• Read _value state variable from storage
• Return the read v

pragma solidity ^0.8.7;

contract Box {
    uint256 private _value;

    event NewValue(uint256 newValue);

    function store(uint256 newValue) public {
        _value = newValue;
        emit NewValue(newValue);
    }

    function retrieve() public view returns (uint256) {
        return _value;
    }
}

Compiled from Solidity to Bytecode.

//bytecode exampl
**608060405234801561**001....36f6c63430008070033

These tiny instructions are called opcodes.

it is nothing but a list of tiny, 1 byte(the number represented in hex decimal so 2hex = 1byte), instructions appended together.

EVM understands/interprets these opcodes during the execution of any operation in the contract.

60 (1 byte), which is code for opcode PUSH1

これはよく0x60とかで表されるけど0x > hexを表すからこうなる！

These opcodes comprise of "EVM dialect".

Solidity < Yul (assembly) < bytecode (opcodes)

Let’s Assembly!

    function retrieve() public view returns (uint256) {
        return _value;
    }

assembly {
    let v := sload(0) // **read** from slot #0
    mstore(0x80, v) 
		// store v at position 0x80 in memory
		// **move call-stack to memory**
    return(0x80, **32**) // v is **32** bytes (uint256)
	 // return({memory position},{size})
		// returnがmemory領域しか返却できないのでmstoreが重要
}