SDL  2.0
SDL_endian.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 
22 /**
23  * \file SDL_endian.h
24  *
25  * Functions for reading and writing endian-specific values
26  */
27 
28 #ifndef SDL_endian_h_
29 #define SDL_endian_h_
30 
31 #include "SDL_stdinc.h"
32 
33 #if defined(_MSC_VER) && (_MSC_VER >= 1400)
34 /* As of Clang 11, '_m_prefetchw' is conflicting with the winnt.h's version,
35  so we define the needed '_m_prefetch' here as a pseudo-header, until the issue is fixed. */
36 #ifdef __clang__
37 #ifndef __PRFCHWINTRIN_H
38 #define __PRFCHWINTRIN_H
39 static __inline__ void __attribute__((__always_inline__, __nodebug__))
40 _m_prefetch(void *__P)
41 {
42  __builtin_prefetch (__P, 0, 3 /* _MM_HINT_T0 */);
43 }
44 #endif /* __PRFCHWINTRIN_H */
45 #endif /* __clang__ */
46 
47 #include <intrin.h>
48 #endif
49 
50 /**
51  * \name The two types of endianness
52  */
53 /* @{ */
54 #define SDL_LIL_ENDIAN 1234
55 #define SDL_BIG_ENDIAN 4321
56 /* @} */
57 
58 #ifndef SDL_BYTEORDER /* Not defined in SDL_config.h? */
59 #ifdef __linux__
60 #include <endian.h>
61 #define SDL_BYTEORDER __BYTE_ORDER
62 #elif defined(__OpenBSD__)
63 #include <endian.h>
64 #define SDL_BYTEORDER BYTE_ORDER
65 #elif defined(__FreeBSD__) || defined(__NetBSD__)
66 #include <sys/endian.h>
67 #define SDL_BYTEORDER BYTE_ORDER
68 /* predefs from newer gcc and clang versions: */
69 #elif defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_BIG_ENDIAN__) && defined(__BYTE_ORDER__)
70 #if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
71 #define SDL_BYTEORDER SDL_LIL_ENDIAN
72 #elif (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
73 #define SDL_BYTEORDER SDL_BIG_ENDIAN
74 #else
75 #error Unsupported endianness
76 #endif /**/
77 #else
78 #if defined(__hppa__) || \
79  defined(__m68k__) || defined(mc68000) || defined(_M_M68K) || \
80  (defined(__MIPS__) && defined(__MIPSEB__)) || \
81  defined(__ppc__) || defined(__POWERPC__) || defined(_M_PPC) || \
82  defined(__sparc__)
83 #define SDL_BYTEORDER SDL_BIG_ENDIAN
84 #else
85 #define SDL_BYTEORDER SDL_LIL_ENDIAN
86 #endif
87 #endif /* __linux__ */
88 #endif /* !SDL_BYTEORDER */
89 
90 
91 #include "begin_code.h"
92 /* Set up for C function definitions, even when using C++ */
93 #ifdef __cplusplus
94 extern "C" {
95 #endif
96 
97 /**
98  * \file SDL_endian.h
99  */
100 
101 /* various modern compilers may have builtin swap */
102 #if defined(__GNUC__) || defined(__clang__)
103 # define HAS_BUILTIN_BSWAP16 (_SDL_HAS_BUILTIN(__builtin_bswap16)) || \
104  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))
105 # define HAS_BUILTIN_BSWAP32 (_SDL_HAS_BUILTIN(__builtin_bswap32)) || \
106  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
107 # define HAS_BUILTIN_BSWAP64 (_SDL_HAS_BUILTIN(__builtin_bswap64)) || \
108  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
109 
110  /* this one is broken */
111 # define HAS_BROKEN_BSWAP (__GNUC__ == 2 && __GNUC_MINOR__ <= 95)
112 #else
113 # define HAS_BUILTIN_BSWAP16 0
114 # define HAS_BUILTIN_BSWAP32 0
115 # define HAS_BUILTIN_BSWAP64 0
116 # define HAS_BROKEN_BSWAP 0
117 #endif
118 
119 #if HAS_BUILTIN_BSWAP16
120 #define SDL_Swap16(x) __builtin_bswap16(x)
121 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
122 #pragma intrinsic(_byteswap_ushort)
123 #define SDL_Swap16(x) _byteswap_ushort(x)
124 #elif defined(__i386__) && !HAS_BROKEN_BSWAP
127 {
128  __asm__("xchgb %b0,%h0": "=q"(x):"0"(x));
129  return x;
130 }
131 #elif defined(__x86_64__)
134 {
135  __asm__("xchgb %b0,%h0": "=Q"(x):"0"(x));
136  return x;
137 }
138 #elif (defined(__powerpc__) || defined(__ppc__))
141 {
142  int result;
143 
144  __asm__("rlwimi %0,%2,8,16,23": "=&r"(result):"0"(x >> 8), "r"(x));
145  return (Uint16)result;
146 }
147 #elif (defined(__m68k__) && !defined(__mcoldfire__))
150 {
151  __asm__("rorw #8,%0": "=d"(x): "0"(x):"cc");
152  return x;
153 }
154 #elif defined(__WATCOMC__) && defined(__386__)
155 extern __inline Uint16 SDL_Swap16(Uint16);
156 #pragma aux SDL_Swap16 = \
157  "xchg al, ah" \
158  parm [ax] \
159  modify [ax];
160 #else
163 {
164  return SDL_static_cast(Uint16, ((x << 8) | (x >> 8)));
165 }
166 #endif
167 
168 #if HAS_BUILTIN_BSWAP32
169 #define SDL_Swap32(x) __builtin_bswap32(x)
170 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
171 #pragma intrinsic(_byteswap_ulong)
172 #define SDL_Swap32(x) _byteswap_ulong(x)
173 #elif defined(__i386__) && !HAS_BROKEN_BSWAP
176 {
177  __asm__("bswap %0": "=r"(x):"0"(x));
178  return x;
179 }
180 #elif defined(__x86_64__)
183 {
184  __asm__("bswapl %0": "=r"(x):"0"(x));
185  return x;
186 }
187 #elif (defined(__powerpc__) || defined(__ppc__))
190 {
191  Uint32 result;
192 
193  __asm__("rlwimi %0,%2,24,16,23": "=&r"(result): "0" (x>>24), "r"(x));
194  __asm__("rlwimi %0,%2,8,8,15" : "=&r"(result): "0" (result), "r"(x));
195  __asm__("rlwimi %0,%2,24,0,7" : "=&r"(result): "0" (result), "r"(x));
196  return result;
197 }
198 #elif (defined(__m68k__) && !defined(__mcoldfire__))
201 {
202  __asm__("rorw #8,%0\n\tswap %0\n\trorw #8,%0": "=d"(x): "0"(x):"cc");
203  return x;
204 }
205 #elif defined(__WATCOMC__) && defined(__386__)
206 extern __inline Uint32 SDL_Swap32(Uint32);
207 #pragma aux SDL_Swap32 = \
208  "bswap eax" \
209  parm [eax] \
210  modify [eax];
211 #else
214 {
215  return SDL_static_cast(Uint32, ((x << 24) | ((x << 8) & 0x00FF0000) |
216  ((x >> 8) & 0x0000FF00) | (x >> 24)));
217 }
218 #endif
219 
220 #if HAS_BUILTIN_BSWAP64
221 #define SDL_Swap64(x) __builtin_bswap64(x)
222 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
223 #pragma intrinsic(_byteswap_uint64)
224 #define SDL_Swap64(x) _byteswap_uint64(x)
225 #elif defined(__i386__) && !HAS_BROKEN_BSWAP
228 {
229  union {
230  struct {
231  Uint32 a, b;
232  } s;
233  Uint64 u;
234  } v;
235  v.u = x;
236  __asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1"
237  : "=r"(v.s.a), "=r"(v.s.b)
238  : "0" (v.s.a), "1"(v.s.b));
239  return v.u;
240 }
241 #elif defined(__x86_64__)
244 {
245  __asm__("bswapq %0": "=r"(x):"0"(x));
246  return x;
247 }
248 #elif defined(__WATCOMC__) && defined(__386__)
249 extern __inline Uint64 SDL_Swap64(Uint64);
250 #pragma aux SDL_Swap64 = \
251  "bswap eax" \
252  "bswap edx" \
253  "xchg eax,edx" \
254  parm [eax edx] \
255  modify [eax edx];
256 #else
259 {
260  Uint32 hi, lo;
261 
262  /* Separate into high and low 32-bit values and swap them */
263  lo = SDL_static_cast(Uint32, x & 0xFFFFFFFF);
264  x >>= 32;
265  hi = SDL_static_cast(Uint32, x & 0xFFFFFFFF);
266  x = SDL_Swap32(lo);
267  x <<= 32;
268  x |= SDL_Swap32(hi);
269  return (x);
270 }
271 #endif
272 
273 
274 SDL_FORCE_INLINE float
276 {
277  union {
278  float f;
279  Uint32 ui32;
280  } swapper;
281  swapper.f = x;
282  swapper.ui32 = SDL_Swap32(swapper.ui32);
283  return swapper.f;
284 }
285 
286 /* remove extra macros */
287 #undef HAS_BROKEN_BSWAP
288 #undef HAS_BUILTIN_BSWAP16
289 #undef HAS_BUILTIN_BSWAP32
290 #undef HAS_BUILTIN_BSWAP64
291 
292 /**
293  * \name Swap to native
294  * Byteswap item from the specified endianness to the native endianness.
295  */
296 /* @{ */
297 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
298 #define SDL_SwapLE16(X) (X)
299 #define SDL_SwapLE32(X) (X)
300 #define SDL_SwapLE64(X) (X)
301 #define SDL_SwapFloatLE(X) (X)
302 #define SDL_SwapBE16(X) SDL_Swap16(X)
303 #define SDL_SwapBE32(X) SDL_Swap32(X)
304 #define SDL_SwapBE64(X) SDL_Swap64(X)
305 #define SDL_SwapFloatBE(X) SDL_SwapFloat(X)
306 #else
307 #define SDL_SwapLE16(X) SDL_Swap16(X)
308 #define SDL_SwapLE32(X) SDL_Swap32(X)
309 #define SDL_SwapLE64(X) SDL_Swap64(X)
310 #define SDL_SwapFloatLE(X) SDL_SwapFloat(X)
311 #define SDL_SwapBE16(X) (X)
312 #define SDL_SwapBE32(X) (X)
313 #define SDL_SwapBE64(X) (X)
314 #define SDL_SwapFloatBE(X) (X)
315 #endif
316 /* @} *//* Swap to native */
317 
318 /* Ends C function definitions when using C++ */
319 #ifdef __cplusplus
320 }
321 #endif
322 #include "close_code.h"
323 
324 #endif /* SDL_endian_h_ */
325 
326 /* vi: set ts=4 sw=4 expandtab: */
SDL_FORCE_INLINE Uint32 SDL_Swap32(Uint32 x)
Definition: SDL_endian.h:213
SDL_FORCE_INLINE Uint16 SDL_Swap16(Uint16 x)
Definition: SDL_endian.h:162
SDL_FORCE_INLINE float SDL_SwapFloat(float x)
Definition: SDL_endian.h:275
SDL_FORCE_INLINE Uint64 SDL_Swap64(Uint64 x)
Definition: SDL_endian.h:258
uint16_t Uint16
Definition: SDL_stdinc.h:208
#define SDL_static_cast(type, expression)
Definition: SDL_stdinc.h:155
uint64_t Uint64
Definition: SDL_stdinc.h:233
uint32_t Uint32
Definition: SDL_stdinc.h:220
#define __inline__
Definition: begin_code.h:132
#define SDL_FORCE_INLINE
Definition: begin_code.h:143