Add Constantinople SSTORE gas/refund prices (EIP1283)

Author: vpulim

hardforks/constantinople.json

@@ -6,7 +6,36 @@
     "status": "Draft"
   },
   "gasConfig": {},
-  "gasPrices": {},
+  "gasPrices": {
+    "netSstoreNoopGas": {
+      "v": 200,
+      "d": "Once per SSTORE operation if the value doesn't change"
+    },
+    "netSstoreInitGas": {
+      "v": 20000,
+      "d": "Once per SSTORE operation from clean zero"
+    },
+    "netSstoreCleanGas": {
+      "v": 5000,
+      "d": "Once per SSTORE operation from clean non-zero"
+    },
+    "netSstoreDirtyGas": {
+      "v": 200,
+      "d": "Once per SSTORE operation from dirty"
+    },
+    "netSstoreClearRefund": {
+      "v": 15000,
+      "d": "Once per SSTORE operation for clearing an originally existing storage slot"
+    },
+    "netSstoreResetRefund": {
+      "v": 4800,
+      "d": "Once per SSTORE operation for resetting to the original non-zero value"
+    },
+    "netSstoreResetClearRefund": {
+      "v": 19800,
+      "d": "Once per SSTORE operation for resetting to the original zero value"
+    }
+  },
   "vm": {},
   "pow": {
     "minerReward": {

tests/params.js

@@ -34,6 +34,7 @@ tape('[Common]: Parameter access', function (t) {
 
     st.equal(c.param('pow', 'minerReward', 'chainstart'), '5000000000000000000', 'Should return correct value for chain start')
     st.equal(c.param('pow', 'minerReward', 'byzantium'), '3000000000000000000', 'Should reflect HF update changes')
+    st.equal(c.param('gasPrices', 'netSstoreNoopGas', 'constantinople'), 200, 'Should return updated sstore gas prices for constantinople')
 
     st.end()
   })