Fixed MSTORE and added some more commets

4 files changed, 51 insertions, 18 deletions

diff --git a/ethchain/closure.go b/ethchain/closure.go
index 4ef43a2da..204fbce06 100644
--- a/ethchain/closure.go
+++ b/ethchain/closure.go
@@ -21,15 +21,17 @@ type ClosureBody interface {
 type Closure struct {
 	callee Callee
 	object ClosureBody
-	state  *State
+	State  *State
 
 	gas *big.Int
 	val *big.Int
+
+	args []byte
 }
 
 // Create a new closure for the given data items
 func NewClosure(callee Callee, object ClosureBody, state *State, gas, val *big.Int) *Closure {
-	return &Closure{callee, object, state, gas, val}
+	return &Closure{callee, object, state, gas, val, nil}
 }
 
 // Retuns the x element in data slice
@@ -42,14 +44,20 @@ func (c *Closure) GetMem(x int64) *ethutil.Value {
 	return m
 }
 
+func (c *Closure) Call(vm *Vm, args []byte) []byte {
+	c.args = args
+
+	return vm.RunClosure(c)
+}
+
 func (c *Closure) Return(ret []byte) []byte {
 	// Return the remaining gas to the callee
 	// If no callee is present return it to
 	// the origin (i.e. contract or tx)
 	if c.callee != nil {
-		c.callee.ReturnGas(c.gas, c.state)
+		c.callee.ReturnGas(c.gas, c.State)
 	} else {
-		c.object.ReturnGas(c.gas, c.state)
+		c.object.ReturnGas(c.gas, c.State)
 		// TODO incase it's a POST contract we gotta serialise the contract again.
 		// But it's not yet defined
 	}
diff --git a/ethchain/stack.go b/ethchain/stack.go
index 349e7817a..bfb19614e 100644
--- a/ethchain/stack.go
+++ b/ethchain/stack.go
@@ -235,6 +235,7 @@ func (st *ValueStack) Peekn() (*ethutil.Value, *ethutil.Value) {
 func (st *ValueStack) Push(d *ethutil.Value) {
 	st.data = append(st.data, d)
 }
+
 func (st *ValueStack) Print() {
 	fmt.Println("### STACK ###")
 	if len(st.data) > 0 {
diff --git a/ethchain/vm.go b/ethchain/vm.go
index 861b041d8..2fa78a748 100644
--- a/ethchain/vm.go
+++ b/ethchain/vm.go
@@ -18,6 +18,8 @@ type Vm struct {
 	mem map[string]*big.Int
 
 	vars RuntimeVars
+
+	state *State
 }
 
 type RuntimeVars struct {
@@ -32,7 +34,11 @@ type RuntimeVars struct {
 	txData      []string
 }
 
-func (vm *Vm) RunClosure(closure *Closure, state *State, vars RuntimeVars) []byte {
+func NewVm(state *State, vars RuntimeVars) *Vm {
+	return &Vm{vars: vars, state: state}
+}
+
+func (vm *Vm) RunClosure(closure *Closure) []byte {
 	// If the amount of gas supplied is less equal to 0
 	if closure.GetGas().Cmp(big.NewInt(0)) <= 0 {
 		// TODO Do something
@@ -71,17 +77,28 @@ func (vm *Vm) RunClosure(closure *Closure, state *State, vars RuntimeVars) []byt
 		}
 
 		switch op {
-		case oSTOP:
+		case oSTOP: // Stop the closure
 			return closure.Return(nil)
-		case oPUSH:
+		case oPUSH: // Push PC+1 on to the stack
 			pc++
 			val := closure.GetMem(pc).BigInt()
 			stack.Push(val)
-		case oMSTORE:
+		case oMSTORE: // Store the value at stack top-1 in to memory at location stack top
 			// Pop value of the stack
-			val := stack.Pop()
-			// Set the bytes to the memory field
-			mem = append(mem, ethutil.BigToBytes(val, 256)...)
+			val, mStart := stack.Popn()
+			// Ensure that memory is large enough to hold the data
+			// If it isn't resize the memory slice so that it may hold the value
+			bytesLen := big.NewInt(32)
+			totSize := new(big.Int).Add(mStart, bytesLen)
+			lenSize := big.NewInt(int64(len(mem)))
+			if totSize.Cmp(lenSize) > 0 {
+				// Calculate the diff between the sizes
+				diff := new(big.Int).Sub(totSize, lenSize)
+				// Create a new empty slice and append it
+				newSlice := make([]byte, diff.Int64()+1)
+				mem = append(mem, newSlice...)
+			}
+			copy(mem[mStart.Int64():mStart.Int64()+bytesLen.Int64()+1], ethutil.BigToBytes(val, 256))
 		case oCALL:
 			// Pop return size and offset
 			retSize, retOffset := stack.Popn()
@@ -93,20 +110,25 @@ func (vm *Vm) RunClosure(closure *Closure, state *State, vars RuntimeVars) []byt
 			gas, value := stack.Popn()
 			// Closure addr
 			addr := stack.Pop()
-
-			contract := state.GetContract(addr.Bytes())
-			closure := NewClosure(closure, contract, state, gas, value)
-			ret := vm.RunClosure(closure, state, vars)
+			// Fetch the contract which will serve as the closure body
+			contract := vm.state.GetContract(addr.Bytes())
+			// Create a new callable closure
+			closure := NewClosure(closure, contract, vm.state, gas, value)
+			// Executer the closure and get the return value (if any)
+			ret := closure.Call(vm, nil)
 
 			// Ensure that memory is large enough to hold the returned data
+			// If it isn't resize the memory slice so that it may hold the value
 			totSize := new(big.Int).Add(retOffset, retSize)
 			lenSize := big.NewInt(int64(len(mem)))
-			// Resize the current memory slice so that the return value may fit
 			if totSize.Cmp(lenSize) > 0 {
+				// Calculate the diff between the sizes
 				diff := new(big.Int).Sub(totSize, lenSize)
+				// Create a new empty slice and append it
 				newSlice := make([]byte, diff.Int64()+1)
 				mem = append(mem, newSlice...)
 			}
+			// Copy over the returned values to the memory given the offset and size
 			copy(mem[retOffset.Int64():retOffset.Int64()+retSize.Int64()+1], ret)
 		case oRETURN:
 			size, offset := stack.Popn()
diff --git a/ethchain/vm_test.go b/ethchain/vm_test.go
index 4e72c9249..654ddb566 100644
--- a/ethchain/vm_test.go
+++ b/ethchain/vm_test.go
@@ -117,8 +117,10 @@ func TestRun3(t *testing.T) {
 
 	script := Compile([]string{
 		"PUSH", "300",
+		"PUSH", "0",
 		"MSTORE",
 		"PUSH", "300",
+		"PUSH", "31",
 		"MSTORE",
 		"PUSH", "62",
 		"PUSH", "0",
@@ -147,8 +149,7 @@ func TestRun3(t *testing.T) {
 	executer.Sign([]byte("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"))
 	callerClosure := NewClosure(executer, MakeContract(callerTx, state), state, big.NewInt(1000000000), new(big.Int))
 
-	vm := &Vm{}
-	vm.RunClosure(callerClosure, state, RuntimeVars{
+	vm := NewVm(state, RuntimeVars{
 		address:     callerAddr,
 		blockNumber: 1,
 		sender:      ethutil.FromHex("cd1722f3947def4cf144679da39c4c32bdc35681"),
@@ -159,4 +160,5 @@ func TestRun3(t *testing.T) {
 		txValue:     big.NewInt(10000),
 		txData:      nil,
 	})
+	callerClosure.Call(vm, nil)
 }