qmk-firmware/keyboards/mechmini/v2/keymaps/split_space/keymap.c

#include QMK_KEYBOARD_H

#define _BL 0
#define _FN1 1
#define _FN2 2

#define MODS_CTRL_MASK  (MOD_BIT(KC_LSHIFT)|MOD_BIT(KC_RSHIFT))
const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {

	[_BL] = LAYOUT_split_space(
		F(0), KC_Q, KC_W, KC_E, KC_R, KC_T, KC_Y, KC_U, KC_I, KC_O, KC_P, KC_BSPC,
		KC_TAB, KC_A, KC_S, KC_D, KC_F, KC_G, KC_H, KC_J, KC_K, KC_L, KC_ENT,
		KC_LSFT, KC_Z, KC_X, KC_C, KC_V, KC_B, KC_N, KC_M, KC_COMM, KC_RSFT, KC_DOT,
		KC_LCTL, KC_LALT, KC_LGUI, KC_SPC, KC_SPC, KC_RCTL, MO(1), MO(2)),

	[_FN1] = LAYOUT_split_space(
		KC_GRV, KC_1, KC_2, KC_3, KC_4, KC_5, KC_6, KC_7, KC_8, KC_9, KC_0, KC_DEL,
		KC_TRNS, KC_PGUP, KC_VOLU, KC_TRNS, KC_TRNS, KC_TRNS, KC_LBRC, KC_RBRC, KC_MINS, KC_EQL, KC_TRNS,
		KC_LSFT, KC_PGDN, KC_VOLD, KC_TRNS, KC_TRNS, KC_SCLN, KC_QUOT, KC_SLSH, KC_COMM, KC_TRNS, KC_HOME,
		KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS),

	[_FN2] = LAYOUT_split_space(
		KC_PWR, KC_F1, KC_F2, KC_F3, KC_F4, KC_F5, KC_F6, KC_F7, KC_F8, KC_F9, KC_F10, RESET,
		KC_TRNS, BL_TOGG, BL_STEP, BL_INC, BL_DEC, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,
		KC_CAPS, RGB_TOG, RGB_MOD, RGB_VAI, RGB_VAD, RGB_HUI, RGB_HUD, RGB_SAI, RGB_SAD, KC_TRNS, KC_END,
		KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS),

};

enum function_id {
    SHIFT_ESC,
};

const uint16_t PROGMEM fn_actions[] = {
  [0]  = ACTION_FUNCTION(SHIFT_ESC),
};

void action_function(keyrecord_t *record, uint8_t id, uint8_t opt) {
  static uint8_t shift_esc_shift_mask;
  switch (id) {
    case SHIFT_ESC:
      shift_esc_shift_mask = get_mods()&MODS_CTRL_MASK;
      if (record->event.pressed) {
        if (shift_esc_shift_mask) {
          add_key(KC_GRV);
          send_keyboard_report();
        } else {
          add_key(KC_ESC);
          send_keyboard_report();
        }
      } else {
        if (shift_esc_shift_mask) {
          del_key(KC_GRV);
          send_keyboard_report();
        } else {
          del_key(KC_ESC);
          send_keyboard_report();
        }
      }
      break;
  }
}