qmk · jackhumbert · Feb 7, 2017 · Dec 9, 2016 · Dec 10, 2016 · Dec 16, 2016
diff --git a/build_keyboard.mk b/build_keyboard.mk
@@ -144,6 +144,11 @@ ifeq ($(strip $(MIDI_ENABLE)), yes)
 	SRC += $(QUANTUM_DIR)/process_keycode/process_midi.c
 endif
 
+ifeq ($(strip $(COMBO_ENABLE)), yes)
+    OPT_DEFS += -DCOMBO_ENABLE
+	SRC += $(QUANTUM_DIR)/process_keycode/process_combo.c
+endif
+
 ifeq ($(strip $(VIRTSER_ENABLE)), yes)
     OPT_DEFS += -DVIRTSER_ENABLE
 endif

diff --git a/quantum/process_keycode/process_combo.c b/quantum/process_keycode/process_combo.c
@@ -0,0 +1,134 @@
+#include "process_combo.h"
+#include "print.h"
+
+
+#define COMBO_TIMER_ELAPSED -1
+
+
+__attribute__ ((weak))
+combo_t key_combos[] = {
+
+};
+
+__attribute__ ((weak))
+void process_combo_event(uint8_t combo_index, bool pressed) {
+
+}
+
+static uint8_t current_combo_index = 0;
+
+static inline void send_combo(uint16_t action, bool pressed)
+{
+    if (action) {
+        if (pressed) {
+            register_code16(action);
+        } else {
+            unregister_code16(action);
+        }
+    } else {
+        process_combo_event(current_combo_index, pressed);
+    }
+}
+
+#define ALL_COMBO_KEYS_ARE_DOWN     (((1<<count)-1) == combo->state)
+#define NO_COMBO_KEYS_ARE_DOWN      (0 == combo->state)
+#define KEY_STATE_DOWN(key)         do{ combo->state |= (1<<key); } while(0)
+#define KEY_STATE_UP(key)           do{ combo->state &= ~(1<<key); } while(0)
+static bool process_single_combo(combo_t *combo, uint16_t keycode, keyrecord_t *record) 
+{
+    uint8_t count = 0;
+    uint8_t index = -1;
+    /* Find index of keycode and number of combo keys */
+    for (const uint16_t *keys = combo->keys; ;++count) {
+        uint16_t key = pgm_read_word(&keys[count]);
+        if (keycode == key) index = count;
+        if (COMBO_END == key) break;
+    }
+
+    /* Return if not a combo key */
+    if (-1 == (int8_t)index) return false;
+
+    /* The combos timer is used to signal whether the combo is active */
+    bool is_combo_active = COMBO_TIMER_ELAPSED == combo->timer ? false : true;
+
+    if (record->event.pressed) {
+        KEY_STATE_DOWN(index);
+
+        if (is_combo_active) {
+            if (ALL_COMBO_KEYS_ARE_DOWN) { /* Combo was pressed */
+                send_combo(combo->keycode, true);
+                combo->timer = COMBO_TIMER_ELAPSED;
+            } else { /* Combo key was pressed */
+                combo->timer = timer_read();
+#ifdef COMBO_ALLOW_ACTION_KEYS
+                combo->prev_record = *record;
+#else
+                combo->prev_key = keycode;
+#endif
+            }
+        }
+    } else {
+        if (ALL_COMBO_KEYS_ARE_DOWN) { /* Combo was released */
+            send_combo(combo->keycode, false);
+        }
+
+        if (is_combo_active) { /* Combo key was tapped */
+#ifdef COMBO_ALLOW_ACTION_KEYS
+            record->event.pressed = true;
+            process_action(record, store_or_get_action(record->event.pressed, record->event.key));
+            record->event.pressed = false;
+            process_action(record, store_or_get_action(record->event.pressed, record->event.key));
+#else
+            register_code16(keycode);
+            send_keyboard_report();
+            unregister_code16(keycode);
+#endif
+            combo->timer = 0;            
+        }
+
+        KEY_STATE_UP(index);        
+    }
+
+    if (NO_COMBO_KEYS_ARE_DOWN) {
+        combo->timer = 0;
+    }
+
+    return is_combo_active;
+}
+
+bool process_combo(uint16_t keycode, keyrecord_t *record)
+{
+    bool is_combo_key = false;
+
+    for (current_combo_index = 0; current_combo_index < COMBO_COUNT; ++current_combo_index) {
+        combo_t *combo = &key_combos[current_combo_index];
+        is_combo_key |= process_single_combo(combo, keycode, record);
+    }    
+
+    return !is_combo_key;
+}
+
+void matrix_scan_combo(void)
+{
+    for (int i = 0; i < COMBO_COUNT; ++i) {
+        combo_t *combo = &key_combos[i];
+        if (combo->timer && 
+            combo->timer != COMBO_TIMER_ELAPSED && 
+            timer_elapsed(combo->timer) > COMBO_TERM) {
+
+            /* This disables the combo, meaning key events for this
+             * combo will be handled by the next processors in the chain 
+             */
+            combo->timer = COMBO_TIMER_ELAPSED;
+
+#ifdef COMBO_ALLOW_ACTION_KEYS
+            process_action(&combo->prev_record, 
+                store_or_get_action(combo->prev_record.event.pressed, 
+                                    combo->prev_record.event.key));
+#else
+            unregister_code16(combo->prev_key);
+            register_code16(combo->prev_key);
+#endif
+        }
+    }
+}
diff --git a/quantum/process_keycode/process_combo.h b/quantum/process_keycode/process_combo.h
@@ -0,0 +1,43 @@
+#ifndef PROCESS_COMBO_H
+#define PROCESS_COMBO_H
+
+#include <stdint.h>
+#include "progmem.h"
+#include "quantum.h"
+
+typedef struct
+{
+    const uint16_t *keys;
+    uint16_t keycode;        
+#ifdef EXTRA_EXTRA_LONG_COMBOS
+    uint32_t state;
+#elif EXTRA_LONG_COMBOS
+    uint16_t state;
+#else
+    uint8_t state;
+#endif
+    uint16_t timer;
+#ifdef COMBO_ALLOW_ACTION_KEYS
+    keyrecord_t prev_record;
+#else
+    uint16_t prev_key;
+#endif
+} combo_t;
+
+
+#define COMBO(ck, ca)       {.keys = &(ck)[0], .keycode = (ca)}
+#define COMBO_ACTION(ck)    {.keys = &(ck)[0]}
+
+#define COMBO_END 0
+#ifndef COMBO_COUNT
+#define COMBO_COUNT 0
+#endif
+#ifndef COMBO_TERM
+#define COMBO_TERM TAPPING_TERM
+#endif
+
+bool process_combo(uint16_t keycode, keyrecord_t *record);
+void matrix_scan_combo(void);
+void process_combo_event(uint8_t combo_index, bool pressed);
+
+#endif
diff --git a/quantum/quantum.c b/quantum/quantum.c
@@ -128,6 +128,9 @@ bool process_record_quantum(keyrecord_t *record) {
   #ifndef DISABLE_CHORDING
     process_chording(keycode, record) &&
   #endif
+  #ifdef COMBO_ENABLE
+    process_combo(keycode, record) &&
+  #endif
   #ifdef UNICODE_ENABLE
     process_unicode(keycode, record) &&
   #endif
@@ -506,6 +509,11 @@ void matrix_scan_quantum() {
   #ifdef TAP_DANCE_ENABLE
     matrix_scan_tap_dance();
   #endif
+
+  #ifdef COMBO_ENABLE
+    matrix_scan_combo();
+  #endif
+
   matrix_scan_kb();
 }
 

diff --git a/quantum/quantum.h b/quantum/quantum.h
@@ -63,6 +63,10 @@ extern uint32_t default_layer_state;
 	#include "process_printer.h"
 #endif
 
+#ifdef COMBO_ENABLE
+	#include "process_combo.h"
+#endif
+
 #define SEND_STRING(str) send_string(PSTR(str))
 void send_string(const char *str);