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use core::{ops::Range, ptr};
use awint_internals::*;
use const_fn::const_fn;
use crate::Bits;
/// # Bitwise
impl Bits {
/// Zero-assigns. Same as the Unsigned-minimum-value. All bits are set to 0.
#[const_fn(cfg(feature = "const_support"))]
pub const fn zero_(&mut self) {
unsafe { self.digit_set(false, 0..self.total_digits(), false) }
}
/// Unsigned-maximum-value-assigns. All bits are set to 1.
#[const_fn(cfg(feature = "const_support"))]
pub const fn umax_(&mut self) {
unsafe { self.digit_set(true, 0..self.total_digits(), true) }
}
/// Signed-maximum-value-assigns. All bits are set to 1, except for the most
/// significant bit.
#[const_fn(cfg(feature = "const_support"))]
pub const fn imax_(&mut self) {
unsafe { self.digit_set(true, 0..self.total_digits(), false) }
*self.last_mut() = (MAX >> 1) >> self.unused();
}
/// Signed-minimum-value-assigns. Only the most significant bit is set.
#[const_fn(cfg(feature = "const_support"))]
pub const fn imin_(&mut self) {
unsafe { self.digit_set(false, 0..self.total_digits(), false) }
*self.last_mut() = (IDigit::MIN as Digit) >> self.unused();
}
/// Unsigned-one-assigns. Only the least significant bit is set. The
/// unsigned distinction is important, because a positive one value does
/// not exist for signed integers with a bitwidth of 1.
#[const_fn(cfg(feature = "const_support"))]
pub const fn uone_(&mut self) {
unsafe { self.digit_set(false, 0..self.total_digits(), false) }
*self.first_mut() = 1;
}
/// Not-assigns `self`
#[const_fn(cfg(feature = "const_support"))]
pub const fn not_(&mut self) {
unsafe_for_each_mut!(self, x, { *x = !*x }, true);
}
/// Copy-assigns the bits of `rhs` to `self`
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn copy_(&mut self, rhs: &Self) -> Option<()> {
if self.bw() != rhs.bw() {
return None
}
unsafe {
ptr::copy_nonoverlapping(rhs.as_ptr(), self.as_mut_ptr(), self.total_digits());
}
Some(())
}
/// Or-assigns `rhs` to `self`
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn or_(&mut self, rhs: &Self) -> Option<()> {
unsafe_binop_for_each_mut!(self, rhs, x, y, { *x |= y }, false)
}
/// And-assigns `rhs` to `self`
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn and_(&mut self, rhs: &Self) -> Option<()> {
unsafe_binop_for_each_mut!(self, rhs, x, y, { *x &= y }, false)
}
/// Xor-assigns `rhs` to `self`
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn xor_(&mut self, rhs: &Self) -> Option<()> {
unsafe_binop_for_each_mut!(self, rhs, x, y, { *x ^= y }, false)
}
/// Or-assigns a range of ones to `self`. An empty or reversed range does
/// nothing to `self`. `None` is returned if `range.start > self.bw()`
/// or `range.end > self.bw()`.
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn range_or_(&mut self, range: Range<usize>) -> Option<()> {
if range.start > self.bw() || range.end > self.bw() {
return None
}
// see `range_and_` for why we chose this
if range.start >= range.end {
return Some(())
}
let start = digits_u(range.start);
let end = digits_u(range.end);
let start_bits = extra_u(range.start);
let end_bits = extra_u(range.end);
// Safety: the early `None` return above prevents any out of bounds indexing.
unsafe {
// set all digits in the full digit range
if (start + 1) < end {
self.digit_set(true, (start + 1)..end, false);
}
match (end_bits == 0, start == end) {
(false, false) => {
*self.get_unchecked_mut(start) |= MAX << start_bits;
*self.get_unchecked_mut(end) |= MAX >> (BITS - end_bits);
}
(false, true) => {
// The range is entirely contained in one digit
*self.get_unchecked_mut(start) |=
(MAX << start_bits) & (MAX >> (BITS - end_bits));
}
(true, _) => {
// Avoid overshift from `(BITS - end_bits)`
*self.get_unchecked_mut(start) |= MAX << start_bits;
}
}
}
Some(())
}
/// And-assigns a range of ones to `self`. Useful for masking. An empty or
/// reversed range zeroes `self`. `None` is returned if `range.start >
/// self.bw()` or `range.end > self.bw()`.
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn range_and_(&mut self, range: Range<usize>) -> Option<()> {
if range.start > self.bw() || range.end > self.bw() {
return None
}
// Originally, I considered returning `None` when `range.start == self.bw()` to
// make things more strict, but I quickly found a case where this made things
// awkard for the [Bits::field] test in `multi_bw.rs`. If the width of the field
// being copied was equal to the bitwidth, a `range_and_` would have an
// input range of `self.bw()..self.bw()`. This zeros `self` as intended because
// of the natural `range.start >= range.end` check.
if range.start >= range.end {
self.zero_();
return Some(())
}
let start = digits_u(range.start);
let end = digits_u(range.end);
let start_bits = extra_u(range.start);
let end_bits = extra_u(range.end);
// Safety: the early `None` return above prevents any out of bounds indexing.
unsafe {
// zero all digits up to the start of the range
self.digit_set(false, 0..start, false);
match (end_bits == 0, start == end) {
(false, false) => {
*self.get_unchecked_mut(start) &= MAX << start_bits;
*self.get_unchecked_mut(end) &= MAX >> (BITS - end_bits);
}
(false, true) => {
// The range is entirely contained in one digit
*self.get_unchecked_mut(start) &=
(MAX << start_bits) & (MAX >> (BITS - end_bits));
}
(true, _) => {
// Avoid overshift from `(BITS - end_bits)`
*self.get_unchecked_mut(start) &= MAX << start_bits;
// zero the end
if end < self.total_digits() {
*self.get_unchecked_mut(end) = 0;
}
}
}
// zero the rest of the digits
if (end + 1) < self.total_digits() {
self.digit_set(false, (end + 1)..self.total_digits(), false);
}
}
Some(())
}
/// Xor-assigns a range of ones to `self`. An empty or reversed range does
/// nothing to `self`. `None` is returned if `range.start > self.bw()`
/// or `range.end > self.bw()`.
#[const_fn(cfg(feature = "const_support"))]
#[must_use]
pub const fn range_xor_(&mut self, range: Range<usize>) -> Option<()> {
if range.start > self.bw() || range.end > self.bw() {
return None
}
// see `range_and_` for why we chose this
if range.start >= range.end {
return Some(())
}
let start = digits_u(range.start);
let end = digits_u(range.end);
let start_bits = extra_u(range.start);
let end_bits = extra_u(range.end);
// Safety: the early `None` return above prevents any out of bounds indexing.
unsafe {
// set all digits in the full digit range
if (start + 1) < end {
const_for!(i in {(start + 1)..end} {
*self.get_unchecked_mut(i) ^= MAX;
});
}
match (end_bits == 0, start == end) {
(false, false) => {
*self.get_unchecked_mut(start) ^= MAX << start_bits;
*self.get_unchecked_mut(end) ^= MAX >> (BITS - end_bits);
}
(false, true) => {
// The range is entirely contained in one digit
*self.get_unchecked_mut(start) ^=
(MAX << start_bits) & (MAX >> (BITS - end_bits));
}
(true, _) => {
// Avoid overshift from `(BITS - end_bits)`
*self.get_unchecked_mut(start) ^= MAX << start_bits;
}
}
}
Some(())
}
/// Or-assigns `rhs` to `self` at a position `shl`. Set bits of `rhs` that
/// are shifted beyond the bitwidth of `self` are truncated.
#[const_fn(cfg(feature = "const_support"))]
pub const fn digit_or_(&mut self, rhs: Digit, shl: usize) {
if shl >= self.bw() {
return
}
// Safety: `digits < self.total_digits()` because of the above check. The
// `digits + 1` index is checked.
let bits = extra_u(shl);
let digits = digits_u(shl);
unsafe {
if bits == 0 {
*self.get_unchecked_mut(digits) |= rhs;
} else {
*self.get_unchecked_mut(digits) |= rhs << bits;
if (digits + 1) < self.total_digits() {
*self.get_unchecked_mut(digits + 1) |= rhs >> (BITS - bits);
}
}
}
}
}