> ## 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.

# dupPosition()

> Get stack position duplicated by DUP opcode

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  Run Opcode examples in the interactive playground
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## Opcode.dupPosition()

Get stack position duplicated by DUP opcode (1-16).

<Tabs>
  <Tab title="Functional API">
    ```typescript theme={null}
    import { dupPosition, DUP1, DUP16 } from 'tevm/Opcode'

    dupPosition(DUP1)   // 1
    dupPosition(DUP16)  // 16
    ```
  </Tab>
</Tabs>

## Parameters

* `opcode: BrandedOpcode` - Opcode to check

## Returns

`number | undefined` - Position (1-16) or undefined if not DUP

## Stack Semantics

```
DUP1:  [..., a] → [..., a, a]           (duplicate top)
DUP2:  [..., b, a] → [..., b, a, b]     (duplicate 2nd)
DUP16: [..., p, ..., a] → [..., p, ..., a, p]  (duplicate 16th)
```

## Related

* [isDup()](/primitives/opcode/is-dup) - Check if DUP opcode