1 files changed, 217 insertions, 0 deletions
diff --git a/users/ericgebhart/extensions/oneshot.c b/users/ericgebhart/extensions/oneshot.c
new file mode 100644
index 0000000000..83c8a04363
--- /dev/null
+++ b/users/ericgebhart/extensions/oneshot.c
@@ -0,0 +1,217 @@
+#include QMK_KEYBOARD_H
+#include USERSPACE_H
+#include "oneshot.h"
+
+#ifdef ONESHOT_MOD_ENABLE
+
+/* -------------------------------------------- */
+// Add to process_record_user.
+/* int8_t keycode_consumed = 0; */
+
+/* #ifdef ONESHOT_ENABLE */
+/* keycode_consumed += update_oneshot_modifiers(keycode, record, keycode_consumed); */
+/* #endif */
+/* -------------------------------------------- */
+
+#define ONESHOT(KEYCODE, MOD) case KEYCODE: return MOD;
+
+#define A_KEY(KEYCODE) case KEYCODE:
+#define BLANK(...)
+
+#define CANCEL_KEY BLANK
+#define IGNORE_KEY BLANK
+
+// the basic states a oneshot modifier can be in
+typedef enum {
+    ONESHOT_STATE_OFF          = 0,
+    ONESHOT_STATE_PRESSED      = 1,
+    ONESHOT_STATE_QUEUED       = 2,
+    ONESHOT_STATE_CAPSWORD     = 3,
+    ONESHOT_STATE_LOCK         = 4,
+    ONESHOT_STATE_END_PRESSED  = 5,
+} oneshot_state;
+
+oneshot_state modifiers_state_transitions_normal[5] = {ONESHOT_STATE_PRESSED, ONESHOT_STATE_QUEUED, ONESHOT_STATE_LOCK, ONESHOT_STATE_END_PRESSED, ONESHOT_STATE_END_PRESSED};
+
+static oneshot_state modifiers_with_state[ONESHOT_MOD_COUNT] = {
+    ONESHOT_STATE_OFF, ONESHOT_STATE_OFF, ONESHOT_STATE_OFF, ONESHOT_STATE_OFF, ONESHOT_STATE_OFF, ONESHOT_STATE_OFF, ONESHOT_STATE_OFF, ONESHOT_STATE_OFF,
+};
+
+// oneshot mods always get registered immediately to the operating system, but we also
+// need to keep track if the mod(s) got combined with a normal key (applied)
+static bool unapplied_mods_present = false;
+
+// keycode of the last pressed 'normal' key which haven't been released yet
+static uint16_t repeating_normal_key = 0;
+
+// utility functions (implemented at the bottom of this file)
+static void          set_modifier_state(oneshot_mod osmod, oneshot_state new_state);
+static int8_t        set_modifier_state_all(oneshot_state new_state);
+static void          set_modifier_state_all_from_to(oneshot_state oneshot_state_from, oneshot_state oneshot_state_to);
+static bool          all_modifiers_are_off(void);
+
+int8_t turnoff_oneshot_modifiers() {
+    return set_modifier_state_all(ONESHOT_STATE_OFF);
+}
+
+// see comment in corresponding headerfile
+int8_t update_oneshot_modifiers(uint16_t keycode, keyrecord_t *record, int8_t keycode_consumed) {
+
+    // cancel keys
+  if (is_oneshot_modifier_cancel_key(keycode) && record->event.pressed) {
+    if (keycode_consumed == 0) {
+      unapplied_mods_present = false;
+      keycode_consumed += set_modifier_state_all(ONESHOT_STATE_OFF);
+    } else {
+      keycode_consumed = 0;
+    }
+    return keycode_consumed;
+  }
+
+  // ignored keys
+  if (is_oneshot_modifier_ignored_key(keycode)) {
+    return keycode_consumed;
+  }
+
+  oneshot_mod osmod = get_modifier_for_trigger_key(keycode);
+
+  // trigger keys
+  if (osmod != ONESHOT_NONE) {
+    oneshot_state state = modifiers_with_state[osmod];
+    if (record->event.pressed) {
+      if (state == ONESHOT_STATE_OFF) {
+        unapplied_mods_present = (repeating_normal_key == 0);
+      }
+      oneshot_state tostate = modifiers_state_transitions_normal[state];
+      set_modifier_state(osmod, tostate);
+    } else {
+      if (state == ONESHOT_STATE_PRESSED) {
+        if (!unapplied_mods_present) {
+          set_modifier_state(osmod, ONESHOT_STATE_OFF);
+        } else {
+          set_modifier_state(osmod, ONESHOT_STATE_QUEUED);
+        }
+      } else if (state == ONESHOT_STATE_END_PRESSED) {
+        set_modifier_state(osmod, ONESHOT_STATE_OFF);
+      }
+    }
+  }
+  // normal keys
+  else {
+    if (record->event.pressed) {
+      if (!all_modifiers_are_off()) {
+        if (unapplied_mods_present) {
+          unapplied_mods_present = false;
+        } else {
+          unregister_code(repeating_normal_key);
+          set_modifier_state_all_from_to(ONESHOT_STATE_QUEUED, ONESHOT_STATE_OFF);
+        }
+      }
+      repeating_normal_key = keycode;
+    } else {
+      if (!all_modifiers_are_off()) {
+        unregister_code(keycode);
+        set_modifier_state_all_from_to(ONESHOT_STATE_QUEUED, ONESHOT_STATE_OFF);
+      }
+      repeating_normal_key = 0;
+    }
+  }
+
+  return 0;
+}
+
+// implementation of utility functions
+
+// registers/unregisters a mod to the operating system on state change if necessary
+void update_modifier(oneshot_mod osmod, oneshot_state previous_state, oneshot_state current_state) {
+    if (previous_state == ONESHOT_STATE_OFF) {
+        register_code(KC_LCTRL + osmod);
+    } else {
+        if (current_state == ONESHOT_STATE_OFF) {
+            unregister_code(KC_LCTRL + osmod);
+        }
+    }
+}
+
+void set_modifier_state(oneshot_mod osmod, oneshot_state new_state) {
+    oneshot_state previous_state = modifiers_with_state[osmod];
+    if (previous_state != new_state) {
+        modifiers_with_state[osmod] = new_state;
+        update_modifier(osmod, previous_state, new_state);
+    }
+}
+
+int8_t set_modifier_state_all(oneshot_state new_state) {
+    int8_t c = 0;
+    for (int8_t i = 0; i < ONESHOT_MOD_COUNT; i++) {
+        oneshot_state previous_state = modifiers_with_state[i];
+        if (previous_state != new_state) {
+            modifiers_with_state[i] = new_state;
+            update_modifier(i, previous_state, new_state);
+            c += 1;
+        }
+    }
+    return c;
+}
+
+void set_modifier_state_all_from_to(oneshot_state oneshot_state_from, oneshot_state oneshot_state_to) {
+    for (int8_t i = 0; i < ONESHOT_MOD_COUNT; i++) {
+        if (modifiers_with_state[i] == oneshot_state_from) {
+            modifiers_with_state[i] = oneshot_state_to;
+            update_modifier(i, oneshot_state_from, oneshot_state_to);
+        }
+    }
+}
+
+bool all_modifiers_are_off() {
+    for (int8_t i = 0; i < ONESHOT_MOD_COUNT; i++) {
+        if (modifiers_with_state[i] != ONESHOT_STATE_OFF) {
+            return false;
+        }
+    }
+    return true;
+}
+
+oneshot_mod get_modifier_for_trigger_key(uint16_t keycode)
+{
+  switch (keycode)
+    {
+#include "oneshot.def"
+      return true;
+    default:
+      return ONESHOT_NONE;
+    }
+}
+
+// turn off the oneshot macros
+#undef ONESHOT
+#define ONESHOT BLANK
+#define NSHOT BLANK
+
+#undef CANCEL_KEY
+#undef IGNORE_KEY
+#define CANCEL_KEY A_KEY
+#define IGNORE_KEY BLANK
+bool is_oneshot_modifier_cancel_key(uint16_t keycode) {
+  switch (keycode) {
+#include "oneshot.def"
+    return true;
+  default:
+    return false;
+  }
+}
+
+#undef CANCEL_KEY
+#undef IGNORE_KEY
+#define CANCEL_KEY BLANK
+#define IGNORE_KEY A_KEY
+bool is_oneshot_modifier_ignored_key(uint16_t keycode) {
+  switch (keycode) {
+#include "oneshot.def"
+    return true;
+  default:
+    return false;
+  }
+}
+
+#endif