1 files changed, 122 insertions, 0 deletions
diff --git a/quantum/sequencer/sequencer.h b/quantum/sequencer/sequencer.h
new file mode 100644
index 0000000000..aeca7a1e9b
--- /dev/null
+++ b/quantum/sequencer/sequencer.h
@@ -0,0 +1,122 @@
+/* Copyright 2020 Rodolphe Belouin
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include "debug.h"
+#include "timer.h"
+
+// Maximum number of steps: 256
+#ifndef SEQUENCER_STEPS
+#    define SEQUENCER_STEPS 16
+#endif
+
+// Maximum number of tracks: 8
+#ifndef SEQUENCER_TRACKS
+#    define SEQUENCER_TRACKS 8
+#endif
+
+#ifndef SEQUENCER_TRACK_THROTTLE
+#    define SEQUENCER_TRACK_THROTTLE 3
+#endif
+
+#ifndef SEQUENCER_PHASE_RELEASE_TIMEOUT
+#    define SEQUENCER_PHASE_RELEASE_TIMEOUT 30
+#endif
+
+/**
+ * Make sure that the items of this enumeration follow the powers of 2, separated by a ternary variant.
+ * Check the implementation of `get_step_duration` for further explanation.
+ */
+typedef enum { SQ_RES_2, SQ_RES_2T, SQ_RES_4, SQ_RES_4T, SQ_RES_8, SQ_RES_8T, SQ_RES_16, SQ_RES_16T, SQ_RES_32, SEQUENCER_RESOLUTIONS } sequencer_resolution_t;
+
+typedef struct {
+    bool                   enabled;
+    uint8_t                steps[SEQUENCER_STEPS];
+    uint16_t               track_notes[SEQUENCER_TRACKS];
+    uint8_t                tempo;  // Is a maximum tempo of 255 reasonable?
+    sequencer_resolution_t resolution;
+} sequencer_config_t;
+
+/**
+ * Because Digital Audio Workstations get overwhelmed when too many MIDI signals are sent concurrently,
+ * We use a "phase" state machine to delay some of the events.
+ */
+typedef enum sequencer_phase_t {
+    SEQUENCER_PHASE_ATTACK,   // t=0ms, send the MIDI note on signal
+    SEQUENCER_PHASE_RELEASE,  // t=SEQUENCER_PHASE_RELEASE_TIMEOUT ms, send the MIDI note off signal
+    SEQUENCER_PHASE_PAUSE     // t=step duration ms, loop
+} sequencer_phase_t;
+
+typedef struct {
+    uint8_t           active_tracks;
+    uint8_t           current_track;
+    uint8_t           current_step;
+    uint16_t          timer;
+    sequencer_phase_t phase;
+} sequencer_state_t;
+
+extern sequencer_config_t sequencer_config;
+
+// We expose the internal state to make the feature more "unit-testable"
+extern sequencer_state_t sequencer_internal_state;
+
+bool is_sequencer_on(void);
+void sequencer_toggle(void);
+void sequencer_on(void);
+void sequencer_off(void);
+
+void sequencer_set_track_notes(const uint16_t track_notes[SEQUENCER_TRACKS]);
+
+bool is_sequencer_track_active(uint8_t track);
+void sequencer_set_track_activation(uint8_t track, bool value);
+void sequencer_toggle_track_activation(uint8_t track);
+void sequencer_toggle_single_active_track(uint8_t track);
+
+#define sequencer_activate_track(track) sequencer_set_track_activation(track, true)
+#define sequencer_deactivate_track(track) sequencer_set_track_activation(track, false)
+
+bool is_sequencer_step_on(uint8_t step);
+bool is_sequencer_step_on_for_track(uint8_t step, uint8_t track);
+void sequencer_set_step(uint8_t step, bool value);
+void sequencer_toggle_step(uint8_t step);
+void sequencer_set_all_steps(bool value);
+
+#define sequencer_set_step_on(step) sequencer_set_step(step, true)
+#define sequencer_set_step_off(step) sequencer_set_step(step, false)
+#define sequencer_set_all_steps_on() sequencer_set_all_steps(true)
+#define sequencer_set_all_steps_off() sequencer_set_all_steps(false)
+
+uint8_t sequencer_get_tempo(void);
+void    sequencer_set_tempo(uint8_t tempo);
+void    sequencer_increase_tempo(void);
+void    sequencer_decrease_tempo(void);
+
+sequencer_resolution_t sequencer_get_resolution(void);
+void                   sequencer_set_resolution(sequencer_resolution_t resolution);
+void                   sequencer_increase_resolution(void);
+void                   sequencer_decrease_resolution(void);
+
+uint8_t sequencer_get_current_step(void);
+
+uint16_t sequencer_get_beat_duration(void);
+uint16_t sequencer_get_step_duration(void);
+
+uint16_t get_beat_duration(uint8_t tempo);
+uint16_t get_step_duration(uint8_t tempo, sequencer_resolution_t resolution);
+
+void matrix_scan_sequencer(void);