Macros for the structure contract

macros.lll

;;;; --------------------------------------------------------------------------
;;;; @title Macros for the structure contract.
;;;; @author Daniel Ellison <daniel@syrinx.net>

(seq

  ;; Memory layout.
  (def '*scratch* 0x00)
  (def '*funcid*  0x20)

  ;; Storage layout.
  (def '*parameter* 0x00)

  ;; The single function hash for this contract.
  (def '*get-constructor-parameter* 0x32cafedd)

  ;; Shifts the leftmost 4 bytes of a 32-byte number right by 28 bytes.
  (def 'shift-right (input)
    (div input (exp 2 224)))

  ;; Gets the function ID and stores it in memory for reference.
  (def 'get-function-id
    (mstore *funcid* (shift-right (calldataload 0x00))))

  ;; Takes a function hash and a sequence of code, compares that hash to the
  ;; hash supplied by the caller (which has been stored in *funcid*), and
  ;; executes the given code if they match.
  (def 'function (function-hash code-body)
    (when (= (mload *funcid*) function-hash)
      code-body))

  ;; Modifier macro to prevent unintended payments.
  (def 'unpayable
    (when (callvalue)
      (panic))))