usbstack: Revise usb string descriptor table to use enum values for indices

This makes it possible for macros of conditionally included string
descriptors to get a correct index no matter what other usb drivers
are enabled or disabled due to the nature behavior of enums.

Change-Id: I8ccebbd316605bed0f5d90b6b73fab4a333c02fa

2 files changed, 17 insertions, 10 deletions

diff --git a/firmware/export/usb_core.h b/firmware/export/usb_core.h
index 75fafc06a8..78a80435e1 100644
--- a/firmware/export/usb_core.h
+++ b/firmware/export/usb_core.h
@@ -39,6 +39,14 @@
 
 extern int usb_max_pkt_size;
 
+enum {
+    USB_STRING_INDEX_LANGUAGE,
+    USB_STRING_INDEX_MANUFACTURER,
+    USB_STRING_INDEX_PRODUCT,
+    USB_STRING_INDEX_SERIAL,
+    USB_STRING_INDEX_MAX,
+};
+
 struct usb_class_driver;
 
 void usb_core_init(void);
diff --git a/firmware/usbstack/usb_core.c b/firmware/usbstack/usb_core.c
index 65bf7293c8..50d93f7561 100644
--- a/firmware/usbstack/usb_core.c
+++ b/firmware/usbstack/usb_core.c
@@ -90,9 +90,9 @@ static struct usb_device_descriptor __attribute__((aligned(2)))
     .idVendor           = USB_VENDOR_ID,
     .idProduct          = USB_PRODUCT_ID,
     .bcdDevice          = 0x0100,
-    .iManufacturer      = 1,
-    .iProduct           = 2,
-    .iSerialNumber      = 3,
+    .iManufacturer      = USB_STRING_INDEX_MANUFACTURER,
+    .iProduct           = USB_STRING_INDEX_PRODUCT,
+    .iSerialNumber      = USB_STRING_INDEX_SERIAL,
     .bNumConfigurations = 1
 } ;
 
@@ -141,12 +141,12 @@ static const struct usb_string_descriptor __attribute__((aligned(2)))
                                     lang_descriptor =
 USB_STRING_INITIALIZER(u"\x0409"); /* LANGID US English */
 
-static const struct usb_string_descriptor* const usb_strings[] =
+static const struct usb_string_descriptor* const usb_strings[USB_STRING_INDEX_MAX] =
 {
-   &lang_descriptor,
-   &usb_string_iManufacturer,
-   &usb_string_iProduct,
-   &usb_string_iSerial
+    [USB_STRING_INDEX_LANGUAGE] = &lang_descriptor,
+    [USB_STRING_INDEX_MANUFACTURER] = &usb_string_iManufacturer,
+    [USB_STRING_INDEX_PRODUCT] = &usb_string_iProduct,
+    [USB_STRING_INDEX_SERIAL] = &usb_string_iSerial,
 };
 
 static int usb_address = 0;
@@ -637,8 +637,7 @@ static void request_handler_device_get_descriptor(struct usb_ctrlrequest* req)
 
         case USB_DT_STRING:
             logf("STRING %d", index);
-            if((unsigned)index < (sizeof(usb_strings) /
-                        sizeof(struct usb_string_descriptor*))) {
+            if((unsigned)index < USB_STRING_INDEX_MAX) {
                 size = usb_strings[index]->bLength;
                 ptr = usb_strings[index];
             }