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Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.5.17+commit.d19bba13.js&optimize=undefined&runs=undefined&gist=
/*
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// SPDX-License-Identifier: Apache-2.0
/*
Copyright 2020 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 ^0.6.5;
import "./errors/LibBytesRichErrorsV06.sol";
import "./errors/LibRichErrorsV06.sol";
library LibBytesV06 {
using LibBytesV06 for bytes;
/// @dev Gets the memory address for a byte array.
/// @param input Byte array to lookup.
/// @return memoryAddress Memory address of byte array. This
/// points to the header of the byte array which contains
/// the length.
function rawAddress(bytes memory input) internal pure returns (uint256 memoryAddress) {
assembly {
memoryAddress := input
}
return memoryAddress;
}
/// @dev Gets the memory address for the contents of a byte array.
/// @param input Byte array to lookup.
/// @return memoryAddress Memory address of the contents of the byte array.
function contentAddress(bytes memory input) internal pure returns (uint256 memoryAddress) {
assembly {
memoryAddress := add(input, 32)
}
return memoryAddress;
}
/// @dev Copies `length` bytes from memory location `source` to `dest`.
/// @param dest memory address to copy bytes to.
/// @param source memory address to copy bytes from.
/// @param length number of bytes to copy.
function memCopy(uint256 dest, uint256 source, uint256 length) internal pure {
if (length < 32) {
// Handle a partial word by reading destination and masking
// off the bits we are interested in.
// This correctly handles overlap, zero lengths and source == dest
assembly {
let mask := sub(exp(256, sub(32, length)), 1)
let s := and(mload(source), not(mask))
let d := and(mload(dest), mask)
mstore(dest, or(s, d))
}
} else {
// Skip the O(length) loop when source == dest.
if (source == dest) {
return;
}
// For large copies we copy whole words at a time. The final
// word is aligned to the end of the range (instead of after the
// previous) to handle partial words. So a copy will look like this:
//
// ####
// ####
// ####
// ####
//
// We handle overlap in the source and destination range by
// changing the copying direction. This prevents us from
// overwriting parts of source that we still need to copy.
//
// This correctly handles source == dest
//
if (source > dest) {
assembly {
// We subtract 32 from `sEnd` and `dEnd` because it
// is easier to compare with in the loop, and these
// are also the addresses we need for copying the
// last bytes.
length := sub(length, 32)
let sEnd := add(source, length)
let dEnd := add(dest, length)
// Remember the last 32 bytes of source
// This needs to be done here and not after the loop
// because we may have overwritten the last bytes in
// source already due to overlap.
let last := mload(sEnd)
// Copy whole words front to back
// Note: the first check is always true,
// this could have been a do-while loop.
for {
} lt(source, sEnd) {
} {
mstore(dest, mload(source))
source := add(source, 32)
dest := add(dest, 32)
}
// Write the last 32 bytes
mstore(dEnd, last)
}
} else {
assembly {
// We subtract 32 from `sEnd` and `dEnd` because those
// are the starting points when copying a word at the end.
length := sub(length, 32)
let sEnd := add(source, length)
let dEnd := add(dest, length)
// Remember the first 32 bytes of source
// This needs to be done here and not after the loop
// because we may have overwritten the first bytes in
// source already due to overlap.
let first := mload(source)
// Copy whole words back to front
// We use a signed comparisson here to allow dEnd to become
// negative (happens when source and dest < 32). Valid
// addresses in local memory will never be larger than
// 2**255, so they can be safely re-interpreted as signed.
// Note: the first check is always true,
// this could have been a do-while loop.
for {
} slt(dest, dEnd) {
} {
mstore(dEnd, mload(sEnd))
sEnd := sub(sEnd, 32)
dEnd := sub(dEnd, 32)
}
// Write the first 32 bytes
mstore(dest, first)
}
}
}
}
/// @dev Returns a slices from a byte array.
/// @param b The byte array to take a slice from.
/// @param from The starting index for the slice (inclusive).
/// @param to The final index for the slice (exclusive).
/// @return result The slice containing bytes at indices [from, to)
function slice(bytes memory b, uint256 from, uint256 to) internal pure returns (bytes memory result) {
// Ensure that the from and to positions are valid positions for a slice within
// the byte array that is being used.
if (from > to) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
from,
to
)
);
}
if (to > b.length) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
to,
b.length
)
);
}
// Create a new bytes structure and copy contents
result = new bytes(to - from);
memCopy(result.contentAddress(), b.contentAddress() + from, result.length);
return result;
}
/// @dev Returns a slice from a byte array without preserving the input.
/// When `from == 0`, the original array will match the slice.
/// In other cases its state will be corrupted.
/// @param b The byte array to take a slice from. Will be destroyed in the process.
/// @param from The starting index for the slice (inclusive).
/// @param to The final index for the slice (exclusive).
/// @return result The slice containing bytes at indices [from, to)
function sliceDestructive(bytes memory b, uint256 from, uint256 to) internal pure returns (bytes memory result) {
// Ensure that the from and to positions are valid positions for a slice within
// the byte array that is being used.
if (from > to) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
from,
to
)
);
}
if (to > b.length) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
to,
b.length
)
);
}
// Create a new bytes structure around [from, to) in-place.
assembly {
result := add(b, from)
mstore(result, sub(to, from))
}
return result;
}
/// @dev Pops the last byte off of a byte array by modifying its length.
/// @param b Byte array that will be modified.
/// @return result The byte that was popped off.
function popLastByte(bytes memory b) internal pure returns (bytes1 result) {
if (b.length == 0) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
b.length,
0
)
);
}
// Store last byte.
result = b[b.length - 1];
assembly {
// Decrement length of byte array.
let newLen := sub(mload(b), 1)
mstore(b, newLen)
}
return result;
}
/// @dev Tests equality of two byte arrays.
/// @param lhs First byte array to compare.
/// @param rhs Second byte array to compare.
/// @return equal True if arrays are the same. False otherwise.
function equals(bytes memory lhs, bytes memory rhs) internal pure returns (bool equal) {
// Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
// We early exit on unequal lengths, but keccak would also correctly
// handle this.
return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
}
/// @dev Reads an address from a position in a byte array.
/// @param b Byte array containing an address.
/// @param index Index in byte array of address.
/// @return result address from byte array.
function readAddress(bytes memory b, uint256 index) internal pure returns (address result) {
if (b.length < index + 20) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
b.length,
index + 20 // 20 is length of address
)
);
}
// Add offset to index:
// 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
// 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
index += 20;
// Read address from array memory
assembly {
// 1. Add index to address of bytes array
// 2. Load 32-byte word from memory
// 3. Apply 20-byte mask to obtain address
result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
}
return result;
}
/// @dev Writes an address into a specific position in a byte array.
/// @param b Byte array to insert address into.
/// @param index Index in byte array of address.
/// @param input Address to put into byte array.
function writeAddress(bytes memory b, uint256 index, address input) internal pure {
if (b.length < index + 20) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
b.length,
index + 20 // 20 is length of address
)
);
}
// Add offset to index:
// 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
// 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
index += 20;
// Store address into array memory
assembly {
// The address occupies 20 bytes and mstore stores 32 bytes.
// First fetch the 32-byte word where we'll be storing the address, then
// apply a mask so we have only the bytes in the word that the address will not occupy.
// Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
// 1. Add index to address of bytes array
// 2. Load 32-byte word from memory
// 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
let neighbors := and(
mload(add(b, index)),
0xffffffffffffffffffffffff0000000000000000000000000000000000000000
)
// Make sure input address is clean.
// (Solidity does not guarantee this)
input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
// Store the neighbors and address into memory
mstore(add(b, index), xor(input, neighbors))
}
}
/// @dev Reads a bytes32 value from a position in a byte array.
/// @param b Byte array containing a bytes32 value.
/// @param index Index in byte array of bytes32 value.
/// @return result bytes32 value from byte array.
function readBytes32(bytes memory b, uint256 index) internal pure returns (bytes32 result) {
if (b.length < index + 32) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
b.length,
index + 32
)
);
}
// Arrays are prefixed by a 256 bit length parameter
index += 32;
// Read the bytes32 from array memory
assembly {
result := mload(add(b, index))
}
return result;
}
/// @dev Writes a bytes32 into a specific position in a byte array.
/// @param b Byte array to insert <input> into.
/// @param index Index in byte array of <input>.
/// @param input bytes32 to put into byte array.
function writeBytes32(bytes memory b, uint256 index, bytes32 input) internal pure {
if (b.length < index + 32) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
b.length,
index + 32
)
);
}
// Arrays are prefixed by a 256 bit length parameter
index += 32;
// Read the bytes32 from array memory
assembly {
mstore(add(b, index), input)
}
}
/// @dev Reads a uint256 value from a position in a byte array.
/// @param b Byte array containing a uint256 value.
/// @param index Index in byte array of uint256 value.
/// @return result uint256 value from byte array.
function readUint256(bytes memory b, uint256 index) internal pure returns (uint256 result) {
result = uint256(readBytes32(b, index));
return result;
}
/// @dev Writes a uint256 into a specific position in a byte array.
/// @param b Byte array to insert <input> into.
/// @param index Index in byte array of <input>.
/// @param input uint256 to put into byte array.
function writeUint256(bytes memory b, uint256 index, uint256 input) internal pure {
writeBytes32(b, index, bytes32(input));
}
/// @dev Reads an unpadded bytes4 value from a position in a byte array.
/// @param b Byte array containing a bytes4 value.
/// @param index Index in byte array of bytes4 value.
/// @return result bytes4 value from byte array.
function readBytes4(bytes memory b, uint256 index) internal pure returns (bytes4 result) {
if (b.length < index + 4) {
LibRichErrorsV06.rrevert(
LibBytesRichErrorsV06.InvalidByteOperationError(
LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
b.length,
index + 4
)
);
}
// Arrays are prefixed by a 32 byte length field
index += 32;
// Read the bytes4 from array memory
assembly {
result := mload(add(b, index))
// Solidity does not require us to clean the trailing bytes.
// We do it anyway
result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
}
return result;
}
/// @dev Writes a new length to a byte array.
/// Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
/// Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
/// @param b Bytes array to write new length to.
/// @param length New length of byte array.
function writeLength(bytes memory b, uint256 length) internal pure {
assembly {
mstore(b, length)
}
}
}
@FuzzysTodd
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Author

Solidity API
TestLibBytes
Contract
TestLibBytes : 0x(copy)/contracts/utils/contracts/test/TestLibBytes.sol

Functions:
publicPopLastByte
function publicPopLastByte(bytes b) public pure returns (bytes, bytes1 result)
Pops the last byte off of a byte array by modifying its length. @param b Byte array that will be modified. @return The byte that was popped off.

publicEquals
function publicEquals(bytes lhs, bytes rhs) public pure returns (bool equal)
Tests equality of two byte arrays. @param lhs First byte array to compare. @param rhs Second byte array to compare. @return True if arrays are the same. False otherwise.

publicEqualsPop1
function publicEqualsPop1(bytes lhs, bytes rhs) public pure returns (bool equal)
publicReadAddress
function publicReadAddress(bytes b, uint256 index) public pure returns (address result)
Reads an address from a position in a byte array. @param b Byte array containing an address. @param index Index in byte array of address. @return address from byte array.

publicWriteAddress
function publicWriteAddress(bytes b, uint256 index, address input) public pure returns (bytes)
Writes an address into a specific position in a byte array. @param b Byte array to insert address into. @param index Index in byte array of address. @param input Address to put into byte array.

publicReadBytes32
function publicReadBytes32(bytes b, uint256 index) public pure returns (bytes32 result)
Reads a bytes32 value from a position in a byte array. @param b Byte array containing a bytes32 value. @param index Index in byte array of bytes32 value. @return bytes32 value from byte array.

publicWriteBytes32
function publicWriteBytes32(bytes b, uint256 index, bytes32 input) public pure returns (bytes)
Writes a bytes32 into a specific position in a byte array. @param b Byte array to insert into. @param index Index in byte array of . @param input bytes32 to put into byte array.

publicReadUint256
function publicReadUint256(bytes b, uint256 index) public pure returns (uint256 result)
Reads a uint256 value from a position in a byte array. @param b Byte array containing a uint256 value. @param index Index in byte array of uint256 value. @return uint256 value from byte array.

publicWriteUint256
function publicWriteUint256(bytes b, uint256 index, uint256 input) public pure returns (bytes)
Writes a uint256 into a specific position in a byte array. @param b Byte array to insert into. @param index Index in byte array of . @param input uint256 to put into byte array.

publicReadBytes4
function publicReadBytes4(bytes b, uint256 index) public pure returns (bytes4 result)
Reads an unpadded bytes4 value from a position in a byte array. @param b Byte array containing a bytes4 value. @param index Index in byte array of bytes4 value. @return bytes4 value from byte array.

testMemcpy
function testMemcpy(bytes mem, uint256 dest, uint256 source, uint256 length) public pure returns (bytes)
Copies a block of memory from one location to another. @param mem Memory contents we want to apply memCopy to @param dest Destination offset into . @param source Source offset into . @param length Length of bytes to copy from to @return mem Memory contents after calling memCopy.

publicSlice
function publicSlice(bytes b, uint256 from, uint256 to) public pure returns (bytes result, bytes original)
Returns a slices from a byte array. @param b The byte array to take a slice from. @param from The starting index for the slice (inclusive). @param to The final index for the slice (exclusive). @return result The slice containing bytes at indices [from, to)

publicSliceDestructive
function publicSliceDestructive(bytes b, uint256 from, uint256 to) public pure returns (bytes result, bytes original)
Returns a slice from a byte array without preserving the input. @param b The byte array to take a slice from. Will be destroyed in the process. @param from The starting index for the slice (inclusive). @param to The final index for the slice (exclusive). @return result The slice containing bytes at indices [from, to) @dev When from == 0, the original array will match the slice. In other cases its state will be corrupted.

publicWriteLength
function publicWriteLength(bytes b, uint256 length, bytes extraBytes) public pure returns (bytes)
Returns a byte array with an updated length. @dev Writes a new length to a byte array. Decreasing length will lead to removing the corresponding lower order bytes from the byte array. Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array. @param b Bytes array to write new length to. @param length New length of byte array. @param extraBytes Bytes that are appended to end of b in memory.

assertBytesUnchangedAfterLengthReset
function assertBytesUnchangedAfterLengthReset(bytes b, uint256 tempLength) public pure

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