From 835bf50b80715f3eb0828d4cbfd2a644bfc4902e Mon Sep 17 00:00:00 2001
From: Vladan Popovic <vladanovic@gmail.com>
Date: Mon, 20 Jun 2022 00:06:44 +0200
Subject: [PATCH] use saturating sub for timeouts, it overflowed at some point

---
 src/modem.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/modem.rs b/src/modem.rs
index 51da832..e019ca0 100644
--- a/src/modem.rs
+++ b/src/modem.rs
@@ -62,7 +62,7 @@ impl<UART: serial::Uart> Iterator for IterableRx<UART> {
                         break None
                     }
                     thread::sleep(Duration::from_millis(200));
-                    self.timeout = Some(timeout - now.elapsed());
+                    self.timeout = Some(timeout.saturating_sub(now.elapsed()));
                 }
             }
         }
@@ -140,7 +140,7 @@ impl<UART: serial::Uart> Modem<UART> {
         let match_text: String = contains.unwrap_or("\n".to_string());
 
         loop {
-            let rdln = self.read_line(start + timeout - Instant::now());
+            let rdln = self.read_line(timeout.saturating_sub(start.elapsed()));
             if let Ok(line) = rdln {
                 println!("Read {} bytes from serial ({})", line.len(), line);
                 response.push_str(&line);