Minimal EIP1967 UUPS Proxy

ERC1967UUPS.huff

/**
  ===================================================
  POTENTIALLY OUT-OF-DATE (last update: 2022-10-15).
  PLEASE REFER TO THE FOLLOWING REPO: https://github.com/Philogy/concise-erc1967-proxies
  ===================================================
*/

#define constant IMPL_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc

#define macro CONSTRUCTOR() = takes (0) returns (0) {
  0x20 0x6d returndatasize codecopy
  returndatasize mload [IMPL_SLOT] sstore
}

#define macro _MAIN(zero) = takes(0) returns(0) {
  <zero> <zero>                           // [0, 0] 
  calldatasize <zero> <zero> calldatacopy // [0, 0]
  <zero> <zero> calldatasize <zero>       // [...call_args, 0, 0]
  [IMPL_SLOT] sload                       // [...call_args, 0, 0]
  gas                                     // [...call_args, 0, 0]
  delegatecall                            // [success, 0, 0]
  returndatasize returndatasize           // [ret_size, ret_size, success, 0, 0]
  swap4                                   // [0, ret_size, success, 0, ret_size]
  dup1 returndatacopy                     // [success, 0, ret_size]
  is_success jumpi                        // [0, ret_size]
    revert
  is_success:
    return
}

#define macro MAIN() = takes(0) returns(0) {
  _MAIN(returndatasize)
}