From a052357872217d5e99e7ee1a7a4b524b53addcdd Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Mon, 1 Dec 2014 22:05:38 +0100
Subject: Fixed EXP gas

---
 vm/vm_debug.go | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

(limited to 'vm')

diff --git a/vm/vm_debug.go b/vm/vm_debug.go
index 4daa3ab5b..ea94987d1 100644
--- a/vm/vm_debug.go
+++ b/vm/vm_debug.go
@@ -172,12 +172,13 @@ func (self *DebugVm) RunClosure(closure *Closure) (ret []byte, err error) {
 		case EXP:
 			require(2)
 
-			expGas := ethutil.FirstBitSet(stack.data[stack.Len()-2])
-			expGas.Div(expGas, u256(8))
-			expGas.Sub(u256(32), expGas)
-			expGas.Add(expGas, u256(1))
-
-			gas.Set(expGas)
+			exp := new(big.Int).Set(stack.data[stack.Len()-2])
+			nbytes := 0
+			for exp.Cmp(ethutil.Big0) > 0 {
+				nbytes += 1
+				exp.Rsh(exp, 8)
+			}
+			gas.Set(big.NewInt(int64(nbytes + 1)))
 		// Gas only
 		case STOP:
 			gas.Set(ethutil.Big0)
-- 
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