summaryrefslogtreecommitdiff
path: root/compat/bswap.h
blob: 512f6f4b9937c8a97904b8ef3a7e21d644695989 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
#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) || defined(_M_ARM64))

#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

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 /* COMPAT_BSWAP_H */