> ## Documentation Index
> Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# GASPRICE (0x3a)

> Get transaction gas price in wei

<Warning>
  **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.
</Warning>

## Overview

**Opcode:** `0x3a`
**Introduced:** Frontier (EVM genesis)

GASPRICE pushes the gas price of the current transaction onto the stack, measured in wei per gas unit.

## Specification

**Stack Input:**

```
[]
```

**Stack Output:**

```
gasPrice (uint256, wei per gas)
```

**Gas Cost:** 2 (GasQuickStep)

**Operation:**

```
stack.push(transaction.gasPrice)
```

## Behavior

Returns the gas price specified in the transaction. For EIP-1559 transactions, this is the effective gas price (baseFee + priorityFee).

Key characteristics:

* Same value throughout transaction
* In wei per gas unit
* For EIP-1559: min(baseFee + maxPriorityFeePerGas, maxFeePerGas)
* For legacy: transaction's gasPrice field

## Examples

### Basic Usage

```typescript theme={null}
import { gasprice } from '@tevm/voltaire/evm/context';
import { createFrame } from '@tevm/voltaire/evm/Frame';

const frame = createFrame({ stack: [] });
const txGasPrice = 20_000_000_000n; // 20 gwei

const err = gasprice(frame, txGasPrice);

console.log(frame.stack[0]); // 20000000000n
```

### Gas Refunds

```solidity theme={null}
contract GasRefunder {
    function expensiveOperation() public {
        uint256 startGas = gasleft();

        // ... expensive operations ...

        uint256 gasUsed = startGas - gasleft();
        uint256 refund = gasUsed * tx.gasprice;

        payable(msg.sender).transfer(refund);
    }
}
```

### Gas Price Oracle

```solidity theme={null}
contract GasPriceTracker {
    uint256[] public recentPrices;

    function record() public {
        recentPrices.push(tx.gasprice);
    }

    function averagePrice() public view returns (uint256) {
        uint256 sum = 0;
        for (uint i = 0; i < recentPrices.length; i++) {
            sum += recentPrices[i];
        }
        return sum / recentPrices.length;
    }
}
```

## Gas Cost

**Cost:** 2 gas (GasQuickStep)

## Common Usage

### Transaction Cost Calculation

```solidity theme={null}
function estimateCost(uint256 gasEstimate) public view returns (uint256) {
    return gasEstimate * tx.gasprice;
}
```

### Minimum Gas Price

```solidity theme={null}
modifier minGasPrice(uint256 min) {
    require(tx.gasprice >= min, "Gas price too low");
    _;
}

function urgentOperation() public minGasPrice(50 gwei) {
    // Only execute if gas price >= 50 gwei
}
```

## Security

### EIP-1559 Considerations

Post-EIP-1559, tx.gasprice is effective gas price, not maxFeePerGas:

```solidity theme={null}
// Block baseFee = 30 gwei
// maxPriorityFeePerGas = 2 gwei
// maxFeePerGas = 100 gwei
// tx.gasprice = 32 gwei (30 + 2)
```

### Gas Price Manipulation

Don't use tx.gasprice for critical logic - miners can manipulate it.

## Implementation

<Tabs>
  <Tab title="TypeScript">
    ```typescript theme={null}
    import { consumeGas } from "../Frame/consumeGas.js";
    import { pushStack } from "../Frame/pushStack.js";

    /**
     * GASPRICE opcode (0x3a) - Get transaction gas price
     *
     * Stack: [] => [gasPrice]
     * Gas: 2 (GasQuickStep)
     */
    export function gasprice(
      frame: FrameType,
      gasPrice: bigint
    ): EvmError | null {
      const gasErr = consumeGas(frame, 2n);
      if (gasErr) return gasErr;

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

      frame.pc += 1;
      return null;
    }
    ```
  </Tab>
</Tabs>

## References

* [Yellow Paper](https://ethereum.github.io/yellowpaper/paper.pdf) - Section 9.3
* [EVM Codes - GASPRICE](https://www.evm.codes/#3a)
* [EIP-1559](https://eips.ethereum.org/EIPS/eip-1559) - Fee market change