ERC20 Token standard written in solidity with different transfer behavior (Work in Progress)
Uses inline assembly to save a little bit on gas.
- Transfer function can't fail
- Transfer function sets the amount to
min(_balances[msg.sender], value)- => either sends specified amount or max-balance (if amount > max-balance)
the min function uses inline assembly without using if branching:
function min(uint256 x, uint256 y) public pure returns (uint256) {
assembly {
x := xor(x,and(xor(y,x), add(not(slt(y,x)), 1)))
}
return x;
}- As the transfer function can't fail anymore for amounts exceeding the balance, it needs to be communicated properly to an end user.
- Usability/Safety for the different transfer logic can be achieved again by a specific UI rather than the underlying contract source code.
E.g., error notice or input fields which show you that the amount >= your balance results always in the max value of your account.
- Example UI can be found in the frontend folder (WIP)
forge test --match-contract gasTest --gas-report
| src/erc20.sol:ERC20 contract | | | | | |
|------------------------------|-----------------|-------|--------|-------|---------|
| Deployment Cost | Deployment Size | | | | |
| 565252 | 3635 | | | | |
| Function Name | min | avg | median | max | calls |
| balanceOf | 2544 | 2544 | 2544 | 2544 | 2 |
| standardTransfer | 23162 | 25239 | 25162 | 29962 | 36 |
| transfer | 22818 | 24895 | 24818 | 29618 | 36 |
forge test --match-contract gasTest --gas-report --optimize --optimizer-runs 3500
| src/erc20.sol:ERC20 contract | | | | | |
|------------------------------|-----------------|-------|--------|-------|---------|
| Deployment Cost | Deployment Size | | | | |
| 645134 | 4034 | | | | |
| Function Name | min | avg | median | max | calls |
| balanceOf | 2543 | 2543 | 2543 | 2543 | 2 |
| standardTransfer | 23082 | 25159 | 25082 | 29882 | 36 |
| transfer | 22750 | 24827 | 24750 | 29550 | 36 |