NoBey/uniswap-v2
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gas golf swap

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This commit is contained in:
Noah Zinsmeister
2020-01-06 13:02:55 -05:00
parent 3d2493ef2c
commit 21618d4106
1 changed files with 21 additions and 17 deletions
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38
contracts/UniswapV2.sol
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@ -52,14 +52,14 @@ contract UniswapV2 is IUniswapV2, ERC20("Uniswap V2", "UNI-V2", 18, 0) {
}
// update reserves + block number and, if necessary, increment price accumulators
function _update(uint balance0, uint balance1) private {
function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
require(balance0 <= uint112(-1) && balance1 <= uint112(-1), "UniswapV2: BALANCE_OVERFLOW");
uint32 blockNumber = uint32(block.number % 2**32);
uint32 blocksElapsed = blockNumber - blockNumberLast; // overflow is desired
if (blocksElapsed > 0 && reserve0 != 0 && reserve1 != 0) {
if (blocksElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
// * never overflows, and + overflow is desired
price0CumulativeLast += uint(UQ112x112.encode(reserve1).qdiv(reserve0)) * blocksElapsed;
price1CumulativeLast += uint(UQ112x112.encode(reserve0).qdiv(reserve1)) * blocksElapsed;
price0CumulativeLast += uint(UQ112x112.encode(_reserve1).qdiv(_reserve0)) * blocksElapsed;
price1CumulativeLast += uint(UQ112x112.encode(_reserve0).qdiv(_reserve1)) * blocksElapsed;
}
// ↓↓↓↓ single SSTORE ↓↓↓↓
reserve0 = uint112(balance0);
@ -87,19 +87,21 @@ contract UniswapV2 is IUniswapV2, ERC20("Uniswap V2", "UNI-V2", 18, 0) {
}
function mint(address to) external lock returns (uint liquidity) {
uint112 _reserve0 = reserve0; // for gas savings
uint112 _reserve1 = reserve1; // for gas savings
uint balance0 = IERC20(token0).balanceOf(address(this));
uint balance1 = IERC20(token1).balanceOf(address(this));
uint amount0 = balance0.sub(reserve0);
uint amount1 = balance1.sub(reserve1);
uint amount0 = balance0.sub(_reserve0);
uint amount1 = balance1.sub(_reserve1);
_mintFee(balance0, balance1);
liquidity = totalSupply == 0 ?
Math.sqrt(amount0.mul(amount1)) :
Math.min(amount0.mul(totalSupply) / reserve0, amount1.mul(totalSupply) / reserve1);
Math.min(amount0.mul(totalSupply) / _reserve0, amount1.mul(totalSupply) / _reserve1);
require(liquidity > 0, "UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED");
_mint(to, liquidity);
_update(balance0, balance1);
_update(balance0, balance1, _reserve0, _reserve1);
emit Mint(msg.sender, amount0, amount1);
}
@ -119,33 +121,35 @@ contract UniswapV2 is IUniswapV2, ERC20("Uniswap V2", "UNI-V2", 18, 0) {
balance1 = IERC20(token1).balanceOf(address(this));
_burn(address(this), liquidity);
_update(balance0, balance1);
_update(balance0, balance1, reserve0, reserve1);
emit Burn(msg.sender, amount0, amount1, to);
}
function swap(address tokenIn, uint amountOut, address to) external lock {
uint112 _reserve0 = reserve0; // for gas savings
uint112 _reserve1 = reserve1; // for gas savings
uint balance0; uint balance1; uint amountIn;
if (tokenIn == token0) {
require(0 < amountOut && amountOut < reserve1, "UniswapV2: INVALID_OUTPUT_AMOUNT");
require(0 < amountOut && amountOut < _reserve1, "UniswapV2: INVALID_OUTPUT_AMOUNT");
balance0 = IERC20(token0).balanceOf(address(this));
amountIn = balance0.sub(reserve0);
amountIn = balance0.sub(_reserve0);
require(amountIn > 0, "UniswapV2: INSUFFICIENT_INPUT_AMOUNT");
require(amountIn.mul(reserve1 - amountOut).mul(997) >= amountOut.mul(reserve0).mul(1000), "UniswapV2: K");
require(amountIn.mul(_reserve1 - amountOut).mul(997) >= amountOut.mul(_reserve0).mul(1000), "UniswapV2: K");
_safeTransfer(token1, to, amountOut);
balance1 = IERC20(token1).balanceOf(address(this));
} else {
require(tokenIn == token1, "UniswapV2: INVALID_INPUT_TOKEN");
require(0 < amountOut && amountOut < reserve0, "UniswapV2: INVALID_OUTPUT_AMOUNT");
require(0 < amountOut && amountOut < _reserve0, "UniswapV2: INVALID_OUTPUT_AMOUNT");
balance1 = IERC20(token1).balanceOf(address(this));
amountIn = balance1.sub(reserve1);
amountIn = balance1.sub(_reserve1);
require(amountIn > 0, "UniswapV2: INSUFFICIENT_INPUT_AMOUNT");
require(amountIn.mul(reserve0 - amountOut).mul(997) >= amountOut.mul(reserve1).mul(1000), "UniswapV2: K");
require(amountIn.mul(_reserve0 - amountOut).mul(997) >= amountOut.mul(_reserve1).mul(1000), "UniswapV2: K");
_safeTransfer(token0, to, amountOut);
balance0 = IERC20(token0).balanceOf(address(this));
}
_update(balance0, balance1);
_update(balance0, balance1, _reserve0, _reserve1);
emit Swap(msg.sender, tokenIn, amountIn, amountOut, to);
}
@ -157,6 +161,6 @@ contract UniswapV2 is IUniswapV2, ERC20("Uniswap V2", "UNI-V2", 18, 0) {
// force reserves to match balances
function sync() external lock {
_update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)));
_update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
}
}