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686 lines
41 KiB
Solidity
686 lines
41 KiB
Solidity
// SPDX-License-Identifier: BUSL-1.1
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pragma solidity 0.8.21;
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import { LibsErrorTypes as ErrorTypes } from "./errorTypes.sol";
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import { LiquiditySlotsLink } from "./liquiditySlotsLink.sol";
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import { BigMathMinified } from "./bigMathMinified.sol";
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/// @notice implements calculation methods used for Fluid liquidity such as updated exchange prices,
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/// borrow rate, withdrawal / borrow limits, revenue amount.
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library LiquidityCalcs {
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error FluidLiquidityCalcsError(uint256 errorId_);
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/// @notice emitted if the calculated borrow rate surpassed max borrow rate (16 bits) and was capped at maximum value 65535
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event BorrowRateMaxCap();
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/// @dev constants as from Liquidity variables.sol
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uint256 internal constant EXCHANGE_PRICES_PRECISION = 1e12;
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/// @dev Ignoring leap years
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uint256 internal constant SECONDS_PER_YEAR = 365 days;
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// constants used for BigMath conversion from and to storage
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uint256 internal constant DEFAULT_EXPONENT_SIZE = 8;
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uint256 internal constant DEFAULT_EXPONENT_MASK = 0xFF;
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uint256 internal constant FOUR_DECIMALS = 1e4;
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uint256 internal constant TWELVE_DECIMALS = 1e12;
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uint256 internal constant X14 = 0x3fff;
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uint256 internal constant X15 = 0x7fff;
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uint256 internal constant X16 = 0xffff;
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uint256 internal constant X18 = 0x3ffff;
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uint256 internal constant X24 = 0xffffff;
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uint256 internal constant X33 = 0x1ffffffff;
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uint256 internal constant X64 = 0xffffffffffffffff;
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///////////////////////////////////////////////////////////////////////////
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////////// CALC EXCHANGE PRICES /////////
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///////////////////////////////////////////////////////////////////////////
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/// @dev calculates interest (exchange prices) for a token given its' exchangePricesAndConfig from storage.
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/// @param exchangePricesAndConfig_ exchange prices and config packed uint256 read from storage
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/// @return supplyExchangePrice_ updated supplyExchangePrice
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/// @return borrowExchangePrice_ updated borrowExchangePrice
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function calcExchangePrices(
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uint256 exchangePricesAndConfig_
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) internal view returns (uint256 supplyExchangePrice_, uint256 borrowExchangePrice_) {
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// Extracting exchange prices
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supplyExchangePrice_ =
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(exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_SUPPLY_EXCHANGE_PRICE) &
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X64;
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borrowExchangePrice_ =
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(exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_BORROW_EXCHANGE_PRICE) &
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X64;
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if (supplyExchangePrice_ == 0 || borrowExchangePrice_ == 0) {
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revert FluidLiquidityCalcsError(ErrorTypes.LiquidityCalcs__ExchangePriceZero);
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}
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uint256 temp_ = exchangePricesAndConfig_ & X16; // temp_ = borrowRate
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unchecked {
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// last timestamp can not be > current timestamp
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uint256 secondsSinceLastUpdate_ = block.timestamp -
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((exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_LAST_TIMESTAMP) & X33);
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uint256 borrowRatio_ = (exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_BORROW_RATIO) &
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X15;
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if (secondsSinceLastUpdate_ == 0 || temp_ == 0 || borrowRatio_ == 1) {
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// if no time passed, borrow rate is 0, or no raw borrowings: no exchange price update needed
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// (if borrowRatio_ == 1 means there is only borrowInterestFree, as first bit is 1 and rest is 0)
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return (supplyExchangePrice_, borrowExchangePrice_);
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}
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// calculate new borrow exchange price.
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// formula borrowExchangePriceIncrease: previous price * borrow rate * secondsSinceLastUpdate_.
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// nominator is max uint112 (uint64 * uint16 * uint32). Divisor can not be 0.
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borrowExchangePrice_ +=
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(borrowExchangePrice_ * temp_ * secondsSinceLastUpdate_) /
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(SECONDS_PER_YEAR * FOUR_DECIMALS);
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// FOR SUPPLY EXCHANGE PRICE:
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// all yield paid by borrowers (in mode with interest) goes to suppliers in mode with interest.
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// formula: previous price * supply rate * secondsSinceLastUpdate_.
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// where supply rate = (borrow rate - revenueFee%) * ratioSupplyYield. And
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// ratioSupplyYield = utilization * supplyRatio * borrowRatio
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//
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// Example:
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// supplyRawInterest is 80, supplyInterestFree is 20. totalSupply is 100. BorrowedRawInterest is 50.
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// BorrowInterestFree is 10. TotalBorrow is 60. borrow rate 40%, revenueFee 10%.
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// yield is 10 (so half a year must have passed).
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// supplyRawInterest must become worth 89. totalSupply must become 109. BorrowedRawInterest must become 60.
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// borrowInterestFree must still be 10. supplyInterestFree still 20. totalBorrow 70.
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// supplyExchangePrice would have to go from 1 to 1,125 (+ 0.125). borrowExchangePrice from 1 to 1,2 (+0.2).
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// utilization is 60%. supplyRatio = 20 / 80 = 25% (only 80% of lenders receiving yield).
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// borrowRatio = 10 / 50 = 20% (only 83,333% of borrowers paying yield):
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// x of borrowers paying yield = 100% - (20 / (100 + 20)) = 100% - 16.6666666% = 83,333%.
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// ratioSupplyYield = 60% * 83,33333% * (100% + 20%) = 62,5%
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// supplyRate = (40% * (100% - 10%)) * = 36% * 62,5% = 22.5%
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// increase in supplyExchangePrice, assuming 100 as previous price.
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// 100 * 22,5% * 1/2 (half a year) = 0,1125.
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// cross-check supplyRawInterest worth = 80 * 1.1125 = 89. totalSupply worth = 89 + 20.
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// -------------- 1. calculate ratioSupplyYield --------------------------------
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// step1: utilization * supplyRatio (or actually part of lenders receiving yield)
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// temp_ => supplyRatio (in 1e2: 100% = 10_000; 1% = 100 -> max value 16_383)
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// if first bit 0 then ratio is supplyInterestFree / supplyWithInterest (supplyWithInterest is bigger)
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// else ratio is supplyWithInterest / supplyInterestFree (supplyInterestFree is bigger)
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temp_ = (exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_SUPPLY_RATIO) & X15;
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if (temp_ == 1) {
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// if no raw supply: no exchange price update needed
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// (if supplyRatio_ == 1 means there is only supplyInterestFree, as first bit is 1 and rest is 0)
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return (supplyExchangePrice_, borrowExchangePrice_);
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}
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// ratioSupplyYield precision is 1e27 as 100% for increased precision when supplyInterestFree > supplyWithInterest
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if (temp_ & 1 == 1) {
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// ratio is supplyWithInterest / supplyInterestFree (supplyInterestFree is bigger)
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temp_ = temp_ >> 1;
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// Note: case where temp_ == 0 (only supplyInterestFree, no yield) already covered by early return
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// in the if statement a little above.
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// based on above example but supplyRawInterest is 20, supplyInterestFree is 80. no fee.
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// supplyRawInterest must become worth 30. totalSupply must become 110.
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// supplyExchangePrice would have to go from 1 to 1,5. borrowExchangePrice from 1 to 1,2.
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// so ratioSupplyYield must come out as 2.5 (250%).
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// supplyRatio would be (20 * 10_000 / 80) = 2500. but must be inverted.
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temp_ = (1e27 * FOUR_DECIMALS) / temp_; // e.g. 1e31 / 2500 = 4e27. (* 1e27 for precision)
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// e.g. 5_000 * (1e27 + 4e27) / 1e27 = 25_000 (=250%).
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temp_ =
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// utilization * (100% + 100% / supplyRatio)
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(((exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_UTILIZATION) & X14) *
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(1e27 + temp_)) / // extract utilization (max 16_383 so there is no way this can overflow).
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(FOUR_DECIMALS);
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// max possible value of temp_ here is 16383 * (1e27 + 1e31) / 1e4 = ~1.64e31
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} else {
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// ratio is supplyInterestFree / supplyWithInterest (supplyWithInterest is bigger)
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temp_ = temp_ >> 1;
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// if temp_ == 0 then only supplyWithInterest => full yield. temp_ is already 0
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// e.g. 5_000 * 10_000 + (20 * 10_000 / 80) / 10_000 = 5000 * 12500 / 10000 = 6250 (=62.5%).
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temp_ =
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// 1e27 * utilization * (100% + supplyRatio) / 100%
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(1e27 *
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((exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_UTILIZATION) & X14) * // extract utilization (max 16_383 so there is no way this can overflow).
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(FOUR_DECIMALS + temp_)) /
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(FOUR_DECIMALS * FOUR_DECIMALS);
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// max possible temp_ value: 1e27 * 16383 * 2e4 / 1e8 = 3.2766e27
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}
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// from here temp_ => ratioSupplyYield (utilization * supplyRatio part) scaled by 1e27. max possible value ~1.64e31
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// step2 of ratioSupplyYield: add borrowRatio (only x% of borrowers paying yield)
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if (borrowRatio_ & 1 == 1) {
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// ratio is borrowWithInterest / borrowInterestFree (borrowInterestFree is bigger)
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borrowRatio_ = borrowRatio_ >> 1;
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// borrowRatio_ => x of total bororwers paying yield. scale to 1e27.
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// Note: case where borrowRatio_ == 0 (only borrowInterestFree, no yield) already covered
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// at the beginning of the method by early return if `borrowRatio_ == 1`.
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// based on above example but borrowRawInterest is 10, borrowInterestFree is 50. no fee. borrowRatio = 20%.
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// so only 16.66% of borrowers are paying yield. so the 100% - part of the formula is not needed.
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// x of borrowers paying yield = (borrowRatio / (100 + borrowRatio)) = 16.6666666%
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// borrowRatio_ => x of total bororwers paying yield. scale to 1e27.
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borrowRatio_ = (borrowRatio_ * 1e27) / (FOUR_DECIMALS + borrowRatio_);
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// max value here for borrowRatio_ is (1e31 / (1e4 + 1e4))= 5e26 (= 50% of borrowers paying yield).
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} else {
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// ratio is borrowInterestFree / borrowWithInterest (borrowWithInterest is bigger)
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borrowRatio_ = borrowRatio_ >> 1;
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// borrowRatio_ => x of total bororwers paying yield. scale to 1e27.
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// x of borrowers paying yield = 100% - (borrowRatio / (100 + borrowRatio)) = 100% - 16.6666666% = 83,333%.
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borrowRatio_ = (1e27 - ((borrowRatio_ * 1e27) / (FOUR_DECIMALS + borrowRatio_)));
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// borrowRatio can never be > 100%. so max subtraction can be 100% - 100% / 200%.
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// or if borrowRatio_ is 0 -> 100% - 0. or if borrowRatio_ is 1 -> 100% - 1 / 101.
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// max value here for borrowRatio_ is 1e27 - 0 = 1e27 (= 100% of borrowers paying yield).
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}
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// temp_ => ratioSupplyYield. scaled down from 1e25 = 1% each to normal percent precision 1e2 = 1%.
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// max nominator value is ~1.64e31 * 1e27 = 1.64e58. max result = 1.64e8
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temp_ = (FOUR_DECIMALS * temp_ * borrowRatio_) / 1e54;
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// 2. calculate supply rate
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// temp_ => supply rate (borrow rate - revenueFee%) * ratioSupplyYield.
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// division part is done in next step to increase precision. (divided by 2x FOUR_DECIMALS, fee + borrowRate)
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// Note that all calculation divisions for supplyExchangePrice are rounded down.
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// Note supply rate can be bigger than the borrowRate, e.g. if there are only few lenders with interest
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// but more suppliers not earning interest.
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temp_ = ((exchangePricesAndConfig_ & X16) * // borrow rate
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temp_ * // ratioSupplyYield
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(FOUR_DECIMALS - ((exchangePricesAndConfig_ >> LiquiditySlotsLink.BITS_EXCHANGE_PRICES_FEE) & X14))); // revenueFee
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// fee can not be > 100%. max possible = 65535 * ~1.64e8 * 1e4 =~1.074774e17.
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// 3. calculate increase in supply exchange price
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supplyExchangePrice_ += ((supplyExchangePrice_ * temp_ * secondsSinceLastUpdate_) /
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(SECONDS_PER_YEAR * FOUR_DECIMALS * FOUR_DECIMALS * FOUR_DECIMALS));
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// max possible nominator = max uint 64 * 1.074774e17 * max uint32 = ~8.52e45. Denominator can not be 0.
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}
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}
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///////////////////////////////////////////////////////////////////////////
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////////// CALC REVENUE /////////
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///////////////////////////////////////////////////////////////////////////
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/// @dev gets the `revenueAmount_` for a token given its' totalAmounts and exchangePricesAndConfig from storage
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/// and the current balance of the Fluid liquidity contract for the token.
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/// @param totalAmounts_ total amounts packed uint256 read from storage
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/// @param exchangePricesAndConfig_ exchange prices and config packed uint256 read from storage
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/// @param liquidityTokenBalance_ current balance of Liquidity contract (IERC20(token_).balanceOf(address(this)))
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/// @return revenueAmount_ collectable revenue amount
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function calcRevenue(
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uint256 totalAmounts_,
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uint256 exchangePricesAndConfig_,
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uint256 liquidityTokenBalance_
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) internal view returns (uint256 revenueAmount_) {
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// @dev no need to super-optimize this method as it is only used by admin
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// calculate the new exchange prices based on earned interest
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(uint256 supplyExchangePrice_, uint256 borrowExchangePrice_) = calcExchangePrices(exchangePricesAndConfig_);
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// total supply = interest free + with interest converted from raw
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uint256 totalSupply_ = getTotalSupply(totalAmounts_, supplyExchangePrice_);
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if (totalSupply_ > 0) {
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// available revenue: balanceOf(token) + totalBorrowings - totalLendings.
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revenueAmount_ = liquidityTokenBalance_ + getTotalBorrow(totalAmounts_, borrowExchangePrice_);
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// ensure there is no possible case because of rounding etc. where this would revert,
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// explicitly check if >
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revenueAmount_ = revenueAmount_ > totalSupply_ ? revenueAmount_ - totalSupply_ : 0;
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// Note: if utilization > 100% (totalSupply < totalBorrow), then all the amount above 100% utilization
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// can only be revenue.
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} else {
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// if supply is 0, then rest of balance can be withdrawn as revenue so that no amounts get stuck
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revenueAmount_ = liquidityTokenBalance_;
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}
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}
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///////////////////////////////////////////////////////////////////////////
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////////// CALC LIMITS /////////
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///////////////////////////////////////////////////////////////////////////
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/// @dev calculates withdrawal limit before an operate execution:
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/// amount of user supply that must stay supplied (not amount that can be withdrawn).
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/// i.e. if user has supplied 100m and can withdraw 5M, this method returns the 95M, not the withdrawable amount 5M
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/// @param userSupplyData_ user supply data packed uint256 from storage
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/// @param userSupply_ current user supply amount already extracted from `userSupplyData_` and converted from BigMath
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/// @return currentWithdrawalLimit_ current withdrawal limit updated for expansion since last interaction.
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/// returned value is in raw for with interest mode, normal amount for interest free mode!
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function calcWithdrawalLimitBeforeOperate(
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uint256 userSupplyData_,
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uint256 userSupply_
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) internal view returns (uint256 currentWithdrawalLimit_) {
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// @dev must support handling the case where timestamp is 0 (config is set but no interactions yet).
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// first tx where timestamp is 0 will enter `if (lastWithdrawalLimit_ == 0)` because lastWithdrawalLimit_ is not set yet.
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// returning max withdrawal allowed, which is not exactly right but doesn't matter because the first interaction must be
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// a deposit anyway. Important is that it would not revert.
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// Note the first time a deposit brings the user supply amount to above the base withdrawal limit, the active limit
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// is the fully expanded limit immediately.
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// extract last set withdrawal limit
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uint256 lastWithdrawalLimit_ = (userSupplyData_ >>
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LiquiditySlotsLink.BITS_USER_SUPPLY_PREVIOUS_WITHDRAWAL_LIMIT) & X64;
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lastWithdrawalLimit_ =
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(lastWithdrawalLimit_ >> DEFAULT_EXPONENT_SIZE) <<
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(lastWithdrawalLimit_ & DEFAULT_EXPONENT_MASK);
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if (lastWithdrawalLimit_ == 0) {
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// withdrawal limit is not activated. Max withdrawal allowed
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return 0;
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}
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uint256 maxWithdrawableLimit_;
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uint256 temp_;
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unchecked {
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// extract max withdrawable percent of user supply and
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// calculate maximum withdrawable amount expandPercentage of user supply at full expansion duration elapsed
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// e.g.: if 10% expandPercentage, meaning 10% is withdrawable after full expandDuration has elapsed.
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// userSupply_ needs to be atleast 1e73 to overflow max limit of ~1e77 in uint256 (no token in existence where this is possible).
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maxWithdrawableLimit_ =
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(((userSupplyData_ >> LiquiditySlotsLink.BITS_USER_SUPPLY_EXPAND_PERCENT) & X14) * userSupply_) /
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FOUR_DECIMALS;
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// time elapsed since last withdrawal limit was set (in seconds)
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// @dev last process timestamp is guaranteed to exist for withdrawal, as a supply must have happened before.
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// last timestamp can not be > current timestamp
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temp_ =
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block.timestamp -
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((userSupplyData_ >> LiquiditySlotsLink.BITS_USER_SUPPLY_LAST_UPDATE_TIMESTAMP) & X33);
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}
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// calculate withdrawable amount of expandPercent that is elapsed of expandDuration.
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// e.g. if 60% of expandDuration has elapsed, then user should be able to withdraw 6% of user supply, down to 94%.
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// Note: no explicit check for this needed, it is covered by setting minWithdrawalLimit_ if needed.
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temp_ =
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(maxWithdrawableLimit_ * temp_) /
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// extract expand duration: After this, decrement won't happen (user can withdraw 100% of withdraw limit)
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((userSupplyData_ >> LiquiditySlotsLink.BITS_USER_SUPPLY_EXPAND_DURATION) & X24); // expand duration can never be 0
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// calculate expanded withdrawal limit: last withdrawal limit - withdrawable amount.
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// Note: withdrawable amount here can grow bigger than userSupply if timeElapsed is a lot bigger than expandDuration,
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// which would cause the subtraction `lastWithdrawalLimit_ - withdrawableAmount_` to revert. In that case, set 0
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// which will cause minimum (fully expanded) withdrawal limit to be set in lines below.
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unchecked {
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// underflow explicitly checked & handled
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currentWithdrawalLimit_ = lastWithdrawalLimit_ > temp_ ? lastWithdrawalLimit_ - temp_ : 0;
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// calculate minimum withdrawal limit: minimum amount of user supply that must stay supplied at full expansion.
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// subtraction can not underflow as maxWithdrawableLimit_ is a percentage amount (<=100%) of userSupply_
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temp_ = userSupply_ - maxWithdrawableLimit_;
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}
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// if withdrawal limit is decreased below minimum then set minimum
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// (e.g. when more than expandDuration time has elapsed)
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if (temp_ > currentWithdrawalLimit_) {
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currentWithdrawalLimit_ = temp_;
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}
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}
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/// @dev calculates withdrawal limit after an operate execution:
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/// amount of user supply that must stay supplied (not amount that can be withdrawn).
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/// i.e. if user has supplied 100m and can withdraw 5M, this method returns the 95M, not the withdrawable amount 5M
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/// @param userSupplyData_ user supply data packed uint256 from storage
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/// @param userSupply_ current user supply amount already extracted from `userSupplyData_` and added / subtracted with the executed operate amount
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/// @param newWithdrawalLimit_ current withdrawal limit updated for expansion since last interaction, result from `calcWithdrawalLimitBeforeOperate`
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/// @return withdrawalLimit_ updated withdrawal limit that should be written to storage. returned value is in
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/// raw for with interest mode, normal amount for interest free mode!
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function calcWithdrawalLimitAfterOperate(
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uint256 userSupplyData_,
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uint256 userSupply_,
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uint256 newWithdrawalLimit_
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) internal pure returns (uint256) {
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// temp_ => base withdrawal limit. below this, maximum withdrawals are allowed
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uint256 temp_ = (userSupplyData_ >> LiquiditySlotsLink.BITS_USER_SUPPLY_BASE_WITHDRAWAL_LIMIT) & X18;
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temp_ = (temp_ >> DEFAULT_EXPONENT_SIZE) << (temp_ & DEFAULT_EXPONENT_MASK);
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// if user supply is below base limit then max withdrawals are allowed
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if (userSupply_ < temp_) {
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return 0;
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}
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// temp_ => withdrawal limit expandPercent (is in 1e2 decimals)
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temp_ = (userSupplyData_ >> LiquiditySlotsLink.BITS_USER_SUPPLY_EXPAND_PERCENT) & X14;
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unchecked {
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// temp_ => minimum withdrawal limit: userSupply - max withdrawable limit (userSupply * expandPercent))
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// userSupply_ needs to be atleast 1e73 to overflow max limit of ~1e77 in uint256 (no token in existence where this is possible).
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// subtraction can not underflow as maxWithdrawableLimit_ is a percentage amount (<=100%) of userSupply_
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temp_ = userSupply_ - ((userSupply_ * temp_) / FOUR_DECIMALS);
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}
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// if new (before operation) withdrawal limit is less than minimum limit then set minimum limit.
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// e.g. can happen on new deposits. withdrawal limit is instantly fully expanded in a scenario where
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// increased deposit amount outpaces withrawals.
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if (temp_ > newWithdrawalLimit_) {
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return temp_;
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}
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return newWithdrawalLimit_;
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}
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/// @dev calculates borrow limit before an operate execution:
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/// total amount user borrow can reach (not borrowable amount in current operation).
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/// i.e. if user has borrowed 50M and can still borrow 5M, this method returns the total 55M, not the borrowable amount 5M
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/// @param userBorrowData_ user borrow data packed uint256 from storage
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/// @param userBorrow_ current user borrow amount already extracted from `userBorrowData_`
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/// @return currentBorrowLimit_ current borrow limit updated for expansion since last interaction. returned value is in
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/// raw for with interest mode, normal amount for interest free mode!
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function calcBorrowLimitBeforeOperate(
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uint256 userBorrowData_,
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uint256 userBorrow_
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) internal view returns (uint256 currentBorrowLimit_) {
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// @dev must support handling the case where timestamp is 0 (config is set but no interactions yet) -> base limit.
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// first tx where timestamp is 0 will enter `if (maxExpandedBorrowLimit_ < baseBorrowLimit_)` because `userBorrow_` and thus
|
|
// `maxExpansionLimit_` and thus `maxExpandedBorrowLimit_` is 0 and `baseBorrowLimit_` can not be 0.
|
|
|
|
// temp_ = extract borrow expand percent (is in 1e2 decimals)
|
|
uint256 temp_ = (userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_EXPAND_PERCENT) & X14;
|
|
|
|
uint256 maxExpansionLimit_;
|
|
uint256 maxExpandedBorrowLimit_;
|
|
unchecked {
|
|
// calculate max expansion limit: Max amount limit can expand to since last interaction
|
|
// userBorrow_ needs to be atleast 1e73 to overflow max limit of ~1e77 in uint256 (no token in existence where this is possible).
|
|
maxExpansionLimit_ = ((userBorrow_ * temp_) / FOUR_DECIMALS);
|
|
|
|
// calculate max borrow limit: Max point limit can increase to since last interaction
|
|
maxExpandedBorrowLimit_ = userBorrow_ + maxExpansionLimit_;
|
|
}
|
|
|
|
// currentBorrowLimit_ = extract base borrow limit
|
|
currentBorrowLimit_ = (userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_BASE_BORROW_LIMIT) & X18;
|
|
currentBorrowLimit_ =
|
|
(currentBorrowLimit_ >> DEFAULT_EXPONENT_SIZE) <<
|
|
(currentBorrowLimit_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
if (maxExpandedBorrowLimit_ < currentBorrowLimit_) {
|
|
return currentBorrowLimit_;
|
|
}
|
|
// time elapsed since last borrow limit was set (in seconds)
|
|
unchecked {
|
|
// temp_ = timeElapsed_ (last timestamp can not be > current timestamp)
|
|
temp_ =
|
|
block.timestamp -
|
|
((userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_LAST_UPDATE_TIMESTAMP) & X33); // extract last update timestamp
|
|
}
|
|
|
|
// currentBorrowLimit_ = expandedBorrowableAmount + extract last set borrow limit
|
|
currentBorrowLimit_ =
|
|
// calculate borrow limit expansion since last interaction for `expandPercent` that is elapsed of `expandDuration`.
|
|
// divisor is extract expand duration (after this, full expansion to expandPercentage happened).
|
|
((maxExpansionLimit_ * temp_) /
|
|
((userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_EXPAND_DURATION) & X24)) + // expand duration can never be 0
|
|
// extract last set borrow limit
|
|
BigMathMinified.fromBigNumber(
|
|
(userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_PREVIOUS_BORROW_LIMIT) & X64,
|
|
DEFAULT_EXPONENT_SIZE,
|
|
DEFAULT_EXPONENT_MASK
|
|
);
|
|
|
|
// if timeElapsed is bigger than expandDuration, new borrow limit would be > max expansion,
|
|
// so set to `maxExpandedBorrowLimit_` in that case.
|
|
// also covers the case where last process timestamp = 0 (timeElapsed would simply be very big)
|
|
if (currentBorrowLimit_ > maxExpandedBorrowLimit_) {
|
|
currentBorrowLimit_ = maxExpandedBorrowLimit_;
|
|
}
|
|
// temp_ = extract hard max borrow limit. Above this user can never borrow (not expandable above)
|
|
temp_ = (userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_MAX_BORROW_LIMIT) & X18;
|
|
temp_ = (temp_ >> DEFAULT_EXPONENT_SIZE) << (temp_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
if (currentBorrowLimit_ > temp_) {
|
|
currentBorrowLimit_ = temp_;
|
|
}
|
|
}
|
|
|
|
/// @dev calculates borrow limit after an operate execution:
|
|
/// total amount user borrow can reach (not borrowable amount in current operation).
|
|
/// i.e. if user has borrowed 50M and can still borrow 5M, this method returns the total 55M, not the borrowable amount 5M
|
|
/// @param userBorrowData_ user borrow data packed uint256 from storage
|
|
/// @param userBorrow_ current user borrow amount already extracted from `userBorrowData_` and added / subtracted with the executed operate amount
|
|
/// @param newBorrowLimit_ current borrow limit updated for expansion since last interaction, result from `calcBorrowLimitBeforeOperate`
|
|
/// @return borrowLimit_ updated borrow limit that should be written to storage.
|
|
/// returned value is in raw for with interest mode, normal amount for interest free mode!
|
|
function calcBorrowLimitAfterOperate(
|
|
uint256 userBorrowData_,
|
|
uint256 userBorrow_,
|
|
uint256 newBorrowLimit_
|
|
) internal pure returns (uint256 borrowLimit_) {
|
|
// temp_ = extract borrow expand percent
|
|
uint256 temp_ = (userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_EXPAND_PERCENT) & X14; // (is in 1e2 decimals)
|
|
|
|
unchecked {
|
|
// borrowLimit_ = calculate maximum borrow limit at full expansion.
|
|
// userBorrow_ needs to be at least 1e73 to overflow max limit of ~1e77 in uint256 (no token in existence where this is possible).
|
|
borrowLimit_ = userBorrow_ + ((userBorrow_ * temp_) / FOUR_DECIMALS);
|
|
}
|
|
|
|
// temp_ = extract base borrow limit
|
|
temp_ = (userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_BASE_BORROW_LIMIT) & X18;
|
|
temp_ = (temp_ >> DEFAULT_EXPONENT_SIZE) << (temp_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
if (borrowLimit_ < temp_) {
|
|
// below base limit, borrow limit is always base limit
|
|
return temp_;
|
|
}
|
|
// temp_ = extract hard max borrow limit. Above this user can never borrow (not expandable above)
|
|
temp_ = (userBorrowData_ >> LiquiditySlotsLink.BITS_USER_BORROW_MAX_BORROW_LIMIT) & X18;
|
|
temp_ = (temp_ >> DEFAULT_EXPONENT_SIZE) << (temp_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
// make sure fully expanded borrow limit is not above hard max borrow limit
|
|
if (borrowLimit_ > temp_) {
|
|
borrowLimit_ = temp_;
|
|
}
|
|
// if new borrow limit (from before operate) is > max borrow limit, set max borrow limit.
|
|
// (e.g. on a repay shrinking instantly to fully expanded borrow limit from new borrow amount. shrinking is instant)
|
|
if (newBorrowLimit_ > borrowLimit_) {
|
|
return borrowLimit_;
|
|
}
|
|
return newBorrowLimit_;
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
////////// CALC RATES /////////
|
|
///////////////////////////////////////////////////////////////////////////
|
|
|
|
/// @dev Calculates new borrow rate from utilization for a token
|
|
/// @param rateData_ rate data packed uint256 from storage for the token
|
|
/// @param utilization_ totalBorrow / totalSupply. 1e4 = 100% utilization
|
|
/// @return rate_ rate for that particular token in 1e2 precision (e.g. 5% rate = 500)
|
|
function calcBorrowRateFromUtilization(uint256 rateData_, uint256 utilization_) internal returns (uint256 rate_) {
|
|
// extract rate version: 4 bits (0xF) starting from bit 0
|
|
uint256 rateVersion_ = (rateData_ & 0xF);
|
|
|
|
if (rateVersion_ == 1) {
|
|
rate_ = calcRateV1(rateData_, utilization_);
|
|
} else if (rateVersion_ == 2) {
|
|
rate_ = calcRateV2(rateData_, utilization_);
|
|
} else {
|
|
revert FluidLiquidityCalcsError(ErrorTypes.LiquidityCalcs__UnsupportedRateVersion);
|
|
}
|
|
|
|
if (rate_ > X16) {
|
|
// hard cap for borrow rate at maximum value 16 bits (65535) to make sure it does not overflow storage space.
|
|
// this is unlikely to ever happen if configs stay within expected levels.
|
|
rate_ = X16;
|
|
// emit event to more easily become aware
|
|
emit BorrowRateMaxCap();
|
|
}
|
|
}
|
|
|
|
/// @dev calculates the borrow rate based on utilization for rate data version 1 (with one kink) in 1e2 precision
|
|
/// @param rateData_ rate data packed uint256 from storage for the token
|
|
/// @param utilization_ in 1e2 (100% = 1e4)
|
|
/// @return rate_ rate in 1e2 precision
|
|
function calcRateV1(uint256 rateData_, uint256 utilization_) internal pure returns (uint256 rate_) {
|
|
/// For rate v1 (one kink) ------------------------------------------------------
|
|
/// Next 16 bits => 4 - 19 => Rate at utilization 0% (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 20- 35 => Utilization at kink1 (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 36- 51 => Rate at utilization kink1 (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 52- 67 => Rate at utilization 100% (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Last 188 bits => 68-255 => blank, might come in use in future
|
|
|
|
// y = mx + c.
|
|
// y is borrow rate
|
|
// x is utilization
|
|
// m = slope (m can also be negative for declining rates)
|
|
// c is constant (c can be negative)
|
|
|
|
uint256 y1_;
|
|
uint256 y2_;
|
|
uint256 x1_;
|
|
uint256 x2_;
|
|
|
|
// extract kink1: 16 bits (0xFFFF) starting from bit 20
|
|
// kink is in 1e2, same as utilization, so no conversion needed for direct comparison of the two
|
|
uint256 kink1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V1_UTILIZATION_AT_KINK) & X16;
|
|
if (utilization_ < kink1_) {
|
|
// if utilization is less than kink
|
|
y1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V1_RATE_AT_UTILIZATION_ZERO) & X16;
|
|
y2_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V1_RATE_AT_UTILIZATION_KINK) & X16;
|
|
x1_ = 0; // 0%
|
|
x2_ = kink1_;
|
|
} else {
|
|
// else utilization is greater than kink
|
|
y1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V1_RATE_AT_UTILIZATION_KINK) & X16;
|
|
y2_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V1_RATE_AT_UTILIZATION_MAX) & X16;
|
|
x1_ = kink1_;
|
|
x2_ = FOUR_DECIMALS; // 100%
|
|
}
|
|
|
|
int256 constant_;
|
|
int256 slope_;
|
|
unchecked {
|
|
// calculating slope with twelve decimal precision. m = (y2 - y1) / (x2 - x1).
|
|
// utilization of x2 can not be <= utilization of x1 (so no underflow or 0 divisor)
|
|
// y is in 1e2 so can not overflow when multiplied with TWELVE_DECIMALS
|
|
slope_ = (int256(y2_ - y1_) * int256(TWELVE_DECIMALS)) / int256((x2_ - x1_));
|
|
|
|
// calculating constant at 12 decimal precision. slope is already in 12 decimal hence only multiple with y1. c = y - mx.
|
|
// maximum y1_ value is 65535. 65535 * 1e12 can not overflow int256
|
|
// maximum slope is 65535 - 0 * TWELVE_DECIMALS / 1 = 65535 * 1e12;
|
|
// maximum x1_ is 100% (9_999 actually) => slope_ * x1_ can not overflow int256
|
|
// subtraction most extreme case would be 0 - max value slope_ * x1_ => can not underflow int256
|
|
constant_ = int256(y1_ * TWELVE_DECIMALS) - (slope_ * int256(x1_));
|
|
|
|
// calculating new borrow rate
|
|
// - slope_ max value is 65535 * 1e12,
|
|
// - utilization max value is let's say 500% (extreme case where borrow rate increases borrow amount without new supply)
|
|
// - constant max value is 65535 * 1e12
|
|
// so max values are 65535 * 1e12 * 50_000 + 65535 * 1e12 -> 3.2768*10^21, which easily fits int256
|
|
// divisor TWELVE_DECIMALS can not be 0
|
|
slope_ = (slope_ * int256(utilization_)) + constant_; // reusing `slope_` as variable for gas savings
|
|
if (slope_ < 0) {
|
|
revert FluidLiquidityCalcsError(ErrorTypes.LiquidityCalcs__BorrowRateNegative);
|
|
}
|
|
rate_ = uint256(slope_) / TWELVE_DECIMALS;
|
|
}
|
|
}
|
|
|
|
/// @dev calculates the borrow rate based on utilization for rate data version 2 (with two kinks) in 1e4 precision
|
|
/// @param rateData_ rate data packed uint256 from storage for the token
|
|
/// @param utilization_ in 1e2 (100% = 1e4)
|
|
/// @return rate_ rate in 1e4 precision
|
|
function calcRateV2(uint256 rateData_, uint256 utilization_) internal pure returns (uint256 rate_) {
|
|
/// For rate v2 (two kinks) -----------------------------------------------------
|
|
/// Next 16 bits => 4 - 19 => Rate at utilization 0% (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 20- 35 => Utilization at kink1 (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 36- 51 => Rate at utilization kink1 (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 52- 67 => Utilization at kink2 (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 68- 83 => Rate at utilization kink2 (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Next 16 bits => 84- 99 => Rate at utilization 100% (in 1e2: 100% = 10_000; 1% = 100 -> max value 65535)
|
|
/// Last 156 bits => 100-255 => blank, might come in use in future
|
|
|
|
// y = mx + c.
|
|
// y is borrow rate
|
|
// x is utilization
|
|
// m = slope (m can also be negative for declining rates)
|
|
// c is constant (c can be negative)
|
|
|
|
uint256 y1_;
|
|
uint256 y2_;
|
|
uint256 x1_;
|
|
uint256 x2_;
|
|
|
|
// extract kink1: 16 bits (0xFFFF) starting from bit 20
|
|
// kink is in 1e2, same as utilization, so no conversion needed for direct comparison of the two
|
|
uint256 kink1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_UTILIZATION_AT_KINK1) & X16;
|
|
if (utilization_ < kink1_) {
|
|
// if utilization is less than kink1
|
|
y1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_RATE_AT_UTILIZATION_ZERO) & X16;
|
|
y2_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_RATE_AT_UTILIZATION_KINK1) & X16;
|
|
x1_ = 0; // 0%
|
|
x2_ = kink1_;
|
|
} else {
|
|
// extract kink2: 16 bits (0xFFFF) starting from bit 52
|
|
uint256 kink2_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_UTILIZATION_AT_KINK2) & X16;
|
|
if (utilization_ < kink2_) {
|
|
// if utilization is less than kink2
|
|
y1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_RATE_AT_UTILIZATION_KINK1) & X16;
|
|
y2_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_RATE_AT_UTILIZATION_KINK2) & X16;
|
|
x1_ = kink1_;
|
|
x2_ = kink2_;
|
|
} else {
|
|
// else utilization is greater than kink2
|
|
y1_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_RATE_AT_UTILIZATION_KINK2) & X16;
|
|
y2_ = (rateData_ >> LiquiditySlotsLink.BITS_RATE_DATA_V2_RATE_AT_UTILIZATION_MAX) & X16;
|
|
x1_ = kink2_;
|
|
x2_ = FOUR_DECIMALS;
|
|
}
|
|
}
|
|
|
|
int256 constant_;
|
|
int256 slope_;
|
|
unchecked {
|
|
// calculating slope with twelve decimal precision. m = (y2 - y1) / (x2 - x1).
|
|
// utilization of x2 can not be <= utilization of x1 (so no underflow or 0 divisor)
|
|
// y is in 1e2 so can not overflow when multiplied with TWELVE_DECIMALS
|
|
slope_ = (int256(y2_ - y1_) * int256(TWELVE_DECIMALS)) / int256((x2_ - x1_));
|
|
|
|
// calculating constant at 12 decimal precision. slope is already in 12 decimal hence only multiple with y1. c = y - mx.
|
|
// maximum y1_ value is 65535. 65535 * 1e12 can not overflow int256
|
|
// maximum slope is 65535 - 0 * TWELVE_DECIMALS / 1 = 65535 * 1e12;
|
|
// maximum x1_ is 100% (9_999 actually) => slope_ * x1_ can not overflow int256
|
|
// subtraction most extreme case would be 0 - max value slope_ * x1_ => can not underflow int256
|
|
constant_ = int256(y1_ * TWELVE_DECIMALS) - (slope_ * int256(x1_));
|
|
|
|
// calculating new borrow rate
|
|
// - slope_ max value is 65535 * 1e12,
|
|
// - utilization max value is let's say 500% (extreme case where borrow rate increases borrow amount without new supply)
|
|
// - constant max value is 65535 * 1e12
|
|
// so max values are 65535 * 1e12 * 50_000 + 65535 * 1e12 -> 3.2768*10^21, which easily fits int256
|
|
// divisor TWELVE_DECIMALS can not be 0
|
|
slope_ = (slope_ * int256(utilization_)) + constant_; // reusing `slope_` as variable for gas savings
|
|
if (slope_ < 0) {
|
|
revert FluidLiquidityCalcsError(ErrorTypes.LiquidityCalcs__BorrowRateNegative);
|
|
}
|
|
rate_ = uint256(slope_) / TWELVE_DECIMALS;
|
|
}
|
|
}
|
|
|
|
/// @dev reads the total supply out of Liquidity packed storage `totalAmounts_` for `supplyExchangePrice_`
|
|
function getTotalSupply(
|
|
uint256 totalAmounts_,
|
|
uint256 supplyExchangePrice_
|
|
) internal pure returns (uint256 totalSupply_) {
|
|
// totalSupply_ => supplyInterestFree
|
|
totalSupply_ = (totalAmounts_ >> LiquiditySlotsLink.BITS_TOTAL_AMOUNTS_SUPPLY_INTEREST_FREE) & X64;
|
|
totalSupply_ = (totalSupply_ >> DEFAULT_EXPONENT_SIZE) << (totalSupply_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
uint256 totalSupplyRaw_ = totalAmounts_ & X64; // no shifting as supplyRaw is first 64 bits
|
|
totalSupplyRaw_ = (totalSupplyRaw_ >> DEFAULT_EXPONENT_SIZE) << (totalSupplyRaw_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
// totalSupply = supplyInterestFree + supplyRawInterest normalized from raw
|
|
totalSupply_ += ((totalSupplyRaw_ * supplyExchangePrice_) / EXCHANGE_PRICES_PRECISION);
|
|
}
|
|
|
|
/// @dev reads the total borrow out of Liquidity packed storage `totalAmounts_` for `borrowExchangePrice_`
|
|
function getTotalBorrow(
|
|
uint256 totalAmounts_,
|
|
uint256 borrowExchangePrice_
|
|
) internal pure returns (uint256 totalBorrow_) {
|
|
// totalBorrow_ => borrowInterestFree
|
|
// no & mask needed for borrow interest free as it occupies the last bits in the storage slot
|
|
totalBorrow_ = (totalAmounts_ >> LiquiditySlotsLink.BITS_TOTAL_AMOUNTS_BORROW_INTEREST_FREE);
|
|
totalBorrow_ = (totalBorrow_ >> DEFAULT_EXPONENT_SIZE) << (totalBorrow_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
uint256 totalBorrowRaw_ = (totalAmounts_ >> LiquiditySlotsLink.BITS_TOTAL_AMOUNTS_BORROW_WITH_INTEREST) & X64;
|
|
totalBorrowRaw_ = (totalBorrowRaw_ >> DEFAULT_EXPONENT_SIZE) << (totalBorrowRaw_ & DEFAULT_EXPONENT_MASK);
|
|
|
|
// totalBorrow = borrowInterestFree + borrowRawInterest normalized from raw
|
|
totalBorrow_ += ((totalBorrowRaw_ * borrowExchangePrice_) / EXCHANGE_PRICES_PRECISION);
|
|
}
|
|
} |