450 lines
12 KiB
Rust
450 lines
12 KiB
Rust
//! Fixed point numbers.
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use std::{fmt::{self, Write}, ops::*};
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macro_rules! fixed_ref_unop {
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(impl $imp:ident, $method:ident for $t:ty) => {
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impl $imp for &$t
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{
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type Output = <$t as $imp>::Output;
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#[inline]
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fn $method(self) -> <$t as $imp>::Output {$imp::$method(*self)}
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}
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};
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}
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macro_rules! fixed_ref_binop {
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(impl $imp:ident, $method:ident for $t:ty, $u:ty) => {
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impl<'a> $imp<$u> for &'a $t
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{
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type Output = <$t as $imp<$u>>::Output;
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#[inline]
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fn $method(self, other: $u) -> <$t as $imp<$u>>::Output
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{
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$imp::$method(*self, other)
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}
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}
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impl<'a> $imp<&'a $u> for $t
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{
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type Output = <$t as $imp<$u>>::Output;
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#[inline]
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fn $method(self, other: &'a $u) -> <$t as $imp<$u>>::Output
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{
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$imp::$method(self, *other)
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}
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}
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impl<'a, 'b> $imp<&'a $u> for &'b $t
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{
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type Output = <$t as $imp<$u>>::Output;
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#[inline]
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fn $method(self, other: &'a $u) -> <$t as $imp<$u>>::Output
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{
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$imp::$method(*self, *other)
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}
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}
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};
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}
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macro_rules! fixed_ref_op_assign {
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(impl $imp:ident, $method:ident for $t:ty, $u:ty) => {
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impl<'a> $imp<&'a $u> for $t
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{
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#[inline]
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fn $method(&mut self, other: &'a $u) {$imp::$method(self, *other);}
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}
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};
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}
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macro_rules! define_fixed_types {
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(
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$(
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$(#[$outer:meta])*
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struct $t:ident ( $ti:ident, $bytes:expr ) :
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$tu:ident, $frac_bits:expr; $test:ident
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)*
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) => {$(
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$(#[$outer])*
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#[derive(Copy, Clone, Default, PartialEq, PartialOrd, serde::Serialize)]
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pub struct $t($ti);
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impl $t
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{
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/// The number of fractional bits in this type.
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#[inline]
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pub const fn frac_bits() -> $tu {$frac_bits}
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/// The unsigned mask for the fractional bits.
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#[inline]
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pub const fn frac_mask() -> $tu {(1 << $t::frac_bits()) - 1}
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/// The integer mask for the fractional bits.
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#[inline]
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pub const fn frac_mask_i() -> $ti {(1 << $t::frac_bits()) - 1}
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/// The representation of `1.0` in this type.
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#[inline]
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pub const fn one() -> $tu {1 << $t::frac_bits()}
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/// Returns the largest value that can be represented.
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#[inline]
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pub const fn max_value() -> $t {$t($ti::max_value())}
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/// Returns the smallest value that can be represented.
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#[inline]
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pub const fn min_value() -> $t {$t($ti::min_value())}
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/// Returns the integer part of a number.
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#[inline]
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pub const fn trunc(self) -> $t {$t(self.0 & !$t::frac_mask_i())}
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/// Returns the fractional part of a number.
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#[inline]
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pub const fn fract(self) -> $t {$t(self.0 & $t::frac_mask_i())}
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/// Returns the number of ones in the bit representation of self.
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#[inline]
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pub fn count_ones(self) -> u32 {self.0.count_ones()}
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/// Returns the number of zeros in the bit representation of self.
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#[inline]
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pub fn count_zeros(self) -> u32 {self.0.count_zeros()}
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/// Returns the number of leading zeros in the bit representation of
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/// self.
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#[inline]
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pub fn leading_zeros(self) -> u32 {self.0.leading_zeros()}
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/// Returns the number of trailing zeros in the bit representation of
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/// self.
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#[inline]
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pub fn trailing_zeros(self) -> u32 {self.0.trailing_zeros()}
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/// Rotates all bits left by `n`.
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#[inline]
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pub fn rotate_left(self, n: u32) -> $t {$t(self.0.rotate_left(n))}
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/// Rotates all bits right by `n`.
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#[inline]
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pub fn rotate_right(self, n: u32) -> $t {$t(self.0.rotate_right(n))}
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/// Reverses the byte order of the bit representation of self.
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#[inline]
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pub fn swap_bytes(self) -> $t {$t(self.0.swap_bytes())}
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/// Raises self to the power of `exp`.
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#[inline]
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pub fn pow(self, exp: u32) -> $t {$t(self.0.pow(exp))}
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/// Returns the absolute value of self.
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#[inline]
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pub fn abs(self) -> $t {$t(self.0.abs())}
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/// Returns a number representing sign of self.
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#[inline]
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pub fn signum(self) -> $t {$t(self.0.signum() << $t::frac_bits())}
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/// Returns true if self is positive and false if the number is zero
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/// or negative.
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#[inline]
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pub fn is_positive(self) -> bool {self.0.is_positive()}
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/// Returns true if self is negative and false if the number is zero
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/// or positive.
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#[inline]
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pub fn is_negative(self) -> bool {self.0.is_negative()}
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/// Return the memory representation of this integer as a byte array
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/// in big-endian (network) byte order.
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#[inline]
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pub fn to_be_bytes(self) -> [u8; $bytes] {self.0.to_be_bytes()}
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/// Return the memory representation of this integer as a byte array
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/// in little-endian byte order.
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#[inline]
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pub fn to_le_bytes(self) -> [u8; $bytes] {self.0.to_le_bytes()}
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/// Return the memory representation of this integer as a byte array
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/// in native byte order.
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#[inline]
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pub fn to_ne_bytes(self) -> [u8; $bytes] {self.0.to_ne_bytes()}
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/// Create a value from its representation as a byte array in
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/// big-endian byte order.
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#[inline]
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pub fn from_be_bytes(b: [u8; $bytes]) -> $t
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{
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$t($ti::from_be_bytes(b))
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}
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/// Create a value from its representation as a byte array in
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/// little-endian byte order.
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#[inline]
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pub fn from_le_bytes(b: [u8; $bytes]) -> $t
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{
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$t($ti::from_le_bytes(b))
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}
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/// Create a value from its representation as a byte array in
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/// native byte order.
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#[inline]
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pub fn from_ne_bytes(b: [u8; $bytes]) -> $t
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{
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$t($ti::from_ne_bytes(b))
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}
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/// Creates a value of this type with the bit pattern `bits`.
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#[inline]
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pub const fn from_bits(bits: $tu) -> $t {$t(bits as $ti)}
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/// Creates a value of this type with the integral portion `n`.
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#[inline]
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pub const fn from_int(n: $ti) -> $t {$t(n << $t::frac_bits())}
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/// Returns the raw bit pattern.
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#[inline]
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pub fn to_bits(self) -> $tu {self.0 as $tu}
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/// Sets the raw bit pattern to `bits`.
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#[inline]
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pub fn set_bits(&mut self, bits: $tu) {self.0 = bits as $ti}
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#[inline]
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const fn mul_i(x: $ti, y: $ti) -> $ti {x * y}
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#[inline]
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const fn div_i(x: $ti, y: $ti) -> $ti {x / y}
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#[inline]
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fn div_k(x: $ti, y: $ti) -> $ti
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{
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(i64::from(x) * i64::from($t::one()) / i64::from(y)) as $ti
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}
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#[inline]
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fn mul_k(x: $ti, y: $ti) -> $ti
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{
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(i64::from(x) * i64::from(y) / i64::from($t::one())) as $ti
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}
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}
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#[cfg(test)]
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mod $test {
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use super::$t;
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#[test]
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fn basic_ops()
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{
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let one = $t::one();
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let two = 2 << $t::frac_bits();
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let twelve = 12 << $t::frac_bits();
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assert_eq!(($t::from(1) + $t::from(1)).to_bits(), two);
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assert_eq!(($t::from(2) - $t::from(1)).to_bits(), one);
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assert_eq!(($t::from(6) * $t::from(2)).to_bits(), twelve);
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assert_eq!(($t::from(6) * 2) .to_bits(), twelve);
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}
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#[test]
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fn fractions()
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{
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let three_pt_5 = 3 << $t::frac_bits() | $t::one() / 2;
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let one_pt_2 = 1 << $t::frac_bits() | $t::one() / 5;
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let two_pt_4 = one_pt_2 * 2;
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assert_eq!(($t::from(7) / $t::from(2)) .to_bits(), three_pt_5);
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assert_eq!(($t::from(7) / 2) .to_bits(), three_pt_5);
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assert_eq!(($t::from_bits(one_pt_2) * 2).to_bits(), two_pt_4);
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}
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#[test]
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fn printing()
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{
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assert_eq!(format!("{}", $t::from(6)), "6.0");
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assert_eq!(format!("{:2.3}", $t::from(7) / 2), " 3.500");
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}
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}
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impl From<$ti> for $t
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{
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#[inline]
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fn from(n: $ti) -> $t {$t::from_int(n)}
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}
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impl Add<$t> for $t
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{
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type Output = $t;
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#[inline]
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fn add(self, o: $t) -> $t {$t(self.0 + o.0)}
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}
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fixed_ref_binop! {impl Add, add for $t, $t}
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impl Sub<$t> for $t
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{
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type Output = $t;
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#[inline]
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fn sub(self, o: $t) -> $t {$t(self.0 - o.0)}
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}
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fixed_ref_binop! {impl Sub, sub for $t, $t}
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impl Mul<$t> for $t
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{
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type Output = $t;
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#[inline]
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fn mul(self, o: $t) -> $t {$t($t::mul_k(self.0, o.0))}
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}
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fixed_ref_binop! {impl Mul, mul for $t, $t}
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impl Mul<$ti> for $t
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{
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type Output = $t;
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#[inline]
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fn mul(self, o: $ti) -> $t {$t($t::mul_i(self.0, o))}
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}
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fixed_ref_binop! {impl Mul, mul for $t, $ti}
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impl Div<$t> for $t
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{
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type Output = $t;
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#[inline]
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fn div(self, o: $t) -> $t {$t($t::div_k(self.0, o.0))}
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}
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fixed_ref_binop! {impl Div, div for $t, $t}
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impl Div<$ti> for $t
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{
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type Output = $t;
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#[inline]
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fn div(self, o: $ti) -> $t {$t($t::div_i(self.0, o))}
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}
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fixed_ref_binop! {impl Div, div for $t, $ti}
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impl Neg for $t
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{
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type Output = $t;
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#[inline]
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fn neg(self) -> $t {$t(-self.0)}
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}
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fixed_ref_unop! {impl Neg, neg for $t}
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impl Not for $t
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{
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type Output = $t;
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#[inline]
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fn not(self) -> $t {$t(!self.0)}
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}
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fixed_ref_unop! {impl Not, not for $t}
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impl AddAssign for $t
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{
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#[inline]
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fn add_assign(&mut self, other: $t) {self.0 += other.0}
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}
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fixed_ref_op_assign! {impl AddAssign, add_assign for $t, $t}
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impl SubAssign for $t
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{
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#[inline]
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fn sub_assign(&mut self, other: $t) {self.0 -= other.0}
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}
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fixed_ref_op_assign! {impl SubAssign, sub_assign for $t, $t}
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impl MulAssign for $t
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{
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#[inline]
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fn mul_assign(&mut self, other: $t) {self.0 = (*self * other).0}
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}
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fixed_ref_op_assign! {impl MulAssign, mul_assign for $t, $t}
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impl DivAssign for $t
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{
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#[inline]
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fn div_assign(&mut self, other: $t) {self.0 = (*self / other).0}
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}
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fixed_ref_op_assign! {impl DivAssign, div_assign for $t, $t}
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impl fmt::Display for $t
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{
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
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{
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let prec = f.precision().unwrap_or(1);
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let widt = f.width().unwrap_or(0);
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write!(f, "{:widt$}.", self.0 >> $t::frac_bits(), widt = widt)?;
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let mut k = self.to_bits();
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for _ in 0..prec {
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k &= $t::frac_mask();
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k *= 10;
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let d = k >> $t::frac_bits();
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let d = d % 10;
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f.write_char(char::from(d as u8 + b'0'))?;
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}
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Ok(())
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}
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}
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impl fmt::Debug for $t
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{
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
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{
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fmt::Display::fmt(self, f)
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}
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}
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)*};
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}
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define_fixed_types! {
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/// A fixed point type representing an angle.
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///
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/// The format of this type is `0.9s`, but because of the implementation,
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/// the real format is `7.9s`.
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struct Angle(i16, 2) : u16, 9; angle_tests
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/// A fixed point type representing a world unit.
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///
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/// The format of this type is `5.10s`. This has caused eternal suffering.
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struct Unit(i16, 2) : u16, 10; unit_tests
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/// A generic fixed point type.
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///
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/// The format of this type is `15.16s`.
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struct Fixed(i32, 4) : u32, 16; fixed_tests
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}
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#[test]
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#[should_panic]
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#[allow(unused_must_use)]
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fn fixed_overflow() {Fixed::from(i16::max_value() as i32) + Fixed::from(1);}
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// EOF
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