1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 // Note: ported from Chromium commit head: 60f9667
5 
6 #include "base/sys_info.h"
7 #include "shared_memory_region.h"
8 
9 namespace media {
10 
11 SharedMemoryRegion::SharedMemoryRegion(const base::SharedMemoryHandle& handle,
12                                        off_t offset,
13                                        size_t size,
14                                        bool read_only)
15     : shm_(handle, read_only),
16       offset_(offset),
17       size_(size),
18       alignment_size_(offset % base::SysInfo::VMAllocationGranularity()) {
19   DCHECK_GE(offset_, 0) << "Invalid offset: " << offset_;
20 }
21 
22 SharedMemoryRegion::SharedMemoryRegion(const BitstreamBuffer& bitstream_buffer,
23                                        bool read_only)
24     : SharedMemoryRegion(bitstream_buffer.handle(),
25                          bitstream_buffer.offset(),
26                          bitstream_buffer.size(),
27                          read_only) {}
28 
29 bool SharedMemoryRegion::Map() {
30   if (offset_ < 0) {
31     DVLOG(1) << "Invalid offset: " << offset_;
32     return false;
33   }
34   return shm_.MapAt(offset_ - alignment_size_, size_ + alignment_size_);
35 }
36 
37 void* SharedMemoryRegion::memory() {
38   int8_t* addr = reinterpret_cast<int8_t*>(shm_.memory());
39   return addr ? addr + alignment_size_ : nullptr;
40 }
41 
42 }  // namespace media
43