Fixed remote Arithmetic tests

1 files changed, 20 insertions, 9 deletions

diff --git a/ethutil/big.go b/ethutil/big.go
index e23d8f659..bdcf86421 100644
--- a/ethutil/big.go
+++ b/ethutil/big.go
@@ -1,8 +1,8 @@
 package ethutil
 
-import (
-	"math/big"
-)
+import "math/big"
+
+var MaxInt256 *big.Int = BigD(Hex2Bytes("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"))
 
 // Big pow
 //
@@ -37,18 +37,29 @@ func BigD(data []byte) *big.Int {
 // To256
 //
 // "cast" the big int to a 256 big int (i.e., limit to)
-var tt256 = new(big.Int).Sub(new(big.Int).Lsh(big.NewInt(1), 256), big.NewInt(1))
+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 To256(x *big.Int) *big.Int {
-	x.And(x, tt256)
+func U256(x *big.Int) *big.Int {
+	//if x.Cmp(Big0) < 0 {
+	//		return new(big.Int).Add(tt256, x)
+	//	}
 
-	if x.Cmp(new(big.Int)) < 0 {
-		x.SetInt64(0)
-	}
+	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)
+	}
+}
+
 // Big to bytes
 //
 // Returns the bytes of a big integer with the size specified by **base**