HF Muir Glacier Difficulty bomb delay

src/header.ts

@@ -161,7 +161,13 @@ export class BlockHeader {
       dif = parentDif.add(offset.mul(a))
     }
 
-    if (this._common.hardforkGteHardfork(hardfork, 'constantinople')) {
+    if (this._common.hardforkGteHardfork(hardfork, 'mountainGlacier')) {
+      // Istanbul/Berlin difficulty bomb delay (EIP2384)
+      num.isubn(9000000)
+      if (num.ltn(0)) {
+        num = new BN(0)
+      }
+    } else if (this._common.hardforkGteHardfork(hardfork, 'constantinople')) {
       // Constantinople difficulty bomb delay (EIP1234)
       num.isubn(5000000)
       if (num.ltn(0)) {

test/difficulty.ts

@@ -29,6 +29,11 @@ tape('[Header]: difficulty tests', t => {
     homestead: require('./difficultyHomestead.json').tests,
     byzantium: require('./difficultyByzantium.json').tests,
     constantinople: require('./difficultyConstantinople.json').tests,
+    mountainGlacier: Object.assign(
+      require('./difficultyEIP2384.json').tests,
+      require('./difficultyEIP2384_random.json').tests,
+      require('./difficultyEIP2384_random_to20M.json').tests,
+    ),
   }
   for (const hardfork in hardforkTestData) {
     const testData = hardforkTestData[hardfork]
@@ -44,7 +49,12 @@ tape('[Header]: difficulty tests', t => {
       block.header.difficulty = test.currentDifficulty
       block.header.number = test.currentBlockNumber
 
-      runDifficultyTests(test, parentBlock, block, 'fork determination by hardfork param')
+      runDifficultyTests(
+        test,
+        parentBlock,
+        block,
+        `fork determination by hardfork param (${hardfork})`,
+      )
     }
   }
 
@@ -66,7 +76,12 @@ tape('[Header]: difficulty tests', t => {
       block.header.difficulty = test.currentDifficulty
       block.header.number = test.currentBlockNumber
 
-      runDifficultyTests(test, parentBlock, block, 'fork determination by block number')
+      runDifficultyTests(
+        test,
+        parentBlock,
+        block,
+        `fork determination by block number (${test.currentBlockNumber})`,
+      )
     }
   }