qmk-firmware/users/ericgebhart/extensions/oneshot.c

#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(void) {
    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_LCTL + osmod);
    } else {
        if (current_state == ONESHOT_STATE_OFF) {
            unregister_code(KC_LCTL + 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(void) {
    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