# `EEVM.Gas.Static`
[🔗](https://github.com/mw2000/eevm/blob/v0.1.0/lib/eevm/gas/static.ex#L1)

Static gas costs for each EVM opcode.

Every opcode has a fixed ("static") gas cost that is charged before execution,
independent of the operand values. These costs come from the Ethereum Yellow Paper
(Appendix G) and subsequent EIPs.

## Gas Tiers (Yellow Paper, Appendix G)

| Tier       | Cost | Opcodes |
|------------|------|---------|
| Zero       | 0    | STOP, RETURN, REVERT |
| Base       | 2    | ADDRESS, ORIGIN, CALLER, CALLVALUE, CALLDATASIZE, CODESIZE, GASPRICE, COINBASE, TIMESTAMP, NUMBER, PREVRANDAO, GASLIMIT, CHAINID, BASEFEE, POP, PC, MSIZE, PUSH0 |
| Very Low   | 3    | ADD, SUB, NOT, LT, GT, SLT, SGT, EQ, ISZERO, AND, OR, XOR, BYTE, SHL, SHR, SAR, CALLDATALOAD, MLOAD, MSTORE, MSTORE8, PUSH1–PUSH32, DUP1–DUP16, SWAP1–SWAP16 |
| Low        | 5    | MUL, DIV, SDIV, MOD, SMOD, SIGNEXTEND, CLZ |
| Mid        | 8    | ADDMOD, MULMOD, JUMP |
| High       | 10   | JUMPI |

Some opcodes have a static cost of 0 because their full cost is computed dynamically
(e.g., BALANCE, EXTCODESIZE, SLOAD, SSTORE use EIP-2929 access costs instead).

## Pre-Berlin schedule

`static_cost/1` is the Berlin-onward schedule. Before EIP-2929, the
state-access opcodes carried flat static prices instead, which
`static_cost/2` applies by hardfork:

| Opcode | Frontier | EIP-150 (Tangerine Whistle) | EIP-1884 (Istanbul) |
|--------|----------|-----------------------------|---------------------|
| BALANCE | 20 | 400 | 700 |
| EXTCODESIZE, EXTCODECOPY | 20 | 700 | 700 |
| EXTCODEHASH | — | 400 (EIP-1052) | 700 |
| SLOAD | 50 | 200 | 800 |
| CALL, CALLCODE, DELEGATECALL, STATICCALL | 40 | 700 | 700 |
| SELFDESTRUCT | 0 | 5000 | 5000 |

## References

- [Ethereum Yellow Paper, Appendix G](https://ethereum.github.io/yellowpaper/paper.pdf)
- [EIP-150: Gas cost changes for IO-heavy operations](https://eips.ethereum.org/EIPS/eip-150)
- [EIP-1884: Repricing for trie-size-dependent opcodes](https://eips.ethereum.org/EIPS/eip-1884)
- [EIP-2929: Gas cost increases for state access opcodes](https://eips.ethereum.org/EIPS/eip-2929)

# `static_cost`

```elixir
@spec static_cost(non_neg_integer()) :: non_neg_integer()
```

Returns the static gas cost for the given opcode byte under the
Berlin-onward schedule. See `static_cost/2` for earlier hardforks.

This cost is charged by the executor before dispatching to the opcode handler.
Dynamic costs (memory expansion, storage access, etc.) are charged separately
within each opcode's implementation.

# `static_cost`

```elixir
@spec static_cost(non_neg_integer(), EEVM.HardforkConfig.spec_id()) ::
  non_neg_integer()
```

Returns the static gas cost of `opcode` under hardfork `spec_id`.

From Berlin on this is `static_cost/1`; earlier forks price the
state-access opcodes with the flat schedules in the module docs.

## Examples

    iex> EEVM.Gas.Static.static_cost(0x54, :frontier)
    50

    iex> EEVM.Gas.Static.static_cost(0x54, :istanbul)
    800

    iex> EEVM.Gas.Static.static_cost(0x54, :berlin)
    0

---

*Consult [api-reference.md](api-reference.md) for complete listing*