How to assign values to Schema.sobjectField[]?

I am working on after update trigger and I want to know what fields were updated. I got a code on StackExchange which would serve my purpose : But can anyone please help me on how to assign values (The fields that I want to pass to getChangedFields function) to Schema.ObjectField[] fieldList in the calling function ?

public Schema.sObjectField[] getChangedFields(ID recordId, Schema.sObjectField[] fieldList) {
    Schema.sObjectField[] changedFields = new list ();
    SObject o1 = Trigger.oldMap.get(recordId);
    SObject o2 = Trigger.newMap.get(recordId);
    for (Schema.sObjectField field : fieldList) {
        Object v1 = o1.get(field);
        Object v2 = o2.get(field);
        if (didFieldChange(v1, v2)) {
            changedFields.add(field);
        }
    }
    return changedFields;
}
private static Boolean didFieldChange(Object v1, Object v2) {
    if (v1 == null && v2 == null) {
        return false;
    }
    if (v1 != v2) {
        return true;
    }
    return false;
}