1 files changed, 35 insertions, 14 deletions
diff --git a/vm/address.go b/vm/address.go
index 611979c94..1c9369ab7 100644
--- a/vm/address.go
+++ b/vm/address.go
@@ -20,20 +20,37 @@ func (self PrecompiledAccount) Call(in []byte) []byte {
 	return self.fn(in)
 }
 
-var Precompiled = map[string]*PrecompiledAccount{
-	string(ethutil.LeftPadBytes([]byte{1}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-		return GasEcrecover
-	}, ecrecoverFunc},
-	string(ethutil.LeftPadBytes([]byte{2}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-		n := big.NewInt(int64(l+31)/32 + 1)
-		n.Mul(n, GasSha256)
-		return n
-	}, sha256Func},
-	string(ethutil.LeftPadBytes([]byte{3}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-		n := big.NewInt(int64(l+31)/32 + 1)
-		n.Mul(n, GasRipemd)
-		return n
-	}, ripemd160Func},
+var Precompiled = PrecompiledContracts()
+
+// XXX Could set directly. Testing requires resetting and setting of pre compiled contracts.
+func PrecompiledContracts() map[string]*PrecompiledAccount {
+	return map[string]*PrecompiledAccount{
+		// ECRECOVER
+		string(ethutil.LeftPadBytes([]byte{1}, 20)): &PrecompiledAccount{func(l int) *big.Int {
+			return GasEcrecover
+		}, ecrecoverFunc},
+
+		// SHA256
+		string(ethutil.LeftPadBytes([]byte{2}, 20)): &PrecompiledAccount{func(l int) *big.Int {
+			n := big.NewInt(int64(l+31)/32 + 1)
+			n.Mul(n, GasSha256)
+			return n
+		}, sha256Func},
+
+		// RIPEMD160
+		string(ethutil.LeftPadBytes([]byte{3}, 20)): &PrecompiledAccount{func(l int) *big.Int {
+			n := big.NewInt(int64(l+31)/32 + 1)
+			n.Mul(n, GasRipemd)
+			return n
+		}, ripemd160Func},
+
+		string(ethutil.LeftPadBytes([]byte{4}, 20)): &PrecompiledAccount{func(l int) *big.Int {
+			n := big.NewInt(int64(l+31)/32 + 1)
+			n.Mul(n, GasMemCpy)
+
+			return n
+		}, memCpy},
+	}
 }
 
 func sha256Func(in []byte) []byte {
@@ -54,3 +71,7 @@ func ecrecoverFunc(in []byte) []byte {
 
 	return ethutil.LeftPadBytes(crypto.Sha3(crypto.Ecrecover(append(hash, sig...))[1:])[12:], 32)
 }
+
+func memCpy(in []byte) []byte {
+	return in
+}