cleanups

beacon_chain/ssz.nim

@@ -295,7 +295,7 @@ proc readValue*[T](r: var SszReader, val: var T) {.raises: [Defect, MalformedSsz
     readSszValue(r.stream.read(r.stream.len.get), val)
 
 const
-  zeroChunk = default array[32, byte]
+  zero64 = default array[64, byte]
 
 func hash(a, b: openArray[byte]): Eth2Digest =
   result = withEth2Hash:
@@ -319,14 +319,14 @@ func mergeBranches(existing: Eth2Digest, newData: openarray[byte]): Eth2Digest =
     let paddingBytes = bytesPerChunk - newData.len
     if paddingBytes > 0:
       trs "USING ", paddingBytes, " PADDING BYTES"
-      h.update zeroChunk.toOpenArray(0, paddingBytes - 1)
+      h.update zero64.toOpenArray(0, paddingBytes - 1)
   trs "HASH RESULT ", result
 
 template mergeBranches(a, b: Eth2Digest): Eth2Digest =
   hash(a.data, b.data)
 
 func computeZeroHashes: array[sizeof(Limit) * 8, Eth2Digest] =
-  result[0] = Eth2Digest(data: zeroChunk)
+  result[0] = Eth2Digest()
   for i in 1 .. result.high:
     result[i] = mergeBranches(result[i - 1], result[i - 1])
 
@@ -533,11 +533,7 @@ func maxChunksCount(T: type, maxLen: int64): int64 =
   when T is BitList|BitArray:
     (maxLen + bitsPerChunk - 1) div bitsPerChunk
   elif T is array|List:
-    type E = ElemType(T)
+    maxChunkIdx(ElemType(T), maxLen)
-    when E is BasicType:
-      (maxLen * sizeof(E) + bytesPerChunk - 1) div bytesPerChunk
-    else:
-      maxLen
   else:
     unsupported T # This should never happen
 
@@ -579,8 +575,28 @@ func hashTreeRootAux[T](x: T): Eth2Digest =
   else:
     unsupported T
 
+func hashTreeRootList(x: List|BitList): Eth2Digest =
+  const maxLen = static(x.maxLen)
+  type T = type(x)
+  const limit = maxChunksCount(T, maxLen)
+  var merkleizer = createMerkleizer(limit)
+
+  when x is BitList:
+    merkleizer.bitListHashTreeRoot(BitSeq x)
+  else:
+    type E = ElemType(T)
+    let contentsHash = when E is BasicType:
+      chunkedHashTreeRootForBasicTypes(merkleizer, asSeq x)
+    else:
+      for elem in x:
+        let elemHash = hash_tree_root(elem)
+        merkleizer.addChunk(elemHash.data)
+      merkleizer.getFinalHash()
+    mixInLength(contentsHash, x.len)
+
+
 func mergedDataHash(x: HashList|HashArray, chunkIdx: int64): Eth2Digest =
-  # The hash of the two cached
+  # The merged hash of the data at `chunkIdx` and `chunkIdx + 1`
   trs "DATA HASH ", chunkIdx, " ", x.data.len
 
   when x.T is BasicType:
@@ -592,8 +608,6 @@ func mergedDataHash(x: HashList|HashArray, chunkIdx: int64): Eth2Digest =
       byteIdx = chunkIdx * bytesPerChunk
       byteLen = x.data.len * sizeof(x.T)
 
-    const zero64 = default(array[64, byte])
-
     if byteIdx >= byteLen:
       zeroHashes[1]
     else:
@@ -616,8 +630,20 @@ func mergedDataHash(x: HashList|HashArray, chunkIdx: int64): Eth2Digest =
         hash_tree_root(x.data[chunkIdx]),
         hash_tree_root(x.data[chunkIdx + 1]))
 
-func cachedHash*(x: HashList, vIdx: int64): Eth2Digest =
+template mergedHash(x: HashList|HashArray, vIdxParam: int64): Eth2Digest =
-  doAssert vIdx >= 1
+  # The merged hash of the data at `vIdx` and `vIdx + 1`
+
+  let vIdx = vIdxParam
+  if vIdx >= x.maxChunks:
+    let dataIdx = vIdx - x.maxChunks
+    mergedDataHash(x, dataIdx)
+  else:
+    mergeBranches(
+      hashTreeRootCached(x, vIdx),
+      hashTreeRootCached(x, vIdx + 1))
+
+func hashTreeRootCached*(x: HashList, vIdx: int64): Eth2Digest =
+  doAssert vIdx >= 1, "Only valid for flat merkle tree indices"
 
   let
     layer = layer(vIdx)
@@ -636,71 +662,46 @@ func cachedHash*(x: HashList, vIdx: int64): Eth2Digest =
 
       trs "REFRESHING ", vIdx, " ", layerIdx, " ", layer
 
-      px[].hashes[layerIdx] =
+      px[].hashes[layerIdx] = mergedHash(x, vIdx * 2)
-        if layer == x.maxDepth - 1:
-          let dataIdx = vIdx * 2 - 1'i64 shl (x.maxDepth)
-          mergedDataHash(x, dataIdx)
-        else:
-          mergeBranches(
-            cachedHash(x, vIdx * 2),
-            cachedHash(x, vIdx * 2 + 1))
     else:
       trs "CACHED ", layerIdx
 
     x.hashes[layerIdx]
 
-func cachedHash*(x: HashArray, i: int): Eth2Digest =
+func hashTreeRootCached*(x: HashArray, vIdx: int): Eth2Digest =
-  doAssert i > 0, "Only valid for flat merkle tree indices"
+  doAssert vIdx >= 1, "Only valid for flat merkle tree indices"
 
-  if not isCached(x.hashes[i]):
+  if not isCached(x.hashes[vIdx]):
     # TODO oops. so much for maintaining non-mutability.
     let px = unsafeAddr x
 
-    px[].hashes[i] =
+    px[].hashes[vIdx] = mergedHash(x, vIdx * 2)
-      if i * 2 >= x.hashes.len():
-        let dataIdx = i * 2 - x.hashes.len()
-        mergedDataHash(x, dataIdx)
-      else:
-        mergeBranches(
-          cachedHash(x, i * 2),
-          cachedHash(x, i * 2 + 1))
 
-  return x.hashes[i]
+  return x.hashes[vIdx]
 
-func hash_tree_root*(x: auto): Eth2Digest {.raises: [Defect], nbench.} =
+func hashTreeRootCached*(x: HashArray): Eth2Digest =
-  trs "STARTING HASH TREE ROOT FOR TYPE ", name(type(x))
+  hashTreeRootCached(x, 1) # Array does not use idx 0
-  mixin toSszType
 
-  result = when x is HashArray:
+func hashTreeRootCached*(x: HashList): Eth2Digest =
-      cachedHash(x, 1)
+  if x.data.len == 0:
-    elif x is HashList:
-      if x.hashes.len < 2:
     mixInLength(zeroHashes[x.maxDepth], x.data.len())
   else:
     if not isCached(x.hashes[0]):
       # TODO oops. so much for maintaining non-mutability.
       let px = unsafeAddr x
+      px[].hashes[0] = mixInLength(hashTreeRootCached(x, 1), x.data.len)
 
-          px[].hashes[0] = mixInLength(cachedHash(x, 1), x.data.len)
     x.hashes[0]
-  elif x is List|BitList:
-    const maxLen = static(x.maxLen)
-    type T = type(x)
-    const limit = maxChunksCount(T, maxLen)
-    var merkleizer = createMerkleizer(limit)
 
-    when x is BitList:
+func hash_tree_root*(x: auto): Eth2Digest {.raises: [Defect], nbench.} =
-      merkleizer.bitListHashTreeRoot(BitSeq x)
+  trs "STARTING HASH TREE ROOT FOR TYPE ", name(type(x))
-    else:
+  mixin toSszType
-      type E = ElemType(T)
+
-      let contentsHash = when E is BasicType:
+  result =
-        chunkedHashTreeRootForBasicTypes(merkleizer, asSeq x)
+    when x is HashArray|HashList:
-      else:
+      hashTreeRootCached(x)
-        for elem in x:
+    elif x is List|BitList:
-          let elemHash = hash_tree_root(elem)
+      hashTreeRootList(x)
-          merkleizer.addChunk(elemHash.data)
-        merkleizer.getFinalHash()
-      mixInLength(contentsHash, x.len)
     else:
       hashTreeRootAux toSszType(x)
 

beacon_chain/ssz/types.nim

@@ -8,6 +8,8 @@ import
 
 const
   offsetSize* = 4
+  bytesPerChunk* = 32
+
 
 # A few index types from here onwards:
 # * dataIdx - leaf index starting from 0 to maximum length of collection
@@ -18,7 +20,7 @@ const
 proc dataPerChunk(T: type): int =
   # How many data items fit in a chunk
   when T is bool|SomeUnsignedInt: # BasicType
-    32 div sizeof(T)
+    bytesPerChunk div sizeof(T)
   else:
     1
 
@@ -26,7 +28,7 @@ template chunkIdx*(T: type, dataIdx: int64): int64 =
   # Given a data index, which chunk does it belong to?
   dataIdx div dataPerChunk(T)
 
-template maxChunkIdx(T: type, maxLen: int64): int64 =
+template maxChunkIdx*(T: type, maxLen: int64): int64 =
   # Given a number of data items, how many chunks are needed?
   chunkIdx(T, maxLen + dataPerChunk(T) - 1)