refactor: replace BytesLib with assembly block

lukso-network · Oct 12, 2023 · e908016 · e908016
1 parent abeac4f
commit e908016
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Showing 2 changed files with 38 additions and 16 deletions.
diff --git a/contracts/LSP8IdentifiableDigitalAsset/extensions/LSP8CompatibleERC721.sol b/contracts/LSP8IdentifiableDigitalAsset/extensions/LSP8CompatibleERC721.sol
@@ -15,7 +15,6 @@ import {
 import {
     EnumerableSet
 } from "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";
-import {BytesLib} from "solidity-bytes-utils/contracts/BytesLib.sol";
 
 // modules
 import {
@@ -103,14 +102,26 @@ abstract contract LSP8CompatibleERC721 is
     ) public view virtual returns (string memory) {
         bytes memory data = _getData(_LSP4_METADATA_KEY);
 
-        // offset = bytes4(hashSig) + bytes32(contentHash) -> 4 + 32 = 36
-        uint256 offset = 36;
+        if (data.length <= 36) {
+            return "";
+        }
 
-        bytes memory uriBytes = BytesLib.slice(
-            data,
-            offset,
-            data.length - offset
-        );
+        uint256 requiredLength = data.length - 36;
+        bytes memory uriBytes;
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+            uriBytes := mload(0x40)
+            mstore(uriBytes, requiredLength)
+            for {
+                let i := 0
+            } lt(i, requiredLength) {
+                i := add(i, 32)
+            } {
+                mstore(add(uriBytes, add(i, 32)), mload(add(data, add(i, 68))))
+            }
+            // Update the free memory pointer
+            mstore(0x40, add(uriBytes, add(32, requiredLength)))
+        }
         return string(uriBytes);
     }
 

diff --git a/contracts/LSP8IdentifiableDigitalAsset/extensions/LSP8CompatibleERC721InitAbstract.sol b/contracts/LSP8IdentifiableDigitalAsset/extensions/LSP8CompatibleERC721InitAbstract.sol
@@ -15,7 +15,6 @@ import {
 import {
     EnumerableSet
 } from "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";
-import {BytesLib} from "solidity-bytes-utils/contracts/BytesLib.sol";
 
 // modules
 import {
@@ -111,14 +110,26 @@ abstract contract LSP8CompatibleERC721InitAbstract is
     ) public view virtual returns (string memory) {
         bytes memory data = _getData(_LSP4_METADATA_KEY);
 
-        // offset = bytes4(hashSig) + bytes32(contentHash) -> 4 + 32 = 36
-        uint256 offset = 36;
+        if (data.length <= 36) {
+            return "";
+        }
 
-        bytes memory uriBytes = BytesLib.slice(
-            data,
-            offset,
-            data.length - offset
-        );
+        uint256 requiredLength = data.length - 36;
+        bytes memory uriBytes;
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+            uriBytes := mload(0x40)
+            mstore(uriBytes, requiredLength)
+            for {
+                let i := 0
+            } lt(i, requiredLength) {
+                i := add(i, 32)
+            } {
+                mstore(add(uriBytes, add(i, 32)), mload(add(data, add(i, 68))))
+            }
+            // Update the free memory pointer
+            mstore(0x40, add(uriBytes, add(32, requiredLength)))
+        }
         return string(uriBytes);
     }