Skip to content
This repository has been archived by the owner on May 23, 2023. It is now read-only.

Commit

Permalink
Remove unused functions in BytesLib.
Browse files Browse the repository at this point in the history
  • Loading branch information
@scnale
scnale committed Feb 14, 2023
1 parent 1ce645d commit 738584a
Showing 1 changed file with 1 addition and 319 deletions.
320 changes: 1 addition & 319 deletions ethereum/contracts/libraries/external/BytesLib.sol
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,211 +4,11 @@
* @author Gonçalo Sá <[email protected]>
*
* @dev Bytes tightly packed arrays utility library for ethereum contracts written in Solidity.
* The library lets you concatenate, slice and type cast bytes arrays both in memory and storage.
* This is a reduced version of the library.
*/
pragma solidity >=0.8.0 <0.9.0;

library BytesLib {
function concat(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bytes memory) {
bytes memory tempBytes;

assembly ("memory-safe") {
// Get a location of some free memory and store it in tempBytes as
// Solidity does for memory variables.
tempBytes := mload(0x40)

// Store the length of the first bytes array at the beginning of
// the memory for tempBytes.
let length := mload(_preBytes)
mstore(tempBytes, length)

// Maintain a memory counter for the current write location in the
// temp bytes array by adding the 32 bytes for the array length to
// the starting location.
let mc := add(tempBytes, 0x20)
// Stop copying when the memory counter reaches the length of the
// first bytes array.
let end := add(mc, length)

for {
// Initialize a copy counter to the start of the _preBytes data,
// 32 bytes into its memory.
let cc := add(_preBytes, 0x20)
} lt(mc, end) {
// Increase both counters by 32 bytes each iteration.
mc := add(mc, 0x20)
cc := add(cc, 0x20)
} {
// Write the _preBytes data into the tempBytes memory 32 bytes
// at a time.
mstore(mc, mload(cc))
}

// Add the length of _postBytes to the current length of tempBytes
// and store it as the new length in the first 32 bytes of the
// tempBytes memory.
length := mload(_postBytes)
mstore(tempBytes, add(length, mload(tempBytes)))

// Move the memory counter back from a multiple of 0x20 to the
// actual end of the _preBytes data.
mc := end
// Stop copying when the memory counter reaches the new combined
// length of the arrays.
end := add(mc, length)

for { let cc := add(_postBytes, 0x20) } lt(mc, end) {
mc := add(mc, 0x20)
cc := add(cc, 0x20)
} { mstore(mc, mload(cc)) }

// Update the free-memory pointer by padding our last write location
// to 32 bytes: add 31 bytes to the end of tempBytes to move to the
// next 32 byte block, then round down to the nearest multiple of
// 32. If the sum of the length of the two arrays is zero then add
// one before rounding down to leave a blank 32 bytes (the length block with 0).
mstore(
0x40,
and(
add(add(end, iszero(add(length, mload(_preBytes)))), 31),
not(31) // Round down to the nearest 32 bytes.
)
)
}

return tempBytes;
}

function concatStorage(bytes storage _preBytes, bytes memory _postBytes) internal {
assembly ("memory-safe") {
// Read the first 32 bytes of _preBytes storage, which is the length
// of the array. (We don't need to use the offset into the slot
// because arrays use the entire slot.)
let fslot := sload(_preBytes.slot)
// Arrays of 31 bytes or less have an even value in their slot,
// while longer arrays have an odd value. The actual length is
// the slot divided by two for odd values, and the lowest order
// byte divided by two for even values.
// If the slot is even, bitwise and the slot with 255 and divide by
// two to get the length. If the slot is odd, bitwise and the slot
// with -1 and divide by two.
let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
let mlength := mload(_postBytes)
let newlength := add(slength, mlength)
// slength can contain both the length and contents of the array
// if length < 32 bytes so let's prepare for that
// v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
switch add(lt(slength, 32), lt(newlength, 32))
case 2 {
// Since the new array still fits in the slot, we just need to
// update the contents of the slot.
// uint256(bytes_storage) = uint256(bytes_storage) + uint256(bytes_memory) + new_length
sstore(
_preBytes.slot,
// all the modifications to the slot are inside this
// next block
add(
// we can just add to the slot contents because the
// bytes we want to change are the LSBs
fslot,
add(
mul(
div(
// load the bytes from memory
mload(add(_postBytes, 0x20)),
// zero all bytes to the right
exp(0x100, sub(32, mlength))
),
// and now shift left the number of bytes to
// leave space for the length in the slot
exp(0x100, sub(32, newlength))
),
// increase length by the double of the memory
// bytes length
mul(mlength, 2)
)
)
)
}
case 1 {
// The stored value fits in the slot, but the combined value
// will exceed it.
// get the keccak hash to get the contents of the array
mstore(0x0, _preBytes.slot)
let sc := add(keccak256(0x0, 0x20), div(slength, 32))

// save new length
sstore(_preBytes.slot, add(mul(newlength, 2), 1))

// The contents of the _postBytes array start 32 bytes into
// the structure. Our first read should obtain the `submod`
// bytes that can fit into the unused space in the last word
// of the stored array. To get this, we read 32 bytes starting
// from `submod`, so the data we read overlaps with the array
// contents by `submod` bytes. Masking the lowest-order
// `submod` bytes allows us to add that value directly to the
// stored value.

let submod := sub(32, slength)
let mc := add(_postBytes, submod)
let end := add(_postBytes, mlength)
let mask := sub(exp(0x100, submod), 1)

sstore(
sc,
add(
and(fslot, 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00),
and(mload(mc), mask)
)
)

for {
mc := add(mc, 0x20)
sc := add(sc, 1)
} lt(mc, end) {
sc := add(sc, 1)
mc := add(mc, 0x20)
} { sstore(sc, mload(mc)) }

mask := exp(0x100, sub(mc, end))

sstore(sc, mul(div(mload(mc), mask), mask))
}
default {
// get the keccak hash to get the contents of the array
mstore(0x0, _preBytes.slot)
// Start copying to the last used word of the stored array.
let sc := add(keccak256(0x0, 0x20), div(slength, 32))

// save new length
sstore(_preBytes.slot, add(mul(newlength, 2), 1))

// Copy over the first `submod` bytes of the new data as in
// case 1 above.
let slengthmod := mod(slength, 32)
let mlengthmod := mod(mlength, 32)
let submod := sub(32, slengthmod)
let mc := add(_postBytes, submod)
let end := add(_postBytes, mlength)
let mask := sub(exp(0x100, submod), 1)

sstore(sc, add(sload(sc), and(mload(mc), mask)))

for {
sc := add(sc, 1)
mc := add(mc, 0x20)
} lt(mc, end) {
sc := add(sc, 1)
mc := add(mc, 0x20)
} { sstore(sc, mload(mc)) }

mask := exp(0x100, sub(mc, end))

sstore(sc, mul(div(mload(mc), mask), mask))
}
}
}

function slice(bytes memory _bytes, uint256 _start, uint256 _length) internal pure returns (bytes memory) {
require(_length + 31 >= _length, "slice_overflow");
require(_bytes.length >= _start + _length, "slice_outOfBounds");
Expand Down Expand Up @@ -323,17 +123,6 @@ library BytesLib {
return tempUint;
}

function toUint96(bytes memory _bytes, uint256 _start) internal pure returns (uint96) {
require(_bytes.length >= _start + 12, "toUint96_outOfBounds");
uint96 tempUint;

assembly ("memory-safe") {
tempUint := mload(add(add(_bytes, 0xc), _start))
}

return tempUint;
}

function toUint128(bytes memory _bytes, uint256 _start) internal pure returns (uint128) {
require(_bytes.length >= _start + 16, "toUint128_outOfBounds");
uint128 tempUint;
Expand Down Expand Up @@ -366,111 +155,4 @@ library BytesLib {

return tempBytes32;
}

function equal(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bool) {
bool success = true;

assembly ("memory-safe") {
let length := mload(_preBytes)

// if lengths don't match the arrays are not equal
switch eq(length, mload(_postBytes))
case 1 {
// cb is a circuit breaker in the for loop since there's
// no said feature for inline assembly loops
// cb = 1 - don't breaker
// cb = 0 - break
let cb := 1

let mc := add(_preBytes, 0x20)
let end := add(mc, length)

for { let cc := add(_postBytes, 0x20) }
// the next line is the loop condition:
// while(uint256(mc < end) + cb == 2)
eq(add(lt(mc, end), cb), 2) {
mc := add(mc, 0x20)
cc := add(cc, 0x20)
} {
// if any of these checks fails then arrays are not equal
if iszero(eq(mload(mc), mload(cc))) {
// unsuccess:
success := 0
cb := 0
}
}
}
default {
// unsuccess:
success := 0
}
}

return success;
}

function equalStorage(bytes storage _preBytes, bytes memory _postBytes) internal view returns (bool) {
bool success = true;

assembly ("memory-safe") {
// we know _preBytes_offset is 0
let fslot := sload(_preBytes.slot)
// Decode the length of the stored array like in concatStorage().
let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
let mlength := mload(_postBytes)

// if lengths don't match the arrays are not equal
switch eq(slength, mlength)
case 1 {
// slength can contain both the length and contents of the array
// if length < 32 bytes so let's prepare for that
// v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
if iszero(iszero(slength)) {
switch lt(slength, 32)
case 1 {
// blank the last byte which is the length
fslot := mul(div(fslot, 0x100), 0x100)

if iszero(eq(fslot, mload(add(_postBytes, 0x20)))) {
// unsuccess:
success := 0
}
}
default {
// cb is a circuit breaker in the for loop since there's
// no said feature for inline assembly loops
// cb = 1 - don't breaker
// cb = 0 - break
let cb := 1

// get the keccak hash to get the contents of the array
mstore(0x0, _preBytes.slot)
let sc := keccak256(0x0, 0x20)

let mc := add(_postBytes, 0x20)
let end := add(mc, mlength)

// the next line is the loop condition:
// while(uint256(mc < end) + cb == 2)
for {} eq(add(lt(mc, end), cb), 2) {
sc := add(sc, 1)
mc := add(mc, 0x20)
} {
if iszero(eq(sload(sc), mload(mc))) {
// unsuccess:
success := 0
cb := 0
}
}
}
}
}
default {
// unsuccess:
success := 0
}
}

return success;
}
}

0 comments on commit 738584a

Please sign in to comment.