base/internal/endian.h

0001 // Protocol Buffers - Google's data interchange format
0002 // Copyright 2023 Google LLC.  All rights reserved.
0003 //
0004 // Use of this source code is governed by a BSD-style
0005 // license that can be found in the LICENSE file or at
0006 // https://developers.google.com/open-source/licenses/bsd
0007
0008 #ifndef UPB_BASE_INTERNAL_ENDIAN_H_
0009 #define UPB_BASE_INTERNAL_ENDIAN_H_
0010
0011 #include <stdint.h>
0012
0013 // Must be last.
0014 #include "upb/port/def.inc"
0015
0016 #ifdef __cplusplus
0017 extern "C" {
0018 #endif
0019
0020 UPB_INLINE bool upb_IsLittleEndian(void) {
0021   const int x = 1;
0022   return *(char*)&x == 1;
0023 }
0024
0025 UPB_INLINE uint32_t upb_BigEndian32(uint32_t val) {
0026   if (upb_IsLittleEndian()) return val;
0027
0028   return ((val & 0xff) << 24) | ((val & 0xff00) << 8) |
0029          ((val & 0xff0000) >> 8) | ((val & 0xff000000) >> 24);
0030 }
0031
0032 UPB_INLINE uint64_t upb_BigEndian64(uint64_t val) {
0033   if (upb_IsLittleEndian()) return val;
0034
0035   const uint64_t hi = ((uint64_t)upb_BigEndian32((uint32_t)val)) << 32;
0036   const uint64_t lo = upb_BigEndian32((uint32_t)(val >> 32));
0037   return hi | lo;
0038 }
0039
0040 #ifdef __cplusplus
0041 } /* extern "C" */
0042 #endif
0043
0044 #include "upb/port/undef.inc"
0045
0046 #endif /* UPB_BASE_INTERNAL_ENDIAN_H_ */