chainvm

A simple stack-based VM for executing smart contract bytecode, written in Rust.

Bytecode

Bytecode is just a sequence of numbers (bytes) that represent instructions.

Our VM reads these numbers and executes them:

Bytecode: [0x01, 0x0A, 0x01, 0x14, 0x02, 0x00]

Means:
  0x01 0x0A  →  PUSH 10 (Note: 0x0A = 10 in Hexadecimal)
  0x01 0x14  →  PUSH 20 (Note: 0x14 = 20 in Hexadecimal)
  0x02       →  POP
  0x00       →  HALT

Execution trace:

Step 1: PUSH 10     Stack: [10]
Step 2: PUSH 20     Stack: [10, 20]
Step 3: POP         Stack: [10]           (removed 20 from top)
Step 4: HALT        Stack: [10]           (program halts)

Result: 10

Instructions

Our VM supports three simple stack operations:

Opcode	Byte	Arguments	Description
HALT	0x00	none	Stop or halt the execution
PUSH	0x01	1 byte	Push a number (0-255) onto the stack
POP	0x02	none	Remove the top number from the stack
ADD	0x03	none	Adds the top two numbers from the stack
SUB	0x04	none	Subtracts the top two numbers from the stack
MUL	0x05	none	Multiplies the top two numbers from the stack
DIV	0x06	none	Divides the top two numbers from the stack
MSTORE	0x20	none	Pop offset and value from stack. Write value to memory at offset.
MLOAD	0x21	none	Pop offset from stack. Read value from memory at offset and push to stack.

License

^{Licensed under Apache License, Version 2.0 or MIT License at your discretion.}

Contribution

^{Contributions to this crate will be dual-licensed under Apache-2.0 and MIT by default, unless specifically indicated otherwise.}