#[inline(never)]
/// Split a float at the decimal point, for use with integeral-to-string
/// heapless no_std conversions, like `numtoa`.
fn split_at_decimal(v: f32, precision: u8) -> (u16, u16) {
    let multiplier = 10_i8.pow(precision as u32); // 10^decimal precision
    let rhs = v % 1.;

    ((v - rhs) as u16, (rhs * multiplier as f32).round() as u16)
}

#[inline(never)]
/// Process a float into a pair of strings: left of decimal, right of decimal.
fn float_to_strs<'a>(
    v: f32,
    buffer_l: &'a mut [u8],
    buffer_r: &'a mut [u8],
    precision: u8,
) -> (&'a str, &'a str) {
    let (lhs, rhs) = split_at_decimal(v, precision);
    let result_l = lhs.numtoa_str(10, buffer_l);
    let result_r = rhs.numtoa_str(10, buffer_r);

    (result_l, result_r)
}

#[inline(never)]
/// Process a float into a &str.
pub fn float_to_str<'a>(
    v: f32,
    buff_l: &'a mut [u8],
    buff_r: &'a mut [u8],
    buff_result: &'a mut [u8],
    precision: u8,
) -> usize {
    let (l, r) = float_to_strs(v, buff_l, buff_r, precision);

    // todo: This works, but is awk. Have it return the str if able, and
    // todo not require the post-processing. Running into ownership(?) issues.

    let mut i = 0;
    for c in l.as_bytes() {
        buff_result[i] = *c;
        i += 1;
    }
    buff_result[i] = ".".as_bytes()[0];
    i += 1;
    for c in r.as_bytes() {
        buff_result[i] = *c;
        i += 1;
    }
    (l.len() + 1 + r.len()) as usize
}

Dominoes fucked around with this message at 01:03 on Jun 1, 2020

my_float.to_string()

format!("some var: {}", my_float)

Dominoes fucked around with this message at 01:11 on Jun 1, 2020

Dominoes fucked around with this message at 01:46 on Jun 1, 2020

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Ambrose Burnside fucked around with this message at 04:02 on Jun 4, 2020