hxd/core-decimal-calc
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use generics for float operations

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This commit is contained in:
Hexa Dust
2025-07-18 21:19:30 +01:00
parent cfee5d2214
commit cd6f9486f7
2 changed files with 133 additions and 101 deletions
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36
src/calc.rs
View File

@@ -1,6 +1,6 @@
use core::{convert::Infallible, fmt::Display};
use core::{convert::Infallible, fmt::Display, marker::PhantomData};
use num_traits::{PrimInt, Unsigned};
use num_traits::{float::FloatCore, PrimInt, Unsigned};
use crate::{Decimal, DecimalError};
@@ -22,16 +22,20 @@ impl Display for StackCalcError {
}
#[derive(Debug, Clone)]
pub struct StackCalc<const SS: usize = 2, const DS: usize = 5, E = u16> {
stack: [Decimal<DS, E>; SS],
pub struct StackCalc<F: FloatCore, const STACK: usize = 2, const DSIZE: usize = 5, EXP = u16> {
stack: [Decimal<DSIZE, EXP>; STACK],
index: usize,
phantom: PhantomData<F>,
}
impl<const SS: usize, const DS: usize, E: PrimInt> Default for StackCalc<SS, DS, E> {
impl<F: FloatCore, const STACK: usize, const DSIZE: usize, EXP: PrimInt> Default
for StackCalc<F, STACK, DSIZE, EXP>
{
fn default() -> Self {
StackCalc {
stack: [Decimal::default(); SS],
stack: [Decimal::default(); STACK],
index: 0,
phantom: PhantomData,
}
}
}
@@ -48,12 +52,14 @@ impl From<Infallible> for StackCalcError {
}
}
impl<const SS: usize, const DS: usize, E: PrimInt + Unsigned> StackCalc<SS, DS, E> {
impl<F: FloatCore, const STACK: usize, const DSIZE: usize, EXP: PrimInt + Unsigned>
StackCalc<F, STACK, DSIZE, EXP>
{
pub fn push(
&mut self,
val: impl TryInto<Decimal<DS, E>, Error: Into<StackCalcError>>,
val: impl TryInto<Decimal<DSIZE, EXP>, Error: Into<StackCalcError>>,
) -> Result<(), StackCalcError> {
if self.index == SS {
if self.index == STACK {
return Err(StackCalcError::StackOverflow);
}
self.stack[self.index] = val.try_into().map_err(Into::into)?;
@@ -61,7 +67,7 @@ impl<const SS: usize, const DS: usize, E: PrimInt + Unsigned> StackCalc<SS, DS,
Ok(())
}
pub fn pop(&mut self) -> Result<Decimal<DS, E>, StackCalcError> {
pub fn pop(&mut self) -> Result<Decimal<DSIZE, EXP>, StackCalcError> {
if self.index == 0 {
return Err(StackCalcError::StackUnderflow);
}
@@ -69,12 +75,12 @@ impl<const SS: usize, const DS: usize, E: PrimInt + Unsigned> StackCalc<SS, DS,
Ok(self.stack[self.index])
}
pub fn add(&mut self) -> Result<Decimal<DS, E>, StackCalcError> {
pub fn add(&mut self) -> Result<Decimal<DSIZE, EXP>, StackCalcError> {
let a = self.pop()?;
let b = self.pop()?;
let a = f32::try_from(a)?;
let b = f32::try_from(b)?;
let res = Decimal::try_from(a + b)?;
let a = a.to_float::<F>()?;
let b = b.to_float::<F>()?;
let res = Decimal::from_float(a + b)?;
self.push(res)?;
Ok(res)
}
@@ -85,7 +91,7 @@ mod tests {
use super::*;
#[test]
fn test_add() -> Result<(), StackCalcError> {
let mut calc = StackCalc::<3, 7>::default();
let mut calc = StackCalc::<f64, 3, 7>::default();
calc.push(Decimal::default())?;
calc.push(1337.42)?;
assert_eq!(calc.add()?, Decimal::try_from(1337.42)?);

198
src/lib.rs
View File

@@ -3,7 +3,6 @@
pub mod calc;
use core::fmt::Display;
#[cfg(not(test))]
use num_traits::float::FloatCore;
use num_traits::{one, zero, PrimInt, Unsigned};
@@ -23,30 +22,102 @@ impl Display for DecimalError {
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Decimal<const S: usize = 5, E = u16> {
pub struct Decimal<const SIZE: usize = 5, EXP = u16> {
pub minus: bool,
pub significant: [u8; S],
pub significant: [u8; SIZE],
pub minus_exponent: bool,
pub exponent: E,
pub exponent: EXP,
}
impl<const S: usize, E: PrimInt> Default for Decimal<S, E> {
impl<const SIZE: usize, EXP: PrimInt + Unsigned> Decimal<SIZE, EXP> {
pub fn from_float<F: FloatCore>(mut f: F) -> Result<Decimal<SIZE, EXP>, DecimalError> {
if !f.is_finite() {
return Err(DecimalError::NotANumber);
}
let minus = f.is_sign_negative();
if minus {
f = f * F::from(-1).unwrap();
}
let mut exponent: EXP = zero();
let minus_exponent = f < one() && f > zero();
while f > F::from(10).unwrap() {
f = f / F::from(10).unwrap();
exponent = exponent
.checked_add(&one())
.ok_or(DecimalError::ExponentOverflow)?;
}
while f < one() {
if f == f * F::from(10).unwrap() {
break;
}
f = f * F::from(10).unwrap();
exponent = exponent
.checked_add(&one())
.ok_or(DecimalError::ExponentOverflow)?;
}
let mut significant = [0; SIZE];
for i in 0..SIZE {
let s = f.trunc().to_u8().unwrap();
f = f * F::from(10).unwrap();
f = f - F::from(s * 10).ok_or(DecimalError::ExponentOverflow)?;
debug_assert!(s < 10);
significant[i] = s;
}
Ok(Decimal {
minus,
significant,
minus_exponent,
exponent,
})
}
pub fn to_float<F: FloatCore>(&self) -> Result<F, DecimalError> {
let Decimal {
minus,
significant,
minus_exponent,
exponent,
} = *self;
let mut e = exponent.to_i32().ok_or(DecimalError::ExponentOverflow)?;
if minus_exponent {
e = -e;
}
let e = F::from(10).unwrap().powi(e);
let mut f: F = zero();
for i in (0..SIZE).rev() {
f = f / F::from(10).unwrap();
let s = significant[i];
f = f + F::from(s).unwrap() * e;
}
if minus {
f = f * F::from(-1).unwrap();
}
Ok(f)
}
}
impl<const SIZE: usize, EXP: PrimInt> Default for Decimal<SIZE, EXP> {
fn default() -> Self {
Decimal {
minus: false,
significant: [0; S],
significant: [0; SIZE],
minus_exponent: false,
exponent: zero(),
}
}
}
impl<const S: usize, E: Display> Display for Decimal<S, E> {
impl<const SIZE: usize, EXP: Display> Display for Decimal<SIZE, EXP> {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
if self.minus {
write!(f, "-")?;
}
for i in 0..S {
for i in 0..SIZE {
write!(f, "{}", self.significant[i])?;
if i == 0 {
write!(f, ".")?;
@@ -60,80 +131,35 @@ impl<const S: usize, E: Display> Display for Decimal<S, E> {
}
}
impl<const S: usize, E: PrimInt + Unsigned> TryFrom<f32> for Decimal<S, E> {
impl<const SIZE: usize, EXP: PrimInt + Unsigned> TryFrom<f32> for Decimal<SIZE, EXP> {
type Error = DecimalError;
fn try_from(mut f: f32) -> Result<Self, Self::Error> {
if !f.is_finite() {
return Err(DecimalError::NotANumber);
}
let minus = f.is_sign_negative();
if minus {
f *= -1.0;
}
let mut exponent: E = zero();
let minus_exponent = f < 1.0 && f > 0.0;
while f > 10.0 {
f /= 10.0;
exponent = exponent
.checked_add(&one())
.ok_or(DecimalError::ExponentOverflow)?;
}
while f < 1.0 {
if f == f * 10.0 {
break;
}
f *= 10.0;
exponent = exponent
.checked_add(&one())
.ok_or(DecimalError::ExponentOverflow)?;
}
let mut significant = [0; S];
for i in 0..S {
let s = f as u8;
f *= 10.0;
f -= (s * 10) as f32;
significant[i] = s;
}
Ok(Decimal {
minus,
significant,
minus_exponent,
exponent,
})
fn try_from(f: f32) -> Result<Self, Self::Error> {
Self::from_float(f)
}
}
impl<const S: usize, E: PrimInt + Unsigned> TryFrom<Decimal<S, E>> for f32 {
impl<const SIZE: usize, EXP: PrimInt + Unsigned> TryFrom<f64> for Decimal<SIZE, EXP> {
type Error = DecimalError;
fn try_from(val: Decimal<S, E>) -> Result<Self, Self::Error> {
let Decimal {
minus,
significant,
minus_exponent,
exponent,
} = val;
fn try_from(f: f64) -> Result<Self, Self::Error> {
Self::from_float(f)
}
}
let mut e = exponent.to_i32().ok_or(DecimalError::ExponentOverflow)?;
if minus_exponent {
e = -e;
}
let e = 10.0f32.powi(e);
impl<const SIZE: usize, EXP: PrimInt + Unsigned> TryFrom<Decimal<SIZE, EXP>> for f32 {
type Error = DecimalError;
let mut f: f32 = 0.0;
fn try_from(val: Decimal<SIZE, EXP>) -> Result<Self, Self::Error> {
val.to_float()
}
}
for i in (0..S).rev() {
f /= 10.0;
let s = significant[i];
f += (s as f32) * e;
}
impl<const SIZE: usize, EXP: PrimInt + Unsigned> TryFrom<Decimal<SIZE, EXP>> for f64 {
type Error = DecimalError;
if minus {
f *= -1.0;
}
Ok(f)
fn try_from(val: Decimal<SIZE, EXP>) -> Result<Self, Self::Error> {
val.to_float()
}
}
@@ -189,13 +215,13 @@ mod tests {
#[test]
fn float_to_decimal_nan() {
let err = Decimal::<7>::try_from(f32::NAN).unwrap_err();
let err = Decimal::<7>::try_from(f64::NAN).unwrap_err();
assert!(matches!(err, DecimalError::NotANumber));
}
#[test]
fn float_to_decimal_max() {
let dec = Decimal::<7>::try_from(f32::MAX).unwrap();
let dec = Decimal::<7>::try_from(f64::MAX).unwrap();
assert!(!dec.minus);
assert_eq!(dec.significant, [1, 7, 9, 7, 6, 9, 3]);
assert!(!dec.minus_exponent);
@@ -204,13 +230,13 @@ mod tests {
#[test]
fn float_to_decimal_max_overflow() {
let err = Decimal::<7, u8>::try_from(f32::MAX).unwrap_err();
let err = Decimal::<7, u8>::try_from(f64::MAX).unwrap_err();
assert!(matches!(err, DecimalError::ExponentOverflow));
}
#[test]
fn float_to_decimal_min() {
let dec = Decimal::<7>::try_from(f32::MIN).unwrap();
let dec = Decimal::<7>::try_from(f64::MIN).unwrap();
assert!(dec.minus);
assert_eq!(dec.significant, [1, 7, 9, 7, 6, 9, 3]);
assert!(!dec.minus_exponent);
@@ -219,13 +245,13 @@ mod tests {
#[test]
fn float_to_decimal_min_overflow() {
let err = Decimal::<7, u8>::try_from(f32::MIN).unwrap_err();
let err = Decimal::<7, u8>::try_from(f64::MIN).unwrap_err();
assert!(matches!(err, DecimalError::ExponentOverflow));
}
#[test]
fn float_to_decimal_epsilon() {
let dec = Decimal::<7>::try_from(f32::EPSILON).unwrap();
let dec = Decimal::<7>::try_from(f64::EPSILON).unwrap();
assert!(!dec.minus);
assert_eq!(dec.significant, [2, 2, 2, 0, 4, 4, 6]);
assert!(dec.minus_exponent);
@@ -235,7 +261,7 @@ mod tests {
#[test]
fn decimal_to_float_zero() {
let dec = Decimal::<5, u8>::default();
assert_eq!(f32::try_from(dec).unwrap(), 0.0);
assert_eq!(f64::try_from(dec).unwrap(), 0.0);
}
#[test]
@@ -243,16 +269,16 @@ mod tests {
let mut dec = Decimal::<7, u8>::default();
dec.significant = [1, 3, 3, 7, 4, 2, 0];
dec.exponent = 3;
assert_eq!(f32::try_from(dec).unwrap(), 1337.42);
assert_eq!(f64::try_from(dec).unwrap(), 1337.42);
}
#[test]
fn decimal_to_float_small() {
let mut dec = Decimal::<7, u8>::default();
dec.significant = [1, 3, 3, 7, 4, 2, 0];
dec.significant = [1, 3, 3, 7, 4, 2, 1];
dec.minus_exponent = true;
dec.exponent = 2;
assert_eq!(f32::try_from(dec).unwrap(), 0.0133742);
assert_eq!(f64::try_from(dec).unwrap(), 0.01337421);
}
#[test]
@@ -261,24 +287,24 @@ mod tests {
dec.minus = true;
dec.significant = [1, 3, 3, 7, 4, 2, 0];
dec.exponent = 3;
assert_eq!(f32::try_from(dec).unwrap(), -1337.42);
assert_eq!(f64::try_from(dec).unwrap(), -1337.42);
}
#[test]
fn decimal_to_float_neg_small() {
let mut dec = Decimal::<7, u8>::default();
dec.minus = true;
dec.significant = [1, 3, 3, 7, 4, 2, 0];
dec.significant = [1, 3, 3, 7, 4, 2, 1];
dec.minus_exponent = true;
dec.exponent = 2;
assert_eq!(f32::try_from(dec).unwrap(), -0.0133742);
assert_eq!(f64::try_from(dec).unwrap(), -0.01337421);
}
#[test]
#[ignore = "not working due to precission issues"]
fn decimal_to_float_max() {
let dec = Decimal::<16>::try_from(f32::MAX).unwrap();
assert_eq!(f32::try_from(dec).unwrap(), f32::MAX);
let dec = Decimal::<16>::try_from(f64::MAX).unwrap();
assert_eq!(f64::try_from(dec).unwrap(), f64::MAX);
}
#[test]