Add gas optimization by implementing unchecked index increment

gas-snapshot

@@ -1,21 +1,21 @@
 ERC721ReadOnlyTest:testApprove() (gas: 10677)
-ERC721ReadOnlyTest:testGetApproved() (gas: 16236)
+ERC721ReadOnlyTest:testGetApproved() (gas: 16241)
 ERC721ReadOnlyTest:testIsApprovedForAll() (gas: 10051)
 ERC721ReadOnlyTest:testSetApprovalForAll() (gas: 10714)
 ERC721ReadOnlyTest:testTransferFunctions() (gas: 19077)
-PBTSimpleTest:testGetTokenDataForChipSignature() (gas: 127958)
-PBTSimpleTest:testGetTokenDataForChipSignatureBlockNumTooOld() (gas: 122512)
-PBTSimpleTest:testGetTokenDataForChipSignatureInvalid() (gas: 131804)
-PBTSimpleTest:testGetTokenDataForChipSignatureInvalidBlockNumber() (gas: 122351)
-PBTSimpleTest:testIsChipSignatureForToken() (gas: 217369)
-PBTSimpleTest:testMintTokenWithChip() (gas: 176650)
-PBTSimpleTest:testSeedChipToTokenMapping() (gas: 115247)
-PBTSimpleTest:testSeedChipToTokenMappingExistingToken() (gas: 212294)
+PBTSimpleTest:testGetTokenDataForChipSignature() (gas: 127772)
+PBTSimpleTest:testGetTokenDataForChipSignatureBlockNumTooOld() (gas: 122321)
+PBTSimpleTest:testGetTokenDataForChipSignatureInvalid() (gas: 131618)
+PBTSimpleTest:testGetTokenDataForChipSignatureInvalidBlockNumber() (gas: 122155)
+PBTSimpleTest:testIsChipSignatureForToken() (gas: 217173)
+PBTSimpleTest:testMintTokenWithChip() (gas: 176459)
+PBTSimpleTest:testSeedChipToTokenMapping() (gas: 115101)
+PBTSimpleTest:testSeedChipToTokenMappingExistingToken() (gas: 212146)
 PBTSimpleTest:testSeedChipToTokenMappingInvalidInput() (gas: 17178)
 PBTSimpleTest:testSupportsInterface() (gas: 7059)
-PBTSimpleTest:testTokenIdFor() (gas: 117084)
-PBTSimpleTest:testTokenIdMappedFor() (gas: 66558)
-PBTSimpleTest:testTransferTokenWithChip(bool) (runs: 256, μ: 211956, ~: 211875)
-PBTSimpleTest:testUpdateChips() (gas: 171052)
-PBTSimpleTest:testUpdateChipsInvalidInput() (gas: 16433)
-PBTSimpleTest:testUpdateChipsUnsetChip() (gas: 23430)
+PBTSimpleTest:testTokenIdFor() (gas: 117009)
+PBTSimpleTest:testTokenIdMappedFor() (gas: 66483)
+PBTSimpleTest:testTransferTokenWithChip(bool) (runs: 256, μ: 211765, ~: 211684)
+PBTSimpleTest:testUpdateChips() (gas: 170817)
+PBTSimpleTest:testUpdateChipsInvalidInput() (gas: 16436)
+PBTSimpleTest:testUpdateChipsUnsetChip() (gas: 23431)

src/PBTSimple.sol

@@ -49,25 +49,41 @@ contract PBTSimple is ERC721ReadOnly, IPBT {
         if (tokenIdsLength != chipAddresses.length) {
             revert ArrayLengthMismatch();
         }
-        for (uint256 i = 0; i < tokenIdsLength; ++i) {
+
+        if (tokenIdsLength == 0) {
+            return;
+        }
+
+        uint256 i = 0;
+        do {
             address chipAddress = chipAddresses[i];
             uint256 tokenId = tokenIds[i];
             if (throwIfTokenAlreadyMinted && _exists(tokenId)) {
                 revert SeedingChipDataForExistingToken();
             }
             _tokenDatas[chipAddress] = TokenData(tokenId, chipAddress, true);
-        }
+            unchecked {
+                i++;
+            }
+        } while (i < tokenIdsLength);
     }
 
     // Should only be called for tokenIds that have been minted
     // If the tokenId hasn't been minted yet, use _seedChipToTokenMapping instead
     // Should only be used and called with care and rails to avoid a centralized entity swapping out valid chips.
     // TODO: consider preventing multiple chip addresses mapping to the same tokenId (store a tokenId->chip mapping)
     function _updateChips(address[] calldata chipAddressesOld, address[] calldata chipAddressesNew) internal {
-        if (chipAddressesOld.length != chipAddressesNew.length) {
+        uint256 chipAddressesOldLength = chipAddressesOld.length;
+        if (chipAddressesOldLength != chipAddressesNew.length) {
             revert ArrayLengthMismatch();
         }
-        for (uint256 i = 0; i < chipAddressesOld.length; ++i) {
+
+        if (chipAddressesOldLength == 0) {
+            return;
+        }
+
+        uint256 i = 0;
+        do {
             address oldChipAddress = chipAddressesOld[i];
             TokenData memory oldTokenData = _tokenDatas[oldChipAddress];
             if (!oldTokenData.set) {
@@ -80,7 +96,10 @@ contract PBTSimple is ERC721ReadOnly, IPBT {
                 emit PBTChipRemapping(tokenId, oldChipAddress, newChipAddress);
             }
             delete _tokenDatas[oldChipAddress];
-        }
+            unchecked {
+                i++;
+            }
+        } while (i < chipAddressesOldLength);
     }
 
     function tokenIdFor(address chipAddress) external view override returns (uint256) {