Changed prev_hash to block_hash, state transition now uses vm env

* PREVHASH => BLOCKHASH( N )
* State transition object uses VMEnv as it's query interface
* Updated vm.Enviroment has GetHash( n ) for BLOCKHASH instruction
* Added GetHash to xeth, core, utils & test environments

1 files changed, 11 insertions, 8 deletions

diff --git a/vm/vm_debug.go b/vm/vm_debug.go
index 6ad385fd0..baacf752b 100644
--- a/vm/vm_debug.go
+++ b/vm/vm_debug.go
@@ -42,9 +42,9 @@ func (self *DebugVm) Run(me, caller ContextRef, code []byte, value, gas, price *
 
 	msg := self.env.State().Manifest().AddMessage(&state.Message{
 		To: me.Address(), From: caller.Address(),
-		Input:  callData,
-		Origin: self.env.Origin(),
-		Block:  self.env.BlockHash(), Timestamp: self.env.Time(), Coinbase: self.env.Coinbase(), Number: self.env.BlockNumber(),
+		Input:     callData,
+		Origin:    self.env.Origin(),
+		Timestamp: self.env.Time(), Coinbase: self.env.Coinbase(), Number: self.env.BlockNumber(),
 		Value: value,
 	})
 	context := NewContext(msg, caller, me, code, gas, price)
@@ -516,12 +516,15 @@ func (self *DebugVm) Run(me, caller ContextRef, code []byte, value, gas, price *
 			self.Printf(" => %v", context.Price)
 
 			// 0x40 range
-		case PREVHASH:
-			prevHash := self.env.PrevHash()
-
-			stack.Push(ethutil.BigD(prevHash))
+		case BLOCKHASH:
+			num := stack.Pop()
+			if num.Cmp(new(big.Int).Sub(self.env.BlockNumber(), ethutil.Big256)) < 0 {
+				stack.Push(ethutil.Big0)
+			} else {
+				stack.Push(ethutil.BigD(self.env.GetHash(num.Uint64())))
+			}
 
-			self.Printf(" => 0x%x", prevHash)
+			self.Printf(" => 0x%x", stack.Peek().Bytes())
 		case COINBASE:
 			coinbase := self.env.Coinbase()