From aab5fac67b7ef963bac2c9404c7dba584229611e Mon Sep 17 00:00:00 2001
From: Maxim Kulkin <maxim.kulkin@gmail.com>
Date: Mon, 15 Aug 2022 20:46:28 -0400
Subject: [PATCH] shared-module/usb_hid: Fix behavior of
 Device.get_last_received_report()

Documentation states that get_last_received_report() function should
return None if there was no report received previously, otherwise it
should return report. Moreover, same report should be returned only
once. That makes it possible to reliably process incoming OUT/Feature
reports.

This patch adds an array that stores flags if report with particular
ID was received and updates get_last_received_report() to match its
documentation.
---
 shared-module/usb_hid/Device.c | 7 +++++++
 shared-module/usb_hid/Device.h | 1 +
 2 files changed, 8 insertions(+)

diff --git a/shared-module/usb_hid/Device.c b/shared-module/usb_hid/Device.c
index f92c93baa3..680bb83893 100644
--- a/shared-module/usb_hid/Device.c
+++ b/shared-module/usb_hid/Device.c
@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include <stdbool.h>
 #include <string.h>
 
 #include "py/gc.h"
@@ -241,6 +242,10 @@ void common_hal_usb_hid_device_send_report(usb_hid_device_obj_t *self, uint8_t *
 mp_obj_t common_hal_usb_hid_device_get_last_received_report(usb_hid_device_obj_t *self, uint8_t report_id) {
     // report_id has already been validated for this device.
     size_t id_idx = get_report_id_idx(self, report_id);
+    if (!self->out_report_buffers_updated[id_idx]) {
+        return mp_const_none;
+    }
+    self->out_report_buffers_updated[id_idx] = false;
     return mp_obj_new_bytes(self->out_report_buffers[id_idx], self->out_report_lengths[id_idx]);
 }
 
@@ -258,6 +263,7 @@ void usb_hid_device_create_report_buffers(usb_hid_device_obj_t *self) {
             ? gc_alloc(self->out_report_lengths[i], false, true /*long-lived*/)
             : NULL;
     }
+    memset(self->out_report_buffers_updated, 0, sizeof(self->out_report_buffers_updated));
 }
 
 
@@ -304,6 +310,7 @@ void tud_hid_set_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t rep
             hid_device->out_report_buffers[id_idx] &&
             hid_device->out_report_lengths[id_idx] >= bufsize) {
             memcpy(hid_device->out_report_buffers[id_idx], buffer, bufsize);
+            hid_device->out_report_buffers_updated[id_idx] = true;
         }
     }
 }
diff --git a/shared-module/usb_hid/Device.h b/shared-module/usb_hid/Device.h
index f265712be4..06729f3c7d 100644
--- a/shared-module/usb_hid/Device.h
+++ b/shared-module/usb_hid/Device.h
@@ -38,6 +38,7 @@ typedef struct  {
     const uint8_t *report_descriptor;
     uint8_t *in_report_buffers[CIRCUITPY_USB_HID_MAX_REPORT_IDS_PER_DESCRIPTOR];
     uint8_t *out_report_buffers[CIRCUITPY_USB_HID_MAX_REPORT_IDS_PER_DESCRIPTOR];
+    uint8_t out_report_buffers_updated[CIRCUITPY_USB_HID_MAX_REPORT_IDS_PER_DESCRIPTOR];
     uint16_t report_descriptor_length;
     uint8_t report_ids[CIRCUITPY_USB_HID_MAX_REPORT_IDS_PER_DESCRIPTOR];
     uint8_t in_report_lengths[CIRCUITPY_USB_HID_MAX_REPORT_IDS_PER_DESCRIPTOR];