CODECOPY (0x39)

Copy executing code to memory

This page is a placeholder. All examples on this page are currently AI-generated and are not correct. This documentation will be completed in the future with accurate, tested examples.

Overview

Opcode: 0x39 Introduced: Frontier (EVM genesis)

CODECOPY copies a specified range of the currently executing code to memory.

Specification

Stack Input:

destOffset (memory offset)
offset (code offset)
length (bytes to copy)

Stack Output:

[]

Gas Cost: 3 + memory expansion + (length / 32) * 3 (rounded up)

Behavior

Copies length bytes from executing code at offset to memory at destOffset. Zero-pads if code bounds exceeded.

Examples

Copy Runtime Code

function getRuntimeCode() public pure returns (bytes memory code) {
    assembly {
        let size := codesize()
        code := mload(0x40)
        mstore(code, size)
        codecopy(add(code, 0x20), 0, size)
        mstore(0x40, add(add(code, 0x20), size))
    }
}

CREATE2 Factory

function deploy() public returns (address) {
    bytes memory code;
    assembly {
        let size := codesize()
        code := mload(0x40)
        codecopy(add(code, 0x20), 0, size)
    }
    // Use code for CREATE2
}

Gas Cost

Base: 3 gas Memory expansion: Variable Copy cost: 3 gas per 32-byte word

Implementation

TypeScript

export function codecopy(frame: FrameType): EvmError | null {
  // Pop destOffset, offset, length
  // Calculate gas (base + memory + copy cost)
  // Copy bytecode to memory
  // See full implementation in codebase

  frame.pc += 1;
  return null;
}

References

• Yellow Paper - Section 9.1
• EVM Codes - CODECOPY