blob: eb00a2703247f11d06fbb4ef5f3163d66b5fae04 [file] [log] [blame]
// 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 "services/device/public/cpp/hid/hid_report_descriptor_item.h"
#include <stdlib.h>
#include "base/logging.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,
size_t size,
HidReportDescriptorItem* previous)
: previous_(previous),
next_(NULL),
parent_(NULL),
shortData_(0),
payload_size_(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.
if (size >= 2)
payload_size_ = bytes[1];
} else {
// As per HID spec, a bSize value of 3 means 4 bytes.
payload_size_ = header->size == 0x3 ? 4 : header->size;
DCHECK(payload_size_ <= sizeof(shortData_));
if (GetHeaderSize() + payload_size() <= size)
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 kCollectionTypeApplication;
case 0x02:
return kCollectionTypeLogical;
case 0x03:
return kCollectionTypeReport;
case 0x04:
return kCollectionTypeNamedArray;
case 0x05:
return kCollectionTypeUsageSwitch;
case 0x06:
return kCollectionTypeUsageModifier;
default:
break;
}
if (0x80 < value && value < 0xFF)
return kCollectionTypeVendor;
return kCollectionTypeReserved;
}
} // namespace device