mirror of
https://github.com/git/git
synced 2024-08-27 11:39:22 +00:00
![Sebastian Schuberth](/assets/img/avatar_default.png)
When compiling with MSVC on x86-compatible, use an intrinsic for byte swapping. In contrast to the GCC path, we do not prefer inline assembly here as it is not supported for the x64 platform. Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
47 lines
1,017 B
C
47 lines
1,017 B
C
/*
|
|
* Let's make sure we always have a sane definition for ntohl()/htonl().
|
|
* Some libraries define those as a function call, just to perform byte
|
|
* shifting, bringing significant overhead to what should be a simple
|
|
* operation.
|
|
*/
|
|
|
|
/*
|
|
* Default version that the compiler ought to optimize properly with
|
|
* constant values.
|
|
*/
|
|
static inline uint32_t default_swab32(uint32_t val)
|
|
{
|
|
return (((val & 0xff000000) >> 24) |
|
|
((val & 0x00ff0000) >> 8) |
|
|
((val & 0x0000ff00) << 8) |
|
|
((val & 0x000000ff) << 24));
|
|
}
|
|
|
|
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
|
|
|
|
#define bswap32(x) ({ \
|
|
uint32_t __res; \
|
|
if (__builtin_constant_p(x)) { \
|
|
__res = default_swab32(x); \
|
|
} else { \
|
|
__asm__("bswap %0" : "=r" (__res) : "0" (x)); \
|
|
} \
|
|
__res; })
|
|
|
|
#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
|
|
|
|
#include <stdlib.h>
|
|
|
|
#define bswap32(x) _byteswap_ulong(x)
|
|
|
|
#endif
|
|
|
|
#ifdef bswap32
|
|
|
|
#undef ntohl
|
|
#undef htonl
|
|
#define ntohl(x) bswap32(x)
|
|
#define htonl(x) bswap32(x)
|
|
|
|
#endif
|