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use core::{
borrow::BorrowMut,
fmt,
fmt::Debug,
hash::{Hash, Hasher},
num::NonZeroUsize,
ops::{Deref, DerefMut},
};
use awint_core::{awint_internals::Digit, Bits};
use crate::ExtAwi;
/// Fixed-Point Type, containing signedness, bitwidth, and fixed point
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub struct FPType {
pub signed: bool,
pub bw: NonZeroUsize,
pub fp: isize,
}
impl FPType {
// TODO: when adding `unique_min_integer_digits` add a note for the user to
// handle the sign indicator by making space for a ' ' character.
/// Returns the minimum number of digits in a given `radix` needed for
/// unique representation of the fraction part of this fixed point type.
/// This function performs allocation. Returns `None` if `radix < 2`.
#[must_use]
pub fn unique_min_fraction_digits(&self, radix: u8) -> Option<usize> {
if radix < 2 {
return None
}
if self.fp <= 0 {
return Some(0)
}
let mut test = ExtAwi::uone(NonZeroUsize::new(self.fp.unsigned_abs()).unwrap());
let mut digits = 0;
loop {
digits += 1;
if test.digit_cin_mul_(0, radix as Digit) != 0 {
// as soon as overflow happens, that means
// `(((radix^digits) * 1 ULP) >> this.fp()) > 0`
break
}
}
Some(digits)
}
}
/// Fixed-Point generic struct for `B` that implement `Borrow<Bits>` and
/// `BorrowMut<Bits>`. Adds on signedness and fixed-point information.
/// Implements many traits if `B` also implements them.
///
/// In order to make many operations infallible, `self.fp().unsigned_abs()` and
/// `self.bw()` follow an invariant that they are never greater than
/// `usize::MAX >> 2`.
///
/// NOTE: `B` should not change the bitwidth of the underlying `Bits` during the
/// lifetime of the `FP` struct unless the invariants are upheld. Otherwise,
/// panics and arithmetic errors can occur. Preferably, `into_b` and `FP::new`
/// should be used to create a fresh struct.
pub struct FP<B: BorrowMut<Bits>> {
signed: bool,
fp: isize,
bits: B,
}
// TODO we will probably store the signed and reversimal bits in the 2 lsb bits
// of `fp`
impl<B: BorrowMut<Bits>> FP<B> {
/// Creates a fixed-point generic `FP<B>` from a specified signedness
/// `signed`, wrapped value `B`, and fixed point `fp`. This returns `None`
/// if `bits.bw()` or `fp.unsigned_abs()` are greater than
/// `usize::MAX >> 2`.
#[inline]
pub fn new(signed: bool, bits: B, fp: isize) -> Option<Self> {
if (bits.borrow().bw() > (usize::MAX >> 2)) || (fp.unsigned_abs() > (usize::MAX >> 2)) {
None
} else {
Some(Self { signed, fp, bits })
}
}
/// Consumes `this`, returning the inner `B`
#[inline]
pub fn into_b(self) -> B {
self.bits
}
/// Returns a reference to the `B` in `self`
#[inline]
pub fn b(&self) -> &B {
&self.bits
}
/// Returns a mutable reference to the `B` in `self`
#[inline]
pub fn b_mut(&mut self) -> &mut B {
&mut self.bits
}
/// Returns the signedness of `self`
#[inline]
pub fn signed(&self) -> bool {
self.signed
}
/// Returns the sign of `self`, returning `Some(self.msb())`
/// if `self.signed()`, and `None` otherwise.
#[inline]
pub fn sign(&self) -> Option<bool> {
if self.signed() {
Some(self.msb())
} else {
None
}
}
/// Returns if `self.signed() && self.msb()`
#[inline]
pub fn is_negative(&self) -> bool {
self.signed() && self.msb()
}
/// Returns the bitwidth of `self` as a `NonZeroUsize`
#[inline]
pub fn nzbw(&self) -> NonZeroUsize {
self.b().borrow().nzbw()
}
/// Returns the bitwidth of `self` as a `usize`
#[inline]
pub fn bw(&self) -> usize {
self.b().borrow().bw()
}
/// Returns the bitwidth of `self` as an `isize`
#[inline]
pub fn ibw(&self) -> isize {
// this is ok because of the guard in `FP::new`
self.bw() as isize
}
/// Returns the fixed point of `self`
#[inline]
pub fn fp(&self) -> isize {
self.fp
}
/// Returns the `FPType` of `self`. Because `FPType` impls `PartialEq`, this
/// is useful for quickly determining if two different `FP`s have the same
/// fixed point type.
#[inline]
pub fn fp_ty(&self) -> FPType {
FPType {
signed: self.signed(),
fp: self.fp(),
bw: self.nzbw(),
}
}
/// Sets the fixed point of `self`. Returns `None` if `fp.unsigned_abs()` is
/// greater than `usize::MAX >> 2`.
pub fn set_fp(&mut self, fp: isize) -> Option<()> {
if fp.unsigned_abs() > (usize::MAX >> 2) {
None
} else {
self.fp = fp;
Some(())
}
}
}
impl<B: BorrowMut<Bits>> Deref for FP<B> {
type Target = Bits;
#[inline]
fn deref(&self) -> &Self::Target {
self.b().borrow()
}
}
impl<B: BorrowMut<Bits>> DerefMut for FP<B> {
#[inline]
fn deref_mut(&mut self) -> &mut Bits {
self.b_mut().borrow_mut()
}
}
impl<B: Clone + BorrowMut<Bits>> Clone for FP<B> {
fn clone(&self) -> Self {
Self {
signed: self.signed,
fp: self.fp,
bits: self.bits.clone(),
}
}
}
impl<B: Copy + BorrowMut<Bits>> Copy for FP<B> {}
impl<B: PartialEq + BorrowMut<Bits>> PartialEq for FP<B> {
/// The signedness, fixed point, and `PartialEq` implementation on
/// [FP::into_b] must all be `true` in order for this to return
/// `true`
fn eq(&self, rhs: &Self) -> bool {
(self.signed == rhs.signed) && (self.fp == rhs.fp) && (self.bits == rhs.bits)
}
}
impl<B: PartialEq + Eq + BorrowMut<Bits>> Eq for FP<B> {}
macro_rules! impl_fmt {
($($ty:ident, $radix_str:expr, $radix:expr, $upper:expr);*;) => {
$(
/// Note: `max_ufp` for the internal [FP::to_str_general] call
/// is set to 4096, if it results in an overflow then the
/// formatting is a no-op rather than causing `format!` to panic.
impl<B: fmt::$ty + BorrowMut<Bits>> fmt::$ty for FP<B> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if let Ok((integer, fraction)) =
FP::to_str_general(self, $radix, $upper, 1, 1, 4096) {
let sign = if self.is_negative() {
"-"
} else {
""
};
let signed = if self.signed() {
'i'
} else {
'u'
};
f.write_fmt(format_args!(
"{}{}{}.{}_{}{}f{}",
sign,
$radix_str,
integer,
fraction,
signed,
self.bw(),
self.fp()
))
} else {
// else no-op, it would be really bad
// if `format!` could panic on numerics
Ok(())
}
}
}
)*
};
}
impl_fmt!(
Debug, "", 10, false;
Display, "", 10, false;
LowerHex, "0x", 16, false;
UpperHex, "0x", 16, true;
Octal, "0o", 8, false;
Binary, "0b", 2, false;
);
impl<B: Hash + BorrowMut<Bits>> Hash for FP<B> {
/// Uses the hash of `self.signed()`, `self.fp()`, and the `Hash`
/// implementation on `self.b()` (not `self.as_ref()`)
fn hash<H: Hasher>(&self, state: &mut H) {
self.signed.hash(state);
self.fp.hash(state);
// should include other state that `B` might have
self.bits.hash(state);
}
}