| // Copyright (c) 2012 The WebM project authors. All Rights Reserved. |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the LICENSE file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| |
| #include "webm_endian.h" |
| |
| namespace { |
| |
| // Swaps unsigned 64 bit values to big endian if needed. Returns |value| |
| // unmodified if architecture is big endian. Returns swapped bytes of |value| |
| // if architecture is little endian. Returns 0 otherwise. |
| webm_tools::uint64 swap64_check_little_endian(webm_tools::uint64 value) { |
| // Check endianness. |
| union { |
| webm_tools::uint64 val64; |
| webm_tools::uint8 c[8]; |
| } check; |
| check.val64 = 0x0123456789ABCDEFULL; |
| |
| // Check for big endian. |
| if (check.c[7] == 0xEF) |
| return value; |
| |
| // Check for not little endian. |
| if (check.c[0] != 0xEF) |
| return 0; |
| |
| return value << 56 | |
| ((value << 40) & 0x00FF000000000000ULL) | |
| ((value << 24) & 0x0000FF0000000000ULL) | |
| ((value << 8) & 0x000000FF00000000ULL) | |
| ((value >> 8) & 0x00000000FF000000ULL) | |
| ((value >> 24) & 0x0000000000FF0000ULL) | |
| ((value >> 40) & 0x000000000000FF00ULL) | |
| value >> 56; |
| } |
| |
| } // namespace |
| |
| namespace webm_tools { |
| |
| uint64 host_to_bigendian(uint64 value) { |
| return swap64_check_little_endian(value); |
| } |
| |
| uint64 bigendian_to_host(uint64 value) { |
| return swap64_check_little_endian(value); |
| } |
| |
| } // namespace webm_tools |