From 5d5dbb6c19b7bd477dba45cb959bfeab63e8faec Mon Sep 17 00:00:00 2001
From: John Adler <john.adler@protonmail.ch>
Date: Sun, 20 Mar 2022 14:03:06 -0400
Subject: [PATCH 1/2] Bump to solc v0.8.4.

---
 contracts/ProtobufLib.sol | 2 +-
 contracts/TestFixture.sol | 2 +-
 hardhat.config.js         | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/contracts/ProtobufLib.sol b/contracts/ProtobufLib.sol
index 38cd04b..8b8bc90 100644
--- a/contracts/ProtobufLib.sol
+++ b/contracts/ProtobufLib.sol
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: Apache-2.0
-pragma solidity >=0.6.0 <8.0.0;
+pragma solidity >=0.8.4 <0.9.0;
 
 library ProtobufLib {
     /// @notice Protobuf wire types.
diff --git a/contracts/TestFixture.sol b/contracts/TestFixture.sol
index 79846cb..9a9e667 100644
--- a/contracts/TestFixture.sol
+++ b/contracts/TestFixture.sol
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: Apache-2.0
-pragma solidity >=0.6.0 <8.0.0;
+pragma solidity >=0.8.4 <0.9.0;
 
 import "./ProtobufLib.sol";
 
diff --git a/hardhat.config.js b/hardhat.config.js
index b546963..0786f66 100644
--- a/hardhat.config.js
+++ b/hardhat.config.js
@@ -1,5 +1,5 @@
 require("@nomiclabs/hardhat-truffle5");
 
 module.exports = {
-    solidity: "0.6.12",
+    solidity: "0.8.4",
 };

From 513e8955dcd582fe9842d4d516f24d2bc088e126 Mon Sep 17 00:00:00 2001
From: John Adler <john.adler@protonmail.ch>
Date: Sun, 20 Mar 2022 14:06:33 -0400
Subject: [PATCH 2/2] Fixes.

---
 contracts/ProtobufLib.sol | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/contracts/ProtobufLib.sol b/contracts/ProtobufLib.sol
index 8b8bc90..3e25cd1 100644
--- a/contracts/ProtobufLib.sol
+++ b/contracts/ProtobufLib.sol
@@ -3,7 +3,15 @@ pragma solidity >=0.8.4 <0.9.0;
 
 library ProtobufLib {
     /// @notice Protobuf wire types.
-    enum WireType { Varint, Bits64, LengthDelimited, StartGroup, EndGroup, Bits32, WIRE_TYPE_MAX }
+    enum WireType {
+        Varint,
+        Bits64,
+        LengthDelimited,
+        StartGroup,
+        EndGroup,
+        Bits32,
+        WIRE_TYPE_MAX
+    }
 
     /// @dev Maximum number of bytes for a varint.
     /// @dev 64 bits, in groups of base-128 (7 bits).
@@ -252,7 +260,10 @@ library ProtobufLib {
         }
 
         // https://stackoverflow.com/questions/2210923/zig-zag-decoding/2211086#2211086
-        uint64 zigzag_val = (val >> 1) ^ (-(val & 1));
+        uint64 zigzag_val;
+        unchecked {
+            zigzag_val = (val >> 1) - (~(val & 1) + 1);
+        }
 
         return (true, pos, int32(uint32(zigzag_val)));
     }
@@ -278,7 +289,10 @@ library ProtobufLib {
         }
 
         // https://stackoverflow.com/questions/2210923/zig-zag-decoding/2211086#2211086
-        uint64 zigzag_val = (val >> 1) ^ (-(val & 1));
+        uint64 zigzag_val;
+        unchecked {
+            zigzag_val = (val >> 1) - (~(val & 1) + 1);
+        }
 
         return (true, pos, int64(zigzag_val));
     }
@@ -512,8 +526,10 @@ library ProtobufLib {
         }
 
         // Check for overflow
-        if (pos + size < pos) {
-            return (false, pos, 0);
+        unchecked {
+            if (pos + size < pos) {
+                return (false, pos, 0);
+            }
         }
 
         // Check that index is within bounds
@@ -655,7 +671,7 @@ library ProtobufLib {
     /// @param n Number
     /// @return Marshaled bytes
     function encode_int32(int32 n) internal pure returns (bytes memory) {
-        return encode_varint(uint64(n));
+        return encode_varint(uint64(int64(n)));
     }
 
     /// @notice Decode varint int64.
@@ -686,7 +702,9 @@ library ProtobufLib {
         // https://developers.google.com/protocol-buffers/docs/encoding#signed_integers
         uint32 mask = 0;
         if (n < 0) {
-            mask -= 1;
+            unchecked {
+                mask -= 1;
+            }
         }
         uint32 zigzag_val = (uint32(n) << 1) ^ mask;
 
@@ -700,7 +718,9 @@ library ProtobufLib {
         // https://developers.google.com/protocol-buffers/docs/encoding#signed_integers
         uint64 mask = 0;
         if (n < 0) {
-            mask -= 1;
+            unchecked {
+                mask -= 1;
+            }
         }
         uint64 zigzag_val = (uint64(n) << 1) ^ mask;