assembly version

contracts/token/ERC1155/ERC1155.sol

@@ -207,8 +207,9 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
  function _safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes memory data) internal {
  require(to != address(0), "ERC1155: transfer to the zero address");
  require(from != address(0), "ERC1155: transfer from the zero address");
- uint256[] memory ids = _asSingletonArray(id);
- uint256[] memory amounts = _asSingletonArray(amount);
+ uint256[] memory ids;
+ uint256[] memory amounts;
+ (ids, amounts) = _asSingletonArrays(id, amount);
  _update(from, to, ids, amounts, data);
  }
 
@@ -383,4 +384,23 @@ contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
 
  return array;
  }
+
+ function _asSingletonArrays(uint256 element1, uint256 element2) private pure returns (uint256[] memory, uint256[] memory) {
+ uint256[] memory array1;
+ uint256[] memory array2;
+
+ assembly {
+ array1 := mload(0x40)
+ mstore(array1, 1)
+ mstore(add(array1, 0x20), element1)
+
+ array2 := add(array1, 0x40)
+ mstore(array2, 1)
+ mstore(add(array2, 0x20), element2)
+
+ mstore(0x40, add(array2, 0x40))
+ }
+
+ return (array1, array2);
+ }
 }