# PairParameterHelper

[Git Source](https://github.com/traderjoe-xyz/joe-v2/blob/16f011d25e6bf6d0a0c479974345b623d491104f/src/libraries/PairParameterHelper.sol)

**Author:**\
Trader Joe

*This library contains functions to get and set parameters of a pair*\
*The parameters are stored in a single bytes32 variable in the following format:*\
*\[0 - 16\[: base factor (16 bits)*\
*\[16 - 28\[: filter period (12 bits)*\
*\[28 - 40\[: decay period (12 bits)*\
*\[40 - 54\[: reduction factor (14 bits)*\
*\[54 - 78\[: variable fee control (24 bits)*\
*\[78 - 92\[: protocol share (14 bits)*\
*\[92 - 112\[: max volatility accumulator (20 bits)*\
*\[112 - 132\[: volatility accumulator (20 bits)*\
*\[132 - 152\[: volatility reference (20 bits)*\
*\[152 - 176\[: index reference (24 bits)*\
*\[176 - 216\[: time of last update (40 bits)*\
*\[216 - 232\[: oracle index (16 bits)*\
*\[232 - 256\[: active index (24 bits)*

## State Variables

### OFFSET\_BASE\_FACTOR

```solidity
uint256 internal constant OFFSET_BASE_FACTOR = 0;
```

### OFFSET\_FILTER\_PERIOD

```solidity
uint256 internal constant OFFSET_FILTER_PERIOD = 16;
```

### OFFSET\_DECAY\_PERIOD

```solidity
uint256 internal constant OFFSET_DECAY_PERIOD = 28;
```

### OFFSET\_REDUCTION\_FACTOR

```solidity
uint256 internal constant OFFSET_REDUCTION_FACTOR = 40;
```

### OFFSET\_VAR\_FEE\_CONTROL

```solidity
uint256 internal constant OFFSET_VAR_FEE_CONTROL = 54;
```

### OFFSET\_PROTOCOL\_SHARE

```solidity
uint256 internal constant OFFSET_PROTOCOL_SHARE = 78;
```

### OFFSET\_MAX\_VOL\_ACC

```solidity
uint256 internal constant OFFSET_MAX_VOL_ACC = 92;
```

### OFFSET\_VOL\_ACC

```solidity
uint256 internal constant OFFSET_VOL_ACC = 112;
```

### OFFSET\_VOL\_REF

```solidity
uint256 internal constant OFFSET_VOL_REF = 132;
```

### OFFSET\_ID\_REF

```solidity
uint256 internal constant OFFSET_ID_REF = 152;
```

### OFFSET\_TIME\_LAST\_UPDATE

```solidity
uint256 internal constant OFFSET_TIME_LAST_UPDATE = 176;
```

### OFFSET\_ORACLE\_ID

```solidity
uint256 internal constant OFFSET_ORACLE_ID = 216;
```

### OFFSET\_ACTIVE\_ID

```solidity
uint256 internal constant OFFSET_ACTIVE_ID = 232;
```

### MASK\_STATIC\_PARAMETER

```solidity
uint256 internal constant MASK_STATIC_PARAMETER = 0xffffffffffffffffffffffffffff;
```

## Functions

### getBaseFactor

*Get the base factor from the encoded pair parameters*

```solidity
function getBaseFactor(bytes32 params) internal pure returns (uint16 baseFactor);
```

**Parameters**

| Name     | Type      | Description                                                                                               |
| -------- | --------- | --------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 16\[: base factor (16 bits) \[16 - 256\[: other parameters |

**Returns**

| Name         | Type     | Description     |
| ------------ | -------- | --------------- |
| `baseFactor` | `uint16` | The base factor |

### getFilterPeriod

*Get the filter period from the encoded pair parameters*

```solidity
function getFilterPeriod(bytes32 params) internal pure returns (uint16 filterPeriod);
```

**Parameters**

| Name     | Type      | Description                                                                                                                               |
| -------- | --------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 16\[: other parameters \[16 - 28\[: filter period (12 bits) \[28 - 256\[: other parameters |

**Returns**

| Name           | Type     | Description       |
| -------------- | -------- | ----------------- |
| `filterPeriod` | `uint16` | The filter period |

### getDecayPeriod

*Get the decay period from the encoded pair parameters*

```solidity
function getDecayPeriod(bytes32 params) internal pure returns (uint16 decayPeriod);
```

**Parameters**

| Name     | Type      | Description                                                                                                                              |
| -------- | --------- | ---------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 28\[: other parameters \[28 - 40\[: decay period (12 bits) \[40 - 256\[: other parameters |

**Returns**

| Name          | Type     | Description      |
| ------------- | -------- | ---------------- |
| `decayPeriod` | `uint16` | The decay period |

### getReductionFactor

*Get the reduction factor from the encoded pair parameters*

```solidity
function getReductionFactor(bytes32 params) internal pure returns (uint16 reductionFactor);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                  |
| -------- | --------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 40\[: other parameters \[40 - 54\[: reduction factor (14 bits) \[54 - 256\[: other parameters |

**Returns**

| Name              | Type     | Description          |
| ----------------- | -------- | -------------------- |
| `reductionFactor` | `uint16` | The reduction factor |

### getVariableFeeControl

*Get the variable fee control from the encoded pair parameters*

```solidity
function getVariableFeeControl(bytes32 params) internal pure returns (uint24 variableFeeControl);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                      |
| -------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 54\[: other parameters \[54 - 78\[: variable fee control (24 bits) \[78 - 256\[: other parameters |

**Returns**

| Name                 | Type     | Description              |
| -------------------- | -------- | ------------------------ |
| `variableFeeControl` | `uint24` | The variable fee control |

### getProtocolShare

*Get the protocol share from the encoded pair parameters*

```solidity
function getProtocolShare(bytes32 params) internal pure returns (uint16 protocolShare);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                |
| -------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 78\[: other parameters \[78 - 92\[: protocol share (14 bits) \[92 - 256\[: other parameters |

**Returns**

| Name            | Type     | Description        |
| --------------- | -------- | ------------------ |
| `protocolShare` | `uint16` | The protocol share |

### getMaxVolatilityAccumulator

*Get the max volatility accumulator from the encoded pair parameters*

```solidity
function getMaxVolatilityAccumulator(bytes32 params) internal pure returns (uint24 maxVolatilityAccumulator);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                              |
| -------- | --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 92\[: other parameters \[92 - 112\[: max volatility accumulator (20 bits) \[112 - 256\[: other parameters |

**Returns**

| Name                       | Type     | Description                    |
| -------------------------- | -------- | ------------------------------ |
| `maxVolatilityAccumulator` | `uint24` | The max volatility accumulator |

### getVolatilityAccumulator

*Get the volatility accumulator from the encoded pair parameters*

```solidity
function getVolatilityAccumulator(bytes32 params) internal pure returns (uint24 volatilityAccumulator);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                            |
| -------- | --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 112\[: other parameters \[112 - 132\[: volatility accumulator (20 bits) \[132 - 256\[: other parameters |

**Returns**

| Name                    | Type     | Description                |
| ----------------------- | -------- | -------------------------- |
| `volatilityAccumulator` | `uint24` | The volatility accumulator |

### getVolatilityReference

*Get the volatility reference from the encoded pair parameters*

```solidity
function getVolatilityReference(bytes32 params) internal pure returns (uint24 volatilityReference);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                          |
| -------- | --------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 132\[: other parameters \[132 - 152\[: volatility reference (20 bits) \[152 - 256\[: other parameters |

**Returns**

| Name                  | Type     | Description              |
| --------------------- | -------- | ------------------------ |
| `volatilityReference` | `uint24` | The volatility reference |

### getIdReference

*Get the index reference from the encoded pair parameters*

```solidity
function getIdReference(bytes32 params) internal pure returns (uint24 idReference);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                     |
| -------- | --------- | ----------------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 152\[: other parameters \[152 - 176\[: index reference (24 bits) \[176 - 256\[: other parameters |

**Returns**

| Name          | Type     | Description         |
| ------------- | -------- | ------------------- |
| `idReference` | `uint24` | The index reference |

### getTimeOfLastUpdate

*Get the time of last update from the encoded pair parameters*

```solidity
function getTimeOfLastUpdate(bytes32 params) internal pure returns (uint40 timeOflastUpdate);
```

**Parameters**

| Name     | Type      | Description                                                                                                                                         |
| -------- | --------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 176\[: other parameters \[176 - 216\[: time of last update (40 bits) \[216 - 256\[: other parameters |

**Returns**

| Name               | Type     | Description             |
| ------------------ | -------- | ----------------------- |
| `timeOflastUpdate` | `uint40` | The time of last update |

### getOracleId

*Get the oracle id from the encoded pair parameters*

```solidity
function getOracleId(bytes32 params) internal pure returns (uint16 oracleId);
```

**Parameters**

| Name     | Type      | Description                                                                                                                               |
| -------- | --------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 216\[: other parameters \[216 - 232\[: oracle id (16 bits) \[232 - 256\[: other parameters |

**Returns**

| Name       | Type     | Description   |
| ---------- | -------- | ------------- |
| `oracleId` | `uint16` | The oracle id |

### getActiveId

*Get the active index from the encoded pair parameters*

```solidity
function getActiveId(bytes32 params) internal pure returns (uint24 activeId);
```

**Parameters**

| Name     | Type      | Description                                                                                                  |
| -------- | --------- | ------------------------------------------------------------------------------------------------------------ |
| `params` | `bytes32` | The encoded pair parameters, as follows: \[0 - 232\[: other parameters \[232 - 256\[: active index (24 bits) |

**Returns**

| Name       | Type     | Description      |
| ---------- | -------- | ---------------- |
| `activeId` | `uint24` | The active index |

### getDeltaId

*Get the delta between the current active index and the cached active index*

```solidity
function getDeltaId(bytes32 params, uint24 activeId) internal pure returns (uint24);
```

**Parameters**

| Name       | Type      | Description                                                                                                  |
| ---------- | --------- | ------------------------------------------------------------------------------------------------------------ |
| `params`   | `bytes32` | The encoded pair parameters, as follows: \[0 - 232\[: other parameters \[232 - 256\[: active index (24 bits) |
| `activeId` | `uint24`  | The current active index                                                                                     |

**Returns**

| Name     | Type     | Description |
| -------- | -------- | ----------- |
| `<none>` | `uint24` | The delta   |

### getBaseFee

*Calculates the base fee, with 18 decimals*

```solidity
function getBaseFee(bytes32 params, uint16 binStep) internal pure returns (uint256);
```

**Parameters**

| Name      | Type      | Description                    |
| --------- | --------- | ------------------------------ |
| `params`  | `bytes32` | The encoded pair parameters    |
| `binStep` | `uint16`  | The bin step (in basis points) |

**Returns**

| Name     | Type      | Description          |
| -------- | --------- | -------------------- |
| `<none>` | `uint256` | baseFee The base fee |

### getVariableFee

*Calculates the variable fee*

```solidity
function getVariableFee(bytes32 params, uint16 binStep) internal pure returns (uint256 variableFee);
```

**Parameters**

| Name      | Type      | Description                    |
| --------- | --------- | ------------------------------ |
| `params`  | `bytes32` | The encoded pair parameters    |
| `binStep` | `uint16`  | The bin step (in basis points) |

**Returns**

| Name          | Type      | Description      |
| ------------- | --------- | ---------------- |
| `variableFee` | `uint256` | The variable fee |

### getTotalFee

*Calculates the total fee, which is the sum of the base fee and the variable fee*

```solidity
function getTotalFee(bytes32 params, uint16 binStep) internal pure returns (uint128);
```

**Parameters**

| Name      | Type      | Description                    |
| --------- | --------- | ------------------------------ |
| `params`  | `bytes32` | The encoded pair parameters    |
| `binStep` | `uint16`  | The bin step (in basis points) |

**Returns**

| Name     | Type      | Description            |
| -------- | --------- | ---------------------- |
| `<none>` | `uint128` | totalFee The total fee |

### setOracleId

*Set the oracle id in the encoded pair parameters*

```solidity
function setOracleId(bytes32 params, uint16 oracleId) internal pure returns (bytes32);
```

**Parameters**

| Name       | Type      | Description                 |
| ---------- | --------- | --------------------------- |
| `params`   | `bytes32` | The encoded pair parameters |
| `oracleId` | `uint16`  | The oracle id               |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

### setVolatilityReference

*Set the volatility reference in the encoded pair parameters*

```solidity
function setVolatilityReference(bytes32 params, uint24 volRef) internal pure returns (bytes32);
```

**Parameters**

| Name     | Type      | Description                 |
| -------- | --------- | --------------------------- |
| `params` | `bytes32` | The encoded pair parameters |
| `volRef` | `uint24`  | The volatility reference    |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

### setVolatilityAccumulator

*Set the volatility accumulator in the encoded pair parameters*

```solidity
function setVolatilityAccumulator(bytes32 params, uint24 volAcc) internal pure returns (bytes32);
```

**Parameters**

| Name     | Type      | Description                 |
| -------- | --------- | --------------------------- |
| `params` | `bytes32` | The encoded pair parameters |
| `volAcc` | `uint24`  | The volatility accumulator  |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

### setActiveId

*Set the active id in the encoded pair parameters*

```solidity
function setActiveId(bytes32 params, uint24 activeId) internal pure returns (bytes32 newParams);
```

**Parameters**

| Name       | Type      | Description                 |
| ---------- | --------- | --------------------------- |
| `params`   | `bytes32` | The encoded pair parameters |
| `activeId` | `uint24`  | The active id               |

**Returns**

| Name        | Type      | Description                         |
| ----------- | --------- | ----------------------------------- |
| `newParams` | `bytes32` | The updated encoded pair parameters |

### setStaticFeeParameters

*Sets the static fee parameters in the encoded pair parameters*

```solidity
function setStaticFeeParameters(
    bytes32 params,
    uint16 baseFactor,
    uint16 filterPeriod,
    uint16 decayPeriod,
    uint16 reductionFactor,
    uint24 variableFeeControl,
    uint16 protocolShare,
    uint24 maxVolatilityAccumulator
) internal pure returns (bytes32 newParams);
```

**Parameters**

| Name                       | Type      | Description                    |
| -------------------------- | --------- | ------------------------------ |
| `params`                   | `bytes32` | The encoded pair parameters    |
| `baseFactor`               | `uint16`  | The base factor                |
| `filterPeriod`             | `uint16`  | The filter period              |
| `decayPeriod`              | `uint16`  | The decay period               |
| `reductionFactor`          | `uint16`  | The reduction factor           |
| `variableFeeControl`       | `uint24`  | The variable fee control       |
| `protocolShare`            | `uint16`  | The protocol share             |
| `maxVolatilityAccumulator` | `uint24`  | The max volatility accumulator |

**Returns**

| Name        | Type      | Description                         |
| ----------- | --------- | ----------------------------------- |
| `newParams` | `bytes32` | The updated encoded pair parameters |

### updateIdReference

*Updates the index reference in the encoded pair parameters*

```solidity
function updateIdReference(bytes32 params) internal pure returns (bytes32 newParams);
```

**Parameters**

| Name     | Type      | Description                 |
| -------- | --------- | --------------------------- |
| `params` | `bytes32` | The encoded pair parameters |

**Returns**

| Name        | Type      | Description                         |
| ----------- | --------- | ----------------------------------- |
| `newParams` | `bytes32` | The updated encoded pair parameters |

### updateTimeOfLastUpdate

*Updates the time of last update in the encoded pair parameters*

```solidity
function updateTimeOfLastUpdate(bytes32 params, uint256 timestamp) internal pure returns (bytes32 newParams);
```

**Parameters**

| Name        | Type      | Description                 |
| ----------- | --------- | --------------------------- |
| `params`    | `bytes32` | The encoded pair parameters |
| `timestamp` | `uint256` | The timestamp               |

**Returns**

| Name        | Type      | Description                         |
| ----------- | --------- | ----------------------------------- |
| `newParams` | `bytes32` | The updated encoded pair parameters |

### updateVolatilityReference

*Updates the volatility reference in the encoded pair parameters*

```solidity
function updateVolatilityReference(bytes32 params) internal pure returns (bytes32);
```

**Parameters**

| Name     | Type      | Description                 |
| -------- | --------- | --------------------------- |
| `params` | `bytes32` | The encoded pair parameters |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

### updateVolatilityAccumulator

*Updates the volatility accumulator in the encoded pair parameters*

```solidity
function updateVolatilityAccumulator(bytes32 params, uint24 activeId) internal pure returns (bytes32);
```

**Parameters**

| Name       | Type      | Description                 |
| ---------- | --------- | --------------------------- |
| `params`   | `bytes32` | The encoded pair parameters |
| `activeId` | `uint24`  | The active id               |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

### updateReferences

*Updates the volatility reference and the volatility accumulator in the encoded pair parameters*

```solidity
function updateReferences(bytes32 params, uint256 timestamp) internal pure returns (bytes32);
```

**Parameters**

| Name        | Type      | Description                 |
| ----------- | --------- | --------------------------- |
| `params`    | `bytes32` | The encoded pair parameters |
| `timestamp` | `uint256` | The timestamp               |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

### updateVolatilityParameters

*Updates the volatility reference and the volatility accumulator in the encoded pair parameters*

```solidity
function updateVolatilityParameters(bytes32 params, uint24 activeId, uint256 timestamp)
    internal
    pure
    returns (bytes32);
```

**Parameters**

| Name        | Type      | Description                 |
| ----------- | --------- | --------------------------- |
| `params`    | `bytes32` | The encoded pair parameters |
| `activeId`  | `uint24`  | The active id               |
| `timestamp` | `uint256` | The timestamp               |

**Returns**

| Name     | Type      | Description                         |
| -------- | --------- | ----------------------------------- |
| `<none>` | `bytes32` | The updated encoded pair parameters |

## Errors

### PairParametersHelper\_\_InvalidParameter

```solidity
error PairParametersHelper__InvalidParameter();
```


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