Allow elapsed time to go negative so that NMEA line reader can detect

timeouts correctly.

diff --git a/gbser_posix.c b/gbser_posix.c
index afbc5ba6666e9736082c25c684b5447d3b9f3b6c..6e398c13f5f18c28d370e6ebb5a030f351d3aafe 100644 (file)
--- a/gbser_posix.c
+++ b/gbser_posix.c
@@ -404,8 +404,9 @@ int gbser_read_line(void *handle, void *buf,
     get_time(&tv);
     bp[pos] = '\0';
     for (;;) {
-        unsigned time_left = ms - elapsed(&tv);
+        signed time_left = ms - elapsed(&tv);
         int c;
+
         if (time_left <= 0) {
             return gbser_TIMEOUT;
         }