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use num::basic::signeds::PrimitiveSigned;
use num::basic::unsigneds::PrimitiveUnsigned;
use num::logic::traits::BitAccess;
fn get_bit_unsigned<T: PrimitiveUnsigned>(x: &T, index: u64) -> bool {
index < T::WIDTH && *x & T::power_of_2(index) != T::ZERO
}
fn set_bit_unsigned<T: PrimitiveUnsigned>(x: &mut T, index: u64) {
if index < T::WIDTH {
*x |= T::power_of_2(index);
} else {
panic!(
"Cannot set bit {} in non-negative value of width {}",
index,
T::WIDTH
);
}
}
fn clear_bit_unsigned<T: PrimitiveUnsigned>(x: &mut T, index: u64) {
if index < T::WIDTH {
*x &= !T::power_of_2(index);
}
}
macro_rules! impl_bit_access_unsigned {
($t:ident) => {
impl BitAccess for $t {
/// Determines whether the $i$th bit of an unsigned primitive integer, or the
/// coefficient of $2^i$ in its binary expansion, is 0 or 1.
///
/// `false` means 0 and `true` means 1. Getting bits beyond the type's width is allowed;
/// those bits are false.
///
/// Let
/// $$
/// n = \sum_{i=0}^\infty 2^{b_i},
/// $$
/// where for all $i$, $b_i\in \\{0, 1\\}$; so finitely many of the bits are 1, and the
/// rest are 0. Then $f(n, j) = (b_j = 1)$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::bit_access#get_bit).
#[inline]
fn get_bit(&self, index: u64) -> bool {
get_bit_unsigned(self, index)
}
/// Sets the $i$th bit of an unsigned primitive integer, or the coefficient of $2^i$ in
/// its binary expansion, to 1.
///
/// Setting bits beyond the type's width is disallowed.
///
/// Let
/// $$
/// n = \sum_{i=0}^{W-1} 2^{b_i},
/// $$
/// where for all $i$, $b_i\in \\{0, 1\\}$, and $W$ is the width of the type. Then
/// $$
/// n \gets \\begin{cases}
/// n + 2^j & \text{if} \\quad b_j = 0, \\\\
/// n & \text{otherwise},
/// \\end{cases}
/// $$
/// where $j < W$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if $i \geq W$, where $i$ is `index` and $W$ is `$t::WIDTH`.
///
/// # Examples
/// See [here](super::bit_access#set_bit).
#[inline]
fn set_bit(&mut self, index: u64) {
set_bit_unsigned(self, index)
}
/// Sets the $i$th bit of an unsigned primitive integer, or the coefficient of $2^i$ in
/// its binary expansion, to 0.
///
/// Clearing bits beyond the type's width is allowed; since those bits are already
/// `false`, clearing them does nothing.
///
/// Let
/// $$
/// n = \sum_{i=0}^{W-1} 2^{b_i},
/// $$
/// where for all $i$, $b_i\in \\{0, 1\\}$, and $W$ is the width of the type. Then
/// $$
/// n \gets \\begin{cases}
/// n - 2^j & \text{if} \\quad b_j = 1, \\\\
/// n & \text{otherwise}.
/// \\end{cases}
/// $$
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::bit_access#clear_bit).
#[inline]
fn clear_bit(&mut self, index: u64) {
clear_bit_unsigned(self, index)
}
}
};
}
apply_to_unsigneds!(impl_bit_access_unsigned);
fn get_bit_signed<T: PrimitiveSigned>(x: &T, index: u64) -> bool {
if index < T::WIDTH {
*x & (T::ONE << index) != T::ZERO
} else {
*x < T::ZERO
}
}
fn set_bit_signed<T: PrimitiveSigned>(x: &mut T, index: u64) {
if index < T::WIDTH {
*x |= T::ONE << index;
} else if *x >= T::ZERO {
panic!(
"Cannot set bit {} in non-negative value of width {}",
index,
T::WIDTH
);
}
}
fn clear_bit_signed<T: PrimitiveSigned>(x: &mut T, index: u64) {
if index < T::WIDTH {
*x &= !(T::ONE << index);
} else if *x < T::ZERO {
panic!(
"Cannot clear bit {} in negative value of width {}",
index,
T::WIDTH
);
}
}
macro_rules! impl_bit_access_signed {
($t:ident) => {
impl BitAccess for $t {
/// Determines whether the $i$th bit of a signed primitive integer is 0 or 1.
///
/// `false` means 0 and `true` means 1. Getting bits beyond the type's width is allowed;
/// those bits are `true` if the value is negative, and `false` otherwise.
///
/// If $n \geq 0$, let
/// $$
/// n = \sum_{i=0}^\infty 2^{b_i},
/// $$
/// where for all $i$, $b_i\in \\{0, 1\\}$; so finitely many of the bits are 1, and the
/// rest are 0. Then $f(n, i) = (b_i = 1)$.
///
/// If $n < 0$, let
/// $$
/// 2^W + n = \sum_{i=0}^{W-1} 2^{b_i},
/// $$
/// where
/// - $W$ is the type's width
/// - for all $i$, $b_i\in \\{0, 1\\}$, and $b_i = 1$ for $i \geq W$.
///
/// Then $f(n, j) = (b_j = 1)$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::bit_access#get_bit).
#[inline]
fn get_bit(&self, index: u64) -> bool {
get_bit_signed(self, index)
}
/// Sets the $i$th bit of a signed primitive integer to 1.
///
/// Setting bits beyond the type's width is disallowed if the number is non-negative.
///
/// If $n \geq 0$ and $j \neq W - 1$, let
/// $$
/// n = \sum_{i=0}^{W-1} 2^{b_i};
/// $$
/// but if $n < 0$ or $j = W - 1$, let
/// $$
/// 2^W + n = \sum_{i=0}^{W-1} 2^{b_i},
/// $$
/// where for all $i$, $b_i\in \\{0, 1\\}$, and $W$ is the width of the type. Then
/// $$
/// n \gets \\begin{cases}
/// n + 2^j & \text{if} \\quad b_j = 0, \\\\
/// n & \text{otherwise},
/// \\end{cases}
/// $$
/// where $n < 0$ or $j < W$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if $n \geq 0$ and $i \geq W$, where $n$ is `self`, $i$ is `index` and $W$ is
/// the width of the type.
///
/// # Examples
/// See [here](super::bit_access#set_bit).
#[inline]
fn set_bit(&mut self, index: u64) {
set_bit_signed(self, index)
}
/// Sets the $i$th bit of a signed primitive integer to 0.
///
/// Clearing bits beyond the type's width is disallowed if the number is negative.
///
/// If $n \geq 0$ or $j = W - 1$, let
/// $$
/// n = \sum_{i=0}^{W-1} 2^{b_i};
/// $$
/// but if $n < 0$ or $j = W - 1$, let
/// $$
/// 2^W + n = \sum_{i=0}^{W-1} 2^{b_i},
/// $$
/// where for all $i$, $b_i\in \\{0, 1\\}$ and $W$ is the width of the type. Then
/// $$
/// n \gets \\begin{cases}
/// n - 2^j & \text{if} \\quad b_j = 1, \\\\
/// n & \text{otherwise},
/// \\end{cases}
/// $$
/// where $n \geq 0$ or $j < W$.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Panics
/// Panics if $n < 0$ and $i \geq W$, where $n$ is `self`, $i$ is `index` and $W$ is
/// the width of the type.
///
/// # Examples
/// See [here](super::bit_access#clear_bit).
#[inline]
fn clear_bit(&mut self, index: u64) {
clear_bit_signed(self, index)
}
}
};
}
apply_to_signeds!(impl_bit_access_signed);