add precision support for fixnums

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Corwin 2023-06-02 00:03:27 +01:00
parent da5aed83e3
commit 6e0d58a674
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@ -536,16 +536,44 @@ impl<I: FixedWidthUnsignedInteger, const N: usize> Display for Num<I, N> {
// //
// But if you think of a negative number, you'd like it to be `negative number - non negative fraction` // But if you think of a negative number, you'd like it to be `negative number - non negative fraction`
// So we have to add 1 to the integral bit, and take 1 - fractional bit // So we have to add 1 to the integral bit, and take 1 - fractional bit
if fractional != I::zero() && integral < I::zero() { let sign = if fractional != I::zero() && integral < I::zero() {
integral = integral + I::one(); integral = integral + I::one();
if integral == I::zero() {
// If the number is in the range (-1, 0), then we just bumped `integral` from -1 to 0,
// so we need to compensate for the missing negative sign.
write!(f, "-")?;
}
fractional = (I::one() << N) - fractional; fractional = (I::one() << N) - fractional;
-1
} else {
1
};
if let Some(precision) = f.precision() {
let precision_multiplier = I::from_as_i32(10_i32.pow(precision as u32));
let fractional_as_integer = fractional * precision_multiplier * I::ten();
let mut fractional_as_integer = fractional_as_integer >> N;
if fractional_as_integer % I::ten() >= I::from_as_i32(5) {
fractional_as_integer = fractional_as_integer + I::ten();
} }
let mut fraction_to_write = fractional_as_integer / I::ten();
if fraction_to_write >= precision_multiplier {
integral = integral + I::from_as_i32(sign);
fraction_to_write = fraction_to_write - precision_multiplier;
}
if sign == -1 && integral == I::zero() && fraction_to_write != I::zero() {
write!(f, "-")?;
}
write!(f, "{integral}")?;
if precision != 0 {
write!(f, ".{:#0width$}", fraction_to_write, width = precision)?;
}
} else {
if sign == -1 && integral == I::zero() {
write!(f, "-")?;
}
write!(f, "{integral}")?; write!(f, "{integral}")?;
if fractional != I::zero() { if fractional != I::zero() {
@ -557,6 +585,7 @@ impl<I: FixedWidthUnsignedInteger, const N: usize> Display for Num<I, N> {
write!(f, "{}", (fractional & !mask) >> N)?; write!(f, "{}", (fractional & !mask) >> N)?;
fractional = fractional & mask; fractional = fractional & mask;
} }
}
Ok(()) Ok(())
} }
@ -1066,6 +1095,35 @@ mod tests {
assert_eq!(format!("{d}"), "-0.25"); assert_eq!(format!("{d}"), "-0.25");
} }
#[test]
fn formats_precision_correctly() {
macro_rules! num_ {
($n: literal) => {{
let a: Num<i32, 20> = num!($n);
a
}};
}
assert_eq!(format!("{:.2}", num_!(1.2345678)), "1.23");
assert_eq!(format!("{:.2}", num_!(1.237)), "1.24");
assert_eq!(format!("{:.2}", num_!(-1.237)), "-1.24");
assert_eq!(format!("{:.2}", num_!(1.5)), "1.50");
assert_eq!(format!("{:.2}", num_!(1.05)), "1.05");
assert_eq!(format!("{:.2}", num_!(3.999)), "4.00");
assert_eq!(format!("{:.2}", num_!(-3.999)), "-4.00");
assert_eq!(format!("{:.2}", num_!(-0.999)), "-1.00");
assert_eq!(format!("{:.2}", num_!(0.999)), "1.00");
assert_eq!(format!("{:.2}", num_!(0.001)), "0.00");
assert_eq!(format!("{:.2}", num_!(-0.001)), "0.00");
assert_eq!(format!("{:.0}", num_!(-0.001)), "0");
assert_eq!(format!("{:.0}", num_!(-0.001)), "0");
}
#[test] #[test]
fn sqrt() { fn sqrt() {
for x in 1..1024 { for x in 1..1024 {