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compile time endianess check, faster on little endian cpus

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This commit is contained in:
Michael Gartsbein 2016-04-28 12:02:29 +03:00
parent a15accf4eb
commit ec9bb1417e
1 changed files with 40 additions and 20 deletions
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60
lib/capnp_c.h
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@ -24,6 +24,8 @@ extern "C" {
#define CAPN_INLINE static #define CAPN_INLINE static
#endif #endif
#define IS_BIG_ENDIAN (*(uint16_t *)"\0\xff" < 0x100)
#define CAPN_VERSION 1 #define CAPN_VERSION 1
/* struct capn is a common structure shared between segments in the same /* struct capn is a common structure shared between segments in the same
@ -299,30 +301,48 @@ 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) {
union { uint16_t u; uint8_t v[2]; } s; #if __BYTE_ORDER == __BIG_ENDIAN
s.v[0] = (uint8_t)v; union { uint16_t u; uint8_t v[2]; } s;
s.v[1] = (uint8_t)(v>>8); s.v[0] = (uint8_t)v;
return s.u; s.v[1] = (uint8_t)(v>>8);
return s.u;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
return v;
#else
#error "Unable to determine endianess ";
#endif
} }
CAPN_INLINE uint32_t capn_flip32(uint32_t v) { CAPN_INLINE uint32_t capn_flip32(uint32_t v) {
union { uint32_t u; uint8_t v[4]; } s; #if __BYTE_ORDER == __BIG_ENDIAN
s.v[0] = (uint8_t)v; union { uint32_t u; uint8_t v[4]; } s;
s.v[1] = (uint8_t)(v>>8); s.v[0] = (uint8_t)v;
s.v[2] = (uint8_t)(v>>16); s.v[1] = (uint8_t)(v>>8);
s.v[3] = (uint8_t)(v>>24); s.v[2] = (uint8_t)(v>>16);
return s.u; s.v[3] = (uint8_t)(v>>24);
return s.u;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
return v;
#else
#error "Unable to determine endianess ";
#endif
} }
CAPN_INLINE uint64_t capn_flip64(uint64_t v) { CAPN_INLINE uint64_t capn_flip64(uint64_t v) {
union { uint64_t u; uint8_t v[8]; } s; #if __BYTE_ORDER == __BIG_ENDIAN
s.v[0] = (uint8_t)v; union { uint64_t u; uint8_t v[8]; } s;
s.v[1] = (uint8_t)(v>>8); s.v[0] = (uint8_t)v;
s.v[2] = (uint8_t)(v>>16); s.v[1] = (uint8_t)(v>>8);
s.v[3] = (uint8_t)(v>>24); s.v[2] = (uint8_t)(v>>16);
s.v[4] = (uint8_t)(v>>32); s.v[3] = (uint8_t)(v>>24);
s.v[5] = (uint8_t)(v>>40); s.v[4] = (uint8_t)(v>>32);
s.v[6] = (uint8_t)(v>>48); s.v[5] = (uint8_t)(v>>40);
s.v[7] = (uint8_t)(v>>56); s.v[6] = (uint8_t)(v>>48);
return s.u; s.v[7] = (uint8_t)(v>>56);
return s.u;
#elif __BYTE_ORDER == __LITTLE_ENDIAN
return v;
#else
#error "Unable to determine endianess ";
#endif
} }
CAPN_INLINE int capn_write1(capn_ptr p, int off, int val) { CAPN_INLINE int capn_write1(capn_ptr p, int off, int val) {