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// 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 "common/webm_endian.h"
#include <stdint.h>
namespace {
// Swaps unsigned 32 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.
uint32_t swap32_check_little_endian(uint32_t value) {
// Check endianness.
union {
uint32_t val32;
uint8_t c[4];
} check;
check.val32 = 0x01234567U;
// Check for big endian.
if (check.c[3] == 0x67)
return value;
// Check for not little endian.
if (check.c[0] != 0x67)
return 0;
return value << 24 | ((value << 8) & 0x0000FF00U) |
((value >> 8) & 0x00FF0000U) | value >> 24;
}
// 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.
uint64_t swap64_check_little_endian(uint64_t value) {
// Check endianness.
union {
uint64_t val64;
uint8_t 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 libwebm {
uint32_t host_to_bigendian(uint32_t value) {
return swap32_check_little_endian(value);
}
uint32_t bigendian_to_host(uint32_t value) {
return swap32_check_little_endian(value);
}
uint64_t host_to_bigendian(uint64_t value) {
return swap64_check_little_endian(value);
}
uint64_t bigendian_to_host(uint64_t value) {
return swap64_check_little_endian(value);
}
} // namespace libwebm
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