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

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://docs.ton.org/feedback

```json
{
  "path": "/foundations/precompiled",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

# Precompiled contracts

export const Aside = ({type = "note", title = "", icon = "", iconType = "regular", children}) => {
  const asideVariants = ["note", "tip", "caution", "danger"];
  const asideComponents = {
    note: {
      outerStyle: "border-sky-500/20 bg-sky-50/50 dark:border-sky-500/30 dark:bg-sky-500/10",
      innerStyle: "text-sky-900 dark:text-sky-200",
      calloutType: "note",
      icon: <svg width="14" height="14" viewBox="0 0 14 14" fill="currentColor" xmlns="http://www.w3.org/2000/svg" className="w-4 h-4 text-sky-500" aria-label="Note">
          <path fill-rule="evenodd" clip-rule="evenodd" d="M7 1.3C10.14 1.3 12.7 3.86 12.7 7C12.7 10.14 10.14 12.7 7 12.7C5.48908 12.6974 4.0408 12.096 2.97241 11.0276C1.90403 9.9592 1.30264 8.51092 1.3 7C1.3 3.86 3.86 1.3 7 1.3ZM7 0C3.14 0 0 3.14 0 7C0 10.86 3.14 14 7 14C10.86 14 14 10.86 14 7C14 3.14 10.86 0 7 0ZM8 3H6V8H8V3ZM8 9H6V11H8V9Z"></path>
        </svg>
    },
    tip: {
      outerStyle: "border-emerald-500/20 bg-emerald-50/50 dark:border-emerald-500/30 dark:bg-emerald-500/10",
      innerStyle: "text-emerald-900 dark:text-emerald-200",
      calloutType: "tip",
      icon: <svg width="11" height="14" viewBox="0 0 11 14" fill="currentColor" xmlns="http://www.w3.org/2000/svg" className="text-emerald-600 dark:text-emerald-400/80 w-3.5 h-auto" aria-label="Tip">
          <path d="M3.12794 12.4232C3.12794 12.5954 3.1776 12.7634 3.27244 12.907L3.74114 13.6095C3.88471 13.8248 4.21067 14 4.46964 14H6.15606C6.41415 14 6.74017 13.825 6.88373 13.6095L7.3508 12.9073C7.43114 12.7859 7.49705 12.569 7.49705 12.4232L7.50055 11.3513H3.12521L3.12794 12.4232ZM5.31288 0C2.52414 0.00875889 0.5 2.26889 0.5 4.78826C0.5 6.00188 0.949566 7.10829 1.69119 7.95492C2.14321 8.47011 2.84901 9.54727 3.11919 10.4557C3.12005 10.4625 3.12175 10.4698 3.12261 10.4771H7.50342C7.50427 10.4698 7.50598 10.463 7.50684 10.4557C7.77688 9.54727 8.48281 8.47011 8.93484 7.95492C9.67728 7.13181 10.1258 6.02703 10.1258 4.78826C10.1258 2.15486 7.9709 0.000106649 5.31288 0ZM7.94902 7.11267C7.52078 7.60079 6.99082 8.37878 6.6077 9.18794H4.02051C3.63739 8.37878 3.10743 7.60079 2.67947 7.11294C2.11997 6.47551 1.8126 5.63599 1.8126 4.78826C1.8126 3.09829 3.12794 1.31944 5.28827 1.3126C7.2435 1.3126 8.81315 2.88226 8.81315 4.78826C8.81315 5.63599 8.50688 6.47551 7.94902 7.11267ZM4.87534 2.18767C3.66939 2.18767 2.68767 3.16939 2.68767 4.37534C2.68767 4.61719 2.88336 4.81288 3.12521 4.81288C3.36705 4.81288 3.56274 4.61599 3.56274 4.37534C3.56274 3.6515 4.1515 3.06274 4.87534 3.06274C5.11719 3.06274 5.31288 2.86727 5.31288 2.62548C5.31288 2.38369 5.11599 2.18767 4.87534 2.18767Z"></path>
        </svg>
    },
    caution: {
      outerStyle: "border-amber-500/20 bg-amber-50/50 dark:border-amber-500/30 dark:bg-amber-500/10",
      innerStyle: "text-amber-900 dark:text-amber-200",
      calloutType: "warning",
      icon: <svg className="flex-none w-5 h-5 text-amber-400 dark:text-amber-300/80" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2" aria-label="Warning">
          <path stroke-linecap="round" stroke-linejoin="round" d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z"></path>
        </svg>
    },
    danger: {
      outerStyle: "border-red-500/20 bg-red-50/50 dark:border-red-500/30 dark:bg-red-500/10",
      innerStyle: "text-red-900 dark:text-red-200",
      calloutType: "danger",
      icon: <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" fill="currentColor" className="text-red-600 dark:text-red-400/80 w-4 h-4" aria-label="Danger">
          <path d="M17.1 292c-12.9-22.3-12.9-49.7 0-72L105.4 67.1c12.9-22.3 36.6-36 62.4-36l176.6 0c25.7 0 49.5 13.7 62.4 36L494.9 220c12.9 22.3 12.9 49.7 0 72L406.6 444.9c-12.9 22.3-36.6 36-62.4 36l-176.6 0c-25.7 0-49.5-13.7-62.4-36L17.1 292zm41.6-48c-4.3 7.4-4.3 16.6 0 24l88.3 152.9c4.3 7.4 12.2 12 20.8 12l176.6 0c8.6 0 16.5-4.6 20.8-12L453.4 268c4.3-7.4 4.3-16.6 0-24L365.1 91.1c-4.3-7.4-12.2-12-20.8-12l-176.6 0c-8.6 0-16.5 4.6-20.8 12L58.6 244zM256 128c13.3 0 24 10.7 24 24l0 112c0 13.3-10.7 24-24 24s-24-10.7-24-24l0-112c0-13.3 10.7-24 24-24zM224 352a32 32 0 1 1 64 0 32 32 0 1 1 -64 0z"></path>
        </svg>
    }
  };
  let variant = type;
  let gotInvalidVariant = false;
  if (!asideVariants.includes(type)) {
    gotInvalidVariant = true;
    variant = "danger";
  }
  const iconVariants = ["regular", "solid", "light", "thin", "sharp-solid", "duotone", "brands"];
  if (!iconVariants.includes(iconType)) {
    iconType = "regular";
  }
  return <>
      <div className={`callout my-4 px-5 py-4 overflow-hidden rounded-2xl flex gap-3 border ${asideComponents[variant].outerStyle}`} data-callout-type={asideComponents[variant].calloutType}>
        <div className="mt-0.5 w-4" data-component-part="callout-icon">
          {}
          {icon === "" ? asideComponents[variant].icon : <Icon icon={icon} iconType={iconType} size={14} />}
        </div>
        <div className={`text-sm prose min-w-0 w-full ${asideComponents[variant].innerStyle}`} data-component-part="callout-content">
          {gotInvalidVariant ? <p>
              <span className="font-bold">
                Invalid <code>type</code> passed!
              </span>
              <br />
              <span className="font-bold">Received: </span>
              {type}
              <br />
              <span className="font-bold">Expected one of: </span>
              {asideVariants.join(", ")}
            </p> : <>
              {title && <p className="font-bold">{title}</p>}
              {children}
            </>}
        </div>
      </div>
    </>;
};

A precompiled smart contract is a contract with a native C++ implementation in the validator node. When a validator processes a transaction for such a contract, it can execute this native implementation instead of TVM. This improves performance and reduces computation fees.

## Config

The list of precompiled contracts is stored in the blockchain configuration:

```tlb theme={"theme":{"light":"github-light-default","dark":"dark-plus"},"languages":{"custom":["/resources/grammars/tolk.tmLanguage.json","/resources/grammars/tlb.tmLanguage.json","/resources/grammars/fift.tmLanguage.json","/resources/grammars/tasm.tmLanguage.json","/resources/grammars/func.tmLanguage.json"]}}
precompiled_smc#b0 gas_usage:uint64 = PrecompiledSmc;
precompiled_contracts_config#c0 list:(HashmapE 256 PrecompiledSmc) = PrecompiledContractsConfig;
_ PrecompiledContractsConfig = ConfigParam 45;
```

The `list:(HashmapE 256 PrecompiledSmc)` represents a mapping of contract code hash to constant gas amount. A contract is considered precompiled if its code hash exists in this map.

<Aside>
  View current values on mainnet at [ConfigParam 45 on Tonviewer](https://tonviewer.com/config#45).
</Aside>

## Accessing precompiled gas value

Contracts can check their precompiled gas value using the [`GETPRECOMPILEDGAS`](/tvm/instructions#f839-getprecompiledgas) opcode:

* Returns the configured `gas_usage` value if the contract code hash is in `ConfigParam 45`
* Returns `null` if the contract code hash is not in `ConfigParam 45`

The value is also available in the [`c7`](/tvm/registers#c7--environment-information-and-global-variables) register environment tuple.

## Execution modes

When a validator processes a transaction, the execution mode depends on whether the contract code hash is listed in `ConfigParam 45`.

### 1. Contract is not precompiled

The contract code hash is not in `ConfigParam 45`. TVM executes normally with standard gas accounting.

[`GETPRECOMPILEDGAS`](#accessing-precompiled-gas-value) returns `null`. Transaction result: `gas_used` reflects actual TVM consumption.

### 2. Contract is precompiled

The contract code hash exists in `ConfigParam 45`. The validator checks the contract balance against the configured `gas_usage`. If insufficient, the compute phase fails with `cskip_no_gas`.

Otherwise, execution proceeds via one of two paths.

#### Contract has native C++ implementation

The native C++ implementation is available and enabled in the validator node. The validator executes the C++ code directly without invoking TVM.

Transaction [result](/foundations/phases#compute-phase):

* `gas_used` set to the value from `ConfigParam 45`
* `vm_steps`, `vm_init_state_hash`, `vm_final_state_hash` set to zero

#### Contract has no native C++ implementation

The native C++ implementation is disabled or unavailable in the validator node. TVM executes the contract code normally.

[`GETPRECOMPILEDGAS`](#accessing-precompiled-gas-value) returns the configured gas value during execution.

After execution completes, the validator overrides the compute phase values.

Transaction result:

* `gas_used` set to the value from `ConfigParam 45`
* `vm_steps`, `vm_init_state_hash`, `vm_final_state_hash` set to zero

<Aside type="note">
  The override ensures that both execution paths produce identical transaction results. This allows validators with and without native C++ implementations to coexist in the network and enables gradual adoption when adding new entries to `ConfigParam 45`.
</Aside>

## Example: Stablecoin jetton wallet

The jetton wallet from the [stablecoin-contract](https://github.com/ton-blockchain/stablecoin-contract) project is the first contract code hash added to `ConfigParam 45` on mainnet. This jetton wallet is optimized as a precompiled contract to reduce computation fees for stablecoin transfers.

The contract implements standard jetton wallet functionality with additional governance features. The precompiled gas logic is implemented in [`gas.fc`](https://github.com/ton-blockchain/stablecoin-contract/blob/5e1d79f4009430f2f7f255c5093a59d9a1628d75/contracts/gas.fc).