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https://github.com/mohanson/evm
This is a guide to understanding the EVM
https://github.com/mohanson/evm
Last synced: about 2 months ago
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This is a guide to understanding the EVM
- Host: GitHub
- URL: https://github.com/mohanson/evm
- Owner: mohanson
- Created: 2018-11-29T14:02:49.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2023-05-06T03:50:45.000Z (over 1 year ago)
- Last Synced: 2024-06-20T10:19:07.952Z (6 months ago)
- Language: Go
- Homepage:
- Size: 45.9 KB
- Stars: 4
- Watchers: 3
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# EVM
Inspired by , though `evm` has been modified to support persistence.
# Installation
```sh
$ go get github.com/mohanson/evm/cmd/evm
```
# Feat: disassemble bytecode
Here is some very simple bytecode I wrote:
```text
0x6005600401
```
To disassemble, run `evm disasm -code 0x6005600401`, which produces:
```text
[0000] PUSH1 0x05
[0002] PUSH1 0x04
[0004] ADD
```
# Feat: execute bytecode
Let's use a test case to demonstrate: [return0.json](https://github.com/ethereum/tests/blob/develop/VMTests/vmSystemOperations/return0.json). To execute the test, run
```sh
$ evm exec -code 0x603760005360005160005560016000f3
```
```text
[Many Outputs]
...
Return = 0x37
```
# Feat: execute solidity
Let us begin with the most basic example. It is fine if you do not understand everything right now, we will go into more detail later. Create a file named "SimpleStorage.sol" with content:
```text
pragma solidity ^0.4.24;
contract SimpleStorage {
uint storedData;
function set(uint x) public {
storedData = x;
}
function get() view public returns (uint) {
return storedData;
}
}
```
Use `solc` to compile it to bytecode:
```sh
$ solc --bin SimpleStorage.sol
# The output bytecode. I will use the $BYTECODE to instead of the original text.
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
```
```sh
# create it at /tmp/db.json.
$ evm create -db /tmp/db.json
-data $BYTECODE
Cost = 55307
Address = 0xBd770416a3345F91E4B34576cb804a576fa48EB1
# let's call SimpleStorage.set(42)
$ evm call -db /tmp/db.json
-address 0xBd770416a3345F91E4B34576cb804a576fa48EB1
-data 0x60fe47b1000000000000000000000000000000000000000000000000000000000000002a
# let's call SimpleStorage.get()
$ evm call -db /tmp/db.json
-address 0xBd770416a3345F91E4B34576cb804a576fa48EB1
-data 0x6d4ce63c
Cost = 424
Return = 000000000000000000000000000000000000000000000000000000000000002a
```
Perfect!
---
Note: data `0x60fe47b1000000000000000000000000000000000000000000000000000000000000002a` = `0x60fe47b1` + `0x2a`, where `60fe47b1` provided by `python -c "import eth_utils; print(eth_utils.keccak(b'set(uint256)')[0:4].hex())"`.