();
 
     // Initialize text engine.
diff --git a/src/sequencer.c b/src/sequencer.c
index 5db1b5d..b55ceca 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -101,7 +101,7 @@ u32 sprite_env_label_volume[] = {
     0xaaeaaaaa, 0xae000000, 0x0e020602, 0x0e000000,
 };
 
-u32 sprite_env_label_time[] = {
+u32 sprite_env_sweep_label_time[] = {
     0x00000000, 0x00000000, 0xee444444, 0xe4000000,
     0xea2e6a2a, 0xea000000, 0x00000000, 0x00000000,
 };
@@ -116,6 +116,16 @@ u32 sprite_env_label_env[] = {
     0x62a2a2a2, 0xee000000, 0xee2a6e22, 0xe2000000,
 };
 
+u32 sprite_sweep_number_label[] = {
+    0x60a0a0a0, 0xa0000000, 0xaaeaaaaa, 0xae000000,
+    0xee2a662a, 0xee000000, 0x0e0a060a, 0x0a000000,
+};
+
+u32 sprite_sweep_label[] = {
+    0x8040c000, 0xc0000000, 0xa5a4a5b5, 0xa8000000,
+    0xbb889988, 0xbb000000, 0x03020300, 0x00000000,
+};
+
 u32 sprite_duty_cycle_label[] = {
     0x00000000, 0x00000080, 0xa6aaaaaa, 0xe60000ab,
     0xaea4e444, 0x4400008b, 0x00000000, 0x00000003,
@@ -195,6 +205,25 @@ u32 sprite_env_sweep_direction[] = {
     0xb2b2b2b2, 0xb2ba9400, 0x0d0f0e0c, 0x0c0c0c00,
 };
 
+u32 sprite_sweep_time_number[] = {
+    0x7c646464, 0x64647c00, 0x18181818, 0x18181800,
+    0x7c60607c, 0x0c0c7c00, 0x7c606078, 0x60607c00,
+    0x60706864, 0x7c606000, 0x7c0c0c7c, 0x60607c00,
+    0x7c0c0c7c, 0x4c4c7c00, 0x7c606030, 0x180c0c00,
+};
+
+u32 sprite_synth_param_selector[] = {
+    0x07010100, 0x00000000, 0x00000000, 0x00000000,
+    0x00000000, 0x00000000, 0xe0808000, 0x00000000,
+    0x00000000, 0x00000000, 0x00000000, 0x00000000,
+    0x00000000, 0x00000000, 0x00000000, 0x00000000,
+    0x00000101, 0x07000000, 0x00000000, 0x00000000,
+    0x00000000, 0x00000000, 0x00008080, 0xe0000000,
+    0x00000000, 0x00000000, 0x00000000, 0x00000000,
+    0x00000000, 0x00000000, 0x00000000, 0x00000000,
+};
+
+
 typedef struct SeqTrigger {
     bool trigger;
     Note note;
@@ -202,29 +231,32 @@ typedef struct SeqTrigger {
     u8 env_time;
     u8 env_direction;
     u8 duty_cycle;
+    u8 sweep_number;
+    u8 sweep_time;
+    u8 sweep_direction;
     // TODO: ...
 } SeqTrigger;
 
 static SeqTrigger sequence_synth[] = {
-    {true  , NOTE_D_4       , 0, 0, 0, 0},
-    {true  , NOTE_F_4       , 1, 1, 0, 0},
-    {true  , NOTE_A_4       , 2, 2, 0, 1},
-    {true  , NOTE_C_5       , 3, 3, 0, 1},
-
-    {true  , NOTE_D_4       , 4, 4, 1, 2},
-    {false , NOTE_C_SHARP_4 , 5, 5, 1, 2},
-    {false , NOTE_D_4       , 6, 6, 1, 3},
-    {false , NOTE_D_4       , 7, 7, 1, 3},
-
-    {true  , NOTE_D_4       , 8, 0, 0, 0},
-    {true  , NOTE_F_4       , 9, 1, 0, 0},
-    {true  , NOTE_A_4       , 10, 2, 0, 1},
-    {true  , NOTE_C_5       , 11, 3, 0, 1},
-
-    {true  , NOTE_D_4       , 12, 4, 1, 2},
-    {false , NOTE_D_4       , 13, 5, 1, 2},
-    {true  , NOTE_A_4       , 14, 6, 1, 3},
-    {false , NOTE_A_5       , 15, 7, 1, 3},
+    {true  , NOTE_D_4       , 0, 0, 0, 0, 0, 0, 0},
+    {true  , NOTE_F_4       , 1, 1, 0, 0, 1, 1, 0},
+    {true  , NOTE_A_4       , 2, 2, 0, 1, 2, 2, 1},
+    {true  , NOTE_C_5       , 3, 3, 0, 1, 3, 3, 1},
+
+    {true  , NOTE_D_4       , 4, 4, 1, 2, 4, 4, 0},
+    {false , NOTE_C_SHARP_4 , 5, 5, 1, 2, 5, 5, 0},
+    {false , NOTE_D_4       , 6, 6, 1, 3, 6, 6, 1},
+    {false , NOTE_D_4       , 7, 7, 1, 3, 7, 7, 1},
+
+    {true  , NOTE_D_4       , 8, 0, 0, 0, 7, 0, 0},
+    {true  , NOTE_F_4       , 9, 1, 0, 0, 6, 1, 0},
+    {true  , NOTE_A_4       , 10, 2, 0, 1, 5, 2, 1},
+    {true  , NOTE_C_5       , 11, 3, 0, 1, 4, 3, 1},
+
+    {true  , NOTE_D_4       , 12, 4, 1, 2, 3, 4, 0},
+    {false , NOTE_D_4       , 13, 5, 1, 2, 2, 5, 0},
+    {true  , NOTE_A_4       , 14, 6, 1, 3, 1, 6, 1},
+    {false , NOTE_A_5       , 15, 7, 1, 3, 0, 7, 1},
 };
 
 static int bpm = 120;
@@ -236,11 +268,15 @@ irq_timer_0(void) {
     SeqTrigger *trig = &sequence_synth[step_counter];
     active_note = trig->note;
     if (trig->trigger) {
+        SOUND_SQUARE1_SWEEP = SOUND_SWEEP_NUMBER(trig->sweep_number)
+            | SOUND_SWEEP_DIR(trig->sweep_direction)
+            | SOUND_SWEEP_TIME(trig->sweep_time);
         SOUND_SQUARE1_CTRL = SOUND_SQUARE_ENV_VOL(trig->env_volume)
             | SOUND_SQUARE_ENV_TIME(trig->env_time)
-            | SOUND_SQUARE_ENV_INC(trig->env_direction)
+            | SOUND_SQUARE_ENV_DIR(trig->env_direction)
             | SOUND_SQUARE_DUTY(trig->duty_cycle);
-        SOUND_SQUARE1_FREQ = SOUND_SQUARE_RESET | sound_rates[active_note];
+        SOUND_SQUARE1_FREQ = SOUND_SQUARE_RESET
+            | sound_rates[active_note];
     }
     step_counter = (step_counter + 1) % 16;
 }
@@ -250,7 +286,7 @@ set_time(int bpm) {
     // 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
+    //     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;
@@ -291,6 +327,14 @@ set_time(int bpm) {
 // - 040-040 envelope: envelope label.
 // - 041-041 duty-cycle label.
 // - 042-042 duty-cycle indicator.
+// - 043-043 sweep: number label.
+// - 044-044 sweep: number indicator.
+// - 045-045 sweep: time label.
+// - 046-046 sweep: time indicator.
+// - 047-047 sweep: direction label.
+// - 048-048 sweep: direction indicator.
+// - 049-049 sweep: sweep label.
+// - 050-050 synth parameter selector.
 //
 
 
@@ -300,9 +344,11 @@ set_time(int bpm) {
 #define SEQ_TRIG_DIST 20
 #define SEQ_ENV_POS_X 10
 #define SEQ_ENV_POS_Y 10
-#define SEQ_ENV_DIST  34
+#define SEQ_ENV_DIST  32
 #define SEQ_DUTYCYCLE_POS_X SEQ_ENV_POS_X + SEQ_ENV_DIST * 3
 #define SEQ_DUTYCYCLE_POS_Y 10 - 8
+#define SEQ_SWEEP_POS_X SEQ_DUTYCYCLE_POS_X + SEQ_ENV_DIST
+#define SEQ_SWEEP_POS_Y SEQ_ENV_POS_Y
 
 size_t obj_counter = 0;
 
@@ -316,12 +362,27 @@ typedef struct SeqSprite {
     u16 obj_attr_2;
 } SeqSprite;
 
-int trig_selection_loc = 1;
 
-SeqSprite seq_sprites[43] = {0};
+typedef enum {
+    SEQ_SELECT_TRIGGER,
+    SEQ_SELECT_PARAMETER,
+} SeqSelect;
+
+int trig_selection_loc = 0;
+int param_selection_loc = 0;
+SeqSelect current_selection = SEQ_SELECT_TRIGGER;
+
+SeqSprite seq_sprites[51] = {0};
 
 void
 init_sequencer_sprites(void) {
+    // Load palette.
+    init_sprite_pal(0, COLOR_WHITE);
+    init_sprite_pal(16, COLOR_CYAN);
+    init_sprite_pal(32, COLOR_RED);
+    init_sprite_pal(48, COLOR_GREY);
+    init_sprites(0);
+
     // Sprite note names.
     size_t sprite_id = load_packed_sprite_data(&sprite_note_names, 2, 73);
     for (size_t i = 0; i < 16; ++i) {
@@ -396,7 +457,7 @@ init_sequencer_sprites(void) {
         seq_sprites[34].base_tile = base_tile;
         seq_sprites[34].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[34].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[34].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[34].obj_attr_2 = base_tile;
     }
 
     sprite_id = load_packed_sprite_data(&sprite_env_volume, 4, 16);
@@ -408,10 +469,10 @@ init_sequencer_sprites(void) {
         seq_sprites[35].base_tile = base_tile;
         seq_sprites[35].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[35].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[35].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[35].obj_attr_2 = base_tile;
     }
 
-    sprite_id = load_packed_sprite_data(&sprite_env_label_time, 4, 1);
+    sprite_id = load_packed_sprite_data(&sprite_env_sweep_label_time, 4, 1);
     {
         int x = SEQ_ENV_POS_X + SEQ_ENV_DIST;
         int y = SEQ_ENV_POS_Y;
@@ -420,7 +481,17 @@ init_sequencer_sprites(void) {
         seq_sprites[36].base_tile = base_tile;
         seq_sprites[36].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[36].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[36].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[36].obj_attr_2 = base_tile;
+    }
+    {
+        int x = SEQ_SWEEP_POS_X + SEQ_ENV_DIST;
+        int y = SEQ_SWEEP_POS_Y;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[45].id = obj_counter++;
+        seq_sprites[45].base_tile = base_tile;
+        seq_sprites[45].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
+        seq_sprites[45].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
+        seq_sprites[45].obj_attr_2 = base_tile;
     }
 
     sprite_id = load_packed_sprite_data(&sprite_env_time, 4, 8);
@@ -432,7 +503,7 @@ init_sequencer_sprites(void) {
         seq_sprites[37].base_tile = base_tile;
         seq_sprites[37].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[37].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[37].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[37].obj_attr_2 = base_tile;
     }
 
     sprite_id = load_packed_sprite_data(&sprite_env_label_direction, 4, 1);
@@ -444,7 +515,17 @@ init_sequencer_sprites(void) {
         seq_sprites[38].base_tile = base_tile;
         seq_sprites[38].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[38].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[38].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[38].obj_attr_2 = base_tile;
+    }
+    {
+        int x = SEQ_SWEEP_POS_X + SEQ_ENV_DIST * 2;
+        int y = SEQ_SWEEP_POS_Y;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[47].id = obj_counter++;
+        seq_sprites[47].base_tile = base_tile;
+        seq_sprites[47].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
+        seq_sprites[47].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
+        seq_sprites[47].obj_attr_2 = base_tile;
     }
 
     sprite_id = load_packed_sprite_data(&sprite_env_sweep_direction, 4, 2);
@@ -456,19 +537,29 @@ init_sequencer_sprites(void) {
         seq_sprites[39].base_tile = base_tile;
         seq_sprites[39].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[39].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[39].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[39].obj_attr_2 = base_tile;
+    }
+    {
+        int x = SEQ_SWEEP_POS_X + SEQ_ENV_DIST * 2;
+        int y = SEQ_SWEEP_POS_Y + 8;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[48].id = obj_counter++;
+        seq_sprites[48].base_tile = base_tile;
+        seq_sprites[48].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
+        seq_sprites[48].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
+        seq_sprites[48].obj_attr_2 = base_tile;
     }
 
     sprite_id = load_packed_sprite_data(&sprite_env_label_env, 4, 1);
     {
         int x = SEQ_ENV_POS_X + SEQ_ENV_DIST;
-        int y = SEQ_ENV_POS_Y - 8;
+        int y = SEQ_ENV_POS_Y - 10;
         int base_tile = sprites[sprite_id].tile_start;
         seq_sprites[40].id = obj_counter++;
         seq_sprites[40].base_tile = base_tile;
         seq_sprites[40].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[40].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[40].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[40].obj_attr_2 = base_tile;
     }
 
     sprite_id = load_packed_sprite_data(&sprite_duty_cycle_label, 8, 1);
@@ -480,8 +571,9 @@ init_sequencer_sprites(void) {
         seq_sprites[41].base_tile = base_tile;
         seq_sprites[41].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[41].obj_attr_1 = OBJ_SIZE_BIG | OBJ_X_COORD(x);
-        seq_sprites[41].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[41].obj_attr_2 = base_tile;
     }
+
     sprite_id = load_packed_sprite_data(&sprite_duty_cycle, 4, 4);
     {
         int x = SEQ_DUTYCYCLE_POS_X;
@@ -491,7 +583,65 @@ init_sequencer_sprites(void) {
         seq_sprites[42].base_tile = base_tile;
         seq_sprites[42].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
         seq_sprites[42].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
-        seq_sprites[42].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        seq_sprites[42].obj_attr_2 = base_tile;
+    }
+
+    sprite_id = load_packed_sprite_data(&sprite_sweep_number_label, 4, 1);
+    {
+        int x = SEQ_SWEEP_POS_X;
+        int y = SEQ_SWEEP_POS_Y;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[43].id = obj_counter++;
+        seq_sprites[43].base_tile = base_tile;
+        seq_sprites[43].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
+        seq_sprites[43].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
+        seq_sprites[43].obj_attr_2 = base_tile;
+    }
+
+    sprite_id = load_packed_sprite_data(&sprite_sweep_time_number, 1, 8);
+    {
+        int x = SEQ_SWEEP_POS_X + 12;
+        int y = SEQ_SWEEP_POS_Y + 8;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[44].id = obj_counter++;
+        seq_sprites[44].base_tile = base_tile;
+        seq_sprites[44].obj_attr_0 = OBJ_SHAPE_SQUARE | OBJ_Y_COORD(y);
+        seq_sprites[44].obj_attr_1 = OBJ_SIZE_SMALL | OBJ_X_COORD(x);
+        seq_sprites[44].obj_attr_2 = base_tile;
+    }
+    {
+        int x = SEQ_SWEEP_POS_X + 12 + SEQ_ENV_DIST;
+        int y = SEQ_SWEEP_POS_Y + 8;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[46].id = obj_counter++;
+        seq_sprites[46].base_tile = base_tile;
+        seq_sprites[46].obj_attr_0 = OBJ_SHAPE_SQUARE | OBJ_Y_COORD(y);
+        seq_sprites[46].obj_attr_1 = OBJ_SIZE_SMALL | OBJ_X_COORD(x);
+        seq_sprites[46].obj_attr_2 = base_tile;
+    }
+
+    sprite_id = load_packed_sprite_data(&sprite_sweep_label, 4, 1);
+    {
+        int x = SEQ_SWEEP_POS_X + SEQ_ENV_DIST;
+        int y = SEQ_SWEEP_POS_Y - 10;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[49].id = obj_counter++;
+        seq_sprites[49].base_tile = base_tile;
+        seq_sprites[49].obj_attr_0 = OBJ_SHAPE_WIDE | OBJ_Y_COORD(y);
+        seq_sprites[49].obj_attr_1 = OBJ_SIZE_MID | OBJ_X_COORD(x);
+        seq_sprites[49].obj_attr_2 = base_tile;
+    }
+
+    sprite_id = load_packed_sprite_data(&sprite_synth_param_selector, 16, 1);
+    {
+        int x = SEQ_ENV_POS_X + 1;
+        int y = SEQ_ENV_POS_Y - 3;
+        int base_tile = sprites[sprite_id].tile_start;
+        seq_sprites[50].id = obj_counter++;
+        seq_sprites[50].base_tile = base_tile;
+        seq_sprites[50].obj_attr_0 = OBJ_SHAPE_SQUARE | OBJ_Y_COORD(y);
+        seq_sprites[50].obj_attr_1 = OBJ_SIZE_BIG | OBJ_X_COORD(x);
+        seq_sprites[50].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
     }
 }
 
@@ -534,79 +684,227 @@ update_sequencer_sprites(void) {
             y += 32;
             x -= 8 * SEQ_TRIG_DIST;
         }
-        // TODO: Mask and update instead.
         seq_sprites[33].obj_attr_0 = OBJ_SHAPE_SQUARE | OBJ_Y_COORD(y);
         seq_sprites[33].obj_attr_1 = OBJ_SIZE_BIG | OBJ_X_COORD(x);
+        int base_tile = seq_sprites[33].base_tile;
+        if (current_selection == SEQ_SELECT_TRIGGER) {
+            seq_sprites[33].obj_attr_2 = base_tile | OBJ_PAL_BANK(2);
+        } else {
+            seq_sprites[33].obj_attr_2 = base_tile | OBJ_PAL_BANK(3);
+        }
     }
 
-    // 36: Envelope initial volume
+    // 36: Envelope initial volume.
     {
         size_t tile_diff =  sequence_synth[trig_selection_loc].env_volume * 4;
         size_t base_tile = seq_sprites[35].base_tile;
         size_t tile = base_tile + tile_diff;
-        seq_sprites[35].obj_attr_2 = tile | OBJ_PAL_BANK(2);
+        seq_sprites[35].obj_attr_2 = tile;
     }
 
-    // 38: Envelope initial volume
+    // 38: Envelope time.
     {
         size_t tile_diff =  sequence_synth[trig_selection_loc].env_time * 4;
         size_t base_tile = seq_sprites[37].base_tile;
         size_t tile = base_tile + tile_diff;
-        seq_sprites[37].obj_attr_2 = tile | OBJ_PAL_BANK(2);
+        seq_sprites[37].obj_attr_2 = tile;
     }
 
-    // 40: Envelope initial volume
+    // 40: Envelope direction.
     {
-        size_t tile_diff =  sequence_synth[trig_selection_loc].env_direction * 4;
+        size_t tile_diff = 0;
+        if (sequence_synth[trig_selection_loc].env_direction == 0) {
+            tile_diff = 4;
+        }
         size_t base_tile = seq_sprites[39].base_tile;
         size_t tile = base_tile + tile_diff;
-        seq_sprites[39].obj_attr_2 = tile | OBJ_PAL_BANK(2);
+        seq_sprites[39].obj_attr_2 = tile;
     }
 
-    // 43: Envelope initial volume
+    // 43: Duty cycle.
     {
         size_t tile_diff =  sequence_synth[trig_selection_loc].duty_cycle * 4;
         size_t base_tile = seq_sprites[42].base_tile;
         size_t tile = base_tile + tile_diff;
-        seq_sprites[42].obj_attr_2 = tile | OBJ_PAL_BANK(2);
+        seq_sprites[42].obj_attr_2 = tile;
+    }
+
+    // 45: Sweep number.
+    {
+        size_t tile_diff =  sequence_synth[trig_selection_loc].sweep_number;
+        size_t base_tile = seq_sprites[44].base_tile;
+        size_t tile = base_tile + tile_diff;
+        seq_sprites[44].obj_attr_2 = tile;
+    }
+
+    // 47: Sweep time.
+    {
+        size_t tile_diff =  sequence_synth[trig_selection_loc].sweep_time;
+        size_t base_tile = seq_sprites[46].base_tile;
+        size_t tile = base_tile + tile_diff;
+        seq_sprites[46].obj_attr_2 = tile;
+    }
+
+    // 49: Sweep direction.
+    {
+        size_t tile_diff =  sequence_synth[trig_selection_loc].sweep_direction * 4;
+        size_t base_tile = seq_sprites[48].base_tile;
+        size_t tile = base_tile + tile_diff;
+        seq_sprites[48].obj_attr_2 = tile;
+    }
+
+    // 51: Parameter selector.
+    {
+        int x = SEQ_ENV_POS_X + 1 + (param_selection_loc % 7) * SEQ_ENV_DIST;
+        int y = SEQ_ENV_POS_Y - 2;
+        if (param_selection_loc >= 8) {
+            y += 32;
+            x -= 8 * SEQ_TRIG_DIST;
+        }
+        int hidden = 0;
+        if (current_selection != SEQ_SELECT_PARAMETER) {
+            hidden = OBJ_HIDDEN;
+        }
+        seq_sprites[50].obj_attr_0 = OBJ_SHAPE_SQUARE | OBJ_Y_COORD(y) | hidden;
+        seq_sprites[50].obj_attr_1 = OBJ_SIZE_BIG | OBJ_X_COORD(x);
     }
 }
 
 void
 handle_sequencer_input(void) {
-    if (key_pressed(KEY_LEFT)) {
-        if (trig_selection_loc == 0) {
-            trig_selection_loc = 15;
-        } else {
-            trig_selection_loc = CLAMP(trig_selection_loc - 1, 0, 15);
+    if (current_selection == SEQ_SELECT_TRIGGER) {
+        if (key_pressed(KEY_LEFT)) {
+            if (trig_selection_loc == 0) {
+                trig_selection_loc = 15;
+            } else {
+                trig_selection_loc = CLAMP(trig_selection_loc - 1, 0, 15);
+            }
         }
-    }
-    if (key_pressed(KEY_RIGHT)) {
-        if (trig_selection_loc == 15) {
-            trig_selection_loc = 0;
-        } else {
-            trig_selection_loc = CLAMP(trig_selection_loc + 1, 0, 15);
+        if (key_pressed(KEY_RIGHT)) {
+            if (trig_selection_loc == 15) {
+                trig_selection_loc = 0;
+            } else {
+                trig_selection_loc = CLAMP(trig_selection_loc + 1, 0, 15);
+            }
+        }
+        if (key_pressed(KEY_UP) || key_pressed(KEY_DOWN)) {
+            trig_selection_loc = (trig_selection_loc + 8) % 16;
+        }
+        if (key_pressed(KEY_B)) {
+            sequence_synth[trig_selection_loc].trigger ^= 1;
+        }
+        if (key_pressed(KEY_L)) {
+            sequence_synth[trig_selection_loc].note = CLAMP(sequence_synth[trig_selection_loc].note - 1, NOTE_C_2, NOTE_C_8);
+        }
+        if (key_pressed(KEY_R)) {
+            sequence_synth[trig_selection_loc].note = CLAMP(sequence_synth[trig_selection_loc].note + 1, NOTE_C_2, NOTE_C_8);
+        }
+
+        // Switch to parameter selection.
+        if (key_pressed(KEY_A)) {
+            current_selection = SEQ_SELECT_PARAMETER;
+        }
+    } else if (current_selection == SEQ_SELECT_PARAMETER) {
+        // Move through the selected synth parameters.
+        if (key_pressed(KEY_LEFT)) {
+            if (param_selection_loc == 0) {
+                param_selection_loc = 6;
+            } else {
+                param_selection_loc = CLAMP(param_selection_loc - 1, 0, 6);
+            }
+        }
+        if (key_pressed(KEY_RIGHT)) {
+            if (param_selection_loc == 6) {
+                param_selection_loc = 0;
+            } else {
+                param_selection_loc = CLAMP(param_selection_loc + 1, 0, 6);
+            }
+        }
+
+        // Adjust the parameters up or down.
+        if (key_pressed(KEY_L)) {
+            switch (param_selection_loc) {
+                case 0: {
+                    sequence_synth[trig_selection_loc].env_volume = CLAMP(
+                        sequence_synth[trig_selection_loc].env_volume - 1, 0, 15);
+                } break;
+                case 1: {
+                    sequence_synth[trig_selection_loc].env_time = CLAMP(
+                        sequence_synth[trig_selection_loc].env_time - 1, 0, 7);
+                } break;
+                case 2: {
+                    sequence_synth[trig_selection_loc].env_direction ^= 1;
+                } break;
+                case 3: {
+                    sequence_synth[trig_selection_loc].duty_cycle = CLAMP(
+                        sequence_synth[trig_selection_loc].duty_cycle - 1, 0, 3);
+                } break;
+                case 4: {
+                    sequence_synth[trig_selection_loc].sweep_number = CLAMP(
+                        sequence_synth[trig_selection_loc].sweep_number - 1, 0, 7);
+                } break;
+                case 5: {
+                    sequence_synth[trig_selection_loc].sweep_time = CLAMP(
+                        sequence_synth[trig_selection_loc].sweep_time - 1, 0, 7);
+                } break;
+                case 6: {
+                    if (sequence_synth[trig_selection_loc].sweep_direction == 0) {
+                        sequence_synth[trig_selection_loc].sweep_direction = 1;
+                    } else {
+                        sequence_synth[trig_selection_loc].sweep_direction = 0;
+                    }
+                } break;
+            }
+        }
+        if (key_pressed(KEY_R)) {
+            switch (param_selection_loc) {
+                case 0: {
+                    sequence_synth[trig_selection_loc].env_volume = CLAMP(
+                        sequence_synth[trig_selection_loc].env_volume + 1, 0, 15);
+                } break;
+                case 1: {
+                    sequence_synth[trig_selection_loc].env_time = CLAMP(
+                        sequence_synth[trig_selection_loc].env_time + 1, 0, 7);
+                } break;
+                case 2: {
+                    sequence_synth[trig_selection_loc].env_direction ^= 1;
+                } break;
+                case 3: {
+                    sequence_synth[trig_selection_loc].duty_cycle = CLAMP(
+                        sequence_synth[trig_selection_loc].duty_cycle + 1, 0, 3);
+                } break;
+                case 4: {
+                    sequence_synth[trig_selection_loc].sweep_number = CLAMP(
+                        sequence_synth[trig_selection_loc].sweep_number + 1, 0, 7);
+                } break;
+                case 5: {
+                    sequence_synth[trig_selection_loc].sweep_time = CLAMP(
+                        sequence_synth[trig_selection_loc].sweep_time + 1, 0, 7);
+                } break;
+                case 6: {
+                    sequence_synth[trig_selection_loc].sweep_direction ^= 1;
+                } break;
+            }
+        }
+
+        // Go back to trigger selection.
+        if (key_pressed(KEY_A)) {
+            current_selection = SEQ_SELECT_TRIGGER;
         }
-    }
-    if (key_pressed(KEY_UP) || key_pressed(KEY_DOWN)) {
-        trig_selection_loc = (trig_selection_loc + 8) % 16;
-    }
-    if (key_pressed(KEY_B)) {
-        sequence_synth[trig_selection_loc].trigger ^= 1;
-    }
-    if (key_pressed(KEY_L)) {
-        sequence_synth[trig_selection_loc].note = CLAMP(sequence_synth[trig_selection_loc].note - 1, NOTE_C_2, NOTE_C_8);
-    }
-    if (key_pressed(KEY_R)) {
-        sequence_synth[trig_selection_loc].note = CLAMP(sequence_synth[trig_selection_loc].note + 1, NOTE_C_2, NOTE_C_8);
     }
 
     if (key_pressed(KEY_START)) {
         step_counter = 0;
-        set_time(bpm);
+        if ((TIMER_CTRL_0 & TIMER_CTRL_ENABLE) == 0) {
+            set_time(bpm);
+        } else {
+            TIMER_CTRL_0 ^= TIMER_CTRL_ENABLE;
+            SOUND_SQUARE1_CTRL = 0;
+        }
     }
     if (key_pressed(KEY_SELECT)) {
         TIMER_CTRL_0 ^= TIMER_CTRL_ENABLE;
+        SOUND_SQUARE1_CTRL = 0;
     }
 }