qmk_firmware/keyboards/preonic/preonic.c

#include "quantum.h"

#ifdef ENCODER_ENABLE
bool encoder_update_kb(uint8_t index, bool clockwise) {
    if (!encoder_update_user(index, clockwise)) { return false; }
    if (get_highest_layer(layer_state) > 0) {
        if (clockwise) {
            tap_code_delay(KC_VOLU, 10);
        } else {
            tap_code_delay(KC_VOLD, 10);
        }
    } else {
        if (clockwise) {
            tap_code(KC_PGDN);
        } else {
            tap_code(KC_PGUP);
        }
    }
    return true;
}
#endif