U0 @function_insert_call(U32 from, U32 to)
{
    *(from(U8*)) = 0xE8;
    *((from + 1)(I32*)) = to - from - 5;
}

U0 @function_patch(U32 from, U32 to)
{
    *(from(U8*)) = 0xE9;
    *((from + 1)(I32*)) = to - from - 5;
}

class @function
{
    U0 (*InsertCall)(U32 from, U32 to);
    U0 (*Patch)(U32 from, U32 to);
};

@function Function;
Function.InsertCall = &@function_insert_call;
Function.Patch = &@function_patch;

// usage: Function.InsertCall(addr, &func);
// usage: Function.Patch(&old_func, &new_func);

"function ";