Intro to lower lavel bytecode

The exercise is to develop the same contract in Solidity, Yul and Huff, plus some inline assembly. This is a great intro to lower level langs which helps to get a clear undestanding of EVM behaviour especially when it comes down to stack, storage, memory and how they interact via stack syntax.

Tools:

These are tools which I found very usefull:

• Scripts:
• Get the Function Signature: cast sig "isHappyHorse(uint256)"
• Conversion Hex to Dex and viceversa: cast to-base 0x15180 dec
• Foundry chisel: REPL
• Test debug: forge test --debug
• huffmate: import Hashmap.huff / CommonErrors.huff

Horse Store V1

1. write basic simplestorage/horsestore

Process

1. I send the data
2. Dispacher selects the function
3. Dispacher sends the data to the funciton

Tests

Set-up:

1. Huff Foundry Extension - Fundry-Huff- to be installed:

$ forge install huff-language/foundry-huff --no-commit

2. Foundry.toml to be updated:

$ ffi = true
$ remappings = [
    'foundry-huff=lib/foundry-huff/src',
    '@openzeppelin/=lib/openzeppelin-contracts/',
]

This will allow to use/import the {HuffDeplo}

Crating tests and running them:

Wrote the following files:

1. Base_TestV1.t.sol: abstract contract that contains all the tests Two test functions:

$ function testReadValue() public {}

$ function testWriteValue() public {}

2. HorseStoreSolc.t.sol: contract is Base_TestV1, used to test solidity contracts
3. HorseStoreHuff.t.sol: contract is Base_TestV1, used to test huff contracts

To run the tests you can simply:

$ forge test

Or if you want to check Huff test only:

$ forge test --match-path *Huff* -vvv

With debag you can check the steps on each Opcode -

$ forge test --match-path *Huff* --debug testReadValue -vvv

Huff

Give us the contract deployment

Yul

We have inline assembly yul where we use yul in solidity,and we have stand alone Yul where we only ise Yul. Install extension: Solidity + Yul Semantic Syntax Yul has not contracts but objects We need to write our contract deployment

Horse Store V2

In version 2, HorseStore is a ERC721 contract so there are few considerations:

• ERC721 Interface Functions need to be declared:

$ '#'define function Transfer(address, uint256) nonpayable returns()

• ERC721 Interfaces Events need to declared

• Storage Slots to be delared as constants

• Immutable offsets also to be declared as constans

• Chisel: Fast, utilitarian, and verbose

Documentation

$ forge build

Test

$ forge test