protobuf/upb/wire/swap_internal.h

/*
 * Copyright (c) 2009-2021, Google LLC
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
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 *       documentation and/or other materials provided with the distribution.
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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#ifndef UPB_WIRE_SWAP_INTERNAL_H_
#define UPB_WIRE_SWAP_INTERNAL_H_

// Must be last.
#include "upb/port/def.inc"

#ifdef __cplusplus
extern "C" {
#endif

UPB_INLINE bool _upb_IsLittleEndian(void) {
  int x = 1;
  return *(char*)&x == 1;
}

UPB_INLINE uint32_t _upb_BigEndian_Swap32(uint32_t val) {
  if (_upb_IsLittleEndian()) return val;

  return ((val & 0xff) << 24) | ((val & 0xff00) << 8) |
         ((val & 0xff0000) >> 8) | ((val & 0xff000000) >> 24);
}

UPB_INLINE uint64_t _upb_BigEndian_Swap64(uint64_t val) {
  if (_upb_IsLittleEndian()) return val;

  return ((uint64_t)_upb_BigEndian_Swap32((uint32_t)val) << 32) |
         _upb_BigEndian_Swap32((uint32_t)(val >> 32));
}

#ifdef __cplusplus
} /* extern "C" */
#endif

#include "upb/port/undef.inc"

#endif /* UPB_WIRE_SWAP_INTERNAL_H_ */