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How to add new functionality to VM

While Pravda is under heavy development we can feel ourselves free to add new opcodes and functions to VM. However it doesn't mean that individual developer can do this by their own decision. Addition of every new opcode should be rationale and should be discussed with colleagues in the chat or in the Github issue. When team agree on addition of the new opcode you can use this guide to implement it in the code.

Do not forget to generate docs!


  1. Add opcode to pravda.vm.Opcodes in vm-api module. Select a section carefully. Use hex number next to last opcode in the section.
  2. Add implementation of the opcode to the module from pravda.vm.operations package that corresponds to the selected section. Do not forget to add documentation for the method.
  3. Add appropriate pattern-match branch to pravda.vm.impl.VmImpl.
  4. Add mnemonic declaration to pravda.vm.asm.Operation orphans. If opcode is complex (takes arguments, for example) take a look to pravda.vm.asm.PravdaAssembler.
  5. Write few test cases in /vm/src/test/resources

Standard Library

  1. Add implementation to pravda.vm.std in vm module. For id use hex number next to last added standard library function.
  2. Add reference to pravda.vm.StandardLibrary object.
  3. Write few test cases in /vm/src/test/resources