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package vm
// TODO Re write VM to use values instead of big integers?
import (
"math/big"
"github.com/ethereum/go-ethereum/ethstate"
"github.com/ethereum/go-ethereum/ethutil"
)
type ClosureRef interface {
ReturnGas(*big.Int, *big.Int)
Address() []byte
Object() *ethstate.StateObject
GetStorage(*big.Int) *ethutil.Value
SetStorage(*big.Int, *ethutil.Value)
}
// Basic inline closure object which implement the 'closure' interface
type Closure struct {
caller ClosureRef
object *ethstate.StateObject
Code []byte
message *ethstate.Message
exe *Execution
Gas, UsedGas, Price *big.Int
Args []byte
}
// Create a new closure for the given data items
func NewClosure(msg *ethstate.Message, caller ClosureRef, object *ethstate.StateObject, code []byte, gas, price *big.Int) *Closure {
c := &Closure{message: msg, caller: caller, object: object, Code: code, Args: nil}
// Gas should be a pointer so it can safely be reduced through the run
// This pointer will be off the state transition
c.Gas = gas //new(big.Int).Set(gas)
// In most cases price and value are pointers to transaction objects
// and we don't want the transaction's values to change.
c.Price = new(big.Int).Set(price)
c.UsedGas = new(big.Int)
return c
}
// Retuns the x element in data slice
func (c *Closure) GetStorage(x *big.Int) *ethutil.Value {
m := c.object.GetStorage(x)
if m == nil {
return ethutil.EmptyValue()
}
return m
}
func (c *Closure) Get(x *big.Int) *ethutil.Value {
return c.Gets(x, big.NewInt(1))
}
func (c *Closure) GetOp(x int) OpCode {
return OpCode(c.GetByte(x))
}
func (c *Closure) GetByte(x int) byte {
if x < len(c.Code) {
return c.Code[x]
}
return 0
}
func (c *Closure) GetBytes(x, y int) []byte {
if x >= len(c.Code) || y >= len(c.Code) {
return nil
}
return c.Code[x : x+y]
}
func (c *Closure) Gets(x, y *big.Int) *ethutil.Value {
if x.Int64() >= int64(len(c.Code)) || y.Int64() >= int64(len(c.Code)) {
return ethutil.NewValue(0)
}
partial := c.Code[x.Int64() : x.Int64()+y.Int64()]
return ethutil.NewValue(partial)
}
func (c *Closure) SetStorage(x *big.Int, val *ethutil.Value) {
c.object.SetStorage(x, val)
}
func (c *Closure) Address() []byte {
return c.object.Address()
}
func (c *Closure) Call(vm VirtualMachine, args []byte) ([]byte, *big.Int, error) {
c.Args = args
ret, err := vm.RunClosure(c)
return ret, c.UsedGas, err
}
func (c *Closure) Return(ret []byte) []byte {
// Return the remaining gas to the caller
c.caller.ReturnGas(c.Gas, c.Price)
return ret
}
func (c *Closure) UseGas(gas *big.Int) bool {
if c.Gas.Cmp(gas) < 0 {
return false
}
// Sub the amount of gas from the remaining
c.Gas.Sub(c.Gas, gas)
c.UsedGas.Add(c.UsedGas, gas)
return true
}
// Implement the caller interface
func (c *Closure) ReturnGas(gas, price *big.Int) {
// Return the gas to the closure
c.Gas.Add(c.Gas, gas)
c.UsedGas.Sub(c.UsedGas, gas)
}
func (c *Closure) Object() *ethstate.StateObject {
return c.object
}
func (c *Closure) Caller() ClosureRef {
return c.caller
}
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