HID: Support top-level collection usages in device info.

device/hid/hid_report_descriptor_item.cc

Index: device/hid/hid_report_descriptor_item.cc
diff --git a/device/hid/hid_report_descriptor_item.cc b/device/hid/hid_report_descriptor_item.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bdd03ce0ebd351619db48252c09d39b963455af2
--- /dev/null
+++ b/device/hid/hid_report_descriptor_item.cc
@@ -0,0 +1,112 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "device/hid/hid_report_descriptor_item.h"
+
+#include <stdlib.h>
+
+#include "base/logging.h"
+#include "device/hid/hid_usage_and_page.h"
+
+namespace device {
+
+namespace {
+
+struct Header {
+  uint8_t size : 2;
+  uint8_t type : 2;
+  uint8_t tag : 4;
+};
+
+}  // namespace
+
+HidReportDescriptorItem::HidReportDescriptorItem(
+    const uint8_t* bytes,
+    HidReportDescriptorItem* previous)
+    : previous_(previous), next_(NULL), parent_(NULL), shortData_(0) {
+  Header* header = (Header*)&bytes[0];
+  tag_ = (Tag)(header->tag << 2 | header->type);
+
+  if (IsLong()) {
+    // In a long item, payload size is the second byte.
+    payload_size_ = bytes[1];
+  } else {
+    payload_size_ = header->size;
+    DCHECK(payload_size_ <= sizeof(shortData_));
+    memcpy(&shortData_, &bytes[GetHeaderSize()], payload_size());
+  }
+
+  if (previous) {
+    DCHECK(!previous->next_);
+    previous->next_ = this;
+    switch (previous->tag()) {
+      case kTagCollection:
+        parent_ = previous;
+        break;
+      default:
+        break;
+    }
+    if (!parent_) {
+      switch (tag()) {
+        case kTagEndCollection:
+          if (previous->parent()) {
+            parent_ = previous->parent()->parent();
+          }
+          break;
+        default:
+          parent_ = previous->parent();
+          break;
+      }
+    }
+  }
+}
+
+size_t HidReportDescriptorItem::GetDepth() const {
+  HidReportDescriptorItem* parent_item = parent();
+  if (parent_item)
+    return parent_item->GetDepth() + 1;
+  return 0;
+}
+
+bool HidReportDescriptorItem::IsLong() const { return tag() == kTagLong; }
+
+size_t HidReportDescriptorItem::GetHeaderSize() const {
+  return IsLong() ? 3 : 1;
+}
+
+size_t HidReportDescriptorItem::GetSize() const {
+  return GetHeaderSize() + payload_size();
+}
+
+uint32_t HidReportDescriptorItem::GetShortData() const {
+  DCHECK(!IsLong());
+  return shortData_;
+}
+
+HidReportDescriptorItem::CollectionType
+HidReportDescriptorItem::GetCollectionTypeFromValue(uint32_t value) {
+  switch (value) {
+    case 0x00:
+      return kCollectionTypePhysical;
+    case 0x01:
+      return kCollectionTypePhysical;
+    case 0x02:
+      return kCollectionTypePhysical;
+    case 0x03:
+      return kCollectionTypePhysical;
+    case 0x04:
+      return kCollectionTypePhysical;
+    case 0x05:
+      return kCollectionTypePhysical;
+    case 0x06:
+      return kCollectionTypePhysical;
+    default:
+      break;
+  }
+  if (0x80 < value && value < 0xFF)
+    return kCollectionTypeVendor;
+  return kCollectionTypeReserved;
+}
+
+}  // namespace device