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Merge branch 'ss/compat-bswap-revamp'

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Clean-up compat/bswap.h mess.

* ss/compat-bswap-revamp:
  bswap.h: provide a built-in based version of bswap32/64 if possible
  bswap.h: remove optimized x86 version of bswap32/64
  bswap.h: always overwrite ntohl/ ntohll macros
  bswap.h: define GIT_LITTLE_ENDIAN on msvc as little endian
  bswap.h: add support for __BYTE_ORDER__
This commit is contained in:
Junio C Hamano
2025-07-24 16:03:56 -07:00
parent 0686fa4216 f4ac32c03a
commit 42eb288158
1 changed files with 48 additions and 66 deletions
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114
compat/bswap.h
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@@ -32,78 +32,35 @@ static inline uint64_t default_bswap64(uint64_t val)
((val & (uint64_t)0xff00000000000000ULL) >> 56));
}
/*
* __has_builtin is available since Clang 10 and GCC 10.
* Below is a fallback for older compilers.
*/
#ifndef __has_builtin
# define __has_builtin(x) 0
#endif
#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) || defined(_M_ARM64))
#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64) || defined(_M_ARM64))
#include <stdlib.h>
#define bswap32(x) _byteswap_ulong(x)
#define bswap64(x) _byteswap_uint64(x)
#endif
#define GIT_LITTLE_ENDIAN 1234
#define GIT_BIG_ENDIAN 4321
#define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
#if defined(bswap32)
#elif __has_builtin(__builtin_bswap32) && __has_builtin(__builtin_bswap64)
#undef ntohl
#undef htonl
#define ntohl(x) bswap32(x)
#define htonl(x) bswap32(x)
#define bswap32(x) __builtin_bswap32((x))
#define bswap64(x) __builtin_bswap64((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
@@ -116,7 +73,13 @@ static inline uint64_t git_bswap64(uint64_t x)
# define GIT_LITTLE_ENDIAN LITTLE_ENDIAN
# define GIT_BIG_ENDIAN BIG_ENDIAN
#else
#elif defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_BIG_ENDIAN__)
# define GIT_BYTE_ORDER __BYTE_ORDER__
# define GIT_LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
# define GIT_BIG_ENDIAN __ORDER_BIG_ENDIAN__
#elif !defined(GIT_BYTE_ORDER)
# define GIT_BIG_ENDIAN 4321
# define GIT_LITTLE_ENDIAN 1234
@@ -135,14 +98,33 @@ static inline uint64_t git_bswap64(uint64_t x)
#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
#undef ntohl
#undef htonl
#undef ntohll
#undef htonll
#if GIT_BYTE_ORDER == GIT_BIG_ENDIAN
# define ntohl(x) (x)
# define htonl(x) (x)
# define ntohll(x) (x)
# define htonll(x) (x)
#else
# if defined(bswap32)
# define ntohl(x) bswap32(x)
# define htonl(x) bswap32(x)
# else
# define ntohl(x) default_swab32(x)
# define htonl(x) default_swab32(x)
# endif
# if defined(bswap64)
# define ntohll(x) bswap64(x)
# define htonll(x) bswap64(x)
# else
# define ntohll(x) default_bswap64(x)
# define htonll(x) default_bswap64(x)
# endif
#endif
static inline uint16_t get_be16(const void *ptr)