handle resending failed HID reports

usb_host.c

@@ -19,6 +19,7 @@ uint8_t num_mounted=0;
 static absolute_time_t request_time;
 static bool enabled=false;
 static uint8_t kb_addr=0;
+static struct hid_report last_report;
 
 static void usb_host_init(void);
 static void host_ready(void);
@@ -79,6 +80,22 @@ void usb_host_main(void) {
 				if (enabled) {
 					rgb_task(kb_addr);
 				}
+
+				if (last_report.len > 0 ) {
+					// previous report was not forwarded, resend
+					if ( forward_report(last_report.instance, last_report.report, last_report.len) ) {
+						// clear queue
+						last_report.len = 0;
+						memset(last_report.report, 0x00, REPORT_MAX_SIZE);
+
+						// continue requesting reports
+						if ( !tuh_hid_receive_report(last_report.dev_addr, last_report.instance) ) {
+							tud_cdc_write_str("Error: cannot request report\r\n");
+						}
+					} else {
+						tud_cdc_write_str("Error: failed resend report\r\n");
+					}
+				}
 				break;
 			default:
 				break;
@@ -142,13 +159,20 @@ void tuh_hid_report_received_cb(uint8_t dev_addr, uint8_t instance, uint8_t cons
 		cdc_print_hex(report, len);
 	}
 
-	forward_report(instance, report, len);
-
+	// forward report to device output
+	if ( !forward_report(instance, report, len) ) {
+		tud_cdc_write_str("Error: cannot forward report\r\n");
+		// queue report for resending
+		last_report.dev_addr = dev_addr;
+		last_report.instance = instance;
+		last_report.len = len;
+		memcpy(last_report.report, report, len);
+	} else {
 		// continue to request to receive report
-	if ( !tuh_hid_receive_report(dev_addr, instance) )
-	{
+		if ( !tuh_hid_receive_report(dev_addr, instance) ) {
 			tud_cdc_write_str("Error: cannot request report\r\n");
 		}
+	}
 }
 
 // start listening on host for HID events

usb_host.h

@@ -23,6 +23,13 @@ struct report_desc {
 	bool listening;
 };
 
+struct hid_report {
+	uint8_t dev_addr;
+	uint8_t instance;
+	uint16_t len;
+	uint8_t report[REPORT_MAX_SIZE];
+};
+
 #define REPORT_DESC_ALLOC() (struct report_desc *)malloc(sizeof(struct report_desc))
 
 extern host_state_t host_state;