Merge pull request #4800 from dhalbert/too-many-hid-devices

Handle too many HID devices properly

Author: tannewt

shared-module/usb_hid/__init__.c

@@ -79,7 +79,7 @@ static const uint8_t usb_hid_descriptor_template[] = {
 static supervisor_allocation *hid_report_descriptor_allocation;
 static usb_hid_device_obj_t hid_devices[MAX_HID_DEVICES];
 // If 0, USB HID is disabled.
-static mp_int_t hid_devices_num;
+static mp_int_t num_hid_devices;
 
 // This tuple is store in usb_hid.devices.
 static mp_obj_tuple_t *hid_devices_tuple;
@@ -97,7 +97,7 @@ static mp_obj_tuple_t default_hid_devices_tuple = {
 };
 
 bool usb_hid_enabled(void) {
-    return hid_devices_num > 0;
+    return num_hid_devices > 0;
 }
 
 void usb_hid_set_defaults(void) {
@@ -140,13 +140,13 @@ size_t usb_hid_add_descriptor(uint8_t *descriptor_buf, descriptor_counts_t *desc
 // Make up a fresh tuple containing the device objects saved in the static
 // devices table. Save the tuple in usb_hid.devices.
 static void usb_hid_set_devices_from_hid_devices(void) {
-    mp_obj_t tuple_items[hid_devices_num];
-    for (mp_int_t i = 0; i < hid_devices_num; i++) {
+    mp_obj_t tuple_items[num_hid_devices];
+    for (mp_int_t i = 0; i < num_hid_devices; i++) {
         tuple_items[i] = &hid_devices[i];
     }
 
     // Remember tuple for gc purposes.
-    hid_devices_tuple = mp_obj_new_tuple(hid_devices_num, tuple_items);
+    hid_devices_tuple = mp_obj_new_tuple(num_hid_devices, tuple_items);
     usb_hid_set_devices(hid_devices_tuple);
 }
 
@@ -160,13 +160,15 @@ bool common_hal_usb_hid_enable(const mp_obj_t devices) {
         return false;
     }
 
-    hid_devices_num = MP_OBJ_SMALL_INT_VALUE(mp_obj_len(devices));
-    if (hid_devices_num > MAX_HID_DEVICES) {
+    const mp_int_t num_devices = MP_OBJ_SMALL_INT_VALUE(mp_obj_len(devices));
+    if (num_devices > MAX_HID_DEVICES) {
         mp_raise_ValueError_varg(translate("No more than %d HID devices allowed"), MAX_HID_DEVICES);
     }
 
+    num_hid_devices = num_devices;
+
     // Remember the devices in static storage so they live across VMs.
-    for (mp_int_t i = 0; i < hid_devices_num; i++) {
+    for (mp_int_t i = 0; i < num_hid_devices; i++) {
         // devices has already been validated to contain only usb_hid_device_obj_t objects.
         usb_hid_device_obj_t *device =
             MP_OBJ_TO_PTR(mp_obj_subscr(devices, MP_OBJ_NEW_SMALL_INT(i), MP_OBJ_SENTINEL));
@@ -183,20 +185,20 @@ void usb_hid_setup_devices(void) {
     usb_hid_set_devices_from_hid_devices();
 
     // Create report buffers on the heap.
-    for (mp_int_t i = 0; i < hid_devices_num; i++) {
+    for (mp_int_t i = 0; i < num_hid_devices; i++) {
         usb_hid_device_create_report_buffers(&hid_devices[i]);
     }
 }
 
 // Total length of the report descriptor, with all configured devices.
 size_t usb_hid_report_descriptor_length(void) {
     size_t total_hid_report_descriptor_length = 0;
-    for (mp_int_t i = 0; i < hid_devices_num; i++) {
+    for (mp_int_t i = 0; i < num_hid_devices; i++) {
         total_hid_report_descriptor_length += hid_devices[i].report_descriptor_length;
     }
 
     // Don't need space for a report id if there's only one device.
-    if (hid_devices_num == 1) {
+    if (num_hid_devices == 1) {
         total_hid_report_descriptor_length -= 2;
     }
     return total_hid_report_descriptor_length;
@@ -210,10 +212,10 @@ void usb_hid_build_report_descriptor(uint8_t *report_descriptor_space, size_t re
 
     uint8_t *report_descriptor_start = report_descriptor_space;
 
-    for (mp_int_t i = 0; i < hid_devices_num; i++) {
+    for (mp_int_t i = 0; i < num_hid_devices; i++) {
         usb_hid_device_obj_t *device = &hid_devices[i];
         // Copy the report descriptor for this device.
-        if (hid_devices_num == 1) {
+        if (num_hid_devices == 1) {
             // There's only one device, so it shouldn't have a report ID.
             // Copy the descriptor, but splice out the report id indicator and value (2 bytes).
             memcpy(report_descriptor_start, device->report_descriptor, device->report_id_index - 1);
@@ -258,13 +260,13 @@ void usb_hid_gc_collect(void) {
     gc_collect_ptr(hid_devices_tuple);
 
     // Mark any heap pointers in the static device list as in use.
-    for (mp_int_t i = 0; i < hid_devices_num; i++) {
+    for (mp_int_t i = 0; i < num_hid_devices; i++) {
         gc_collect_ptr(&hid_devices[i]);
     }
 }
 
 usb_hid_device_obj_t *usb_hid_get_device_with_report_id(uint8_t report_id) {
-    for (uint8_t i = 0; i < hid_devices_num; i++) {
+    for (uint8_t i = 0; i < num_hid_devices; i++) {
         usb_hid_device_obj_t *device = &hid_devices[i];
         if (device->report_id == report_id) {
             return &hid_devices[i];