Function parse_custom_mantissa

pub fn parse_custom_mantissa<'s, E>(
    input: &'s [u8],
    nbits: usize,
) -> IResult<&[u8], f32, E>
where
    E: ParseError<&'s [u8]> + Debug,

Some Double_* values are saved with a custom mantissa… The number of bytes can be found in the comment string of the generated YAML code (for ALICE ESD files at least). This function reconstructs a float from the exponent and mantissa