7 files changed, 565 insertions, 108 deletions

diff --git a/quantum/dynamic_macro.h b/quantum/dynamic_macro.h
new file mode 100644
index 0000000000..a3ad61bc7e
--- /dev/null
+++ b/quantum/dynamic_macro.h
@@ -0,0 +1,226 @@
+/* Author: Wojciech Siewierski < wojciech dot siewierski at onet dot pl > */
+#ifndef DYNAMIC_MACROS_H
+#define DYNAMIC_MACROS_H
+
+#include "action_layer.h"
+
+#ifndef DYNAMIC_MACRO_SIZE
+/* May be overridden with a custom value. Be aware that the effective
+ * macro length is half of this value: each keypress is recorded twice
+ * because of the down-event and up-event. This is not a bug, it's the
+ * intended behavior. */
+#define DYNAMIC_MACRO_SIZE 256
+#endif
+
+/* DYNAMIC_MACRO_RANGE must be set as the last element of user's
+ * "planck_keycodes" enum prior to including this header. This allows
+ * us to 'extend' it.
+ */
+enum dynamic_macro_keycodes {
+    DYN_REC_START1 = DYNAMIC_MACRO_RANGE,
+    DYN_REC_START2,
+    DYN_MACRO_PLAY1,
+    DYN_MACRO_PLAY2,
+};
+
+/* Blink the LEDs to notify the user about some event. */
+void dynamic_macro_led_blink(void)
+{
+    backlight_toggle();
+    _delay_ms(100);
+    backlight_toggle();
+}
+
+/**
+ * Start recording of the dynamic macro.
+ *
+ * @param[out] macro_pointer The new macro buffer iterator.
+ * @param[in]  macro_buffer  The macro buffer used to initialize macro_pointer.
+ */
+void dynamic_macro_record_start(
+    keyrecord_t **macro_pointer, keyrecord_t *macro_buffer)
+{
+    dynamic_macro_led_blink();
+
+    clear_keyboard();
+    layer_clear();
+    *macro_pointer = macro_buffer;
+}
+
+/**
+ * Play the dynamic macro.
+ *
+ * @param macro_buffer[in] The beginning of the macro buffer being played.
+ * @param macro_end[in]    The element after the last macro buffer element.
+ * @param direction[in]    Either +1 or -1, which way to iterate the buffer.
+ */
+void dynamic_macro_play(
+    keyrecord_t *macro_buffer, keyrecord_t *macro_end, int8_t direction)
+{
+    uint32_t saved_layer_state = layer_state;
+
+    clear_keyboard();
+    layer_clear();
+
+    while (macro_buffer != macro_end) {
+        process_record(macro_buffer);
+        macro_buffer += direction;
+    }
+
+    clear_keyboard();
+
+    layer_state = saved_layer_state;
+}
+
+/**
+ * Record a single key in a dynamic macro.
+ *
+ * @param macro_pointer[in,out] The current buffer position.
+ * @param macro_end2[in] The end of the other macro which shouldn't be overwritten.
+ * @param direction[in]  Either +1 or -1, which way to iterate the buffer.
+ * @param record[in]     The current keypress.
+ */
+void dynamic_macro_record_key(
+    keyrecord_t **macro_pointer,
+    keyrecord_t *macro_end2,
+    int8_t direction,
+    keyrecord_t *record)
+{
+    if (*macro_pointer + direction != macro_end2) {
+        **macro_pointer = *record;
+        *macro_pointer += direction;
+    } else {
+        /* Notify about the end of buffer. The blinks are paired
+         * because they should happen on both down and up events. */
+        backlight_toggle();
+    }
+}
+
+/**
+ * End recording of the dynamic macro. Essentially just update the
+ * pointer to the end of the macro.
+ */
+void dynamic_macro_record_end(keyrecord_t *macro_pointer, keyrecord_t **macro_end)
+{
+    dynamic_macro_led_blink();
+
+    *macro_end = macro_pointer;
+}
+
+/* Handle the key events related to the dynamic macros. Should be
+ * called from process_record_user() like this:
+ *
+ *   bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+ *       if (!process_record_dynamic_macro(keycode, record)) {
+ *           return false;
+ *       }
+ *       <...THE REST OF THE FUNCTION...>
+ *   }
+ */
+bool process_record_dynamic_macro(uint16_t keycode, keyrecord_t *record)
+{
+    /* Both macros use the same buffer but read/write on different
+     * ends of it.
+     *
+     * Macro1 is written left-to-right starting from the beginning of
+     * the buffer.
+     *
+     * Macro2 is written right-to-left starting from the end of the
+     * buffer.
+     *
+     * &macro_buffer   macro_end
+     *  v                   v
+     * +------------------------------------------------------------+
+     * |>>>>>> MACRO1 >>>>>>|    |<<<<<<<<<<<<< MACRO2 <<<<<<<<<<<<<|
+     * +------------------------------------------------------------+
+     *                           ^                                 ^
+     *                         r_macro_end                  r_macro_buffer
+     *
+     * During the recording when one macro encounters the end of the
+     * other macro, the recording is stopped. Apart from this, there
+     * are no arbitrary limits for the macros' length in relation to
+     * each other: for example one can either have two medium sized
+     * macros or one long macro and one short macro. Or even one empty
+     * and one using the whole buffer.
+     */
+    static keyrecord_t macro_buffer[DYNAMIC_MACRO_SIZE];
+
+    /* Pointer to the first buffer element after the first macro.
+     * Initially points to the very beginning of the buffer since the
+     * macro is empty. */
+    static keyrecord_t *macro_end = macro_buffer;
+
+    /* The other end of the macro buffer. Serves as the beginning of
+     * the second macro. */
+    static keyrecord_t *const r_macro_buffer = macro_buffer + DYNAMIC_MACRO_SIZE - 1;
+
+    /* Like macro_end but for the second macro. */
+    static keyrecord_t *r_macro_end = r_macro_buffer;
+
+    /* A persistent pointer to the current macro position (iterator)
+     * used during the recording. */
+    static keyrecord_t *macro_pointer = NULL;
+
+    /* 0   - no macro is being recorded right now
+     * 1,2 - either macro 1 or 2 is being recorded */
+    static uint8_t macro_id = 0;
+
+    if (macro_id == 0) {
+        /* No macro recording in progress. */
+        if (!record->event.pressed) {
+            switch (keycode) {
+            case DYN_REC_START1:
+                dynamic_macro_record_start(&macro_pointer, macro_buffer);
+                macro_id = 1;
+                return false;
+            case DYN_REC_START2:
+                dynamic_macro_record_start(&macro_pointer, r_macro_buffer);
+                macro_id = 2;
+                return false;
+            case DYN_MACRO_PLAY1:
+                dynamic_macro_play(macro_buffer, macro_end, +1);
+                return false;
+            case DYN_MACRO_PLAY2:
+                dynamic_macro_play(r_macro_buffer, r_macro_end, -1);
+                return false;
+            }
+        }
+    } else {
+        /* A macro is being recorded right now. */
+        switch (keycode) {
+        case MO(_DYN):
+            /* Use the layer key used to access the macro recording as
+             * a stop button. */
+            if (record->event.pressed) { /* Ignore the initial release
+                                          * just after the recoding
+                                          * starts. */
+                switch (macro_id) {
+                case 1:
+                    dynamic_macro_record_end(macro_pointer, &macro_end);
+                    break;
+                case 2:
+                    dynamic_macro_record_end(macro_pointer, &r_macro_end);
+                    break;
+                }
+                macro_id = 0;
+            }
+            return false;
+        default:
+            /* Store the key in the macro buffer and process it normally. */
+            switch (macro_id) {
+            case 1:
+                dynamic_macro_record_key(&macro_pointer, r_macro_end, +1, record);
+                break;
+            case 2:
+                dynamic_macro_record_key(&macro_pointer, macro_end, -1, record);
+                break;
+            }
+            return true;
+            break;
+        }
+    }
+
+    return true;
+}
+
+#endif
diff --git a/quantum/process_keycode/process_tap_dance.c b/quantum/process_keycode/process_tap_dance.c
index 5429e34383..07de3ecb8f 100644
--- a/quantum/process_keycode/process_tap_dance.c
+++ b/quantum/process_keycode/process_tap_dance.c
@@ -1,26 +1,16 @@
 #include "quantum.h"
+#include "action_tapping.h"
 
-static qk_tap_dance_state_t qk_tap_dance_state;
-bool td_debug_enable = false;
-
-#if CONSOLE_ENABLE
-#define td_debug(s) if (td_debug_enable) \
-    { \
-      xprintf ("D:tap_dance:%s:%s = { keycode = %d, count = %d, active = %d, pressed = %d }\n", __FUNCTION__, s, \
-               qk_tap_dance_state.keycode, qk_tap_dance_state.count, \
-               qk_tap_dance_state.active, qk_tap_dance_state.pressed);  \
-    }
-#else
-#define td_debug(s)
-#endif
+static uint16_t last_td;
+static int8_t highest_td = -1;
 
 void qk_tap_dance_pair_finished (qk_tap_dance_state_t *state, void *user_data) {
   qk_tap_dance_pair_t *pair = (qk_tap_dance_pair_t *)user_data;
 
   if (state->count == 1) {
-    register_code (pair->kc1);
+    register_code16 (pair->kc1);
   } else if (state->count == 2) {
-    register_code (pair->kc2);
+    register_code16 (pair->kc2);
   }
 }
 
@@ -28,105 +18,117 @@ void qk_tap_dance_pair_reset (qk_tap_dance_state_t *state, void *user_data) {
   qk_tap_dance_pair_t *pair = (qk_tap_dance_pair_t *)user_data;
 
   if (state->count == 1) {
-    unregister_code (pair->kc1);
+    unregister_code16 (pair->kc1);
   } else if (state->count == 2) {
-    unregister_code (pair->kc2);
+    unregister_code16 (pair->kc2);
   }
 }
 
 static inline void _process_tap_dance_action_fn (qk_tap_dance_state_t *state,
-                                          void *user_data,
-                                          qk_tap_dance_user_fn_t fn)
+                                                 void *user_data,
+                                                 qk_tap_dance_user_fn_t fn)
 {
   if (fn) {
     fn(state, user_data);
   }
 }
 
-static inline void process_tap_dance_action_on_each_tap (qk_tap_dance_action_t action)
+static inline void process_tap_dance_action_on_each_tap (qk_tap_dance_action_t *action)
 {
-  td_debug("trigger");
-  _process_tap_dance_action_fn (&qk_tap_dance_state, action.user_data, action.fn.on_each_tap);
+  _process_tap_dance_action_fn (&action->state, action->user_data, action->fn.on_each_tap);
 }
 
-static inline void process_tap_dance_action_on_dance_finished (qk_tap_dance_action_t action)
+static inline void process_tap_dance_action_on_dance_finished (qk_tap_dance_action_t *action)
 {
-  td_debug("trigger");
-  _process_tap_dance_action_fn (&qk_tap_dance_state, action.user_data, action.fn.on_dance_finished);
+  if (action->state.finished)
+    return;
+  action->state.finished = true;
+  _process_tap_dance_action_fn (&action->state, action->user_data, action->fn.on_dance_finished);
 }
 
-static inline void process_tap_dance_action_on_reset (qk_tap_dance_action_t action)
+static inline void process_tap_dance_action_on_reset (qk_tap_dance_action_t *action)
 {
-  td_debug("trigger")
-  _process_tap_dance_action_fn (&qk_tap_dance_state, action.user_data, action.fn.on_reset);
+  _process_tap_dance_action_fn (&action->state, action->user_data, action->fn.on_reset);
 }
 
 bool process_tap_dance(uint16_t keycode, keyrecord_t *record) {
-  bool r = true;
   uint16_t idx = keycode - QK_TAP_DANCE;
-  qk_tap_dance_action_t action;
+  qk_tap_dance_action_t *action;
+
+  if (last_td && last_td != keycode) {
+    (&tap_dance_actions[last_td - QK_TAP_DANCE])->state.interrupted = true;
+  }
 
   switch(keycode) {
   case QK_TAP_DANCE ... QK_TAP_DANCE_MAX:
-    action = tap_dance_actions[idx];
-
-    process_tap_dance_action_on_each_tap (action);
-    if (qk_tap_dance_state.keycode && qk_tap_dance_state.keycode != keycode) {
-      process_tap_dance_action_on_dance_finished (action);
-    } else if (qk_tap_dance_state.active && qk_tap_dance_state.pressed) {
-      reset_tap_dance (&qk_tap_dance_state);
-    } else {
-      r = false;
-    }
+    if ((int16_t)idx > highest_td)
+      highest_td = idx;
+    action = &tap_dance_actions[idx];
 
-    qk_tap_dance_state.active = true;
-    qk_tap_dance_state.pressed = record->event.pressed;
+    action->state.keycode = keycode;
+    action->state.pressed = record->event.pressed;
     if (record->event.pressed) {
-      qk_tap_dance_state.keycode = keycode;
-      qk_tap_dance_state.timer = timer_read ();
-      qk_tap_dance_state.count++;
+      action->state.count++;
+      action->state.timer = timer_read();
+
+      if (last_td && last_td != keycode) {
+        qk_tap_dance_action_t *paction = &tap_dance_actions[last_td - QK_TAP_DANCE];
+        paction->state.interrupted = true;
+        process_tap_dance_action_on_dance_finished (paction);
+        reset_tap_dance (&paction->state);
+      }
     }
+    last_td = keycode;
+
     break;
 
   default:
-    if (qk_tap_dance_state.keycode) {
-      // if we are here, the tap dance was interrupted by a different key
-      idx = qk_tap_dance_state.keycode - QK_TAP_DANCE;
-      action = tap_dance_actions[idx];
+    if (!record->event.pressed)
+      return true;
+
+    if (highest_td == -1)
+      return true;
 
-      process_tap_dance_action_on_each_tap (action);
+    for (int i = 0; i <= highest_td; i++) {
+      action = &tap_dance_actions[i];
+      if (action->state.count == 0)
+        continue;
+      action->state.interrupted = true;
       process_tap_dance_action_on_dance_finished (action);
-      reset_tap_dance (&qk_tap_dance_state);
-      qk_tap_dance_state.active = false;
+      reset_tap_dance (&action->state);
     }
     break;
   }
 
-  return r;
+  return true;
 }
 
 void matrix_scan_tap_dance () {
-  if (qk_tap_dance_state.active && timer_elapsed (qk_tap_dance_state.timer) > TAPPING_TERM) {
-    // if we are here, the tap dance was timed out
-    uint16_t idx = qk_tap_dance_state.keycode - QK_TAP_DANCE;
-    qk_tap_dance_action_t action = tap_dance_actions[idx];
+  if (highest_td == -1)
+    return;
+
+  for (int i = 0; i <= highest_td; i++) {
+    qk_tap_dance_action_t *action = &tap_dance_actions[i];
 
-    process_tap_dance_action_on_dance_finished (action);
-    reset_tap_dance (&qk_tap_dance_state);
+    if (action->state.count && timer_elapsed (action->state.timer) > TAPPING_TERM) {
+      process_tap_dance_action_on_dance_finished (action);
+      reset_tap_dance (&action->state);
+    }
   }
 }
 
 void reset_tap_dance (qk_tap_dance_state_t *state) {
-  uint16_t idx = state->keycode - QK_TAP_DANCE;
-  qk_tap_dance_action_t action;
+  qk_tap_dance_action_t *action;
 
   if (state->pressed)
     return;
 
-  action = tap_dance_actions[idx];
+  action = &tap_dance_actions[state->keycode - QK_TAP_DANCE];
+
   process_tap_dance_action_on_reset (action);
 
-  state->keycode = 0;
   state->count = 0;
-  state->active = false;
+  state->interrupted = false;
+  state->finished = false;
+  last_td = 0;
 }
diff --git a/quantum/process_keycode/process_tap_dance.h b/quantum/process_keycode/process_tap_dance.h
index 6a1258067e..d7b857bdc6 100644
--- a/quantum/process_keycode/process_tap_dance.h
+++ b/quantum/process_keycode/process_tap_dance.h
@@ -11,8 +11,9 @@ typedef struct
   uint8_t count;
   uint16_t keycode;
   uint16_t timer;
-  bool active:1;
-  bool pressed:1;
+  bool interrupted;
+  bool pressed;
+  bool finished;
 } qk_tap_dance_state_t;
 
 #define TD(n) (QK_TAP_DANCE + n)
@@ -26,6 +27,7 @@ typedef struct
     qk_tap_dance_user_fn_t on_dance_finished;
     qk_tap_dance_user_fn_t on_reset;
   } fn;
+  qk_tap_dance_state_t state;
   void *user_data;
 } qk_tap_dance_action_t;
 
@@ -48,8 +50,7 @@ typedef struct
     .fn = { user_fn_on_each_tap, user_fn_on_dance_finished, user_fn_on_reset } \
   }
 
-extern const qk_tap_dance_action_t tap_dance_actions[];
-extern bool td_debug_enable;
+extern qk_tap_dance_action_t tap_dance_actions[];
 
 /* To be used internally */
 
diff --git a/quantum/process_keycode/process_unicode.c b/quantum/process_keycode/process_unicode.c
index ad5d7f86b7..72c809c30e 100644
--- a/quantum/process_keycode/process_unicode.c
+++ b/quantum/process_keycode/process_unicode.c
@@ -13,45 +13,192 @@ uint16_t hex_to_keycode(uint8_t hex)
   }
 }
 
-void set_unicode_mode(uint8_t os_target)
+void set_unicode_input_mode(uint8_t os_target)
 {
   input_mode = os_target;
 }
 
+void unicode_input_start (void) {
+  switch(input_mode) {
+  case UC_OSX:
+    register_code(KC_LALT);
+    break;
+  case UC_LNX:
+    register_code(KC_LCTL);
+    register_code(KC_LSFT);
+    register_code(KC_U);
+    unregister_code(KC_U);
+    unregister_code(KC_LSFT);
+    unregister_code(KC_LCTL);
+    break;
+  case UC_WIN:
+    register_code(KC_LALT);
+    register_code(KC_PPLS);
+    unregister_code(KC_PPLS);
+    break;
+  }
+  wait_ms(UNICODE_TYPE_DELAY);
+}
+
+void unicode_input_finish (void) {
+  switch(input_mode) {
+  case UC_OSX:
+  case UC_WIN:
+    unregister_code(KC_LALT);
+    break;
+  case UC_LNX:
+    register_code(KC_SPC);
+    unregister_code(KC_SPC);
+    break;
+  }
+}
+
+void register_hex(uint16_t hex) {
+  for(int i = 3; i >= 0; i--) {
+    uint8_t digit = ((hex >> (i*4)) & 0xF);
+    register_code(hex_to_keycode(digit));
+    unregister_code(hex_to_keycode(digit));
+  }
+}
+
 bool process_unicode(uint16_t keycode, keyrecord_t *record) {
   if (keycode > QK_UNICODE && record->event.pressed) {
     uint16_t unicode = keycode & 0x7FFF;
-    switch(input_mode) {
-      case UC_OSX:
-        register_code(KC_LALT);
-        break;
-      case UC_LNX:
-        register_code(KC_LCTL);
-        register_code(KC_LSFT);
-        register_code(KC_U);
-        unregister_code(KC_U);
-        break;
-      case UC_WIN:
-        register_code(KC_LALT);
-        register_code(KC_PPLS);
-        unregister_code(KC_PPLS);
-        break;
+    unicode_input_start();
+    register_hex(unicode);
+    unicode_input_finish();
+  }
+  return true;
+}
+
+#ifdef UCIS_ENABLE
+void qk_ucis_start(void) {
+  qk_ucis_state.count = 0;
+  qk_ucis_state.in_progress = true;
+
+  qk_ucis_start_user();
+}
+
+__attribute__((weak))
+void qk_ucis_start_user(void) {
+  unicode_input_start();
+  register_hex(0x2328);
+  unicode_input_finish();
+}
+
+static bool is_uni_seq(char *seq) {
+  uint8_t i;
+
+  for (i = 0; seq[i]; i++) {
+    uint16_t code;
+    if (('1' <= seq[i]) && (seq[i] <= '0'))
+      code = seq[i] - '1' + KC_1;
+    else
+      code = seq[i] - 'a' + KC_A;
+
+    if (i > qk_ucis_state.count || qk_ucis_state.codes[i] != code)
+      return false;
+  }
+
+  return (qk_ucis_state.codes[i] == KC_ENT ||
+          qk_ucis_state.codes[i] == KC_SPC);
+}
+
+__attribute__((weak))
+void qk_ucis_symbol_fallback (void) {
+  for (uint8_t i = 0; i < qk_ucis_state.count - 1; i++) {
+    uint8_t code = qk_ucis_state.codes[i];
+    register_code(code);
+    unregister_code(code);
+    wait_ms(UNICODE_TYPE_DELAY);
+  }
+}
+
+void register_ucis(const char *hex) {
+  for(int i = 0; hex[i]; i++) {
+    uint8_t kc = 0;
+    char c = hex[i];
+
+    switch (c) {
+    case '0':
+      kc = KC_0;
+      break;
+    case '1' ... '9':
+      kc = c - '1' + KC_1;
+      break;
+    case 'a' ... 'f':
+      kc = c - 'a' + KC_A;
+      break;
+    case 'A' ... 'F':
+      kc = c - 'A' + KC_A;
+      break;
     }
-    for(int i = 3; i >= 0; i--) {
-        uint8_t digit = ((unicode >> (i*4)) & 0xF);
-        register_code(hex_to_keycode(digit));
-        unregister_code(hex_to_keycode(digit));
+
+    if (kc) {
+      register_code (kc);
+      unregister_code (kc);
+      wait_ms (UNICODE_TYPE_DELAY);
     }
-    switch(input_mode) {
-      case UC_OSX:
-      case UC_WIN:
-        unregister_code(KC_LALT);
-        break;
-      case UC_LNX:
-        unregister_code(KC_LCTL);
-        unregister_code(KC_LSFT);
+  }
+}
+
+bool process_ucis (uint16_t keycode, keyrecord_t *record) {
+  uint8_t i;
+
+  if (!qk_ucis_state.in_progress)
+    return true;
+
+  if (qk_ucis_state.count >= UCIS_MAX_SYMBOL_LENGTH &&
+      !(keycode == KC_BSPC || keycode == KC_ESC || keycode == KC_SPC || keycode == KC_ENT)) {
+    return false;
+  }
+
+  if (!record->event.pressed)
+    return true;
+
+  qk_ucis_state.codes[qk_ucis_state.count] = keycode;
+  qk_ucis_state.count++;
+
+  if (keycode == KC_BSPC) {
+    if (qk_ucis_state.count >= 2) {
+      qk_ucis_state.count -= 2;
+      return true;
+    } else {
+      qk_ucis_state.count--;
+      return false;
+    }
+  }
+
+  if (keycode == KC_ENT || keycode == KC_SPC || keycode == KC_ESC) {
+    bool symbol_found = false;
+
+    for (i = qk_ucis_state.count; i > 0; i--) {
+      register_code (KC_BSPC);
+      unregister_code (KC_BSPC);
+      wait_ms(UNICODE_TYPE_DELAY);
+    }
+
+    if (keycode == KC_ESC) {
+      qk_ucis_state.in_progress = false;
+      return false;
+    }
+
+    unicode_input_start();
+    for (i = 0; ucis_symbol_table[i].symbol; i++) {
+      if (is_uni_seq (ucis_symbol_table[i].symbol)) {
+        symbol_found = true;
+        register_ucis(ucis_symbol_table[i].code + 2);
         break;
+      }
     }
+    if (!symbol_found) {
+      qk_ucis_symbol_fallback();
+    }
+    unicode_input_finish();
+
+    qk_ucis_state.in_progress = false;
+    return false;
   }
   return true;
-}
\ No newline at end of file
+}
+#endif
diff --git a/quantum/process_keycode/process_unicode.h b/quantum/process_keycode/process_unicode.h
index ca17f8f669..85364e8eb3 100644
--- a/quantum/process_keycode/process_unicode.h
+++ b/quantum/process_keycode/process_unicode.h
@@ -8,10 +8,46 @@
 #define UC_WIN 2
 #define UC_BSD 3
 
+#ifndef UNICODE_TYPE_DELAY
+#define UNICODE_TYPE_DELAY 10
+#endif
+
 void set_unicode_input_mode(uint8_t os_target);
+void unicode_input_start(void);
+void unicode_input_finish(void);
+void register_hex(uint16_t hex);
 
 bool process_unicode(uint16_t keycode, keyrecord_t *record);
 
+#ifdef UCIS_ENABLE
+#ifndef UCIS_MAX_SYMBOL_LENGTH
+#define UCIS_MAX_SYMBOL_LENGTH 32
+#endif
+
+typedef struct {
+  char *symbol;
+  char *code;
+} qk_ucis_symbol_t;
+
+struct {
+  uint8_t count;
+  uint16_t codes[UCIS_MAX_SYMBOL_LENGTH];
+  bool in_progress:1;
+} qk_ucis_state;
+
+#define UCIS_TABLE(...) {__VA_ARGS__, {NULL, NULL}}
+#define UCIS_SYM(name, code) {name, #code}
+
+extern const qk_ucis_symbol_t ucis_symbol_table[];
+
+void qk_ucis_start(void);
+void qk_ucis_start_user(void);
+void qk_ucis_symbol_fallback (void);
+void register_ucis(const char *hex);
+bool process_ucis (uint16_t keycode, keyrecord_t *record);
+
+#endif
+
 #define UC_BSPC	UC(0x0008)
 
 #define UC_SPC	UC(0x0020)
@@ -119,4 +155,4 @@ bool process_unicode(uint16_t keycode, keyrecord_t *record);
 #define UC_TILD	UC(0x007E)
 #define UC_DEL	UC(0x007F)
 
-#endif
\ No newline at end of file
+#endif
diff --git a/quantum/quantum.c b/quantum/quantum.c
index bc2da510f2..e3a20f43e0 100644
--- a/quantum/quantum.c
+++ b/quantum/quantum.c
@@ -1,5 +1,42 @@
 #include "quantum.h"
 
+static void do_code16 (uint16_t code, void (*f) (uint8_t)) {
+  switch (code) {
+  case QK_MODS ... QK_MODS_MAX:
+    break;
+  default:
+    return;
+  }
+
+  if (code & QK_LCTL)
+    f(KC_LCTL);
+  if (code & QK_LSFT)
+    f(KC_LSFT);
+  if (code & QK_LALT)
+    f(KC_LALT);
+  if (code & QK_LGUI)
+    f(KC_LGUI);
+
+  if (code & QK_RCTL)
+    f(KC_RCTL);
+  if (code & QK_RSFT)
+    f(KC_RSFT);
+  if (code & QK_RALT)
+    f(KC_RALT);
+  if (code & QK_RGUI)
+    f(KC_RGUI);
+}
+
+void register_code16 (uint16_t code) {
+  do_code16 (code, register_code);
+  register_code (code);
+}
+
+void unregister_code16 (uint16_t code) {
+  unregister_code (code);
+  do_code16 (code, unregister_code);
+}
+
 __attribute__ ((weak))
 bool process_action_kb(keyrecord_t *record) {
   return true;
@@ -46,18 +83,20 @@ bool process_record_quantum(keyrecord_t *record) {
   uint16_t keycode;
 
   #if !defined(NO_ACTION_LAYER) && defined(PREVENT_STUCK_MODIFIERS)
-    uint8_t layer;
+    /* TODO: Use store_or_get_action() or a similar function. */
+    if (!disable_action_cache) {
+      uint8_t layer;
 
-    if (record->event.pressed) {
-      layer = layer_switch_get_layer(key);
-      update_source_layers_cache(key, layer);
-    } else {
-      layer = read_source_layers_cache(key);
-    }
-    keycode = keymap_key_to_keycode(layer, key);
-  #else
-    keycode = keymap_key_to_keycode(layer_switch_get_layer(key), key);
+      if (record->event.pressed) {
+        layer = layer_switch_get_layer(key);
+        update_source_layers_cache(key, layer);
+      } else {
+        layer = read_source_layers_cache(key);
+      }
+      keycode = keymap_key_to_keycode(layer, key);
+    } else
   #endif
+    keycode = keymap_key_to_keycode(layer_switch_get_layer(key), key);
 
     // This is how you use actions here
     // if (keycode == KC_LEAD) {
@@ -87,6 +126,9 @@ bool process_record_quantum(keyrecord_t *record) {
   #ifdef UNICODE_ENABLE
     process_unicode(keycode, record) &&
   #endif
+  #ifdef UCIS_ENABLE
+    process_ucis(keycode, record) &&
+  #endif
       true)) {
     return false;
   }
diff --git a/quantum/quantum.h b/quantum/quantum.h
index 6e3fbcc792..0c60466495 100644
--- a/quantum/quantum.h
+++ b/quantum/quantum.h
@@ -83,6 +83,9 @@ void reset_keyboard(void);
 void startup_user(void);
 void shutdown_user(void);
 
+void register_code16 (uint16_t code);
+void unregister_code16 (uint16_t code);
+
 #ifdef BACKLIGHT_ENABLE
 void backlight_init_ports(void);