core/vm, common/math: Add fast getByte for bigints, improve opByte

1 files changed, 43 insertions, 0 deletions

diff --git a/core/vm/instructions_test.go b/core/vm/instructions_test.go
new file mode 100644
index 000000000..50264bc3e
--- /dev/null
+++ b/core/vm/instructions_test.go
@@ -0,0 +1,43 @@
+package vm
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+func TestByteOp(t *testing.T) {
+
+	var (
+		env   = NewEVM(Context{}, nil, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
+		stack = newstack()
+	)
+	tests := []struct {
+		v        string
+		th       uint64
+		expected *big.Int
+	}{
+		{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 0, big.NewInt(0xAB)},
+		{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 1, big.NewInt(0xCD)},
+		{"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 0, big.NewInt(0x00)},
+		{"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 1, big.NewInt(0xCD)},
+		{"0000000000000000000000000000000000000000000000000000000000102030", 31, big.NewInt(0x30)},
+		{"0000000000000000000000000000000000000000000000000000000000102030", 30, big.NewInt(0x20)},
+		{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 32, big.NewInt(0x0)},
+		{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 0xFFFFFFFFFFFFFFFF, big.NewInt(0x0)},
+	}
+	pc := uint64(0)
+	for _, test := range tests {
+		val := new(big.Int).SetBytes(common.Hex2Bytes(test.v))
+		th := new(big.Int).SetUint64(test.th)
+		stack.push(val)
+		stack.push(th)
+		opByte(&pc, env, nil, nil, stack)
+		actual := stack.pop()
+		if actual.Cmp(test.expected) != 0 {
+			t.Fatalf("Expected  [%v] %v:th byte to be %v, was %v.", test.v, test.th, test.expected, actual)
+		}
+	}
+}