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lib: try GCC builtins for endian byteswap

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This commit is contained in:
David Lamparter 2016-06-22 14:14:46 +02:00
parent b3b83e0343
commit 0abd16d62c
1 changed files with 35 additions and 26 deletions
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27
lib/capnp_c.h
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@ -310,29 +310,40 @@ CAPN_INLINE uint8_t capn_flip8(uint8_t v) {
return v; return v;
} }
CAPN_INLINE uint16_t capn_flip16(uint16_t v) { CAPN_INLINE uint16_t capn_flip16(uint16_t v) {
#if !defined(__BYTE_ORDER) || (__BYTE_ORDER != __LITTLE_ENDIAN) #if defined(__BYTE_ORDER) && (__BYTE_ORDER == __LITTLE_ENDIAN)
return v;
#elif defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN) && \
defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8
return __builtin_bswap16(v);
#else
union { uint16_t u; uint8_t v[2]; } s; union { uint16_t u; uint8_t v[2]; } s;
s.v[0] = (uint8_t)v; s.v[0] = (uint8_t)v;
s.v[1] = (uint8_t)(v>>8); s.v[1] = (uint8_t)(v>>8);
return s.u; return s.u;
#else
return v;
#endif #endif
} }
CAPN_INLINE uint32_t capn_flip32(uint32_t v) { CAPN_INLINE uint32_t capn_flip32(uint32_t v) {
#if !defined(__BYTE_ORDER) || (__BYTE_ORDER != __LITTLE_ENDIAN) #if defined(__BYTE_ORDER) && (__BYTE_ORDER == __LITTLE_ENDIAN)
return v;
#elif defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN) && \
defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8
return __builtin_bswap32(v);
#else
union { uint32_t u; uint8_t v[4]; } s; union { uint32_t u; uint8_t v[4]; } s;
s.v[0] = (uint8_t)v; s.v[0] = (uint8_t)v;
s.v[1] = (uint8_t)(v>>8); s.v[1] = (uint8_t)(v>>8);
s.v[2] = (uint8_t)(v>>16); s.v[2] = (uint8_t)(v>>16);
s.v[3] = (uint8_t)(v>>24); s.v[3] = (uint8_t)(v>>24);
return s.u; return s.u;
#else
return v;
#endif #endif
} }
CAPN_INLINE uint64_t capn_flip64(uint64_t v) { CAPN_INLINE uint64_t capn_flip64(uint64_t v) {
#if !defined(__BYTE_ORDER) || (__BYTE_ORDER != __LITTLE_ENDIAN) #if defined(__BYTE_ORDER) && (__BYTE_ORDER == __LITTLE_ENDIAN)
return v;
#elif defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN) && \
defined(__GNUC__) && __GNUC__ >= 4 && __GNUC_MINOR__ >= 8
return __builtin_bswap64(v);
#else
union { uint64_t u; uint8_t v[8]; } s; union { uint64_t u; uint8_t v[8]; } s;
s.v[0] = (uint8_t)v; s.v[0] = (uint8_t)v;
s.v[1] = (uint8_t)(v>>8); s.v[1] = (uint8_t)(v>>8);
@ -343,8 +354,6 @@ CAPN_INLINE uint64_t capn_flip64(uint64_t v) {
s.v[6] = (uint8_t)(v>>48); s.v[6] = (uint8_t)(v>>48);
s.v[7] = (uint8_t)(v>>56); s.v[7] = (uint8_t)(v>>56);
return s.u; return s.u;
#else
return v;
#endif #endif
} }