Official Go implementation of the Ethereum protocol
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go-ethereum/vm/closure.go

108 lines
2.1 KiB

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package vm
import (
"math/big"
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"github.com/ethereum/go-ethereum/state"
)
type ClosureRef interface {
ReturnGas(*big.Int, *big.Int)
Address() []byte
SetCode([]byte)
}
type Closure struct {
caller ClosureRef
object ClosureRef
Code []byte
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message *state.Message
Gas, UsedGas, Price *big.Int
Args []byte
}
// Create a new closure for the given data items
func NewClosure(msg *state.Message, caller ClosureRef, object ClosureRef, 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
}
func (c *Closure) GetOp(x uint64) OpCode {
return OpCode(c.GetByte(x))
}
func (c *Closure) GetByte(x uint64) byte {
if x < uint64(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) GetRangeValue(x, y uint64) []byte {
if x >= uint64(len(c.Code)) || y >= uint64(len(c.Code)) {
return nil
}
return c.Code[x : x+y]
}
func (c *Closure) Return(ret []byte) []byte {
// Return the remaining gas to the caller
c.caller.ReturnGas(c.Gas, c.Price)
return ret
}
/*
* Gas functions
*/
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)
}
/*
* Set / Get
*/
func (c *Closure) Address() []byte {
return c.object.Address()
}
func (self *Closure) SetCode(code []byte) {
self.Code = code
}