Examples of org.ethereum.vm.VM

org.ethereum.vm.VM
The Ethereum Virtual Machine (EVM) is responsible for initialization and executing a transaction on a contract. It is a quasi-Turing-complete machine; the quasi qualification comes from the fact that the computation is intrinsically bounded through a parameter, gas, which limits the total amount of computation done. The EVM is a simple stack-based architecture. The word size of the machine (and thus size of stack item) is 256-bit. This was chosen to facilitate the SHA3-256 hash scheme and elliptic-curve computations. The memory model is a simple word-addressed byte array. The stack has an unlimited size. The machine also has an independent storage model; this is similar in concept to the memory but rather than a byte array, it is a word-addressable word array. Unlike memory, which is volatile, storage is non volatile and is maintained as part of the system state. All locations in both storage and memory are well-defined initially as zero. The machine does not follow the standard von Neumann architecture. Rather than storing program code in generally-accessible memory or storage, it is stored separately in a virtual ROM interactable only though a specialised instruction. The machine can have exceptional execution for several reasons, including stack underflows and invalid instructions. These unambiguously and validly result in immediate halting of the machine with all state changes left intact. The one piece of exceptional execution that does not leave state changes intact is the out-of-gas (OOG) exception. Here, the machine halts immediately and reports the issue to the execution agent (either the transaction processor or, recursively, the spawning execution environment) and which will deal with it separately. www.ethereumJ.com @author : Roman Mandeleil Created on: 01/06/2014 10:44

    }


    @Test // NUMBER OP
    public void testNUMBER_1() {


        VM vm = new VM();
        program = 
                new Program(Hex.decode("43"), invoke);
        String s_expected_1 = "0000000000000000000000000000000000000000000000000000000000000021";


        vm.step(program);


        DataWord item1 = program.stackPop();
        assertEquals(s_expected_1, Hex.toHexString(item1.getData()).toUpperCase());
    }

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    }


    @Test // DIFFICULTY OP
    public void testDIFFICULTY_1() {


        VM vm = new VM();
        program = 
                new Program(Hex.decode("44"), invoke);
        String s_expected_1 = "00000000000000000000000000000000000000000000000000000000003ED290";


        vm.step(program);


        DataWord item1 = program.stackPop();
        assertEquals(s_expected_1, Hex.toHexString(item1.getData()).toUpperCase());
    }

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    }


    @Test // GASPRICE OP
    public void testGASPRICE_1() {


        VM vm = new VM();
        program = 
                new Program(Hex.decode("3A"), invoke);
        String s_expected_1 = "000000000000000000000000000000000000000000000000000009184E72A000";


        vm.step(program);


        DataWord item1 = program.stackPop();
        assertEquals(s_expected_1, Hex.toHexString(item1.getData()).toUpperCase());
    }

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    }


    @Test // GAS OP
    public void testGAS_1() {


        VM vm = new VM();
        program = 
                new Program(Hex.decode("5A"), invoke);
        String s_expected_1 = "00000000000000000000000000000000000000000000000000000000000F423F";


        vm.step(program);


        DataWord item1 = program.stackPop();
        assertEquals(s_expected_1, Hex.toHexString(item1.getData()).toUpperCase());
    }

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    }


    @Test // GASLIMIT OP
    public void testGASLIMIT_1() {


        VM vm = new VM();
        program = 
                new Program(Hex.decode("45"), invoke);
        String s_expected_1 = "00000000000000000000000000000000000000000000000000000000000F4240";


        vm.step(program);


        DataWord item1 = program.stackPop();
        assertEquals(s_expected_1, Hex.toHexString(item1.getData()).toUpperCase());
    }

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    }
    
    @Test(expected=Program.IllegalOperationException.class) // INVALID OP
    public void testINVALID_1() {


        VM vm = new VM();
        program = new Program(Hex.decode("60012F6002"), invoke);
        String s_expected_1 = "0000000000000000000000000000000000000000000000000000000000000001";


        try {
            vm.step(program);
            vm.step(program);
        } finally {
            assertTrue(program.isStopped());
            DataWord item1 = program.stackPop();
            assertEquals(s_expected_1, Hex.toHexString(item1.getData()).toUpperCase());
        }

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