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utils: prefer using gccs builtin swapping functions which support constant folding

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Signed-off-by: Felix Fietkau <nbd@openwrt.org>
This commit is contained in:
Felix Fietkau 2013-02-11 22:00:08 +01:00
parent 5ad190fccf
commit e5a40544ec
1 changed files with 24 additions and 1 deletions
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25
utils.h
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@ -21,6 +21,7 @@
#include <sys/types.h>
#include <sys/time.h>
#include <stdint.h>
#include <time.h>
/*
@ -63,6 +64,12 @@ void clock_gettime(int type, struct timespec *tv);
#endif
#ifdef __GNUC__
#define _GNUC_MIN_VER(maj, min) (((__GNUC__ << 8) + __GNUC_MINOR__) >= (((maj) << 8) + (min)))
#else
#define _GNUC_MIN_VER(maj, min) 0
#endif
#if defined(__linux__) || defined(__CYGWIN__)
#include <byteswap.h>
#include <endian.h>
@ -97,6 +104,20 @@ void clock_gettime(int type, struct timespec *tv);
#if __BYTE_ORDER == __LITTLE_ENDIAN
#if _GNUC_MIN_VER(4, 2)
#define __bswap_constant_16(x) ((uint16_t)((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8)))
#define cpu_to_be64(x) __builtin_bswap64(x)
#define cpu_to_be32(x) __builtin_bswap32(x)
#define cpu_to_be16(x) __bswap_constant_16((uint16_t) x)
#define be64_to_cpu(x) __builtin_bswap64(x)
#define be32_to_cpu(x) __builtin_bswap32(x)
#define be16_to_cpu(x) __bswap_constant_16((uint16_t) x)
#else /* __GNUC__ */
#define cpu_to_be64(x) bswap_64(x)
#define cpu_to_be32(x) bswap_32(x)
#define cpu_to_be16(x) bswap_16(x)
@ -105,7 +126,9 @@ void clock_gettime(int type, struct timespec *tv);
#define be32_to_cpu(x) bswap_32(x)
#define be16_to_cpu(x) bswap_16(x)
#else
#endif /* __GNUC__ */
#else /* __BYTE_ORDER == __LITTLE_ENDIAN */
#define cpu_to_be64(x) (x)
#define cpu_to_be32(x) (x)