An ERC20 contract written in evm bytecode using the Huff language. It supports two function dispatchers which are explained in the following section. I tried to write the most optimal code, but I'm sure there are some areas that can still be improved.
This was originally written over one weekend as a toy project but my work took notice and I ended up revisiting and further optimising/improving. A full test suite has been added taking advantage of Foundry's fuzzing capabilities, and the contract has been formally verified using the K Framework by Nethermind and is proven to behave correctly.
There are two function dispatchers that can be used for this contract: full_dispatcher and micro_dispatcher.
The full dispatcher is compatible with the standard ERC20 function selectors allowing for easier testing and integration with other contracts. The tests rely on the full dispatcher so if tests are failing, check the MAIN macro and ensure that only the full_dispatcher accessible (the micro_dispatcher should be commented out).
The micro dispatcher is designed for maximum gas savings. Instead of passing a function signature in the first 4 bytes of calldata, you pass the jumpdest location for the desired function. This way it can immediately jump to the function and execute rather than spend gas processing a full ERC20 function signature. The jumpdests for each function are listed below. A security note for this dispatcher is that it will work for any valid jumpdest, not just where the "functions" start. This is highly experimental, use at your own risk. Note that the jumpdest locations for the micro dispatcher will depend on the constant total supply chosen. The total supply is currently 32 bytes in size, and a smaller total supply will affect the jumpdests.
You can only have one dispatcher, go to the MAIN macro and comment out the one that you don't want to use. By default the full_dispatcher is used.
| Function | Standard dispatcher sig | Micro dispatcher sig |
|---|---|---|
| totalSupply | 0x18160ddd | 0x00000006 |
| balanceOf | 0x70a08231 | 0x0000002e |
| transfer | 0xa9059cbb | 0x00000039 |
| allowance | 0xdd62ed3e | 0x00000083 |
| approve | 0x095ea7b3 | 0x00000098 |
| transferFrom | 0x23b872dd | 0x000000dc |
This project requires the huff compiler huffc to be installed. Refer to the Huff website for an installation guide.
forge install
forge test
If tests fail, check that the function dispatcher in use is full_dispatcher. The micro_dispatcher should be commented out.