Multi-Feed Contract

A gas-optimized, bit-packed multi-asset price registry. One contract returns the latest prices for many feeds, each identified by a 4-byte feedId, optimized for consistency and gas efficiency.

Multi-Feed contract interface:
IMultiFeed.sol

Codec library:
FeedCodec.sol

Multi-Feed exposes two price query styles:

• Decoded view. Returns a friendly PriceSnapshot struct via fetch / fetchBatch.
• Compact view. Returns a packed bytes32 word via staticcall from fetchCompact / fetchCompactBatch to minimize cross-contract gas overhead. We recommend using the FeedCodec library in your consumer contract to decode the packed data; see the packed word bit layout under fetchCompact.

Read-access policy

Each feed instance runs in one of two modes — whitelist (only addresses on the authorized-caller list, plus regular EOAs that have not been delegated via ERC-7702, may read) or open-read (any caller may read). Functions marked onlyReadAccess below are subject to this policy; all other functions are always callable. Use isOpenRead and isAuthorizedCaller to query the current state.

Functions

Name	Description	View type	Modifier
fetch	Decoded snapshot for a single feed.	Decoded view	onlyReadAccess
fetchBatch	Decoded snapshots for multiple feeds.	Decoded view	onlyReadAccess
fetchCompact	Raw packed word for a single feed.	Compact view	onlyReadAccess
fetchCompactBatch	Raw packed words for multiple feeds.	Compact view	onlyReadAccess
decimals	Decimal precision shared by all feeds.	—	—
description	Human-readable description of this registry.	—	—
version	Version number of the implementation.	—	—
contractType	Contract type identifier (2 for Multi-Feed).	—	—
isAuthorizedCaller	Checks whether an address is whitelisted.	—	—
isOpenRead	Returns whether open-read mode is active.	—	—

1. fetch

Returns a decoded snapshot for a single feed.

function fetch(bytes4 feedId) external view returns (PriceSnapshot memory priceSnapshot)

Parameters

• feedId: 4-byte feed identifier.

Return values

• priceSnapshot: Decoded struct with price and timestamps. A zero-initialized snapshot is returned if the feed has never been updated.

1.1 PriceSnapshot struct definition

Records a price snapshot at a specific point in time. Fields are bit-packed for storage efficiency:

struct PriceSnapshot {
    uint80 price;        // aggregated price
    uint48 aggregatedTs; // off-chain aggregation timestamp
    uint48 onchainTs;    // on-chain update timestamp
}

2. fetchBatch

Returns decoded snapshots for multiple feeds in one call.

function fetchBatch(bytes4[] calldata feedIds) external view returns (PriceSnapshot[] memory priceSnapshots)

Parameters

• feedIds: Array of 4-byte feed identifiers.

Return values

• priceSnapshots: Array of decoded PriceSnapshot structs, index-aligned with feedIds. Feeds that have never been updated yield zero-initialized snapshots.

3. fetchCompact

Returns the raw 256-bit packed word for a single feed. This is the cheapest read path; we recommend using the FeedCodec library in your consumer contract to decode it.

function fetchCompact(bytes4 feedId) external view returns (bytes32 packed)

Parameters

• feedId: 4-byte feed identifier.

Return values

• packed: Raw 256-bit packed word, or bytes32(0) if the feed has never been updated.

3.1 Packed word bit layout

The 256-bit word returned by fetchCompact / fetchCompactBatch:

Bit range	Segment	Type	Meaning
[255:176]	Reserved	—	Zero-filled
[175:128]	OnchainTs	uint48	On-chain update timestamp
[127:80]	AggTs	uint48	Off-chain aggregation timestamp
[79:0]	Price	uint80	Aggregated price

4. fetchCompactBatch

Returns raw packed words for multiple feeds in one call. Same recommendation as fetchCompact: decode locally using FeedCodec for maximum gas efficiency.

function fetchCompactBatch(bytes4[] calldata feedIds) external view returns (bytes32[] memory packedList)

Parameters

• feedIds: Array of 4-byte feed identifiers.

Return values

• packedList: Array of raw 256-bit packed words, index-aligned with feedIds. Feeds that have never been updated yield bytes32(0).

5. decimals

Returns the decimal precision shared by all feeds in this registry.

function decimals() external view returns (uint8 precision)

Parameters

(none)

Return values

• precision: Decimal precision shared by all feeds.

6. description

Returns a human-readable description of this registry.

function description() external view returns (string memory desc)

Parameters

(none)

Return values

• desc: A string identifier.

7. version

Returns the version number of the current implementation.

function version() external view returns (uint256 versionNumber)

Parameters

(none)

Return values

• versionNumber: A monotonically increasing version identifier.

8. contractType

Returns the contract type identifier, used to distinguish feed implementations within the project.

function contractType() external view returns (uint256 typeId)

Parameters

(none)

Return values

• typeId: Type id (2 for Multi-Feed).

9. isAuthorizedCaller

Checks whether an address is whitelisted as an authorized caller for price reads when open-read mode is disabled.

function isAuthorizedCaller(address account) external view returns (bool whitelisted)

Parameters

• account: Address to query.

Return values

• whitelisted: true if the account is on the authorized-caller whitelist.

10. isOpenRead

Returns whether open-read mode is currently active. When true, any caller can read prices; when false, only whitelisted callers and regular EOAs (that have not been delegated via ERC-7702) are permitted.

function isOpenRead() external view returns (bool enabled)

Parameters

(none)

Return values

• enabled: true if open-read mode is active.