mirror of
https://github.com/git/git.git
synced 2024-11-30 21:44:02 +08:00
33aa579a55
Our compat/bswap.h lacks the usual preprocessor guards against multiple inclusion. This usually isn't an issue since it only gets included from git-compat-util.h, which has its own guards. But it would produce redeclaration errors if any file included it separately. Our hdr-check target would complain about this, except that it currently skips items in compat/ entirely. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
218 lines
5.2 KiB
C
218 lines
5.2 KiB
C
#ifndef COMPAT_BSWAP_H
|
|
#define COMPAT_BSWAP_H
|
|
|
|
/*
|
|
* 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) && defined(__LITTLE_ENDIAN) && defined(__BIG_ENDIAN)
|
|
|
|
# define GIT_BYTE_ORDER __BYTE_ORDER
|
|
# define GIT_LITTLE_ENDIAN __LITTLE_ENDIAN
|
|
# define GIT_BIG_ENDIAN __BIG_ENDIAN
|
|
|
|
#elif defined(BYTE_ORDER) && defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
|
|
|
|
# define GIT_BYTE_ORDER BYTE_ORDER
|
|
# define GIT_LITTLE_ENDIAN LITTLE_ENDIAN
|
|
# define GIT_BIG_ENDIAN BIG_ENDIAN
|
|
|
|
#else
|
|
|
|
# define GIT_BIG_ENDIAN 4321
|
|
# define GIT_LITTLE_ENDIAN 1234
|
|
|
|
# if defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN)
|
|
# define GIT_BYTE_ORDER GIT_BIG_ENDIAN
|
|
# elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
|
|
# define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
|
|
# elif defined(__THW_BIG_ENDIAN__) && !defined(__THW_LITTLE_ENDIAN__)
|
|
# define GIT_BYTE_ORDER GIT_BIG_ENDIAN
|
|
# elif defined(__THW_LITTLE_ENDIAN__) && !defined(__THW_BIG_ENDIAN__)
|
|
# define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
|
|
# else
|
|
# error "Cannot determine endianness"
|
|
# endif
|
|
|
|
#endif
|
|
|
|
#if GIT_BYTE_ORDER == GIT_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
|
|
|
|
/*
|
|
* Performance might be improved if the CPU architecture is OK with
|
|
* unaligned 32-bit loads and a fast ntohl() is available.
|
|
* Otherwise fall back to byte loads and shifts which is portable,
|
|
* and is faster on architectures with memory alignment issues.
|
|
*/
|
|
|
|
#if !defined(NO_UNALIGNED_LOADS) && ( \
|
|
defined(__i386__) || defined(__x86_64__) || \
|
|
defined(_M_IX86) || defined(_M_X64) || \
|
|
defined(__ppc__) || defined(__ppc64__) || \
|
|
defined(__powerpc__) || defined(__powerpc64__) || \
|
|
defined(__s390__) || defined(__s390x__))
|
|
|
|
#define get_be16(p) ntohs(*(unsigned short *)(p))
|
|
#define get_be32(p) ntohl(*(unsigned int *)(p))
|
|
#define get_be64(p) ntohll(*(uint64_t *)(p))
|
|
#define put_be32(p, v) do { *(unsigned int *)(p) = htonl(v); } while (0)
|
|
#define put_be64(p, v) do { *(uint64_t *)(p) = htonll(v); } while (0)
|
|
|
|
#else
|
|
|
|
static inline uint16_t get_be16(const void *ptr)
|
|
{
|
|
const unsigned char *p = ptr;
|
|
return (uint16_t)p[0] << 8 |
|
|
(uint16_t)p[1] << 0;
|
|
}
|
|
|
|
static inline uint32_t get_be32(const void *ptr)
|
|
{
|
|
const unsigned char *p = ptr;
|
|
return (uint32_t)p[0] << 24 |
|
|
(uint32_t)p[1] << 16 |
|
|
(uint32_t)p[2] << 8 |
|
|
(uint32_t)p[3] << 0;
|
|
}
|
|
|
|
static inline uint64_t get_be64(const void *ptr)
|
|
{
|
|
const unsigned char *p = ptr;
|
|
return (uint64_t)get_be32(&p[0]) << 32 |
|
|
(uint64_t)get_be32(&p[4]) << 0;
|
|
}
|
|
|
|
static inline void put_be32(void *ptr, uint32_t value)
|
|
{
|
|
unsigned char *p = ptr;
|
|
p[0] = value >> 24;
|
|
p[1] = value >> 16;
|
|
p[2] = value >> 8;
|
|
p[3] = value >> 0;
|
|
}
|
|
|
|
static inline void put_be64(void *ptr, uint64_t value)
|
|
{
|
|
unsigned char *p = ptr;
|
|
p[0] = value >> 56;
|
|
p[1] = value >> 48;
|
|
p[2] = value >> 40;
|
|
p[3] = value >> 32;
|
|
p[4] = value >> 24;
|
|
p[5] = value >> 16;
|
|
p[6] = value >> 8;
|
|
p[7] = value >> 0;
|
|
}
|
|
|
|
#endif
|
|
|
|
#endif /* COMPAT_BSWAP_H */
|