stdlib.lll

;;; ---------------------------------------------------------------------------
;;; @title A standard library of LLL macros.
;;; @author Daniel Ellison <daniel@syrinx.net>
;;;
;;; Copyright 2016 Daniel Ellison
;;;
;;;    Licensed under the Apache License, Version 2.0 (the "License");
;;;    you may not use this file except in compliance with the License.
;;;    You may obtain a copy of the License at
;;;
;;;      http://www.apache.org/licenses/LICENSE-2.0
;;;
;;;    Unless required by applicable law or agreed to in writing, software
;;;    distributed under the License is distributed on an "AS IS" BASIS,
;;;    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;;    See the License for the specific language governing permissions and
;;;    limitations under the License.

(seq

  ;; --------------------------------------------------------------------------
  ;; Constant definitions.

  ;; Booleans.
  (def 'true 1)
  (def 'false 0)

  ;; Miscellaneous.
  (def 'stdlib-version "0.1.2") ; Contracts can abort on version mismatch.
  (def 'invalid-location 0x02)  ; Jumping here causes an EVM panic.
  (def 'hold-back 1000)         ; Amount of gas to hold back on <call>.

  ;; Memory layout.
  (def 'scratch-one 0x0000) ; Scratch space.
  (def 'scratch-two 0x0020) ; More scratch space.
  (def 'return-code 0x0040) ; Boolean returned to calling contract.
  (def 'return-data 0x0060) ; Data returned to calling contract.
  (def 'call-result 0x0160) ; Data returned from called contract.
  (def 'call-data   0x0260) ; Data provided to called contract.
  (def 'user-memory 0x02c4) ; Library user memory start.

  ;; --------------------------------------------------------------------------
  ;; @notice Shifts the rightmost 4 bytes of a 32-byte number left by 28 bytes.
  ;; @dev 0x14ab90388092664827928d90384c73d82c5bf21abb61dd7d4971fc65f4851dfb
  ;;      0xf4851dfb00000000000000000000000000000000000000000000000000000000
  ;; @param input A 32-byte number.

  (def 'shift-left (input)
    (mul input (exp 2 224)))

  ;; --------------------------------------------------------------------------
  ;; @notice Shifts the leftmost 4 bytes of a 32-byte number right by 28 bytes.
  ;; @dev 0x14ab90388092664827928d90384c73d82c5bf21abb61dd7d4971fc65f4851dfb
  ;;      0x0000000000000000000000000000000000000000000000000000000014ab9038
  ;; @param input A 32-byte number.

  (def 'shift-right (input)
    (div input (exp 2 224)))

  ;; --------------------------------------------------------------------------
  ;; @notice Determines whether the supplied function ID matches a known
  ;;         function hash and executes <code-body> if so.
  ;; @dev The function ID is in the leftmost four bytes of the call data.
  ;; @param function-hash The four-byte hash of a known function signature.
  ;; @param code-body The code to run in the case of a match.

  (def 'function (function-hash code-body)
    (when (= (shift-right (calldataload 0x00)) function-hash)
      code-body))

  ;; --------------------------------------------------------------------------
  ;; @notice Calls another contract with no paramaters.
  ;; @dev Sends all but <hold-back> gas to called contract. Assumes no ether to
  ;;      be sent to called contract.
  ;; @param contract-address The address of the contract to call.
  ;; @param function-hash Short hash of the function to call.
  ;; @param return-size The parameter return size of the called function.

  (def 'call0 (contract-address function-hash return-size)
    (seq
      (mstore call-data (shift-left function-hash))
      (call (- (gas) hold-back) 0 contract-address
          call-data 4 return-data return-size)))

  ;; --------------------------------------------------------------------------
  ;; @notice Calls another contract with one paramater.
  ;; @dev Sends all but <hold-back> gas to called contract. Assumes no ether to
  ;;      be sent to called contract. Assumes 32-byte parameters.
  ;; @param contract-address The address of the contract to call.
  ;; @param function-hash Short hash of the function to call.
  ;; @param param1 The first (and only) parameter to the function call.
  ;; @param return-size The parameter return size of the called function.

  (def 'call1 (contract-address function-hash param1 return-size)
    (seq
      (mstore (+ call-data 0x00) (shift-left function-hash))
      (mstore (+ call-data 0x04) param1)
      (call (- (gas) hold-back) 0 contract-address
          call-data 36 return-data return-size)))

  ;; --------------------------------------------------------------------------
  ;; @notice Calls another contract with two paramaters.
  ;; @dev Sends all but <hold-back> gas to called contract. Assumes no ether to
  ;;      be sent to called contract. Assumes 32-byte parameters.
  ;; @param contract-address The address of the contract to call.
  ;; @param function-hash Short hash of the function to call.
  ;; @param param1 The first parameter to the function call.
  ;; @param param2 The second parameter to the function call.
  ;; @param return-size The parameter return size of the called function.

  (def 'call2 (contract-address function-hash param1 param2 return-size)
    (seq
      (mstore (+ call-data 0x00) (shift-left function-hash))
      (mstore (+ call-data 0x04) param1)
      (mstore (+ call-data 0x24) param2)
      (call (- (gas) hold-back) 0 contract-address
          call-data 68 return-data return-size)))

  ;; --------------------------------------------------------------------------
  ;; @notice Calls another contract with three paramaters.
  ;; @dev Sends all but <hold-back> gas to called contract. Assumes no ether to
  ;;      be sent to called contract. Assumes 32-byte parameters.
  ;; @param contract-address The address of the contract to call.
  ;; @param function-hash Short hash of the function to call.
  ;; @param param1 The first parameter to the function call.
  ;; @param param2 The second parameter to the function call.
  ;; @param param3 The third parameter to the function call.
  ;; @param return-size The parameter return size of the called function.

  (def 'call3 (contract-address function-hash param1 param2 param3 return-size)
    (seq
      (mstore (+ call-data 0x00) (shift-left function-hash))
      (mstore (+ call-data 0x04) param1)
      (mstore (+ call-data 0x24) param2)
      (mstore (+ call-data 0x44) param3)
      (call (- (gas) hold-back) 0 contract-address
          call-data 100 return-data return-size)))

  ;; --------------------------------------------------------------------------
  ;; @notice Increments the value @loc by 1.
  ;; @param loc The memory location to increment.

  (def '++ (loc)
    (mstore loc (+ @loc 1)))

  ;; --------------------------------------------------------------------------
  ;; @notice Decrements the value @loc by 1.
  ;; @param loc The memory location to decrement.

  (def '-- (loc)
    (mstore loc (- @loc 1)))

  ;; --------------------------------------------------------------------------
  ;; @notice Returns the smaller of two numbers.
  ;; @param a First number.
  ;; @param b Second number.

  (def 'min (a b)
    (if (< a b) a b))

  ;; --------------------------------------------------------------------------
  ;; @notice Returns the larger of two numbers.
  ;; @param a First number.
  ;; @param b Second number.

  (def 'max (a b)
    (if (> a b) a b))

)