use std::evm::{Create, Evm, RawOps, mem}

#[contract_init(Foo)]

fn init() uses (evm: mut Evm) {

{ // create child contract

let len = evm.code_region_len(child_init)

let offset = evm.code_region_offset(child_init)

let dest = mem::alloc(len)

evm.codecopy(dest: dest, offset: offset, len: len)

evm.create2_raw(value: 0, offset: dest, len: len, salt: 0x1234)

}

let len = evm.code_region_len(runtime)

let offset = evm.code_region_offset(runtime)

let dest = mem::alloc(len)

evm.codecopy(dest: dest, offset: offset, len: len)

evm.return_data(offset: dest, len: len)

}

#[contract_runtime(Foo)]

fn runtime() uses (evm: mut Evm) {

with (RawOps = evm) {

match read_selector() {

0x12345678 => { transfer() }

0x23456789 => { balance() }

_ => {}

}

}

evm.return_data(offset: 0, len: 0)

}

#[contract_init(Child)]

fn child_init() uses (evm: mut Evm) {

let len = evm.code_region_len(child_runtime)

let offset = evm.code_region_offset(child_runtime)

let dest = mem::alloc(len)

evm.codecopy(dest: dest, offset: offset, len: len)

evm.return_data(offset: dest, len: len)

}

#[contract_runtime(Child)]

fn child_runtime() uses (evm: mut Evm) {

evm.calldatacopy(dest: 0, offset: 0, len: 4)

evm.return_data(offset: 0, len: 4)

}

fn balance() uses (ops: RawOps) {

ops.return_data(offset: 0, len: 0)

}

fn transfer() uses (ops: RawOps) {

ops.return_data(offset: 0, len: 0)

}

pub fn read_selector() -> u256 uses (ops: RawOps) {

let word = ops.calldataload(0)

// Shift right by 224 bits to keep only the first four bytes.

word >> 224

}