2022-02-22 04:31:18 -08:00
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use anchor_lang::prelude::*;
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use fixed::types::I80F48;
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2022-02-26 03:04:42 -08:00
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use super::{IndexedPosition, TokenIndex};
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2022-02-23 01:15:33 -08:00
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2022-02-22 04:31:18 -08:00
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#[account(zero_copy)]
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2022-03-07 07:16:34 -08:00
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pub struct Bank {
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2022-02-26 03:17:20 -08:00
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pub group: Pubkey,
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pub mint: Pubkey,
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pub vault: Pubkey,
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2022-02-28 05:44:08 -08:00
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pub oracle: Pubkey,
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2022-02-26 03:17:20 -08:00
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2022-02-22 05:23:13 -08:00
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/// the index used to scale the value of an IndexedPosition
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2022-02-23 01:09:01 -08:00
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/// TODO: should always be >= 0, add checks?
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2022-02-22 05:23:13 -08:00
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pub deposit_index: I80F48,
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pub borrow_index: I80F48,
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2022-02-23 01:09:01 -08:00
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/// total deposits/borrows, for utilization
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pub indexed_total_deposits: I80F48,
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pub indexed_total_borrows: I80F48,
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2022-02-22 04:31:18 -08:00
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// todo: multi-leg interest
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// pub optimal_util: I80F48,
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// pub optimal_rate: I80F48,
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// pub max_rate: I80F48,
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2022-02-26 03:04:42 -08:00
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// This is a _lot_ of bytes (64) - seems unnecessary
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// (could maybe store them in one byte each, as an informal U1F7?
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// that could store values between 0-2 and converting to I80F48 would be a cheap expand+shift)
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pub maint_asset_weight: I80F48,
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pub init_asset_weight: I80F48,
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pub maint_liab_weight: I80F48,
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pub init_liab_weight: I80F48,
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2022-03-04 04:33:27 -08:00
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// Collection of all fractions-of-native-tokens that got rounded away
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pub dust: I80F48,
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// Index into TokenInfo on the group
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pub token_index: TokenIndex,
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}
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2022-03-07 07:16:34 -08:00
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impl Bank {
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2022-02-25 04:10:51 -08:00
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pub fn native_total_deposits(&self) -> I80F48 {
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self.deposit_index * self.indexed_total_deposits
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}
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2022-03-04 04:33:27 -08:00
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/// Returns whether the position is active
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pub fn deposit(&mut self, position: &mut IndexedPosition, native_amount: u64) -> bool {
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let mut native_amount = I80F48::from_num(native_amount);
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let native_position = position.native(self);
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if native_position.is_negative() {
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let new_native_position = native_position + native_amount;
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if new_native_position.is_negative() {
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// pay back borrows only, leaving a negative position
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let indexed_change = native_amount / self.borrow_index + I80F48::DELTA;
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self.indexed_total_borrows -= indexed_change;
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position.indexed_value += indexed_change;
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return true;
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} else if new_native_position < I80F48::ONE {
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// if there's less than one token deposited, zero the position
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self.dust += new_native_position;
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self.indexed_total_borrows += position.indexed_value;
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position.indexed_value = I80F48::ZERO;
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return false;
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}
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// pay back all borrows
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self.indexed_total_borrows += position.indexed_value; // position.value is negative
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position.indexed_value = I80F48::ZERO;
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// deposit the rest
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native_amount += native_position;
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}
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// add to deposits
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// Adding DELTA to amount/index helps because (amount/index)*index <= amount, but
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// we want to ensure that users can withdraw the same amount they have deposited, so
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// (amount/index + delta)*index >= amount is a better guarantee.
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let indexed_change = native_amount / self.deposit_index + I80F48::DELTA;
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self.indexed_total_deposits += indexed_change;
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position.indexed_value += indexed_change;
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true
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}
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/// Returns whether the position is active
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pub fn withdraw(&mut self, position: &mut IndexedPosition, native_amount: u64) -> bool {
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let mut native_amount = I80F48::from_num(native_amount);
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let native_position = position.native(self);
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if native_position.is_positive() {
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let new_native_position = native_position - native_amount;
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if !new_native_position.is_negative() {
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// withdraw deposits only
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if new_native_position < I80F48::ONE {
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// zero the account collecting the leftovers in `dust`
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self.dust += new_native_position;
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self.indexed_total_deposits -= position.indexed_value;
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position.indexed_value = I80F48::ZERO;
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return false;
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} else {
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// withdraw some deposits leaving >1 native token
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let indexed_change = native_amount / self.deposit_index;
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self.indexed_total_deposits -= indexed_change;
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position.indexed_value -= indexed_change;
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return true;
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}
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}
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// withdraw all deposits
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self.indexed_total_deposits -= position.indexed_value;
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position.indexed_value = I80F48::ZERO;
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// borrow the rest
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native_amount = -new_native_position;
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}
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// add to borrows
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let indexed_change = native_amount / self.borrow_index;
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self.indexed_total_borrows += indexed_change;
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position.indexed_value -= indexed_change;
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true
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}
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2022-02-22 04:31:18 -08:00
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}
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