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Overview

Opcode: 0x7D Introduced: Frontier (EVM genesis) PUSH30 pushes a 30-byte immediate value from the bytecode onto the stack. The 30 bytes immediately following the opcode are read and zero-padded to 256 bits.

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Specification

Stack Input: 
[]
Stack Output: 
value (uint256, 30 bytes from bytecode)
Gas Cost: 3 (GasFastestStep) Bytecode: 1 byte opcode + 30 bytes immediate data Operation: 
value = read_bytes(pc + 1, 30)  // Big-endian
stack.push(value)
pc += 31

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Behavior

PUSH30 reads 30 bytes from bytecode starting at position pc + 1, interprets them as a big-endian unsigned integer, and pushes the result onto the stack. Key characteristics:
  • Reads exactly 30 bytes following opcode
  • Big-endian byte order (most significant byte first)
  • Zero-padded to 256 bits if less than 32 bytes
  • InvalidOpcode if insufficient bytecode remaining
  • PC advances by 31 (opcode + data)

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Examples

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Basic Usage

import { handler_0x7D_PUSH30 } from '@tevm/voltaire/evm/stack/handlers';
import { createFrame } from '@tevm/voltaire/evm/Frame';

// Bytecode with PUSH30
const bytecode = new Uint8Array([
  0x7D,  // PUSH30
  0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e   // 30 bytes: 0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e
]);

const frame = createFrame({
  bytecode,
  pc: 0,
  stack: [],
  gasRemaining: 1000n
});

const err = handler_0x7D_PUSH30(frame);

console.log(frame.stack); // [0x0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e0000n]
console.log(frame.pc); // 31
console.log(frame.gasRemaining); // 997n (3 gas consumed)

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Solidity Compilation

contract Example {
    // 30-byte constant
    uint240 constant VALUE = 1.7668470647783843e+72;
    // PUSH30 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
}

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Assembly Usage

assembly {
    // Push 30-byte value
    push30 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
    
}

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Gas Cost

Cost: 3 gas (GasFastestStep) All PUSH1-32 instructions cost the same despite different data sizes. Bytecode size impact:
  • PUSH30: 31 bytes (1 opcode + 30 data)
  • PUSH32: 33 bytes (1 opcode + 32 data)
Comparison:
OpcodeGasBytesUse Case
PUSH021Zero constant (Shanghai+)
PUSH132Small numbers (0-255)

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Common Usage

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30-Byte Constants

assembly {
    // 30-byte literal
    push30 0xabababababababababababababababababababababababababababababab
}

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Big-Endian Encoding

// Bytecode: PUSH30 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e
// Reads as: 0x0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e

// Most significant byte first
// Byte 0: 0x01 (highest significance)
// Byte 29: 0x1e (lowest significance)

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Implementation

/**
 * Read immediate data from bytecode for PUSH operations
 */
function readImmediate(bytecode: Uint8Array, pc: number, size: number): bigint | null {
  if (pc + 1 + size > bytecode.length) {
    return null;
  }

  let result = 0n;
  for (let i = 0; i < size; i++) {
    result = (result << 8n) | BigInt(bytecode[pc + 1 + i]);
  }
  return result;
}

/**
 * PUSH30 opcode (0x7D) - Push 30 bytes onto stack
 *
 * Stack: [] => [value]
 * Gas: 3 (GasFastestStep)
 */
export function handler_0x7D_PUSH30(frame: FrameType): EvmError | null {
  const gasErr = consumeGas(frame, FastestStep);
  if (gasErr) return gasErr;

  const value = readImmediate(frame.bytecode, frame.pc, 30);
  if (value === null) {
    return { type: "InvalidOpcode" };
  }

  const pushErr = pushStack(frame, value);
  if (pushErr) return pushErr;

  frame.pc += 31;
  return null;
}

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Edge Cases

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Insufficient Bytecode

// Bytecode ends before 30 bytes read
const bytecode = new Uint8Array([0x7D, 0x01]); // Only 1 byte instead of 30
const frame = createFrame({ bytecode, pc: 0 });

const err = handler_0x7D_PUSH30(frame);
console.log(err); // { type: "InvalidOpcode" }

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Stack Overflow

// Stack at maximum capacity
const frame = createFrame({
  stack: new Array(1024).fill(0n),
  bytecode: new Uint8Array([0x7D, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00])
});

const err = handler_0x7D_PUSH30(frame);
console.log(err); // { type: "StackOverflow" }

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Out of Gas

// Insufficient gas
const frame = createFrame({
  gasRemaining: 2n,  // Need 3 gas
  bytecode: new Uint8Array([0x7D, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff])
});

const err = handler_0x7D_PUSH30(frame);
console.log(err); // { type: "OutOfGas" }

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Maximum Value

// All bytes 0xFF
const bytecode = new Uint8Array([0x7D, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]);
const frame = createFrame({ bytecode, pc: 0 });

handler_0x7D_PUSH30(frame);
console.log(frame.stack[0]); // 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff0000n

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References