libfxlink: add status functions to avoid looking into fdev fields

fxlink/tui/tui-interactive.c

@@ -469,8 +469,8 @@ bool TUI_core_update(bool allow_console, bool auto_refresh, bool *has_command)
             struct fxlink_device *fdev = &TUI.devices.devices[i];
 
             /* Check for devices ready to connect to */
-            if(fdev->status == FXLINK_FDEV_STATUS_IDLE && fdev->comm
-                    && fdev->comm->ep_bulk_IN != 0xff) {
+            if(fxlink_device_ready_to_connect(fdev)
+            && fxlink_device_has_fxlink_interface(fdev)) {
                 if(fxlink_device_claim_fxlink(fdev))
                     fxlink_device_start_bulk_IN(fdev);
             }

libfxlink/cmake/FindLibFxlink.cmake

@@ -1,6 +1,5 @@
 # Locate the library file and includes
 
-message("test: $ENV{HOME}/.local/lib $ENV{FXSDK_PATH}/lib")
 find_library(
   LIBFXLINK_PATH "fxlink"
   HINTS "$ENV{HOME}/.local/lib" "$ENV{FXSDK_PATH}/lib"

libfxlink/devices.c

@@ -280,10 +280,23 @@ void fxlink_device_analysis_2(struct fxlink_device *fdev)
     fdev->status = FXLINK_FDEV_STATUS_IDLE;
 }
 
+bool fxlink_device_ready_to_connect(struct fxlink_device const *fdev)
+{
+    bool status = (fdev->status == FXLINK_FDEV_STATUS_IDLE) ||
+                  (fdev->status == FXLINK_FDEV_STATUS_CONNECTED);
+    return fdev->calc && fdev->comm && status;
+}
+
+bool fxlink_device_has_fxlink_interface(struct fxlink_device const *fdev)
+{
+    return fdev->calc && fdev->comm && (fdev->comm->ep_bulk_IN != 0xff);
+}
+
 bool fxlink_device_claim_fxlink(struct fxlink_device *fdev)
 {
-    /* Only connect to calculators with an fxlink interface */
-    if(!fdev->comm || fdev->status != FXLINK_FDEV_STATUS_IDLE)
+    if(!fxlink_device_ready_to_connect(fdev) ||
+       !fxlink_device_has_fxlink_interface(fdev) ||
+       fdev->comm->claimed)
         return false;
 
     /* Allocate transfer data */

libfxlink/include/fxlink/devices.h

@@ -195,6 +195,16 @@ struct fxlink_comm {
     bool cancelled_OUT;
 };
 
+/* Check whether the device is ready to have interfaces claimed. This function
+   only checks that the device is a calculator and could be opened; it doesn't
+   guarantee that claiming the interfaces will succeed. This function returns
+   true even after an interface has been claimed since multiple interfaces can
+   be claimed at the same time. */
+bool fxlink_device_ready_to_connect(struct fxlink_device const *fdev);
+
+/* Check whether the device exposes an fxlink interface. */
+bool fxlink_device_has_fxlink_interface(struct fxlink_device const *fdev);
+
 /* Claim the fxlink interface (for a device that has one). Returns false and
    sets the status to ERROR on failure. */
 bool fxlink_device_claim_fxlink(struct fxlink_device *fdev);