0xfnzero
85d2c602f3
calculate_with_slippage_sell previously fell through to the branch that returned 1 when amount <= basis_points/10_000, which is true for amount=0 and typical bps values—yielding a bogus minimum of 1. Short-circuit on zero input so sell quotes stay correct. Co-authored-by: Cursor <cursoragent@cursor.com>
84 lines
2.6 KiB
Rust
84 lines
2.6 KiB
Rust
/// Calculate transaction fee based on amount and fee basis points
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///
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/// # Parameters
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/// * `amount` - Transaction amount
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/// * `fee_basis_points` - Fee basis points, 1 basis point = 0.01%
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///
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/// # Examples
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/// * fee_basis_points = 1 -> 0.01% fee
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/// * fee_basis_points = 10 -> 0.1% fee
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/// * fee_basis_points = 25 -> 0.25% fee (common exchange rate)
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/// * fee_basis_points = 100 -> 1% fee
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#[inline(always)]
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pub const fn compute_fee(amount: u128, fee_basis_points: u128) -> u128 {
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ceil_div(amount * fee_basis_points, 10_000)
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}
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/// Ceiling division implementation
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/// Ceiling division that ensures results are not lost due to integer division precision
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///
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/// # Parameters
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/// * `a` - Dividend
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/// * `b` - Divisor
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///
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/// # Returns
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/// Returns the ceiling result of a/b
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#[inline(always)]
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pub const fn ceil_div(a: u128, b: u128) -> u128 {
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(a + b - 1) / b
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}
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/// Maximum slippage in basis points (99.99% = 9999 bps)
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/// This prevents the wrap amount from doubling when slippage is 100%
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pub const MAX_SLIPPAGE_BASIS_POINTS: u64 = 9999;
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/// Calculate buy amount with slippage protection
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/// Add slippage percentage to the amount to ensure successful purchase
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///
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/// # Parameters
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/// * `amount` - Original transaction amount
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/// * `basis_points` - Slippage basis points, 1 basis point = 0.01%
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///
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/// # Examples
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/// * basis_points = 1 -> 0.01% slippage
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/// * basis_points = 10 -> 0.1% slippage
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/// * basis_points = 100 -> 1% slippage
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/// * basis_points = 500 -> 5% slippage
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///
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/// # Note
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/// Basis points are clamped to MAX_SLIPPAGE_BASIS_POINTS (9999 = 99.99%)
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/// to prevent the amount from doubling when basis_points = 10000.
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#[inline(always)]
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pub const fn calculate_with_slippage_buy(amount: u64, basis_points: u64) -> u64 {
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let bps = if basis_points > MAX_SLIPPAGE_BASIS_POINTS {
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MAX_SLIPPAGE_BASIS_POINTS
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} else {
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basis_points
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};
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amount + (amount * bps / 10000)
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}
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/// Calculate sell amount with slippage protection
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/// Subtract slippage percentage from the amount to ensure successful sale
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///
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/// # Parameters
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/// * `amount` - Original transaction amount
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/// * `basis_points` - Slippage basis points, 1 basis point = 0.01%
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///
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/// # Examples
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/// * basis_points = 1 -> 0.01% slippage
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/// * basis_points = 10 -> 0.1% slippage
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/// * basis_points = 100 -> 1% slippage
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/// * basis_points = 500 -> 5% slippage
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#[inline(always)]
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pub const fn calculate_with_slippage_sell(amount: u64, basis_points: u64) -> u64 {
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if amount == 0 {
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return 0;
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}
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if amount <= basis_points / 10000 {
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1
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} else {
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amount - (amount * basis_points / 10000)
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}
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}
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