chrome.hid : enrich device info with Top-Level collections usages

device/hid/hid_report_descriptor.cc

Index: device/hid/hid_report_descriptor.cc
diff --git a/device/hid/hid_report_descriptor.cc b/device/hid/hid_report_descriptor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c89eebe637ea3575d3afa9bd3fe0398823bbfb2f
--- /dev/null
+++ b/device/hid/hid_report_descriptor.cc
@@ -0,0 +1,160 @@
+// 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.h"
+
+#include <stdlib.h>
+
+#include <algorithm>
+
+using namespace std;
+
+namespace device {
+
+HidReportDescriptorItem::HidReportDescriptorItem(
+  const uint8_t* bytes,
+  HidReportDescriptorItem* previous)
+    : bytes_(bytes)

[Ken Rockot(use gerrit already), 2014/04/15 17:53:38]

Please, commas at the end of lines not at the beginning.

    : bytes_(bytes),
      previous_(previous),
      parent_(NULL) {

+    , previous_(previous)
+    , parent_(NULL) {
+

[Ken Rockot(use gerrit already), 2014/04/15 17:53:38]

Please remove some of this extra vertical whitespace. The style guide
discourages this.

+  if (previous) {
+

[Ken Rockot(use gerrit already), 2014/04/15 17:53:38]

Whitespace

+    previous->next_ = this;
+

[Ken Rockot(use gerrit already), 2014/04/15 17:53:38]

Whitespace

+    switch (previous->tag()) {
+      case kTagCollection:
+        parent_ = previous;
+        break;
+      default:
+        break;
+    }
+

[Ken Rockot(use gerrit already), 2014/04/15 17:53:38]

etc...

+    if (!parent_) {
+      switch (tag()) {
+        case kTagEndCollection:
+          if (previous->parent()) {
+            parent_ = previous->parent()->parent();
+          }
+          break;
+        default:
+          parent_ = previous->parent();
+          break;
+      }
+    }
+  }
+}
+
+HidReportDescriptorItem::~HidReportDescriptorItem() {}
+
+size_t HidReportDescriptorItem::depth() const {
+  HidReportDescriptorItem* parnt = parent();
+  if (parnt)

[Ken Rockot(use gerrit already), 2014/04/15 17:53:38]

Please do not use abbreviated names like this. parent_item would be much better
than parnt.

+    return parnt->depth() + 1;
+  return 0;
+}
+
+bool HidReportDescriptorItem::isLong() const {
+  return tag() == kTagLong;
+}
+
+size_t  HidReportDescriptorItem::headerSize() const {
+  return isLong() ? 3 : 1;
+}
+
+size_t HidReportDescriptorItem::payloadSize() const {
+  return isLong() ? longHeader()->data_size : header()->size;
+}
+
+size_t HidReportDescriptorItem::size() const {
+  return headerSize() + payloadSize();
+}
+
+HidReportDescriptorItem::Header* HidReportDescriptorItem::header() const {
+  return (HidReportDescriptorItem::Header*)(&bytes_[0]);
+}
+
+HidReportDescriptorItem::LongHeader*
+    HidReportDescriptorItem::longHeader() const {
+  DCHECK(isLong());
+  return (HidReportDescriptorItem::LongHeader*)(&bytes_[0]);
+}
+
+HidReportDescriptorItem::Tag HidReportDescriptorItem::tag() const {
+  return (HidReportDescriptorItem::Tag)(header()->tag << 2 | header()->type);
+}
+
+HidReportDescriptorItem::Data* HidReportDescriptorItem::data() const {
+  void *data = malloc(sizeof(HidReportDescriptorItem::Data));
+  memset(data, 0, sizeof(data));
+  memcpy(data, &bytes_[headerSize()], payloadSize());
+  return (HidReportDescriptorItem::Data*)data;
+}
+
+HidReportDescriptor::HidReportDescriptor(const uint8_t *bytes, size_t size)
+  : bytes_(bytes)
+  , size_(size) {
+  size_t header_index = 0;
+  HidReportDescriptorItem *item = NULL;
+  while (header_index < size_) {
+    item = new HidReportDescriptorItem(&bytes_[header_index], item);
+    items_.push_back(item);
+    header_index += item->size();
+  }
+}
+
+const char HidReportDescriptor::kIndentChar = ' ';
+
+HidReportDescriptor::~HidReportDescriptor() {
+  for (vector<HidReportDescriptorItem*>::const_iterator items_iter =
+           items_.begin();
+         items_iter != items_.end();
+         ++items_iter) {
+    delete *items_iter;
+  }
+  items_.clear();
+}
+
+const std::vector<HidReportDescriptorItem*>&
+    HidReportDescriptor::items() const {
+  return items_;
+}
+
+std::vector<HidUsageAndPage> HidReportDescriptor::topLevelCollections() const {
+
+  std::vector<HidUsageAndPage> tlcs;
+
+  for (std::vector<HidReportDescriptorItem*>::const_iterator items_iter =
+           items_.begin();
+         items_iter != items_.end();
+         ++items_iter) {
+    HidReportDescriptorItem* item = *items_iter;
+
+    bool isTopLevelCollection =
+        item->tag() == HidReportDescriptorItem::kTagCollection
+        && item->parent() == NULL;
+
+    if (isTopLevelCollection) {
+      HidReportDescriptorItem*      usage =  item->previous();
+      HidReportDescriptorItem* usage_page = usage->previous();
+
+      HidUsageAndPage usage_and_page;
+      if (usage && usage->tag()
+          == HidReportDescriptorItem::kTagUsage) {
+        usage_and_page.usage
+            = ((HidReportDescriptorItem::Usage*)usage->data())->value;
+      }
+      if (usage_page && usage_page->tag()
+          == HidReportDescriptorItem::kTagUsagePage) {
+        usage_and_page.usage_page
+            = ((HidReportDescriptorItem::UsagePage*)usage_page->data())->value;
+      }
+      tlcs.push_back(usage_and_page);
+    }
+  }
+
+  return tlcs;
+}
+
+}  // namespace device