DrawAccumulatorLib

Git Source

Author: G9 Software Inc.

This contract distributes tokens over time according to an exponential weighted average. Time is divided into discrete "draws", of which each is allocated tokens.

Constants

MAX_OBSERVATION_CARDINALITY

uint16 constant MAX_OBSERVATION_CARDINALITY = 366;

Functions

add

Adds balance for the given draw id to the accumulator.

function add(Accumulator storage accumulator, uint256 _amount, uint24 _drawId) internal returns (bool);

Parameters

Name	Type	Description
accumulator	Accumulator	The accumulator to add to
_amount	uint256	The amount of balance to add
_drawId	uint24	The draw id to which to add balance to. This must be greater than or equal to the previous addition's draw id.

Returns

Name	Type	Description
<none>	bool	True if a new observation was created, false otherwise.

newestDrawId

Returns the newest draw id from the accumulator.

function newestDrawId(Accumulator storage accumulator) internal view returns (uint256);

Parameters

Name	Type	Description
accumulator	Accumulator	The accumulator to get the newest draw id from

Returns

Name	Type	Description
<none>	uint256	The newest draw id

newestObservation

Returns the newest draw id from the accumulator.

function newestObservation(Accumulator storage accumulator) internal view returns (Observation memory);

Parameters

Name	Type	Description
accumulator	Accumulator	The accumulator to get the newest draw id from

Returns

Name	Type	Description
<none>	Observation	The newest draw id

getDisbursedBetween

Gets the balance that was disbursed between the given start and end draw ids, inclusive.

function getDisbursedBetween(Accumulator storage _accumulator, uint24 _startDrawId, uint24 _endDrawId)
    internal
    view
    returns (uint256);

Parameters

Name	Type	Description
_accumulator	Accumulator	The accumulator to get the disbursed balance from
_startDrawId	uint24	The start draw id, inclusive
_endDrawId	uint24	The end draw id, inclusive

Returns

Name	Type	Description
<none>	uint256	The disbursed balance between the given start and end draw ids, inclusive

binarySearch

Binary searches an array of draw ids for the given target draw id.

The _targetDrawId MUST exist between the range of draws at _oldestIndex and _newestIndex (inclusive)

function binarySearch(
    uint24[366] storage _drawRingBuffer,
    uint16 _oldestIndex,
    uint16 _newestIndex,
    uint16 _cardinality,
    uint24 _targetDrawId
)
    internal
    view
    returns (uint16 beforeOrAtIndex, uint24 beforeOrAtDrawId, uint16 afterOrAtIndex, uint24 afterOrAtDrawId);

Parameters

Name	Type	Description
_drawRingBuffer	uint24[366]	The array of draw ids to search
_oldestIndex	uint16	The oldest index in the ring buffer
_newestIndex	uint16	The newest index in the ring buffer
_cardinality	uint16	The number of items in the ring buffer
_targetDrawId	uint24	The target draw id to search for

Returns

Name	Type	Description
beforeOrAtIndex	uint16	The index of the observation occurring at or before the target draw id
beforeOrAtDrawId	uint24	The draw id of the observation occurring at or before the target draw id
afterOrAtIndex	uint16	The index of the observation occurring at or after the target draw id
afterOrAtDrawId	uint24	The draw id of the observation occurring at or after the target draw id

Structs

Accumulator

An accumulator for a draw.

struct Accumulator {
    RingBufferInfo ringBufferInfo;
    uint24[366] drawRingBuffer;
    mapping(uint256 drawId => Observation observation) observations;
}

Properties

Name	Type	Description
ringBufferInfo	RingBufferInfo	The metadata for the drawRingBuffer
drawRingBuffer	uint24[366]	The ring buffer of draw ids
observations	mapping(uint256 drawId => Observation observation)	The observations for each draw id

Observation

The accumulator observation record

struct Observation {
    uint96 available;
    uint160 disbursed;
}

Properties

Name	Type	Description
available	uint96	The total amount available as of this Observation
disbursed	uint160	The total amount disbursed in the past

RingBufferInfo

The metadata for using the ring buffer.

struct RingBufferInfo {
    uint16 nextIndex;
    uint16 cardinality;
}