process_unicode: Add a way to enter unicode symbols by name

The purpose of this change is to allow keymaps to specify a dictionary
of unicode symbol name to code mappings, and let the person at the
keyboard enter unicode symbols by name.

This is done by having a way to trigger unicode symbol input mode, when
all keys are cached until Esc, Enter or Space are pressed. Once that
happens, we try to look up the symbol from our lookup table. If found,
we erase back, and type the unicode magic in to get that symbol. If not
found, we still erase back, start unicode input mode, and replay what
the user typed in.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

3 files changed, 126 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 053c8532af..693edc9f06 100644
--- a/Makefile
+++ b/Makefile
@@ -198,6 +198,11 @@ ifeq ($(strip $(AUDIO_ENABLE)), yes)
 	SRC += $(QUANTUM_DIR)/audio/luts.c
 endif
 
+ifeq ($(strip $(UCIS_ENABLE)), yes)
+	OPT_DEFS += -DUCIS_ENABLE
+	UNICODE_ENABLE = yes
+endif
+
 ifeq ($(strip $(UNICODE_ENABLE)), yes)
     OPT_DEFS += -DUNICODE_ENABLE
 	SRC += $(QUANTUM_DIR)/process_keycode/process_unicode.c
@@ -273,4 +278,4 @@ BUILD_DATE := $(shell date +"%Y-%m-%d-%H:%M:%S")
 OPT_DEFS += -DQMK_KEYBOARD=\"$(KEYBOARD)\" -DQMK_KEYMAP=\"$(KEYMAP)\"
 
 $(shell echo '#define QMK_VERSION "$(GIT_VERSION)"' > $(QUANTUM_PATH)/version.h)
-$(shell echo '#define QMK_BUILDDATE "$(BUILD_DATE)"' >> $(QUANTUM_PATH)/version.h)
\ No newline at end of file
+$(shell echo '#define QMK_BUILDDATE "$(BUILD_DATE)"' >> $(QUANTUM_PATH)/version.h)
diff --git a/quantum/process_keycode/process_unicode.c b/quantum/process_keycode/process_unicode.c
index 55e47f1794..8a65093008 100644
--- a/quantum/process_keycode/process_unicode.c
+++ b/quantum/process_keycode/process_unicode.c
@@ -68,4 +68,95 @@ bool process_unicode(uint16_t keycode, keyrecord_t *record) {
     unicode_input_finish();
   }
   return true;
-}
\ No newline at end of file
+}
+
+#ifdef UCIS_ENABLE
+void qk_ucis_start(void) {
+  qk_ucis_state.count = 0;
+  qk_ucis_state.in_progress = true;
+
+  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);
+  }
+}
+
+bool process_record_ucis (uint16_t keycode, keyrecord_t *record) {
+  uint8_t i;
+
+  if (!qk_ucis_state.in_progress || !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);
+    }
+
+    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;
+        for (uint8_t j = 0; ucis_symbol_table[i].codes[j]; j++) {
+          register_hex(ucis_symbol_table[i].codes[j]);
+        }
+        break;
+      }
+    }
+    if (!symbol_found) {
+      qk_ucis_symbol_fallback();
+    }
+    unicode_input_finish();
+
+    qk_ucis_state.in_progress = false;
+    return false;
+  }
+  return true;
+}
+#endif
diff --git a/quantum/process_keycode/process_unicode.h b/quantum/process_keycode/process_unicode.h
index f719a12261..372ea2f0df 100644
--- a/quantum/process_keycode/process_unicode.h
+++ b/quantum/process_keycode/process_unicode.h
@@ -15,6 +15,33 @@ 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;
+  uint16_t codes[4];
+} 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, {}}}
+#define UCIS_SYM(name, ...) {name, {__VA_ARGS__, 0}}
+
+extern const qk_ucis_symbol_t ucis_symbol_table[];
+
+void qk_ucis_start(void);
+void qk_ucis_symbol_fallback (void);
+bool process_record_ucis (uint16_t keycode, keyrecord_t *record);
+
+#endif
+
 #define UC_BSPC	UC(0x0008)
 
 #define UC_SPC	UC(0x0020)
@@ -122,4 +149,4 @@ 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