From 35131b6d559b43a1ad0caadceaf9f4ee75d64580 Mon Sep 17 00:00:00 2001
From: Daniel Sobol <sobol.daniil@gmail.com>
Date: Mon, 12 Feb 2024 15:39:01 +0300
Subject: [PATCH] nibble encoding update (#2021)

* nibble encoding update

* portal-spec-tests update
---
 fluffy/network/state/state_content.nim        | 43 +++++++++++--------
 .../test_state_content_keys.nim               | 13 +++---
 2 files changed, 32 insertions(+), 24 deletions(-)

diff --git a/fluffy/network/state/state_content.nim b/fluffy/network/state/state_content.nim
index 3abeef595..ae15773e3 100644
--- a/fluffy/network/state/state_content.nim
+++ b/fluffy/network/state/state_content.nim
@@ -19,7 +19,7 @@ import
 export ssz_serialization, common_types, hash, results
 
 const
-  MAX_PACKED_NIBBLES_LEN   = 32
+  MAX_PACKED_NIBBLES_LEN   = 33
   MAX_UNPACKED_NIBBLES_LEN = 64
 
   MAX_TRIE_NODE_LEN  = 1024
@@ -44,10 +44,7 @@ type
     contractTrieNode = 0x21
     contractCode = 0x22
 
-  NibblePair* = byte
-  Nibbles* = object
-    isOddLength*: bool
-    packedNibbles*: List[NibblePair, MAX_PACKED_NIBBLES_LEN]
+  Nibbles* = List[byte, MAX_PACKED_NIBBLES_LEN]
 
   TrieNode*  = List[byte, MAX_TRIE_NODE_LEN]
   TrieProof* = List[TrieNode, MAX_TRIE_PROOF_LEN]
@@ -130,41 +127,53 @@ func toContentId*(contentKey: ContentKey): ContentId =
 
 func packNibbles*(nibbles: seq[byte]): Nibbles =
   doAssert(nibbles.len() <= MAX_UNPACKED_NIBBLES_LEN, "Can't pack more than 64 nibbles")
+
+  if nibbles.len() == 0:
+    return Nibbles(@[byte(0x00)])
   
   let
     isOddLength = (nibbles.len() %% 2 == 1)
     outputLength = (nibbles.len() + 1) div 2
 
   var
-    output = newSeq[NibblePair]()
+    output = newSeq[byte]()
     highNibble = not isOddLength
     currentByte: byte = 0
 
-  for nibble in nibbles:
+  if isOddLength:
+    currentByte = 0x10
+
+  if not isOddLength:
+    output.add(0x00)
+
+  for i, nibble in nibbles:
     if highNibble:
       currentByte = nibble shl 4
     else:
-      output.add(NibblePair(currentByte or nibble))
+      output.add(currentByte or nibble)
       currentByte = 0
     highNibble = not highNibble
 
-  Nibbles(isOddLength: isOddLength, packedNibbles: Nibbles.packedNibbles.init(output))
+  Nibbles(output)
 
 func unpackNibbles*(nibbles: Nibbles): seq[byte] =
-  doAssert(nibbles.packedNibbles.len() <= MAX_PACKED_NIBBLES_LEN, "Can't unpack more than 32 nibbles")
+  doAssert(nibbles.len() <= MAX_PACKED_NIBBLES_LEN, "Can't unpack more than 32 nibbles")
 
   var output = newSeq[byte]()
 
-  for pair in nibbles.packedNibbles:
+  for i, pair in nibbles:
+    if i == 0 and pair == 0x00:
+      continue
+
     let
       first = (pair and 0xF0) shr 4
       second = pair and 0x0F
-  
-    output.add(first)
-    output.add(second)
-  
-  if nibbles.isOddLength:
-    output.delete(0)
+
+    if i == 0 and first == 0x01:
+      output.add(second)
+    else:
+      output.add(first)
+      output.add(second)
 
   output
 
diff --git a/fluffy/tests/state_network_tests/test_state_content_keys.nim b/fluffy/tests/state_network_tests/test_state_content_keys.nim
index 87d67e6bb..5fd6144eb 100644
--- a/fluffy/tests/state_network_tests/test_state_content_keys.nim
+++ b/fluffy/tests/state_network_tests/test_state_content_keys.nim
@@ -13,7 +13,7 @@ import
 
 
 suite "State Content Keys":
-  const evenNibles = "00050000008679e8ed"
+  const evenNibles = "008679e8ed"
   test "Encode/decode even nibbles":
     const
       nibbles: seq[byte] = @[8, 6, 7, 9, 14, 8, 14, 13]
@@ -26,20 +26,20 @@ suite "State Content Keys":
     check encoded.toHex() == evenNibles
     check unpackedNibbles == nibbles
 
-  const oddNibbles = "0105000000018679e8ed"
+  const oddNibbles = "138679e8ed"
   test "Encode/decode odd nibbles":
     const
-      nibbles: seq[byte] = @[1, 8, 6, 7, 9, 14, 8, 14, 13]
+      nibbles: seq[byte] = @[3, 8, 6, 7, 9, 14, 8, 14, 13]
       packedNibbles = packNibbles(nibbles)
       unpackedNibbles = unpackNibbles(packedNibbles)
 
     let
       encoded = SSZ.encode(packedNibbles)
-
+    
     check encoded.toHex() == oddNibbles
     check unpackedNibbles == nibbles
 
-  const accountTrieNodeKeyEncoded = "20240000006225fcc63b22b80301d9f2582014e450e91f9b329b7cc87ad16894722fff529600050000008679e8ed"
+  const accountTrieNodeKeyEncoded = "20240000006225fcc63b22b80301d9f2582014e450e91f9b329b7cc87ad16894722fff5296008679e8ed"
   test "Encode/decode AccountTrieNodeKey":
     const
       nibbles: seq[byte] = @[8, 6, 7, 9, 14, 8, 14, 13]
@@ -58,13 +58,12 @@ suite "State Content Keys":
       decoded.contentType == accountTrieNode
       decoded.accountTrieNodeKey == AccountTrieNodeKey(path: packedNibbles, nodeHash: nodeHash)
 
-  const contractTrieNodeKeyEncoded = "21c02aaa39b223fe8d0a0e5c4f27ead9083c756cc238000000eb43d68008d216e753fef198cf51077f5a89f406d9c244119d1643f0f2b190110005000000405787"
+  const contractTrieNodeKeyEncoded = "21c02aaa39b223fe8d0a0e5c4f27ead9083c756cc238000000eb43d68008d216e753fef198cf51077f5a89f406d9c244119d1643f0f2b1901100405787"
   test "Encode/decode ContractTrieNodeKey":
     const
       nibbles: seq[byte] = @[4, 0, 5, 7, 8, 7]
       packedNibbles = packNibbles(nibbles)
       address = Address.fromHex("c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2")
-      isOddLength = false
       nodeHash = NodeHash.fromHex("eb43d68008d216e753fef198cf51077f5a89f406d9c244119d1643f0f2b19011")
 
     let