Decimals Wrapper

Overview

PendleDecimalsWrapper is a thin ERC-20 wrapper that re-expresses any token with fewer than 18 decimals as a new token with exactly 18 decimals. No interest accrues, there is no rebasing, and no fees are taken — it is a purely mechanical decimal normalisation layer.

Within the Pendle system, this is the foundation of the Scaled18 SY pattern: an SY contract accepts a low-decimal raw token (e.g., LBTC with 8 decimals or USDC with 6 decimals), wraps it through PendleDecimalsWrapper, and exposes the 18-decimal representation to PY contracts and the market. The PendleDecimalsWrapperFactory creates and caches these wrappers so that only one wrapper ever exists per (rawToken, targetDecimals) pair.

Sources:

• PendleDecimalsWrapper.sol
• PendleDecimalsWrapperFactory.sol
• Interface: IPDecimalsWrapper.sol
• Interface: IPDecimalsWrapperFactory.sol

---

PendleDecimalsWrapper

A standard ERC-20 token (inherits PendleERC20) with decimals() = 18. Wrapping and unwrapping is a simple multiply/divide by 10^(18 - rawDecimals).

The constructor enforces rawDecimals <= 18. The contract is always deployed by the factory — do not deploy it directly.

Public State

Variable	Type	Description
factory	address	The PendleDecimalsWrapperFactory that deployed this contract
rawToken	address	The original token being wrapped
rawDecimals	uint8	Decimals of rawToken

wrap

function wrap(uint256 amount) external returns (uint256 amountOut);

Transfers amount of rawToken from msg.sender into the wrapper, then mints rawToWrapped(amount) of the wrapped token to msg.sender.

Important: amount is in raw units (i.e., rawToken decimals). The returned amountOut is in wrapped units (18 decimals). There is no rounding loss in the wrap direction.

unwrap

function unwrap(uint256 amount) external returns (uint256 amountOut);

Burns amount of the wrapped token from msg.sender, then transfers wrappedToRaw(amount) of rawToken back.

Important: amount is in wrapped units (18 decimals). wrappedToRaw performs integer division — the caller may receive slightly fewer raw units than the proportional share (the remainder stays in the contract as recoverable dust). See sweep.

rawToWrapped

function rawToWrapped(uint256 amount) public view returns (uint256);

wrappedAmount = amount × 10^(18 - rawDecimals)

Converts a raw-unit quantity to its 18-decimal representation. No rounding; exact for any amount.

wrappedToRaw

function wrappedToRaw(uint256 amount) public view returns (uint256);

rawAmount = amount / 10^(18 - rawDecimals)    (integer division — truncates)

Converts a wrapped-unit quantity back to raw units. Because of integer truncation, wrappedToRaw(rawToWrapped(x)) always equals x, but rawToWrapped(wrappedToRaw(y)) may be slightly less than y if y is not a multiple of the scale factor. The shortfall remains in the contract as dust.

---

PendleDecimalsWrapperFactory

Idempotent factory that ensures only one wrapper exists per (rawToken, targetDecimals) pair. The factory is the sole deployer of PendleDecimalsWrapper instances.

Current limitation

getOrCreate currently only supports _decimals = 18. Passing any other target decimals will revert. The API accepts _decimals as a parameter for forward-compatibility, but the implementation asserts _decimals == 18 internally.

Constructor

constructor(address _dustReceiver);

Sets the immutable dustReceiver address that receives dust from all wrappers created by this factory.

getOrCreate

function getOrCreate(
    address _rawToken,
    uint8   _decimals
) external returns (address decimalWrapper);

Returns the wrapper address for (_rawToken, _decimals). If no wrapper exists yet, deploys a new PendleDecimalsWrapper and registers it. Subsequent calls with the same arguments return the already-deployed address without re-deploying.

Reverts: implicitly via assert if _decimals != 18 (see note above).

Emits DecimalWrapperCreated(rawToken, decimals, decimalWrapper) on first deployment only.

decimalWrappers

mapping(address => mapping(uint8 => address)) public decimalWrappers;

Registry mapping rawToken → targetDecimals → wrapper address. Returns address(0) if no wrapper has been created for that pair.

dustReceiver

address public immutable dustReceiver;

The address that receives dust when any wrapper's sweep() is called.

Events

Event	Parameters	Description
DecimalWrapperCreated	rawToken, decimals, decimalsWrapper	Emitted when a new wrapper is deployed

---

Token Naming Convention

Wrapper tokens are named automatically by the factory:

Property	Value
name	"{rawToken.name} scaled18"
symbol	"{rawToken.symbol}-scaled18"
decimals	18 (always)

For example, wrapping LBTC (8 decimals) produces a token named "Lombard Staked Bitcoin scaled18" with symbol "LBTC-scaled18".

---

How Scaled18 SY Contracts Use the Wrapper

For concrete implementations, refer to some of our examples:

• PendleLBTCBaseSYScaled18.sol — yield-bearing example with oracle-based exchangeRate()
• PendleUniBTCBeraSYUpgScaled18.sol — simple 1:1 example using ScaledTokenMath

---

Further Reading

• Common SY Contracts — the Scaled18 SY types that rely on this wrapper
• StandardizedYield — pricingInfo() Scaled18 example (PendleLBTCBaseSYScaled18)
• Unit and Decimals — full explanation of Scaled18 SY decimals and conversion rates