Integer wrapping around rather than negative value

[JulianWgs]

A minimal dbc-file:

VERSION "A version string"

BA_ "SingleFrame" BO_ 2364539904 0;

BO_ 643 Message: 8 Vector__XXX
 SG_ Signal : 32|16@1- (1,0) [0|0] "" Vector__XXX

Rust code:

extern crate canparse;
// use std::env;

use canparse::pgn::{PgnLibrary, SpnDefinition, ParseMessage};

fn main() {
    let dbc_filename = "test.dbc";
    let msg_name = "Signal";

    // Parse dbc file into PgnLibrary
    let lib = PgnLibrary::from_dbc_file(dbc_filename).unwrap();

    // Pull signal definition for engine speed
    let enginespeed_def: &SpnDefinition = lib
        .get_spn(msg_name).unwrap();

    // Parse frame containing engine speed
    let msg: [u8; 8] = [0x00, 0x01, 0x00, 0x00, 0xcb, 0xff, 0x02, 0x00];
    let engine_speed = enginespeed_def.parse_message(&msg).unwrap();

    println!("Engine speed: {}", engine_speed);
}

Output:

Engine speed: 65483

But the correct value should be 65483 - 2**16=-53, which cantools correctly decodes.

[jmagnuson]

Ugh, thanks. I should really write more unit tests 🤦