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SYNOPSIS

NPM Package Build Status Coverage Status Gitter or #ethereumjs on freenode

js-standard-style

Implements Ethereum's VM in Javascript.

Fork Support

The VM (v2.6.x release series) currently supports the following hardforks (default: Byzantium):

  • Byzantium
  • Constantinople
  • Petersburg

Parallel HF support was introduced in the v2.5.0 release, if you want some background have a look at the respective release notes.

If you are still looking for a Spurious Dragon compatible version of this library install the latest of the 2.2.x series (see Changelog).

INSTALL

npm install ethereumjs-vm

USAGE

var VM = require('ethereumjs-vm')

//create a new VM instance
var vm = new VM()
var code = '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'

vm.runCode({
  code: Buffer.from(code, 'hex'), // code needs to be a Buffer
  gasLimit: Buffer.from('ffffffff', 'hex')
}, function(err, results){
  console.log('returned: ' + results.return.toString('hex'));
})

Also more examples can be found here

BROWSER

To build for standalone use in the browser, install browserify and check run-transactions-simple example. This will give you a global variable EthVM to use. The generated file will be at ./examples/run-transactions-simple/build.js.

API

VM

For documentation on VM instantiation, exposed API and emitted events see generated API docs.

StateManger

The API for the StateManager is currently in Beta, separate documentation can be found here.

The StateManager API has been largely reworked recently and the StateManager will be removed from the VM and provided as a separate package in a future v3.0.0 release, see release notes for the v2.5.0 VM release for further details.

Internal Structure

The VM processes state changes at many levels.

  • runBlockchain
    • for every block, runBlock
  • runBlock
    • for every tx, runTx
    • pay miner and uncles
  • runTx
    • check sender balance
    • check sender nonce
    • runCall
    • transfer gas charges
  • runCall
    • checkpoint state
    • transfer value
    • load code
    • runCode
    • materialize created contracts
    • revert or commit checkpoint
  • runCode
    • iterate over code
    • run op codes
    • track gas usage
  • OpFns
    • run individual op code
    • modify stack
    • modify memory
    • calculate fee

The opFns for CREATE, CALL, and CALLCODE call back up to runCall.

DEVELOPMENT

Developer documentation - currently mainly with information on testing and debugging - can be found here.

LICENSE

MPL-2.0