EIP 100

Cherry-pick f78ff08

Conflicts:
	ethereum/config.py

Author: vub

ethereum/blocks.py

@@ -63,7 +63,9 @@ def __str__(self):
 def calc_difficulty(parent, timestamp):
     config = parent.config
     offset = parent.difficulty // config['BLOCK_DIFF_FACTOR']
-    if parent.number >= (config['HOMESTEAD_FORK_BLKNUM'] - 1):
+    if parent.number >= (config['METROPOLIS_FORK_BLKNUM'] - 1):
+        sign = max(len(parent.uncles) - ((timestamp - parent.timestamp) // config['METROPOLIS_DIFF_ADJUSTMENT_CUTOFF']), -99)
+    elif parent.number >= (config['HOMESTEAD_FORK_BLKNUM'] - 1):
         sign = max(1 - ((timestamp - parent.timestamp) // config['HOMESTEAD_DIFF_ADJUSTMENT_CUTOFF']), -99)
     else:
         sign = 1 if timestamp - parent.timestamp < config['DIFF_ADJUSTMENT_CUTOFF'] else -1

ethereum/config.py

@@ -54,6 +54,8 @@
     METROPOLIS_BLOCKHASH_STORE=0x20,
     METROPOLIS_WRAPAROUND=65536,
     METROPOLIS_GETTER_CODE=decode_hex('6000355460205260206020f3'),
+    METROPOLIS_DIFF_ADJUSTMENT_CUTOFF=9,
+    # Metropolis fork
 )
 assert default_config['NEPHEW_REWARD'] == \
     default_config['BLOCK_REWARD'] // 32