Added emacs as an "operating system" for input mode. (#16949)

4 files changed, 40 insertions, 7 deletions

diff --git a/docs/feature_unicode.md b/docs/feature_unicode.md
index bced419a03..2389cb735c 100644
--- a/docs/feature_unicode.md
+++ b/docs/feature_unicode.md
@@ -127,7 +127,7 @@ The following input modes are available:
   By default, this mode uses Ctrl+Shift+U (`LCTL(LSFT(KC_U))`) to start Unicode input, but this can be changed by defining [`UNICODE_KEY_LNX`](#input-key-configuration) with a different keycode. This might be required for IBus versions ≥1.5.15, where Ctrl+Shift+U behavior is consolidated into Ctrl+Shift+E.
 
   Users who wish support in non-GTK apps without IBus may need to resort to a more indirect method, such as creating a custom keyboard layout ([more on this method](#custom-linux-layout)).
-  
+
 * **`UC_WIN`**: _(not recommended)_ Windows built-in hex numpad Unicode input. Supports code points up to `0xFFFF`.
 
   To enable, create a registry key under `HKEY_CURRENT_USER\Control Panel\Input Method` of type `REG_SZ` called `EnableHexNumpad` and set its value to `1`. This can be done from the Command Prompt by running `reg add "HKCU\Control Panel\Input Method" -v EnableHexNumpad -t REG_SZ -d 1` with administrator privileges. Reboot afterwards.
@@ -172,6 +172,7 @@ You can switch the input mode at any time by using the following keycodes. Addin
 |`UNICODE_MODE_WIN`    |`UC_M_WI`|`UC_WIN`    |Switch to Windows input                                                      |
 |`UNICODE_MODE_BSD`    |`UC_M_BS`|`UC_BSD`    |Switch to BSD input _(not implemented)_                                      |
 |`UNICODE_MODE_WINC`   |`UC_M_WC`|`UC_WINC`   |Switch to Windows input using WinCompose                                     |
+|`UNICODE_MODE_EMACS`  |`UC_M_EM`|`UC_EMACS`  |Switch to emacs (`C-x-8 RET`)                                               |
 
 You can also switch the input mode by calling `set_unicode_input_mode(x)` in your code, where _x_ is one of the above input mode constants (e.g. `UC_LNX`).
 
diff --git a/quantum/process_keycode/process_unicode_common.c b/quantum/process_keycode/process_unicode_common.c
index 6cb2ba8dbb..8de31c055c 100644
--- a/quantum/process_keycode/process_unicode_common.c
+++ b/quantum/process_keycode/process_unicode_common.c
@@ -117,6 +117,12 @@ __attribute__((weak)) void unicode_input_start(void) {
             tap_code(UNICODE_KEY_WINC);
             tap_code(KC_U);
             break;
+        case UC_EMACS:
+            // The usual way to type unicode in emacs is C-x-8 <RET> then the unicode number in hex
+            tap_code16(LCTL(KC_X));
+            tap_code16(KC_8);
+            tap_code16(KC_ENTER);
+            break;
     }
 
     wait_ms(UNICODE_TYPE_DELAY);
@@ -142,6 +148,9 @@ __attribute__((weak)) void unicode_input_finish(void) {
         case UC_WINC:
             tap_code(KC_ENTER);
             break;
+        case UC_EMACS:
+            tap_code16(KC_ENTER);
+            break;
     }
 
     set_mods(unicode_saved_mods); // Reregister previously set mods
@@ -167,6 +176,9 @@ __attribute__((weak)) void unicode_input_cancel(void) {
                 tap_code(KC_NUM_LOCK);
             }
             break;
+        case UC_EMACS:
+            tap_code16(LCTL(KC_G)); // C-g cancels
+            break;
     }
 
     set_mods(unicode_saved_mods); // Reregister previously set mods
@@ -299,14 +311,30 @@ bool process_unicode_common(uint16_t keycode, keyrecord_t *record) {
                 cycle_unicode_input_mode(shifted ? +1 : -1);
                 audio_helper();
                 break;
-
-            case UNICODE_MODE_MAC ... UNICODE_MODE_WINC: {
-                // Keycodes and input modes follow the same ordering
-                uint8_t delta = keycode - UNICODE_MODE_MAC;
-                set_unicode_input_mode(UC_MAC + delta);
+            case UNICODE_MODE_MAC:
+                set_unicode_input_mode(UC_MAC);
+                audio_helper();
+                break;
+            case UNICODE_MODE_LNX:
+                set_unicode_input_mode(UC_LNX);
+                audio_helper();
+                break;
+            case UNICODE_MODE_WIN:
+                set_unicode_input_mode(UC_WIN);
+                audio_helper();
+                break;
+            case UNICODE_MODE_BSD:
+                set_unicode_input_mode(UC_BSD);
+                audio_helper();
+                break;
+            case UNICODE_MODE_WINC:
+                set_unicode_input_mode(UC_WINC);
+                audio_helper();
+                break;
+            case UNICODE_MODE_EMACS:
+                set_unicode_input_mode(UC_EMACS);
                 audio_helper();
                 break;
-            }
         }
     }
 
diff --git a/quantum/process_keycode/process_unicode_common.h b/quantum/process_keycode/process_unicode_common.h
index 8a4494c939..15e798dbb3 100644
--- a/quantum/process_keycode/process_unicode_common.h
+++ b/quantum/process_keycode/process_unicode_common.h
@@ -64,6 +64,7 @@ enum unicode_input_modes {
     UC_WIN,   // Windows using EnableHexNumpad
     UC_BSD,   // BSD (not implemented)
     UC_WINC,  // Windows using WinCompose (https://github.com/samhocevar/wincompose)
+    UC_EMACS, // Emacs is an operating system in search of a good text editor
     UC__COUNT // Number of available input modes (always leave at the end)
 };
 
diff --git a/quantum/quantum_keycodes.h b/quantum/quantum_keycodes.h
index 7228ee9e08..c8f03fa1ce 100644
--- a/quantum/quantum_keycodes.h
+++ b/quantum/quantum_keycodes.h
@@ -609,6 +609,8 @@ enum quantum_keycodes {
     MAGIC_UNSWAP_ESCAPE_CAPSLOCK,
     MAGIC_TOGGLE_ESCAPE_CAPSLOCK,
 
+    UNICODE_MODE_EMACS,
+
     // Start of custom keycode range for keyboards and keymaps - always leave at the end
     SAFE_RANGE
 };
@@ -894,6 +896,7 @@ enum quantum_keycodes {
 #define UC_M_WI UNICODE_MODE_WIN
 #define UC_M_BS UNICODE_MODE_BSD
 #define UC_M_WC UNICODE_MODE_WINC
+#define UC_M_EM UNICODE_MODE_EMACS
 
 // Swap Hands
 #define SH_T(kc) (QK_SWAP_HANDS | (kc))