port eth2_digest speedups to eth_hash (#716)

* port eth2_digest speedups to eth_hash

* faster comparison
* `hash` integration
* lower-case printing

eth/bloom.nim

@@ -2,7 +2,7 @@ import stint, ./common/eth_hash
 
 type UInt2048 = StUint[2048]
 
-iterator chunksForBloom(h: MDigest[256]): array[2, uint8] =
+iterator chunksForBloom(h: KeccakHash): array[2, uint8] =
   yield [h.data[0], h.data[1]]
   yield [h.data[2], h.data[3]]
   yield [h.data[4], h.data[5]]
@@ -12,25 +12,25 @@ proc chunkToBloomBits(chunk: array[2, uint8]): UInt2048 =
   let l = chunk[1].int
   one(UInt2048) shl ((l + (h shl 8)) and 2047)
 
-iterator bloomBits(h: MDigest[256]): UInt2048 =
+iterator bloomBits(h: KeccakHash): UInt2048 =
   for chunk in chunksForBloom(h):
     yield chunkToBloomBits(chunk)
 
 type BloomFilter* = object
   value*: UInt2048
 
-proc incl*(f: var BloomFilter, h: MDigest[256]) =
+proc incl*(f: var BloomFilter, h: KeccakHash) =
   for bits in bloomBits(h):
     f.value = f.value or bits
 
-proc init*(_: type BloomFilter, h: MDigest[256]): BloomFilter =
+proc init*(_: type BloomFilter, h: KeccakHash): BloomFilter =
   result.incl(h)
 
 # TODO: The following 2 procs should be one genric, but it doesn't compile. Nim bug?
 proc incl*(f: var BloomFilter, v: string) = f.incl(keccakHash(v))
 proc incl*(f: var BloomFilter, v: openArray[byte]) = f.incl(keccakHash(v))
 
-proc contains*(f: BloomFilter, h: MDigest[256]): bool =
+proc contains*(f: BloomFilter, h: KeccakHash): bool =
   for bits in bloomBits(h):
     if (f.value and bits).isZero: return false
   return true

eth/common/eth_hash.nim

@@ -9,16 +9,19 @@
 ## keccak256 is used across ethereum as the "default" hash function and this
 ## module provides a type and some helpers to produce such hashes
 
-import
-  nimcrypto/[keccak, hash]
+import std/hashes
+import nimcrypto/[keccak, utils]
+import nimcrypto/hash except `$`
+
+from nimcrypto/utils import bytesToHex
 
 export
-  keccak.update, keccak.finish, hash
+  keccak.update, keccak.finish, hash.fromHex, hash.toDigest, hashes.Hash
 
 type
   KeccakHash* = MDigest[256]
     ## A hash value computed using keccak256
-    ## note: this aliases Eth2Digest too, which uses a different hash!
+    ## note: this aliases Eth2Digest too, which uses a different hash function!
 
 template withKeccakHash*(body: untyped): KeccakHash =
   ## This little helper will init the hash function and return the sliced
@@ -44,3 +47,23 @@ func keccakHash*(a, b: openArray[byte]): KeccakHash =
   withKeccakHash:
     h.update a
     h.update b
+
+func `$`*(v: KeccakHash): string =
+  var res = newString((len(v.data) shl 1))
+  discard bytesToHex(v.data, res, {HexFlags.LowerCase})
+  res
+
+template hash*(x: KeccakHash): Hash =
+  ## Hash for digests for Nim hash tables
+  # digests are already good hashes
+  var h {.noinit.}: Hash
+  copyMem(addr h, unsafeAddr x.data[0], static(sizeof(Hash)))
+  h
+
+func `==`*(a, b: KeccakHash): bool =
+  when nimvm:
+    a.data == b.data
+  else:
+    # nimcrypto uses a constant-time comparison for all MDigest types which for
+    # KeccakHash is unnecessary - the type should never hold a secret!
+    equalMem(unsafeAddr a.data[0], unsafeAddr b.data[0], sizeof(a.data))

eth/common/eth_hash_rlp.nim

@@ -10,8 +10,8 @@ import
 
 export eth_hash, rlp
 
-proc read*(rlp: var Rlp, T: typedesc[MDigest]): T =
+proc read*(rlp: var Rlp, T: typedesc[KeccakHash]): T =
   result.data = rlp.read(type(result.data))
 
-proc append*(rlpWriter: var RlpWriter, a: MDigest) =
+proc append*(rlpWriter: var RlpWriter, a: KeccakHash) =
   rlpWriter.append(a.data)

eth/common/eth_types.nim

@@ -17,6 +17,8 @@ import
   ./eth_hash,
   ./eth_times
 
+from nimcrypto/hash import MDigest
+
 export
   results,
   stint,

eth/rlp/writer.nim

@@ -302,7 +302,7 @@ proc appendImpl(self: var RlpWriter, data: tuple) {.inline.} =
 # score in order to facilitate easier overloading with user types:
 template append*[T](w: var RlpWriter; data: T) =
   when data is (SomeSignedInt|enum|bool):
-    when data is SomeSignedInt:
+    when false and data is SomeSignedInt:
       # TODO potentially remove signed integer support - we should never make it
       #      this far!
       {.warning: "Signed integers cannot reliably be encoded using RLP".}
@@ -314,7 +314,6 @@ proc initRlpList*(listSize: int): RlpWriter =
   result = initRlpWriter()
   startList(result, listSize)
 
-# TODO: This should return a lent value
 template finish*(self: RlpWriter): seq[byte] =
   doAssert self.pendingLists.len == 0, "Insufficient number of elements written to a started list"
   self.output

eth/trie/trie_utils.nim

@@ -1,5 +1,4 @@
 import
-  stew/byteutils,
   ./trie_defs
 
 export trie_defs
@@ -10,8 +9,3 @@ template checkValidHashZ*(x: untyped) =
 
 template isZeroHash*(x: openArray[byte]): bool =
   x.len == 0
-
-proc hashFromHex*(bits: static[int], input: string): MDigest[bits] =
-  MDigest(data: hexToByteArray[bits div 8](input))
-
-template hashFromHex*(s: static[string]): untyped = hashFromHex(s.len * 4, s)