mirror of
https://github.com/git/git
synced 2024-08-27 11:39:22 +00:00
7e3dae4943
The POSIX standard doesn't currently define a `ntohll`/`htonll` function pair to perform network-to-host and host-to-network swaps of 64-bit data. These 64-bit swaps are necessary for the on-disk storage of EWAH bitmaps if they are not in native byte order. Many thanks to Ramsay Jones <ramsay@ramsay1.demon.co.uk> and Torsten Bögershausen <tboegi@web.de> for cygwin/mingw/msvc portability fixes. Signed-off-by: Vicent Marti <tanoku@gmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
125 lines
2.7 KiB
C
125 lines
2.7 KiB
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));
|
|
}
|
|
|
|
static inline uint64_t default_bswap64(uint64_t val)
|
|
{
|
|
return (((val & (uint64_t)0x00000000000000ffULL) << 56) |
|
|
((val & (uint64_t)0x000000000000ff00ULL) << 40) |
|
|
((val & (uint64_t)0x0000000000ff0000ULL) << 24) |
|
|
((val & (uint64_t)0x00000000ff000000ULL) << 8) |
|
|
((val & (uint64_t)0x000000ff00000000ULL) >> 8) |
|
|
((val & (uint64_t)0x0000ff0000000000ULL) >> 24) |
|
|
((val & (uint64_t)0x00ff000000000000ULL) >> 40) |
|
|
((val & (uint64_t)0xff00000000000000ULL) >> 56));
|
|
}
|
|
|
|
#undef bswap32
|
|
#undef bswap64
|
|
|
|
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
|
|
|
|
#define bswap32 git_bswap32
|
|
static inline uint32_t git_bswap32(uint32_t x)
|
|
{
|
|
uint32_t result;
|
|
if (__builtin_constant_p(x))
|
|
result = default_swab32(x);
|
|
else
|
|
__asm__("bswap %0" : "=r" (result) : "0" (x));
|
|
return result;
|
|
}
|
|
|
|
#define bswap64 git_bswap64
|
|
#if defined(__x86_64__)
|
|
static inline uint64_t git_bswap64(uint64_t x)
|
|
{
|
|
uint64_t result;
|
|
if (__builtin_constant_p(x))
|
|
result = default_bswap64(x);
|
|
else
|
|
__asm__("bswap %q0" : "=r" (result) : "0" (x));
|
|
return result;
|
|
}
|
|
#else
|
|
static inline uint64_t git_bswap64(uint64_t x)
|
|
{
|
|
union { uint64_t i64; uint32_t i32[2]; } tmp, result;
|
|
if (__builtin_constant_p(x))
|
|
result.i64 = default_bswap64(x);
|
|
else {
|
|
tmp.i64 = x;
|
|
result.i32[0] = git_bswap32(tmp.i32[1]);
|
|
result.i32[1] = git_bswap32(tmp.i32[0]);
|
|
}
|
|
return result.i64;
|
|
}
|
|
#endif
|
|
|
|
#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
|
|
|
|
#include <stdlib.h>
|
|
|
|
#define bswap32(x) _byteswap_ulong(x)
|
|
#define bswap64(x) _byteswap_uint64(x)
|
|
|
|
#endif
|
|
|
|
#if defined(bswap32)
|
|
|
|
#undef ntohl
|
|
#undef htonl
|
|
#define ntohl(x) bswap32(x)
|
|
#define htonl(x) bswap32(x)
|
|
|
|
#endif
|
|
|
|
#if defined(bswap64)
|
|
|
|
#undef ntohll
|
|
#undef htonll
|
|
#define ntohll(x) bswap64(x)
|
|
#define htonll(x) bswap64(x)
|
|
|
|
#else
|
|
|
|
#undef ntohll
|
|
#undef htonll
|
|
|
|
#if !defined(__BYTE_ORDER)
|
|
# if defined(BYTE_ORDER) && defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
|
|
# define __BYTE_ORDER BYTE_ORDER
|
|
# define __LITTLE_ENDIAN LITTLE_ENDIAN
|
|
# define __BIG_ENDIAN BIG_ENDIAN
|
|
# endif
|
|
#endif
|
|
|
|
#if !defined(__BYTE_ORDER)
|
|
# error "Cannot determine endianness"
|
|
#endif
|
|
|
|
#if __BYTE_ORDER == __BIG_ENDIAN
|
|
# define ntohll(n) (n)
|
|
# define htonll(n) (n)
|
|
#else
|
|
# define ntohll(n) default_bswap64(n)
|
|
# define htonll(n) default_bswap64(n)
|
|
#endif
|
|
|
|
#endif
|