Improved error reporting

examples/example.py

+#!/usr/bin/python3
+
+import moberg
+
+def scan():
+    result = [[], [], [], [], []]
+    m = moberg.Moberg()
+    for i, f in enumerate([m.analog_in, m.analog_out,
+                           m.digital_in, m.digital_out,
+                           m.encoder_in]):
+        for j in range(0, 100):
+            try:
+                result[i].append((j, f(j)))
+                pass
+            except:
+                pass
+            pass
+        pass
+    return result
+
+def main():
+    channels = scan()
+    for c in channels:
+        print(len(c))
+        pass
+    pass
+    
+if __name__ == '__main__':
+    main()

moberg_device.c

@@ -151,16 +151,22 @@ static struct moberg_status map(
   struct moberg_channel *channel)
 {
   struct moberg_status result = MOBERG_ERRNO(EINVAL);
- 
+
   if (device->range->kind != channel->kind) {
+    fprintf(stderr, "Mapping wrong kind of channel %d != %d\n",
+            device->range->kind, channel->kind);
     return MOBERG_ERRNO(EINVAL);
   }
   if (device->range->min > device->range->max) {
+    fprintf(stderr, "Mapping outside range %d > %d\n",
+            device->range->min, device->range->max);
     return MOBERG_ERRNO(ENOSPC);
   }
   result = add_channel(device, device->range->kind, device->range->min,
                        (union channel) { .channel=channel });
   if (! OK(result)) {
+    fprintf(stderr, "Failed to add channel kind=%d, index=%d\n",
+            device->range->kind, device->range->min);
     return result;
   }
   device->range->min++;