/*
Copyright 2018 ZeroEx Intl.
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.
*/
pragma solidity 0.4.24;
pragma experimental ABIEncoderV2;
import "./LibOrder.sol";
contract LibAbiEncoder {
/// @dev ABI encodes calldata for `fillOrder`.
/// @param order Order struct containing order specifications.
/// @param takerAssetFillAmount Desired amount of takerAsset to sell.
/// @param signature Proof that order has been created by maker.
/// @return ABI encoded calldata for `fillOrder`.
function abiEncodeFillOrder(
LibOrder.Order memory order,
uint256 takerAssetFillAmount,
bytes memory signature
)
internal
pure
returns (bytes memory fillOrderCalldata)
{
// We need to call MExchangeCore.fillOrder using a delegatecall in
// assembly so that we can intercept a call that throws. For this, we
// need the input encoded in memory in the Ethereum ABIv2 format [1].
// | Area | Offset | Length | Contents |
// | -------- |--------|---------|-------------------------------------------- |
// | Header | 0x00 | 4 | function selector |
// | Params | | 3 * 32 | function parameters: |
// | | 0x00 | | 1. offset to order (*) |
// | | 0x20 | | 2. takerAssetFillAmount |
// | | 0x40 | | 3. offset to signature (*) |
// | Data | | 12 * 32 | order: |
// | | 0x000 | | 1. senderAddress |
// | | 0x020 | | 2. makerAddress |
// | | 0x040 | | 3. takerAddress |
// | | 0x060 | | 4. feeRecipientAddress |
// | | 0x080 | | 5. makerAssetAmount |
// | | 0x0A0 | | 6. takerAssetAmount |
// | | 0x0C0 | | 7. makerFeeAmount |
// | | 0x0E0 | | 8. takerFeeAmount |
// | | 0x100 | | 9. expirationTimeSeconds |
// | | 0x120 | | 10. salt |
// | | 0x140 | | 11. Offset to makerAssetData (*) |
// | | 0x160 | | 12. Offset to takerAssetData (*) |
// | | 0x180 | 32 | makerAssetData Length |
// | | 0x1A0 | ** | makerAssetData Contents |
// | | 0x1C0 | 32 | takerAssetData Length |
// | | 0x1E0 | ** | takerAssetData Contents |
// | | 0x200 | 32 | signature Length |
// | | 0x220 | ** | signature Contents |
// * Offsets are calculated from the beginning of the current area: Header, Params, Data:
// An offset stored in the Params area is calculated from the beginning of the Params section.
// An offset stored in the Data area is calculated from the beginning of the Data section.
// ** The length of dynamic array contents are stored in the field immediately preceeding the contents.
// [1]: https://solidity.readthedocs.io/en/develop/abi-spec.html
assembly {
// Areas below may use the following variables:
// 1. Start -- Start of this area in memory
// 2. End -- End of this area in memory. This value may
// be precomputed (before writing contents),
// or it may be computed as contents are written.
// 3. Offset -- Current offset into area. If an area's End
// is precomputed, this variable tracks the
// offsets of contents as they are written.
/////// Setup Header Area ///////
// Load free memory pointer
fillOrderCalldata := mload(0x40)
// bytes4(keccak256("fillOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)"))
// = 0xb4be83d5
// Leave 0x20 bytes to store the length
mstore(add(fillOrderCalldata, 0x20), 0xb4be83d500000000000000000000000000000000000000000000000000000000)
let headerAreaEnd := add(fillOrderCalldata, 0x24)
/////// Setup Params Area ///////
// This area is preallocated and written to later.
// This is because we need to fill in offsets that have not yet been calculated.
let paramsAreaStart := headerAreaEnd
let paramsAreaEnd := add(paramsAreaStart, 0x60)
let paramsAreaOffset := paramsAreaStart
/////// Setup Data Area ///////
let dataAreaStart := paramsAreaEnd
let dataAreaEnd := dataAreaStart
// Offset from the source data we're reading from
let sourceOffset := order
// arrayLenBytes and arrayLenWords track the length of a dynamically-allocated bytes array.
let arrayLenBytes := 0
let arrayLenWords := 0
/////// Write order Struct ///////
// Write memory location of Order, relative to the start of the
// parameter list, then increment the paramsAreaOffset respectively.
mstore(paramsAreaOffset, sub(dataAreaEnd, paramsAreaStart))
paramsAreaOffset := add(paramsAreaOffset, 0x20)
// Write values for each field in the order
// It would be nice to use a loop, but we save on gas by writing
// the stores sequentially.
mstore(dataAreaEnd, mload(sourceOffset)) // makerAddress
mstore(add(dataAreaEnd, 0x20), mload(add(sourceOffset, 0x20))) // takerAddress
mstore(add(dataAreaEnd, 0x40), mload(add(sourceOffset, 0x40))) // feeRecipientAddress
mstore(add(dataAreaEnd, 0x60), mload(add(sourceOffset, 0x60))) // senderAddress
mstore(add(dataAreaEnd, 0x80), mload(add(sourceOffset, 0x80))) // makerAssetAmount
mstore(add(dataAreaEnd, 0xA0), mload(add(sourceOffset, 0xA0))) // takerAssetAmount
mstore(add(dataAreaEnd, 0xC0), mload(add(sourceOffset, 0xC0))) // makerFeeAmount
mstore(add(dataAreaEnd, 0xE0), mload(add(sourceOffset, 0xE0))) // takerFeeAmount
mstore(add(dataAreaEnd, 0x100), mload(add(sourceOffset, 0x100))) // expirationTimeSeconds
mstore(add(dataAreaEnd, 0x120), mload(add(sourceOffset, 0x120))) // salt
mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140))) // Offset to makerAssetData
mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160))) // Offset to takerAssetData
dataAreaEnd := add(dataAreaEnd, 0x180)
sourceOffset := add(sourceOffset, 0x180)
// Write offset to
mstore(add(dataAreaStart, mul(10, 0x20)), sub(dataAreaEnd, dataAreaStart))
// Calculate length of
sourceOffset := mload(add(order, 0x140)) // makerAssetData
arrayLenBytes := mload(sourceOffset)
sourceOffset := add(sourceOffset, 0x20)
arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
// Write length of
mstore(dataAreaEnd, arrayLenBytes)
dataAreaEnd := add(dataAreaEnd, 0x20)
// Write contents of
for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
mstore(dataAreaEnd, mload(sourceOffset))
dataAreaEnd := add(dataAreaEnd, 0x20)
sourceOffset := add(sourceOffset, 0x20)
}
// Write offset to
mstore(add(dataAreaStart, mul(11, 0x20)), sub(dataAreaEnd, dataAreaStart))
// Calculate length of
sourceOffset := mload(add(order, 0x160)) // takerAssetData
arrayLenBytes := mload(sourceOffset)
sourceOffset := add(sourceOffset, 0x20)
arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
// Write length of
mstore(dataAreaEnd, arrayLenBytes)
dataAreaEnd := add(dataAreaEnd, 0x20)
// Write contents of
for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
mstore(dataAreaEnd, mload(sourceOffset))
dataAreaEnd := add(dataAreaEnd, 0x20)
sourceOffset := add(sourceOffset, 0x20)
}
/////// Write takerAssetFillAmount ///////
mstore(paramsAreaOffset, takerAssetFillAmount)
paramsAreaOffset := add(paramsAreaOffset, 0x20)
/////// Write signature ///////
// Write offset to paramsArea
mstore(paramsAreaOffset, sub(dataAreaEnd, paramsAreaStart))
// Calculate length of signature
sourceOffset := signature
arrayLenBytes := mload(sourceOffset)
sourceOffset := add(sourceOffset, 0x20)
arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
// Write length of signature
mstore(dataAreaEnd, arrayLenBytes)
dataAreaEnd := add(dataAreaEnd, 0x20)
// Write contents of signature
for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
mstore(dataAreaEnd, mload(sourceOffset))
dataAreaEnd := add(dataAreaEnd, 0x20)
sourceOffset := add(sourceOffset, 0x20)
}
// Set length of calldata
let calldataLen := sub(dataAreaEnd, add(fillOrderCalldata, 0x20))
mstore(fillOrderCalldata, calldataLen)
// Increment free memory pointer
mstore(0x40, add(fillOrderCalldata, add(calldataLen, 0x20)))
}
return fillOrderCalldata;
}
}