Merge branch 'unflip' of https://github.com/tendermint/tendermint into unflip

Conflicts:
	vm/vm.go

common/word.go

@@ -31,7 +31,10 @@ func (w Word256) Compare(other Word256) int {
 
 func Uint64ToWord256(i uint64) Word256 {
 	word := Word256{}
-	PutUint64(word[:], i)
+	buf := [8]byte{}
+	PutUint64(buf[:], i)
+	word[24], word[25], word[26], word[27] = buf[7], buf[6], buf[5], buf[4]
+	word[28], word[29], word[30], word[31] = buf[3], buf[2], buf[1], buf[0]
 	return word
 }
 
@@ -46,7 +49,10 @@ func LeftPadWord256(bz []byte) (word Word256) {
 }
 
 func Uint64FromWord256(word Word256) uint64 {
-	return binary.LittleEndian.Uint64(word[:])
+	buf := [8]byte{}
+	buf[0], buf[1], buf[2], buf[3] = word[31], word[30], word[29], word[28]
+	buf[4], buf[5], buf[6], buf[7] = word[27], word[26], word[25], word[24]
+	return binary.LittleEndian.Uint64(buf[:])
 }
 
 //-------------------------------------

rpc/core/accounts.go

@@ -36,7 +36,7 @@ func GetStorage(address, key []byte) (*ctypes.ResponseGetStorage, error) {
 	storageRoot := account.StorageRoot
 	storageTree := state.LoadStorage(storageRoot)
 
-	_, value := storageTree.Get(RightPadWord256(key).Bytes())
+	_, value := storageTree.Get(LeftPadWord256(key).Bytes())
 	if value == nil {
 		return &ctypes.ResponseGetStorage{key, nil}, nil
 	}

rpc/core/txs.go

@@ -16,7 +16,7 @@ func toVMAccount(acc *account.Account) *vm.Account {
 		Balance:     acc.Balance,
 		Code:        acc.Code, // This is crazy.
 		Nonce:       uint64(acc.Sequence),
-		StorageRoot: RightPadWord256(acc.StorageRoot),
+		StorageRoot: LeftPadWord256(acc.StorageRoot),
 		Other:       acc.PubKey,
 	}
 }
@@ -37,7 +37,7 @@ func Call(address, data []byte) (*ctypes.ResponseCall, error) {
 	txCache := state.NewTxCache(cache)
 	params := vm.Params{
 		BlockHeight: uint64(st.LastBlockHeight),
-		BlockHash:   RightPadWord256(st.LastBlockHash),
+		BlockHash:   LeftPadWord256(st.LastBlockHash),
 		BlockTime:   st.LastBlockTime.Unix(),
 		GasLimit:    10000000,
 	}
@@ -62,7 +62,7 @@ func CallCode(code, data []byte) (*ctypes.ResponseCall, error) {
 	txCache := state.NewTxCache(cache)
 	params := vm.Params{
 		BlockHeight: uint64(st.LastBlockHeight),
-		BlockHash:   RightPadWord256(st.LastBlockHash),
+		BlockHash:   LeftPadWord256(st.LastBlockHash),
 		BlockTime:   st.LastBlockTime.Unix(),
 		GasLimit:    10000000,
 	}

rpc/test/helpers_test.go

@@ -288,7 +288,7 @@ func simpleContract() ([]byte, []byte, []byte) {
 	// the is the code we need to return the contractCode when the contract is initialized
 	lenCode := len(contractCode)
 	// push code to the stack
-	//code := append([]byte{byte(0x60 + lenCode - 1)}, LeftPadWord256(contractCode).Bytes()...)
+	//code := append([]byte{byte(0x60 + lenCode - 1)}, RightPadWord256(contractCode).Bytes()...)
 	code := append([]byte{0x7f}, RightPadWord256(contractCode).Bytes()...)
 	// store it in memory
 	code = append(code, []byte{0x60, 0x0, 0x52}...)

rpc/test/tests_test.go

@@ -119,8 +119,8 @@ func testGetStorage(t *testing.T, typ string) {
 	mempoolCount = 0
 
 	v := getStorage(t, typ, contractAddr, []byte{0x1})
-	got := RightPadWord256(v)
+	got := LeftPadWord256(v)
-	expected := RightPadWord256([]byte{0x5})
+	expected := LeftPadWord256([]byte{0x5})
 	if got.Compare(expected) != 0 {
 		t.Fatalf("Wrong storage value. Got %x, expected %x", got.Bytes(), expected.Bytes())
 	}

state/block_cache.go

@@ -106,7 +106,7 @@ func (cache *BlockCache) GetStorage(addr Word256, key Word256) (value Word256) {
 	_, val_ := storage.Get(key.Bytes())
 	value = Zero256
 	if val_ != nil {
-		value = RightPadWord256(val_.([]byte))
+		value = LeftPadWord256(val_.([]byte))
 	}
 	cache.storages[Tuple256{addr, key}] = storageInfo{value, false}
 	return value

state/execution.go

@@ -395,7 +395,7 @@ func ExecTx(blockCache *BlockCache, tx_ types.Tx, runCall bool, evc events.Firea
 				txCache             = NewTxCache(blockCache)
 				params              = vm.Params{
 					BlockHeight: uint64(_s.LastBlockHeight),
-					BlockHash:   RightPadWord256(_s.LastBlockHash),
+					BlockHash:   LeftPadWord256(_s.LastBlockHash),
 					BlockTime:   _s.LastBlockTime.Unix(),
 					GasLimit:    10000000,
 				}

state/tx_cache.go

@@ -158,7 +158,7 @@ func toVMAccount(acc *ac.Account) *vm.Account {
 		Balance:     acc.Balance,
 		Code:        acc.Code, // This is crazy.
 		Nonce:       uint64(acc.Sequence),
-		StorageRoot: RightPadWord256(acc.StorageRoot),
+		StorageRoot: LeftPadWord256(acc.StorageRoot),
 		Other:       acc.PubKey,
 	}
 }

vm/common.go

@@ -0,0 +1,26 @@
+package vm
+
+import (
+	"math/big"
+)
+
+// To256
+//
+// "cast" the big int to a 256 big int (i.e., limit to)
+var tt256 = new(big.Int).Lsh(big.NewInt(1), 256)
+var tt256m1 = new(big.Int).Sub(new(big.Int).Lsh(big.NewInt(1), 256), big.NewInt(1))
+var tt255 = new(big.Int).Lsh(big.NewInt(1), 255)
+
+func U256(x *big.Int) *big.Int {
+	x.And(x, tt256m1)
+	return x
+}
+
+func S256(x *big.Int) *big.Int {
+	if x.Cmp(tt255) < 0 {
+		return x
+	} else {
+		// We don't want to modify x, ever
+		return new(big.Int).Sub(x, tt256)
+	}
+}

vm/native.go

@@ -39,7 +39,7 @@ func ecrecoverFunc(input []byte, gas *uint64) (output []byte, err error) {
 		return nil, err
 	}
 	hashed := sha3.Sha3(recovered[1:])
-	return RightPadBytes(hashed, 32), nil
+	return LeftPadBytes(hashed, 32), nil
 }
 
 func sha256Func(input []byte, gas *uint64) (output []byte, err error) {
@@ -73,7 +73,7 @@ func ripemd160Func(input []byte, gas *uint64) (output []byte, err error) {
 	if err != nil {
 		panic(err)
 	}
-	return RightPadBytes(hasher.Sum(nil), 32), nil
+	return LeftPadBytes(hasher.Sum(nil), 32), nil
 }
 
 func identityFunc(input []byte, gas *uint64) (output []byte, err error) {

vm/stack.go

@@ -51,7 +51,7 @@ func (st *Stack) PushBytes(bz []byte) {
 	if len(bz) != 32 {
 		panic("Invalid bytes size: expected 32")
 	}
-	st.Push(RightPadWord256(bz))
+	st.Push(LeftPadWord256(bz))
 }
 
 func (st *Stack) Push64(i uint64) {
@@ -73,7 +73,8 @@ func (st *Stack) PopBytes() []byte {
 }
 
 func (st *Stack) Pop64() uint64 {
-	return GetUint64(st.Pop().Bytes())
+	d := st.Pop()
+	return Uint64FromWord256(d)
 }
 
 func (st *Stack) Len() int {

vm/test/fake_app_state.go

@@ -90,5 +90,5 @@ func createAddress(creator *Account) Word256 {
 	temp := make([]byte, 32+8)
 	copy(temp, creator.Address[:])
 	PutUint64(temp[32:], nonce)
-	return RightPadWord256(sha3.Sha3(temp)[:20])
+	return LeftPadWord256(sha3.Sha3(temp)[:20])
 }

vm/test/vm_test.go

@@ -64,10 +64,10 @@ func TestSubcurrency(t *testing.T) {
 	st := newAppState()
 	// Create accounts
 	account1 := &Account{
-		Address: RightPadWord256(makeBytes(20)),
+		Address: LeftPadWord256(makeBytes(20)),
 	}
 	account2 := &Account{
-		Address: RightPadWord256(makeBytes(20)),
+		Address: LeftPadWord256(makeBytes(20)),
 	}
 	st.accounts[account1.Address.String()] = account1
 	st.accounts[account2.Address.String()] = account2

vm/vm.go

@@ -1,6 +1,7 @@
 package vm
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"math/big"
@@ -131,207 +132,252 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			return nil, nil
 
 		case ADD: // 0x01
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(x + y)
 			x, y := stack.Pop(), stack.Pop()
-			xb := new(big.Int).SetBytes(flip(x[:]))
+			xb := new(big.Int).SetBytes(x[:])
-			yb := new(big.Int).SetBytes(flip(y[:]))
+			yb := new(big.Int).SetBytes(y[:])
 			sum := new(big.Int).Add(xb, yb)
-			stack.Push(RightPadWord256(flip(sum.Bytes())))
+			res := LeftPadWord256(U256(sum).Bytes())
-			dbg.Printf(" %v + %v = %v\n", xb, yb, sum)
+			stack.Push(res)
+			dbg.Printf(" %v + %v = %v (%X)\n", xb, yb, sum, res)
 
 		case MUL: // 0x02
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(x * y)
 			x, y := stack.Pop(), stack.Pop()
-			xb := new(big.Int).SetBytes(flip(x[:]))
+			xb := new(big.Int).SetBytes(x[:])
-			yb := new(big.Int).SetBytes(flip(y[:]))
+			yb := new(big.Int).SetBytes(y[:])
 			prod := new(big.Int).Mul(xb, yb)
-			stack.Push(RightPadWord256(flip(rightMostBytes(prod.Bytes(), 32))))
+			res := LeftPadWord256(U256(prod).Bytes())
-			dbg.Printf(" %v * %v = %v\n", xb, yb, prod)
+			stack.Push(res)
+			dbg.Printf(" %v * %v = %v (%X)\n", xb, yb, prod, res)
 
 		case SUB: // 0x03
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(x - y)
 			x, y := stack.Pop(), stack.Pop()
-			xb := new(big.Int).SetBytes(flip(x[:]))
+			xb := new(big.Int).SetBytes(x[:])
-			yb := new(big.Int).SetBytes(flip(y[:]))
+			yb := new(big.Int).SetBytes(y[:])
 			diff := new(big.Int).Sub(xb, yb)
-			stack.Push(RightPadWord256(flip(diff.Bytes())))
+			res := LeftPadWord256(U256(diff).Bytes())
-			dbg.Printf(" %v - %v = %v\n", xb, yb, diff)
+			stack.Push(res)
+			dbg.Printf(" %v - %v = %v (%X)\n", xb, yb, diff, res)
 
 		case DIV: // 0x04
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(x / y)
 			x, y := stack.Pop(), stack.Pop()
-			if y.IsZero() { // TODO
+			if y.IsZero() {
 				stack.Push(Zero256)
-				dbg.Printf(" %x / %x = %v (TODO)\n", x, y, 0)
+				dbg.Printf(" %x / %x = %v\n", x, y, 0)
 			} else {
-				xb := new(big.Int).SetBytes(flip(x[:]))
+				xb := new(big.Int).SetBytes(x[:])
-				yb := new(big.Int).SetBytes(flip(y[:]))
+				yb := new(big.Int).SetBytes(y[:])
 				div := new(big.Int).Div(xb, yb)
-				stack.Push(RightPadWord256(flip(div.Bytes())))
+				res := LeftPadWord256(U256(div).Bytes())
-				dbg.Printf(" %v / %v = %v\n", xb, yb, div)
+				stack.Push(res)
+				dbg.Printf(" %v / %v = %v (%X)\n", xb, yb, div, res)
 			}
 
 		case SDIV: // 0x05
-			// TODO ... big?
+			x, y := stack.Pop(), stack.Pop()
-			x, y := int64(stack.Pop64()), int64(stack.Pop64())
+			if y.IsZero() {
-			if y == 0 { // TODO
 				stack.Push(Zero256)
-				dbg.Printf(" %v / %v = %v (TODO)\n", x, y, 0)
+				dbg.Printf(" %x / %x = %v\n", x, y, 0)
 			} else {
-				stack.Push64(uint64(x / y))
+				xb := S256(new(big.Int).SetBytes(x[:]))
-				dbg.Printf(" %v / %v = %v\n", x, y, x/y)
+				yb := S256(new(big.Int).SetBytes(y[:]))
+				div := new(big.Int).Div(xb, yb)
+				res := LeftPadWord256(U256(div).Bytes())
+				stack.Push(res)
+				dbg.Printf(" %v / %v = %v (%X)\n", xb, yb, div, res)
 			}
 
 		case MOD: // 0x06
-			//x, y := stack.Pop64(), stack.Pop64()
 			x, y := stack.Pop(), stack.Pop()
-			if y.IsZero() { // TODO
+			if y.IsZero() {
 				stack.Push(Zero256)
-				dbg.Printf(" %v %% %v = %v (TODO)\n", x, y, 0)
+				dbg.Printf(" %v %% %v = %v\n", x, y, 0)
 			} else {
-				xb := new(big.Int).SetBytes(flip(x[:]))
+				xb := new(big.Int).SetBytes(x[:])
-				yb := new(big.Int).SetBytes(flip(y[:]))
+				yb := new(big.Int).SetBytes(y[:])
 				mod := new(big.Int).Mod(xb, yb)
-				stack.Push(RightPadWord256(flip(mod.Bytes())))
+				res := LeftPadWord256(U256(mod).Bytes())
-				dbg.Printf(" %v %% %v = %v\n", xb, yb, mod)
+				stack.Push(res)
+				dbg.Printf(" %v %% %v = %v (%X)\n", xb, yb, mod, res)
 			}
 
 		case SMOD: // 0x07
-			// TODO ... big?
+			x, y := stack.Pop(), stack.Pop()
-			x, y := int64(stack.Pop64()), int64(stack.Pop64())
+			if y.IsZero() {
-			if y == 0 { // TODO
 				stack.Push(Zero256)
-				dbg.Printf(" %v %% %v = %v (TODO)\n", x, y, 0)
+				dbg.Printf(" %v %% %v = %v\n", x, y, 0)
 			} else {
-				stack.Push64(uint64(x % y))
+				xb := S256(new(big.Int).SetBytes(x[:]))
-				dbg.Printf(" %v %% %v = %v\n", x, y, x%y)
+				yb := S256(new(big.Int).SetBytes(y[:]))
+				mod := new(big.Int).Mod(xb, yb)
+				res := LeftPadWord256(U256(mod).Bytes())
+				stack.Push(res)
+				dbg.Printf(" %v %% %v = %v (%X)\n", xb, yb, mod, res)
 			}
 
 		case ADDMOD: // 0x08
-			// TODO ... big?
+			x, y, z := stack.Pop(), stack.Pop(), stack.Pop()
-			x, y, z := stack.Pop64(), stack.Pop64(), stack.Pop64()
+			if z.IsZero() {
-			if z == 0 { // TODO
 				stack.Push(Zero256)
-				dbg.Printf(" (%v + %v) %% %v = %v (TODO)\n", x, y, z, 0)
+				dbg.Printf(" %v %% %v = %v\n", x, y, 0)
 			} else {
-				stack.Push64((x + y) % z)
+				xb := new(big.Int).SetBytes(x[:])
-				dbg.Printf(" (%v + %v) %% %v = %v\n", x, y, z, (x+y)%z)
+				yb := new(big.Int).SetBytes(y[:])
+				zb := new(big.Int).SetBytes(z[:])
+				add := new(big.Int).Add(xb, yb)
+				mod := new(big.Int).Mod(add, zb)
+				res := LeftPadWord256(U256(mod).Bytes())
+				stack.Push(res)
+				dbg.Printf(" %v + %v %% %v = %v (%X)\n",
+					xb, yb, zb, mod, res)
 			}
 
 		case MULMOD: // 0x09
-			// TODO ... big?
+			x, y, z := stack.Pop(), stack.Pop(), stack.Pop()
-			x, y, z := stack.Pop64(), stack.Pop64(), stack.Pop64()
+			if z.IsZero() {
-			if z == 0 { // TODO
 				stack.Push(Zero256)
-				dbg.Printf(" (%v + %v) %% %v = %v (TODO)\n", x, y, z, 0)
+				dbg.Printf(" %v %% %v = %v\n", x, y, 0)
 			} else {
-				stack.Push64((x * y) % z)
+				xb := new(big.Int).SetBytes(x[:])
-				dbg.Printf(" (%v + %v) %% %v = %v\n", x, y, z, (x*y)%z)
+				yb := new(big.Int).SetBytes(y[:])
+				zb := new(big.Int).SetBytes(z[:])
+				mul := new(big.Int).Mul(xb, yb)
+				mod := new(big.Int).Mod(mul, zb)
+				res := LeftPadWord256(U256(mod).Bytes())
+				stack.Push(res)
+				dbg.Printf(" %v * %v %% %v = %v (%X)\n",
+					xb, yb, zb, mod, res)
 			}
 
 		case EXP: // 0x0A
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(ExpUint64(x, y))
 			x, y := stack.Pop(), stack.Pop()
-			xb := new(big.Int).SetBytes(flip(x[:]))
+			xb := new(big.Int).SetBytes(x[:])
-			yb := new(big.Int).SetBytes(flip(y[:]))
+			yb := new(big.Int).SetBytes(y[:])
 			pow := new(big.Int).Exp(xb, yb, big.NewInt(0))
-			stack.Push(RightPadWord256(flip(pow.Bytes())))
+			res := LeftPadWord256(U256(pow).Bytes())
-			dbg.Printf(" %v ** %v = %v\n", xb, yb, pow)
+			dbg.Printf(" %v ** %v = %v (%X)\n", xb, yb, pow, res)
 
 		case SIGNEXTEND: // 0x0B
-			x, y := stack.Pop64(), stack.Pop64()
+			back := stack.Pop()
-			res := (y << uint(x)) >> x
+			backb := new(big.Int).SetBytes(back[:])
-			stack.Push64(res)
+			if backb.Cmp(big.NewInt(31)) < 0 {
-			dbg.Printf(" (%v << %v) >> %v = %v\n", y, x, x, res)
+				bit := uint(backb.Uint64()*8 + 7)
+				num := stack.Pop()
+				numb := new(big.Int).SetBytes(num[:])
+				mask := new(big.Int).Lsh(big.NewInt(1), bit)
+				mask.Sub(mask, big.NewInt(1))
+				if numb.Bit(int(bit)) == 1 {
+					numb.Or(numb, mask.Not(mask))
+				} else {
+					numb.Add(numb, mask)
+				}
+				res := LeftPadWord256(U256(numb).Bytes())
+				dbg.Printf(" = %v (%X)", numb, res)
+				stack.Push(res)
+			}
 
 		case LT: // 0x10
-			x, y := stack.Pop64(), stack.Pop64()
+			x, y := stack.Pop(), stack.Pop()
-			if x < y {
+			xb := new(big.Int).SetBytes(x[:])
+			yb := new(big.Int).SetBytes(y[:])
+			if xb.Cmp(yb) < 0 {
 				stack.Push64(1)
+				dbg.Printf(" %v < %v = %v\n", xb, yb, 1)
 			} else {
 				stack.Push(Zero256)
+				dbg.Printf(" %v < %v = %v\n", xb, yb, 0)
 			}
-			dbg.Printf(" %v < %v = %v\n", x, y, x < y)
 
 		case GT: // 0x11
-			x, y := stack.Pop64(), stack.Pop64()
+			x, y := stack.Pop(), stack.Pop()
-			if x > y {
+			xb := new(big.Int).SetBytes(x[:])
+			yb := new(big.Int).SetBytes(y[:])
+			if xb.Cmp(yb) > 0 {
 				stack.Push64(1)
+				dbg.Printf(" %v > %v = %v\n", xb, yb, 1)
 			} else {
 				stack.Push(Zero256)
+				dbg.Printf(" %v > %v = %v\n", xb, yb, 0)
 			}
-			dbg.Printf(" %v > %v = %v\n", x, y, x > y)
 
 		case SLT: // 0x12
-			x, y := int64(stack.Pop64()), int64(stack.Pop64())
+			x, y := stack.Pop(), stack.Pop()
-			if x < y {
+			xb := S256(new(big.Int).SetBytes(x[:]))
+			yb := S256(new(big.Int).SetBytes(y[:]))
+			if xb.Cmp(yb) < 0 {
 				stack.Push64(1)
+				dbg.Printf(" %v < %v = %v\n", xb, yb, 1)
 			} else {
 				stack.Push(Zero256)
+				dbg.Printf(" %v < %v = %v\n", xb, yb, 0)
 			}
-			dbg.Printf(" %v < %v = %v\n", x, y, x < y)
 
 		case SGT: // 0x13
-			x, y := int64(stack.Pop64()), int64(stack.Pop64())
+			x, y := stack.Pop(), stack.Pop()
-			if x > y {
+			xb := S256(new(big.Int).SetBytes(x[:]))
+			yb := S256(new(big.Int).SetBytes(y[:]))
+			if xb.Cmp(yb) > 0 {
 				stack.Push64(1)
+				dbg.Printf(" %v > %v = %v\n", xb, yb, 1)
 			} else {
 				stack.Push(Zero256)
+				dbg.Printf(" %v > %v = %v\n", xb, yb, 0)
 			}
-			dbg.Printf(" %v > %v = %v\n", x, y, x > y)
 
 		case EQ: // 0x14
-			x, y := stack.Pop64(), stack.Pop64()
+			x, y := stack.Pop(), stack.Pop()
-			if x == y {
+			if bytes.Equal(x[:], y[:]) {
 				stack.Push64(1)
+				dbg.Printf(" %X == %X = %v\n", x, y, 1)
 			} else {
 				stack.Push(Zero256)
+				dbg.Printf(" %X == %X = %v\n", x, y, 0)
 			}
-			dbg.Printf(" %v == %v = %v\n", x, y, x == y)
 
 		case ISZERO: // 0x15
-			x := stack.Pop64()
+			x := stack.Pop()
-			if x == 0 {
+			if x.IsZero() {
 				stack.Push64(1)
+				dbg.Printf(" %v == 0 = %v\n", x, 1)
 			} else {
 				stack.Push(Zero256)
+				dbg.Printf(" %v == 0 = %v\n", x, 0)
 			}
-			dbg.Printf(" %v == 0 = %v\n", x, x == 0)
 
 		case AND: // 0x16
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(x & y)
 			x, y := stack.Pop(), stack.Pop()
-			xb := new(big.Int).SetBytes(flip(x[:]))
+			z := [32]byte{}
-			yb := new(big.Int).SetBytes(flip(y[:]))
+			for i := 0; i < 32; i++ {
-			res := new(big.Int).And(xb, yb)
+				z[i] = x[i] & y[i]
-			stack.Push(RightPadWord256(flip(res.Bytes())))
+			}
-			dbg.Printf(" %v & %v = %v\n", xb, yb, res)
+			stack.Push(z)
+			dbg.Printf(" %X & %X = %X\n", x, y, z)
+
 		case OR: // 0x17
-			//x, y := stack.Pop64(), stack.Pop64()
-			//stack.Push64(x | y)
-			//dbg.Printf(" %v | %v = %v\n", x, y, x|y)
 			x, y := stack.Pop(), stack.Pop()
-			xb := new(big.Int).SetBytes(flip(x[:]))
+			z := [32]byte{}
-			yb := new(big.Int).SetBytes(flip(y[:]))
+			for i := 0; i < 32; i++ {
-			res := new(big.Int).Or(xb, yb)
+				z[i] = x[i] | y[i]
-			stack.Push(RightPadWord256(flip(res.Bytes())))
+			}
-			dbg.Printf(" %v & %v = %v\n", xb, yb, res)
+			stack.Push(z)
+			dbg.Printf(" %X | %X = %X\n", x, y, z)
 
 		case XOR: // 0x18
-			x, y := stack.Pop64(), stack.Pop64()
+			x, y := stack.Pop(), stack.Pop()
-			stack.Push64(x ^ y)
+			z := [32]byte{}
-			dbg.Printf(" %v ^ %v = %v\n", x, y, x^y)
+			for i := 0; i < 32; i++ {
+				z[i] = x[i] ^ y[i]
+			}
+			stack.Push(z)
+			dbg.Printf(" %X ^ %X = %X\n", x, y, z)
 
 		case NOT: // 0x19
-			x := stack.Pop64()
+			x := stack.Pop()
-			stack.Push64(^x)
+			z := [32]byte{}
-			dbg.Printf(" !%v = %v\n", x, ^x)
+			for i := 0; i < 32; i++ {
+				z[i] = ^x[i]
+			}
+			stack.Push(z)
+			dbg.Printf(" !%X = %X\n", x, z)
 
 		case BYTE: // 0x1A
 			idx, val := stack.Pop64(), stack.Pop()
@@ -347,12 +393,12 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 				return nil, firstErr(err, ErrInsufficientGas)
 			}
 			offset, size := stack.Pop64(), stack.Pop64()
-			data, ok := subslice(memory, offset, size, false)
+			data, ok := subslice(memory, offset, size)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
 			data = sha3.Sha3(data)
-			stack.PushBytes(flip(data))
+			stack.PushBytes(data)
 			dbg.Printf(" => (%v) %X\n", size, data)
 
 		case ADDRESS: // 0x30
@@ -364,7 +410,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			if ok = useGas(gas, GasGetAccount); !ok {
 				return nil, firstErr(err, ErrInsufficientGas)
 			}
-			acc := vm.appState.GetAccount(flipWord(addr)) // TODO ensure that 20byte lengths are supported.
+			acc := vm.appState.GetAccount(addr)
 			if acc == nil {
 				return nil, firstErr(err, ErrUnknownAddress)
 			}
@@ -386,12 +432,13 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 
 		case CALLDATALOAD: // 0x35
 			offset := stack.Pop64()
-			data, ok := subslice(input, offset, 32, true)
+			data, ok := subslice(input, offset, 32)
 			if !ok {
 				return nil, firstErr(err, ErrInputOutOfBounds)
 			}
-			stack.Push(RightPadWord256(data))
+			res := LeftPadWord256(data)
-			dbg.Printf(" => 0x%X\n", RightPadWord256(data))
+			stack.Push(res)
+			dbg.Printf(" => 0x%X\n", res)
 
 		case CALLDATASIZE: // 0x36
 			stack.Push64(uint64(len(input)))
@@ -401,11 +448,11 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			memOff := stack.Pop64()
 			inputOff := stack.Pop64()
 			length := stack.Pop64()
-			data, ok := subslice(input, inputOff, length, false)
+			data, ok := subslice(input, inputOff, length)
 			if !ok {
 				return nil, firstErr(err, ErrInputOutOfBounds)
 			}
-			dest, ok := subslice(memory, memOff, length, false)
+			dest, ok := subslice(memory, memOff, length)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -421,11 +468,11 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			memOff := stack.Pop64()
 			codeOff := stack.Pop64()
 			length := stack.Pop64()
-			data, ok := subslice(code, codeOff, length, false)
+			data, ok := subslice(code, codeOff, length)
 			if !ok {
 				return nil, firstErr(err, ErrCodeOutOfBounds)
 			}
-			dest, ok := subslice(memory, memOff, length, false)
+			dest, ok := subslice(memory, memOff, length)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -441,7 +488,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			if ok = useGas(gas, GasGetAccount); !ok {
 				return nil, firstErr(err, ErrInsufficientGas)
 			}
-			acc := vm.appState.GetAccount(flipWord(addr))
+			acc := vm.appState.GetAccount(addr)
 			if acc == nil {
 				return nil, firstErr(err, ErrUnknownAddress)
 			}
@@ -455,7 +502,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			if ok = useGas(gas, GasGetAccount); !ok {
 				return nil, firstErr(err, ErrInsufficientGas)
 			}
-			acc := vm.appState.GetAccount(flipWord(addr))
+			acc := vm.appState.GetAccount(addr)
 			if acc == nil {
 				return nil, firstErr(err, ErrUnknownAddress)
 			}
@@ -463,11 +510,11 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			memOff := stack.Pop64()
 			codeOff := stack.Pop64()
 			length := stack.Pop64()
-			data, ok := subslice(code, codeOff, length, false)
+			data, ok := subslice(code, codeOff, length)
 			if !ok {
 				return nil, firstErr(err, ErrCodeOutOfBounds)
 			}
-			dest, ok := subslice(memory, memOff, length, false)
+			dest, ok := subslice(memory, memOff, length)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -502,20 +549,20 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 
 		case MLOAD: // 0x51
 			offset := stack.Pop64()
-			data, ok := subslice(memory, offset, 32, true)
+			data, ok := subslice(memory, offset, 32)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
-			stack.Push(RightPadWord256(data))
+			stack.Push(LeftPadWord256(data))
 			dbg.Printf(" => 0x%X\n", data)
 
 		case MSTORE: // 0x52
 			offset, data := stack.Pop64(), stack.Pop()
-			dest, ok := subslice(memory, offset, 32, false)
+			dest, ok := subslice(memory, offset, 32)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
-			copy(dest, flip(data[:]))
+			copy(dest, data[:])
 			dbg.Printf(" => 0x%X\n", data)
 
 		case MSTORE8: // 0x53
@@ -543,8 +590,8 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			continue
 
 		case JUMPI: // 0x57
-			pos, cond := stack.Pop64(), stack.Pop64()
+			pos, cond := stack.Pop64(), stack.Pop()
-			if cond >= 1 {
+			if !cond.IsZero() {
 				err = jump(code, pos, &pc)
 				continue
 			}
@@ -566,11 +613,11 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 
 		case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
 			a := uint64(op - PUSH1 + 1)
-			codeSegment, ok := subslice(code, pc+1, a, true)
+			codeSegment, ok := subslice(code, pc+1, a)
 			if !ok {
 				return nil, firstErr(err, ErrCodeOutOfBounds)
 			}
-			res := RightPadWord256(codeSegment)
+			res := LeftPadWord256(codeSegment)
 			stack.Push(res)
 			pc += a
 			dbg.Printf(" => 0x%X\n", res)
@@ -592,7 +639,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			for i := 0; i < n; i++ {
 				topics[i] = stack.Pop()
 			}
-			data, ok := subslice(memory, offset, size, false)
+			data, ok := subslice(memory, offset, size)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -608,7 +655,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 		case CREATE: // 0xF0
 			contractValue := stack.Pop64()
 			offset, size := stack.Pop64(), stack.Pop64()
-			input, ok := subslice(memory, offset, size, false)
+			input, ok := subslice(memory, offset, size)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -638,7 +685,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 			dbg.Printf(" => %X\n", addr)
 
 			// Get the arguments from the memory
-			args, ok := subslice(memory, inOffset, inSize, false)
+			args, ok := subslice(memory, inOffset, inSize)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -662,7 +709,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 				if ok = useGas(gas, GasGetAccount); !ok {
 					return nil, firstErr(err, ErrInsufficientGas)
 				}
-				acc := vm.appState.GetAccount(flipWord(addr))
+				acc := vm.appState.GetAccount(addr)
 				if acc == nil {
 					return nil, firstErr(err, ErrUnknownAddress)
 				}
@@ -678,7 +725,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 				stack.Push(Zero256)
 			} else {
 				stack.Push(One256)
-				dest, ok := subslice(memory, retOffset, retSize, false)
+				dest, ok := subslice(memory, retOffset, retSize)
 				if !ok {
 					return nil, firstErr(err, ErrMemoryOutOfBounds)
 				}
@@ -692,7 +739,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 
 		case RETURN: // 0xF3
 			offset, size := stack.Pop64(), stack.Pop64()
-			ret, ok := subslice(memory, offset, size, false)
+			ret, ok := subslice(memory, offset, size)
 			if !ok {
 				return nil, firstErr(err, ErrMemoryOutOfBounds)
 			}
@@ -705,7 +752,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 				return nil, firstErr(err, ErrInsufficientGas)
 			}
 			// TODO if the receiver is , then make it the fee.
-			receiver := vm.appState.GetAccount(flipWord(addr))
+			receiver := vm.appState.GetAccount(addr)
 			if receiver == nil {
 				return nil, firstErr(err, ErrUnknownAddress)
 			}
@@ -726,7 +773,7 @@ func (vm *VM) call(caller, callee *Account, code, input []byte, value uint64, ga
 	}
 }
 
-func subslice(data []byte, offset, length uint64, flip_ bool) (ret []byte, ok bool) {
+func subslice(data []byte, offset, length uint64) (ret []byte, ok bool) {
 	size := uint64(len(data))
 	if size < offset {
 		return nil, false
@@ -737,9 +784,6 @@ func subslice(data []byte, offset, length uint64, flip_ bool) (ret []byte, ok bo
 		ret, ok = data[offset:offset+length], true
 	}
 
-	if flip_ {
-		ret = flip(ret)
-	}
 	return
 }
 
@@ -794,27 +838,3 @@ func transfer(from, to *Account, amount uint64) error {
 		return nil
 	}
 }
-
-func flip(in []byte) []byte {
-	l2 := len(in) / 2
-	flipped := make([]byte, len(in))
-	// copy the middle bit (if its even it will get overwritten)
-	if len(in) != 0 {
-		flipped[l2] = in[l2]
-	}
-	for i := 0; i < l2; i++ {
-		flipped[i] = in[len(in)-1-i]
-		flipped[len(in)-1-i] = in[i]
-	}
-	return flipped
-}
-
-func flipWord(in Word256) Word256 {
-	word := Word256{}
-	// copy the middle bit (if its even it will get overwritten)
-	for i := 0; i < 16; i++ {
-		word[i] = in[len(in)-1-i]
-		word[len(in)-1-i] = in[i]
-	}
-	return word
-}