How to get Heavyweight report descriptor

[jonesliu-eaton]

I'm referring to one USB HID device, which has two independent HID interfaces (each with a report descriptor, one is Heavyweight report descriptor,another is Lightweight report descriptor).

for libusb

read light descriptor(one report descriptor):
int len = usb_control_msg(hidif->dev_handle,
USB_ENDPOINT_IN+1,
USB_REQ_GET_DESCRIPTOR,
(USB_DT_REPORT << 8), hidif->interfa, // Report desc, index=0
(char*)hidif->ReportDesc, hidif->ReportDescSize,
USB_TIMEOUT);

read weight descriptor(two report descriptor):
int len = usb_control_msg(hidif->dev_handle,
USB_ENDPOINT_IN+1,
USB_REQ_GET_DESCRIPTOR,
(USB_DT_REPORT << 8) + 1, hidif->interfa, // Report desc, index=1
(char*)hidif->ReportDesc, hidif->ReportDescSize,
USB_TIMEOUT);

I print the length of report descriptor is 2555 using libusb to get heavyweight report descriptor.
but for hidAPI, the method "hid_get_report_descriptor(hidif->handle, hidif->ReportDesc, sizeof(descriptor)) " obtain report descriptor for index 0, it seems get the Lightweight report descriptor, because the length is 1826

[jonesliu-eaton]

This is my code for get handle, I need to pass VID/PID array, serial number as parameters.

typedef struct HIDInterfaceMatcher_t {
  unsigned short vendor_id;
  unsigned short product_id;
} HIDInterfaceMatcher;

typedef struct HIDInterface_t {
	hid_device *handle;
	unsigned short vendorId;
	unsigned short productId;
	uchar   ReportDesc[REPORT_DSC_SIZE];  /*!< Store Report Descriptor          */
	ushort  ReportDescSize;               /*!< Size of Report Descriptor        */
} HIDInterface;

static hid_return hid_get_usb_handleOne(HIDInterface* const hidif,unsigned short vendorId,
	int deviceIndex,const char *pSerialNum,HIDInterfaceMatcher const* const matcher,int length)
{
	if (!hidif) 
		return HID_RET_DEVICE_NOT_FOUND;
	int count = 0;
	HIDInterfaceMatcher const* tempMatch = matcher;
	for (int i = 0; i < length; i++, tempMatch++) {
		struct hid_device_info* info = hid_enumerate(tempMatch->vendor_id,tempMatch->product_id);
		struct hid_device_info* devs = info;
		while (devs) {
			/* --- Serial number match case --- */
			if (pSerialNum && pSerialNum[0]) {
				char* serial = WcharToCharStr(devs->serial_number);
				if (serial) {
					if (strcmp(pSerialNum, serial) == 0) {
						printf("found serial %s device\n", pSerialNum);
						free(serial);
						hid_device* handle = hid_open_path(devs->path);
						hidif->handle = handle;
						hidif->vendorId = tempMatch->vendor_id;
						hidif->productId = tempMatch->product_id;
						hid_free_enumeration(info);
						return HID_RET_SUCCESS;
					}
					free(serial);
				}
			}
			/* --- Index match case --- */
			else if (count == deviceIndex) {  //if the device has no serial number, use device index
				printf("found index %d device\n", deviceIndex);
				hid_device* handle = hid_open_path(devs->path);
				hidif->handle = handle;
				hidif->vendorId = tempMatch->vendor_id;
				hidif->productId = tempMatch->product_id;
				hid_free_enumeration(info);
				return HID_RET_SUCCESS;
			}
			count++;
			devs = devs->next;
		}
		hid_free_enumeration(info);
	}
	printf("no matching USB device found.\n");
	return HID_RET_DEVICE_NOT_FOUND;
}

This is my code for getting descriptor, I need to pass in a handle as the parameter to get the descriptor：

static hid_return hid_prepare_report_descriptor(HIDInterface* const hidif)
{
	if (!hidif || !hidif->handle) {
		return HID_RET_FAIL_GET_REPORT;
	}
#if HID_API_VERSION >= HID_API_MAKE_VERSION(0, 14, 0)

	// IMPORTANT: HIDAPI returns int, not unsigned!
	int len = hid_get_report_descriptor(hidif->handle,hidif->ReportDesc,sizeof(hidif->ReportDesc));

	if (len < 0) {
		printf("Failed to get report descriptor, error = %d\n", len);
		return HID_RET_FAIL_GET_REPORT;
	}
	hidif->ReportDescSize = len;
	printf("Report Descriptor length = %d bytes\n", len);
	// Print the descriptor correctly
	for (int i = 0; i < len; i++) {
		if (i % 10 == 0) {
			printf("\n");
		}
		printf("0x%02X, ", hidif->ReportDesc[i]);
	}
	printf("\n");
#else
	(void)hidif; // suppress unused warning
	return HID_RET_FAIL_GET_REPORT;  // Not supported
#endif
	return HID_RET_SUCCESS;
}

[Youw]

@jonesliu-eaton you've ended up almost at the same place, see: #468, #373