# `EEVM.Interpreter.Instructions.StackMemoryStorage.StorageOps`
[🔗](https://github.com/mw2000/eevm/blob/v0.1.0/lib/eevm/interpreter/instructions/stack_memory_storage/storage_ops.ex#L1)

Persistent and transient storage opcodes: SLOAD, SSTORE, TLOAD, and TSTORE.

## Persistent Storage (SLOAD/SSTORE)

Persistent storage is a key-value mapping (256-bit → 256-bit) that persists across
transactions. Gas costs depend on the hardfork:

- **SLOAD** (0x54) — reads a storage slot. Costs 2,100 (cold) or 100 (warm) per
  EIP-2929 from Berlin; a flat static price before (see `EEVM.Gas.Static`).
- **SSTORE** (0x55) — writes a storage slot. Cost depends on the transition from
  original → current → new value (`EEVM.Gas.Dynamic.sstore_cost/4`), plus
  2,100 for a cold slot from Berlin. From Istanbul it fails out of gas when
  no more than 2,300 gas remains (EIP-2200).

## Transient Storage (TLOAD/TSTORE)

Transient storage (EIP-1153) provides a key-value mapping that is automatically
cleared at the end of each transaction. Useful for reentrancy locks and temporary state.

- **TLOAD** (0x5C) — reads from transient storage. Costs 100 gas (warm access).
- **TSTORE** (0x5D) — writes to transient storage. Costs 100 gas (warm access).

# `execute`

```elixir
@spec execute(non_neg_integer(), EEVM.Interpreter.MachineState.t()) ::
  {:ok, EEVM.Interpreter.MachineState.t()}
  | {:error, atom(), EEVM.Interpreter.MachineState.t()}
```

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