Function try_alp_encode

nodedb-codec/src/alp.rs:291–313

(value: f64, factor: f64, decode_exp: u8, mode: DecodeMode)

/// Returns `Some(i64)` if the value round-trips exactly, `None` otherwise.
#[inline]
fn try_alp_encode(value: f64, factor: f64, decode_exp: u8, mode: DecodeMode) -> Option<i64> {
    if !value.is_finite() {
        return None;
    }

    let scaled = value * factor;
    if scaled < i64::MIN as f64 || scaled > i64::MAX as f64 {
        return None;
    }

    let encoded = scaled.round() as i64;

    let decoded = match mode {
        DecodeMode::MultiplyInverse => encoded as f64 * INV_POW10[decode_exp as usize],
        DecodeMode::DivideByFactor => encoded as f64 / POW10[decode_exp as usize],
    };

    if decoded.to_bits() == value.to_bits() {
        Some(encoded)
    } else {
        None
    }
}

/// Reconstruct a single f64 from an ALP-encoded integer.
#[inline]