From f94596f20c48a5db0757a99ce23791406aacba72 Mon Sep 17 00:00:00 2001
From: Sainan <sainan@calamity.inc>
Date: Mon, 2 Dec 2024 15:45:24 +0100
Subject: [PATCH] Properly handle padded input report data on Windows

---
 soup/HidReportDescriptor.cpp |  1 -
 soup/hwHid.cpp               | 19 +++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/soup/HidReportDescriptor.cpp b/soup/HidReportDescriptor.cpp
index 76b7cccc..6d99ffff 100644
--- a/soup/HidReportDescriptor.cpp
+++ b/soup/HidReportDescriptor.cpp
@@ -276,7 +276,6 @@ NAMESPACE_SOUP
 							++pUsageId;
 						}
 					}
-					br.finishByte(); // It seems like in the case of a "Hat Switch", the high nibble is unused.
 					continue;
 				}
 				else if (f.size == 16 && f.logical_max != 0)
diff --git a/soup/hwHid.cpp b/soup/hwHid.cpp
index c55011f6..9b686ab2 100644
--- a/soup/hwHid.cpp
+++ b/soup/hwHid.cpp
@@ -755,6 +755,7 @@ NAMESPACE_SOUP
 				return a.bit_index < b.bit_index;
 			});
 
+			uint32_t bit_index = 8;
 			for (uint32_t i = 0; i != pp_data->header.input_item_count; ++i)
 			{
 				//std::cout << "report_id: " << (int)pp_data->items[i].report_id << std::endl;
@@ -765,6 +766,22 @@ NAMESPACE_SOUP
 					result.report_ids.emplace(pp_data->items[i].report_id);
 				}
 
+				const uint32_t this_item_bit_index = (pp_data->items[i].byte_index * 8) + pp_data->items[i].bit_index;
+				if (this_item_bit_index > bit_index)
+				{
+					const auto pad_bits = this_item_bit_index - bit_index;
+					//std::cout << "inserting " << pad_bits << " bits of padding" << std::endl;
+					result.input_report_fields.emplace_back(HidReportDescriptor::ReportField{
+						1,
+						pad_bits,
+						0,
+						false,
+						0,
+						{}
+					});
+					bit_index = this_item_bit_index;
+				}
+
 				std::vector<uint16_t> usage_ids{};
 				for (uint32_t usage = pp_data->items[i].usage_minimum; usage != (pp_data->items[i].usage_maximum + 1); ++usage)
 				{
@@ -778,6 +795,8 @@ NAMESPACE_SOUP
 					pp_data->items[i].usage_page,
 					std::move(usage_ids)
 				});
+
+				bit_index += pp_data->items[i].bit_size * pp_data->items[i].report_count;
 			}
 
 			HidD_FreePreparsedData(_pp_data);