Merge branch 'ds/midx-expire-repack'
[git/git.git] / compat / bswap.h
CommitLineData
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1#ifndef COMPAT_BSWAP_H
2#define COMPAT_BSWAP_H
3
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4/*
5 * Let's make sure we always have a sane definition for ntohl()/htonl().
6 * Some libraries define those as a function call, just to perform byte
7 * shifting, bringing significant overhead to what should be a simple
8 * operation.
9 */
10
11/*
12 * Default version that the compiler ought to optimize properly with
13 * constant values.
14 */
5322ef20 15static inline uint32_t default_swab32(uint32_t val)
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16{
17 return (((val & 0xff000000) >> 24) |
18 ((val & 0x00ff0000) >> 8) |
19 ((val & 0x0000ff00) << 8) |
20 ((val & 0x000000ff) << 24));
21}
22
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23static inline uint64_t default_bswap64(uint64_t val)
24{
25 return (((val & (uint64_t)0x00000000000000ffULL) << 56) |
26 ((val & (uint64_t)0x000000000000ff00ULL) << 40) |
27 ((val & (uint64_t)0x0000000000ff0000ULL) << 24) |
28 ((val & (uint64_t)0x00000000ff000000ULL) << 8) |
29 ((val & (uint64_t)0x000000ff00000000ULL) >> 8) |
30 ((val & (uint64_t)0x0000ff0000000000ULL) >> 24) |
31 ((val & (uint64_t)0x00ff000000000000ULL) >> 40) |
32 ((val & (uint64_t)0xff00000000000000ULL) >> 56));
33}
34
21e403a7 35#undef bswap32
7e3dae49 36#undef bswap64
21e403a7 37
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38#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
39
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40#define bswap32 git_bswap32
41static inline uint32_t git_bswap32(uint32_t x)
42{
43 uint32_t result;
44 if (__builtin_constant_p(x))
45 result = default_swab32(x);
46 else
47 __asm__("bswap %0" : "=r" (result) : "0" (x));
48 return result;
49}
51ea5519 50
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51#define bswap64 git_bswap64
52#if defined(__x86_64__)
53static inline uint64_t git_bswap64(uint64_t x)
54{
55 uint64_t result;
56 if (__builtin_constant_p(x))
57 result = default_bswap64(x);
58 else
59 __asm__("bswap %q0" : "=r" (result) : "0" (x));
60 return result;
61}
62#else
63static inline uint64_t git_bswap64(uint64_t x)
64{
65 union { uint64_t i64; uint32_t i32[2]; } tmp, result;
66 if (__builtin_constant_p(x))
67 result.i64 = default_bswap64(x);
68 else {
69 tmp.i64 = x;
70 result.i32[0] = git_bswap32(tmp.i32[1]);
71 result.i32[1] = git_bswap32(tmp.i32[0]);
72 }
73 return result.i64;
74}
75#endif
76
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77#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
78
79#include <stdlib.h>
80
81#define bswap32(x) _byteswap_ulong(x)
7e3dae49 82#define bswap64(x) _byteswap_uint64(x)
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83
84#endif
85
7e3dae49 86#if defined(bswap32)
0fcabdeb 87
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88#undef ntohl
89#undef htonl
90#define ntohl(x) bswap32(x)
91#define htonl(x) bswap32(x)
92
93#endif
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94
95#if defined(bswap64)
96
97#undef ntohll
98#undef htonll
99#define ntohll(x) bswap64(x)
100#define htonll(x) bswap64(x)
101
102#else
103
104#undef ntohll
105#undef htonll
106
839fa9c5 107#if defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && defined(__BIG_ENDIAN)
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108
109# define GIT_BYTE_ORDER __BYTE_ORDER
110# define GIT_LITTLE_ENDIAN __LITTLE_ENDIAN
111# define GIT_BIG_ENDIAN __BIG_ENDIAN
112
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113#elif defined(BYTE_ORDER) && defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
114
115# define GIT_BYTE_ORDER BYTE_ORDER
116# define GIT_LITTLE_ENDIAN LITTLE_ENDIAN
117# define GIT_BIG_ENDIAN BIG_ENDIAN
118
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119#else
120
121# define GIT_BIG_ENDIAN 4321
122# define GIT_LITTLE_ENDIAN 1234
123
124# if defined(_BIG_ENDIAN) && !defined(_LITTLE_ENDIAN)
125# define GIT_BYTE_ORDER GIT_BIG_ENDIAN
9c65ee15 126# elif defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
3cf6bb34 127# define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
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128# elif defined(__THW_BIG_ENDIAN__) && !defined(__THW_LITTLE_ENDIAN__)
129# define GIT_BYTE_ORDER GIT_BIG_ENDIAN
130# elif defined(__THW_LITTLE_ENDIAN__) && !defined(__THW_BIG_ENDIAN__)
131# define GIT_BYTE_ORDER GIT_LITTLE_ENDIAN
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132# else
133# error "Cannot determine endianness"
7e3dae49 134# endif
7e3dae49 135
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136#endif
137
3cf6bb34 138#if GIT_BYTE_ORDER == GIT_BIG_ENDIAN
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139# define ntohll(n) (n)
140# define htonll(n) (n)
141#else
142# define ntohll(n) default_bswap64(n)
143# define htonll(n) default_bswap64(n)
144#endif
145
146#endif
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147
148/*
149 * Performance might be improved if the CPU architecture is OK with
150 * unaligned 32-bit loads and a fast ntohl() is available.
151 * Otherwise fall back to byte loads and shifts which is portable,
152 * and is faster on architectures with memory alignment issues.
153 */
154
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155#if !defined(NO_UNALIGNED_LOADS) && ( \
156 defined(__i386__) || defined(__x86_64__) || \
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157 defined(_M_IX86) || defined(_M_X64) || \
158 defined(__ppc__) || defined(__ppc64__) || \
159 defined(__powerpc__) || defined(__powerpc64__) || \
a0df2e5a 160 defined(__s390__) || defined(__s390x__))
802b1233 161
c3d8da57 162#define get_be16(p) ntohs(*(unsigned short *)(p))
802b1233 163#define get_be32(p) ntohl(*(unsigned int *)(p))
b2e39d00 164#define get_be64(p) ntohll(*(uint64_t *)(p))
802b1233 165#define put_be32(p, v) do { *(unsigned int *)(p) = htonl(v); } while (0)
b2e39d00 166#define put_be64(p, v) do { *(uint64_t *)(p) = htonll(v); } while (0)
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167
168#else
169
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170static inline uint16_t get_be16(const void *ptr)
171{
172 const unsigned char *p = ptr;
173 return (uint16_t)p[0] << 8 |
174 (uint16_t)p[1] << 0;
175}
176
177static inline uint32_t get_be32(const void *ptr)
178{
179 const unsigned char *p = ptr;
180 return (uint32_t)p[0] << 24 |
181 (uint32_t)p[1] << 16 |
182 (uint32_t)p[2] << 8 |
183 (uint32_t)p[3] << 0;
184}
185
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186static inline uint64_t get_be64(const void *ptr)
187{
188 const unsigned char *p = ptr;
189 return (uint64_t)get_be32(&p[0]) << 32 |
190 (uint64_t)get_be32(&p[4]) << 0;
191}
192
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193static inline void put_be32(void *ptr, uint32_t value)
194{
195 unsigned char *p = ptr;
196 p[0] = value >> 24;
197 p[1] = value >> 16;
198 p[2] = value >> 8;
199 p[3] = value >> 0;
200}
802b1233 201
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202static inline void put_be64(void *ptr, uint64_t value)
203{
204 unsigned char *p = ptr;
205 p[0] = value >> 56;
206 p[1] = value >> 48;
207 p[2] = value >> 40;
208 p[3] = value >> 32;
209 p[4] = value >> 24;
210 p[5] = value >> 16;
211 p[6] = value >> 8;
212 p[7] = value >> 0;
213}
214
802b1233 215#endif
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216
217#endif /* COMPAT_BSWAP_H */