160 lines
5.5 KiB
Rust
160 lines
5.5 KiB
Rust
// Copyright © 2018–2019 Trevor Spiteri
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// This library is free software: you can redistribute it and/or
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// modify it under the terms of either
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//
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// * the Apache License, Version 2.0 or
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// * the MIT License
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//
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// at your option.
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//
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// You should have recieved copies of the Apache License and the MIT
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// License along with the library. If not, see
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// <https://www.apache.org/licenses/LICENSE-2.0> and
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// <https://opensource.org/licenses/MIT>.
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pub use crate::{float_helper::FloatHelper, int_helper::IntHelper};
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use crate::{
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types::extra::{LeEqU128, LeEqU16, LeEqU32, LeEqU64, LeEqU8},
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FixedI128, FixedI16, FixedI32, FixedI64, FixedI8, FixedU128, FixedU16, FixedU32, FixedU64,
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FixedU8,
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};
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use core::cmp::Ordering;
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// Unsigned can have 0 ≤ x < 2↑128, that is its msb can be 0 or 1.
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// Negative can have −2↑127 ≤ x < 0, that is its msb must be 1.
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pub enum Widest {
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Unsigned(u128),
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Negative(i128),
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}
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pub struct ToFixedHelper {
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pub(crate) bits: Widest,
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pub(crate) dir: Ordering,
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pub(crate) overflow: bool,
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}
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pub struct ToFloatHelper {
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pub(crate) neg: bool,
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pub(crate) abs: u128,
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}
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pub struct FromFloatHelper {
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pub(crate) kind: FloatKind,
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}
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pub enum FloatKind {
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NaN,
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Infinite { neg: bool },
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Finite { neg: bool, conv: ToFixedHelper },
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}
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pub trait Sealed: Copy {
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fn private_to_fixed_helper(self, dst_frac_nbits: u32, dst_int_nbits: u32) -> ToFixedHelper;
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fn private_to_float_helper(self) -> ToFloatHelper;
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fn private_saturating_from_float_helper(src: FromFloatHelper) -> Self;
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fn private_overflowing_from_float_helper(src: FromFloatHelper) -> (Self, bool);
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}
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macro_rules! impl_sealed {
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($Fixed:ident($LeEqU:ident, $Signedness:tt)) => {
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impl<Frac: $LeEqU> Sealed for $Fixed<Frac> {
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#[inline]
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fn private_to_fixed_helper(
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self,
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dst_frac_nbits: u32,
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dst_int_nbits: u32,
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) -> ToFixedHelper {
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self.to_bits().to_fixed_helper(
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Self::FRAC_NBITS as i32,
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dst_frac_nbits,
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dst_int_nbits,
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)
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}
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#[inline]
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fn private_to_float_helper(self) -> ToFloatHelper {
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let (neg, abs) = self.to_bits().neg_abs();
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let abs = abs.into();
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ToFloatHelper { neg, abs }
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}
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#[inline]
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fn private_saturating_from_float_helper(src: FromFloatHelper) -> Self {
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let neg = match src.kind {
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FloatKind::NaN => panic!("NaN"),
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FloatKind::Infinite { neg } => neg,
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FloatKind::Finite { neg, .. } => neg,
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};
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let saturated = if neg {
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Self::min_value()
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} else {
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Self::max_value()
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};
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let conv = match src.kind {
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FloatKind::Finite { conv, .. } => conv,
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_ => return saturated,
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};
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if conv.overflow {
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return saturated;
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}
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let bits = if_signed_unsigned! {
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$Signedness,
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match conv.bits {
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Widest::Unsigned(bits) => {
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let bits = bits as _;
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if bits < 0 {
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return Self::max_value();
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}
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bits
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}
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Widest::Negative(bits) => bits as _,
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},
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match conv.bits {
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Widest::Unsigned(bits) => bits as _,
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Widest::Negative(_) => return Self::min_value(),
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},
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};
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Self::from_bits(bits)
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}
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#[inline]
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fn private_overflowing_from_float_helper(src: FromFloatHelper) -> (Self, bool) {
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let conv = match src.kind {
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FloatKind::NaN => panic!("NaN"),
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FloatKind::Infinite { .. } => panic!("infinite"),
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FloatKind::Finite { conv, .. } => conv,
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};
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let mut new_overflow = false;
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let bits = if_signed_unsigned! {
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$Signedness,
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match conv.bits {
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Widest::Unsigned(bits) => {
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let bits = bits as _;
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if bits < 0 {
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new_overflow = true;
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}
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bits
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}
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Widest::Negative(bits) => bits as _,
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},
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match conv.bits {
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Widest::Unsigned(bits) => bits as _,
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Widest::Negative(bits) => {
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new_overflow = true;
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bits as _
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}
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},
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};
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(Self::from_bits(bits), conv.overflow || new_overflow)
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}
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}
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};
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}
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impl_sealed! { FixedI8(LeEqU8, Signed) }
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impl_sealed! { FixedI16(LeEqU16, Signed) }
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impl_sealed! { FixedI32(LeEqU32, Signed) }
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impl_sealed! { FixedI64(LeEqU64, Signed) }
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impl_sealed! { FixedI128(LeEqU128, Signed) }
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impl_sealed! { FixedU8(LeEqU8, Unsigned) }
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impl_sealed! { FixedU16(LeEqU16, Unsigned) }
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impl_sealed! { FixedU32(LeEqU32, Unsigned) }
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impl_sealed! { FixedU64(LeEqU64, Unsigned) }
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impl_sealed! { FixedU128(LeEqU128, Unsigned) }
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