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  PEPE: 4
  Title: Virtual Machine
  Author: Sérgio Flores <[email protected]>
  Type: Meta
  Status: Active
  Created: 2018-10-2

Table of Contents

Abstract

This PEPE specifies the inner workings of the Phantasma Virtual Machine (PVM).

Motivation

The Phantasma blockchain should have enough flexibility to let developers embed any type of programmability into a transaction. By allowing each transaction to include a small script, which is then executed by the PVM, this goal can be achieved.

Specification

The PVM is a register based virtual machine that executes custom opcodes designed for Phantasma.

Rationale

The are obvious advantages to using a specialized virtual machine to approach the goal of programable transactions. Other alternatives could encompass mainstream virtual machines like JVM or WVM, however the complexity of abstracting a general purpose virtual machine to the context of blockchain transactions bring complex problems.

Opcode List

All PEPEs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The PEPE must explain how the author proposes to deal with these incompatibilities. PEPE submissions without a sufficient backwards compatibility treatise may be rejected outright.

Name Binary 
 Description
NOP 0 Does nothing.
MOVE 1 Copies a register to another, by reference.
COPY 2 Copies a register to another, by value.
LOAD 3 Loads a binary value into a register.
PUSH 4 Pushes a register into the VM stack.
POP 5 Pops a value from the VM stack into a register.
SWAP 6 Swaps the values of two registers.
CALL 7 Calls a function by jumping to it.
EXTCALL 8 Calls an external function registered in the VM.
JMP 9 Jumps to a specific instruction.
JMPIF 10 Jumps to a specific instruction, conditional.
JMPNOT 11 Jumps to a specific instruction, conditional.
RET 12 Jumps back to the function callee.
THROW 12 Aborts execution.
CAT 13 Concatenates two registers and places the result into another.
SUBSTR 14 Copies a part of a register into another.
LEFT 15 Copies a part of a register into another.
RIGHT 16 Copies a part of a register into another.
NOT 17 Logical operator.
AND 18 Logical operator.
OR 19 Logical operator.
XOR 20 Logical operator.
EQUAL 21 Logical operator.
LT 22 Logical operator.
GT 23 Logical operator.
LTE 24 Logical operator.
GTE 25 Logical operator.
INC 26 Increments a register.
DEC 27 Decrements a register.
SIGN 28 Copies the sign of a register into another.
NEGATE 29 Negates the sign of a register.
ABS 30 Absolute value of a register.
ADD 31 Adds two registers, result it put into another.
SUB 32 Subtracts two registers, result it put into another.
MUL 33 Multiples two registers, result it put into another.
DIV 34 Divides two registers, result it put into another.
MOD 35 Modulus two registers, result it put into another.
SHL 36 Shift lefts a register.
SHR 36 Shift right a register.
MIN 37 Selects the minimum value of two registers and put the result into another register.
MAX 38 Selects the maximum value of two registers and put the result into another register.
THIS 39 Puts the active context into a register.
CTX 40 Puts a registered context into a register.
SWITCH 41 Switches the current context.
PUT 42 Sets the field of a struct.
GET 43 Gets the field of a struct.

TODO explain contexts, stack, register sets, etc