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..de6e710ada5f7190647f2182a0fcf82b7acc254f
--- /dev/null
+++ b/device/hid/hid_report_descriptor.cc
@@ -0,0 +1,152 @@
+// 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), previous_(previous), parent_(NULL) {
+

[Ken Rockot(use gerrit already), 2014/04/15 21:18:37]

Sorry - I guess the auto-format tool does not do this, but please ensure that at
the very least, there is no vertical whitespace at the beginning of any block.
The only exception is namespace blocks. So you should never see

FooMethod() {

  foocode;

This should always be rewritten as

FooMethod() {
  foocode;

[jracle (use Gerrit), 2014/04/16 16:39:19]

Oh sorry, got it now.

+  if (previous) {
+
+    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;
+      }
+    }
+  }
+}
+
+HidReportDescriptorItem::~HidReportDescriptorItem() {}
+
+size_t HidReportDescriptorItem::depth() const {
+  HidReportDescriptorItem* parnt = parent();
+  if (parnt)

[Ken Rockot(use gerrit already), 2014/04/15 21:18:37]

Please rename parnt. As a general rule, always prefer longer or more specific
names over shorter or abbreviated names. parent_item would work well in this
case.

[jracle (use Gerrit), 2014/04/16 16:39:19]

Sorry, was done in separate CL. I violated my own practice there..

+    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