Duplicate GD32 `uint16_t*` cast workaround from KeyboardioHID

This is slightly different than the original to make it easier to revert once
the bug is fixed.  I used block comments so that the original lines could be
preserved as-is, and reverting the change only requires the removal of the lines
added for the workaround.

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

src/kaleidoscope/driver/hid/keyboardio/usb/BootKeyboard/BootKeyboard.cpp

@@ -194,7 +194,22 @@ bool BootKeyboard_::setup(USBSetup& setup) {
 
       if (setup.wValueH == HID_REPORT_TYPE_OUTPUT) {
         if (length == sizeof(leds)) {
+          // ------------------------------------------------------------
+          // Workaround for a bug in the GD32 core:
+          //
+          // On GD32, when we call `USV_RecvControl`, it casts the (void*) pointer
+          // we give it to `uint16_t*`, which means that it will alway write an even
+          // number of bytes to that pointer.  Because we don't want to overwrite
+          // the next byte in memory past `leds`, we use a temporary array that is
+          // guaranteed to be big enough, and copy the data from that:
+          uint8_t raw_report_data[2];
+          USB_RecvControl(&raw_report_data, length);
+          leds = raw_report_data[0];
+          // Once the GD32 core bug is fixed, we can replace the above code with the
+          // original code below:
+          /* ------------------------------------------------------------
           USB_RecvControl(&leds, length);
+          // ------------------------------------------------------------ */
           return true;
         }
       }

src/kaleidoscope/driver/hid/keyboardio/usb/HID.cpp

@@ -158,12 +158,37 @@ bool HID_::setup(USBSetup& setup) {
     if (request == HID_SET_REPORT) {
       uint16_t length = setup.wLength;
 
+      // ------------------------------------------------------------
+      // Workaround for a bug in the GD32 core:
+      //
+      // On GD32, when we call `USV_RecvControl`, it casts the (void*) pointer
+      // we give it to `uint16_t*`, which means that it will alway write an even
+      // number of bytes to that pointer.  Because we might be trying to just
+      // read the `leds` byte, and we don't want to overwrite the next byte in
+      // memory, instead of giving it the pointer to the `setReportData` member
+      // variable directly, we have it write into to temporary `raw_report_data`
+      // array that's guaranteed to be big enough, then copy the data from that
+      // array into `setReportData`:
+      uint8_t raw_report_data[sizeof(setReportData) + 1];
+      if (length == sizeof(setReportData)) {
+        USB_RecvControl(&raw_report_data, length);
+        setReportData.reportId = raw_report_data[0];
+        setReportData.leds = raw_report_data[1];
+      } else if (length == sizeof(setReportData.leds)) {
+        USB_RecvControl(&raw_report_data, length);
+        setReportData.reportId = 0;
+        setReportData.leds = raw_report_data[0];
+      }
+      // Once the GD32 core bug is fixed, we can replace the above code with the
+      // original code below:
+      /* ------------------------------------------------------------
       if (length == sizeof(setReportData)) {
         USB_RecvControl(&setReportData, length);
       } else if (length == sizeof(setReportData.leds)) {
         USB_RecvControl(&setReportData.leds, length);
         setReportData.reportId = 0;
       }
+      // ------------------------------------------------------------ */
     }
   }