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 #ifndef SDL_FLOATWORDORDER /* Not defined in SDL_config.h? */
91 /* predefs from newer gcc versions: */
92 #if defined(__ORDER_LITTLE_ENDIAN__) && defined(__ORDER_BIG_ENDIAN__) && defined(__FLOAT_WORD_ORDER__)
93 #if (__FLOAT_WORD_ORDER__ == __ORDER_LITTLE_ENDIAN__)
94 #define SDL_FLOATWORDORDER SDL_LIL_ENDIAN
95 #elif (__FLOAT_WORD_ORDER__ == __ORDER_BIG_ENDIAN__)
96 #define SDL_FLOATWORDORDER SDL_BIG_ENDIAN
97 #else
98 #error Unsupported endianness
99 #endif /**/
100 #elif defined(__MAVERICK__)
101 /* For Maverick, float words are always little-endian. */
102 #define SDL_FLOATWORDORDER SDL_LIL_ENDIAN
103 #elif (defined(__arm__) || defined(__thumb__)) && !defined(__VFP_FP__) && !defined(__ARM_EABI__)
104 /* For FPA, float words are always big-endian. */
105 #define SDL_FLOATWORDORDER SDL_BIG_ENDIAN
106 #else
107 /* By default, assume that floats words follow the memory system mode. */
108 #define SDL_FLOATWORDORDER SDL_BYTEORDER
109 #endif /* __FLOAT_WORD_ORDER__ */
110 #endif /* !SDL_FLOATWORDORDER */
111 
112 
113 #include "begin_code.h"
114 /* Set up for C function definitions, even when using C++ */
115 #ifdef __cplusplus
116 extern "C" {
117 #endif
118 
119 /**
120  * \file SDL_endian.h
121  */
122 
123 /* various modern compilers may have builtin swap */
124 #if defined(__GNUC__) || defined(__clang__)
125 # define HAS_BUILTIN_BSWAP16 (_SDL_HAS_BUILTIN(__builtin_bswap16)) || \
126  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))
127 # define HAS_BUILTIN_BSWAP32 (_SDL_HAS_BUILTIN(__builtin_bswap32)) || \
128  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
129 # define HAS_BUILTIN_BSWAP64 (_SDL_HAS_BUILTIN(__builtin_bswap64)) || \
130  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
131 
132  /* this one is broken */
133 # define HAS_BROKEN_BSWAP (__GNUC__ == 2 && __GNUC_MINOR__ <= 95)
134 #else
135 # define HAS_BUILTIN_BSWAP16 0
136 # define HAS_BUILTIN_BSWAP32 0
137 # define HAS_BUILTIN_BSWAP64 0
138 # define HAS_BROKEN_BSWAP 0
139 #endif
140 
141 #if HAS_BUILTIN_BSWAP16
142 #define SDL_Swap16(x) __builtin_bswap16(x)
143 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
144 #pragma intrinsic(_byteswap_ushort)
145 #define SDL_Swap16(x) _byteswap_ushort(x)
146 #elif defined(__i386__) && !HAS_BROKEN_BSWAP
149 {
150  __asm__("xchgb %b0,%h0": "=q"(x):"0"(x));
151  return x;
152 }
153 #elif defined(__x86_64__)
156 {
157  __asm__("xchgb %b0,%h0": "=Q"(x):"0"(x));
158  return x;
159 }
160 #elif (defined(__powerpc__) || defined(__ppc__))
163 {
164  int result;
165 
166  __asm__("rlwimi %0,%2,8,16,23": "=&r"(result):"0"(x >> 8), "r"(x));
167  return (Uint16)result;
168 }
169 #elif (defined(__m68k__) && !defined(__mcoldfire__))
172 {
173  __asm__("rorw #8,%0": "=d"(x): "0"(x):"cc");
174  return x;
175 }
176 #elif defined(__WATCOMC__) && defined(__386__)
177 extern __inline Uint16 SDL_Swap16(Uint16);
178 #pragma aux SDL_Swap16 = \
179  "xchg al, ah" \
180  parm [ax] \
181  modify [ax];
182 #else
185 {
186  return SDL_static_cast(Uint16, ((x << 8) | (x >> 8)));
187 }
188 #endif
189 
190 #if HAS_BUILTIN_BSWAP32
191 #define SDL_Swap32(x) __builtin_bswap32(x)
192 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
193 #pragma intrinsic(_byteswap_ulong)
194 #define SDL_Swap32(x) _byteswap_ulong(x)
195 #elif defined(__i386__) && !HAS_BROKEN_BSWAP
198 {
199  __asm__("bswap %0": "=r"(x):"0"(x));
200  return x;
201 }
202 #elif defined(__x86_64__)
205 {
206  __asm__("bswapl %0": "=r"(x):"0"(x));
207  return x;
208 }
209 #elif (defined(__powerpc__) || defined(__ppc__))
212 {
213  Uint32 result;
214 
215  __asm__("rlwimi %0,%2,24,16,23": "=&r"(result): "0" (x>>24), "r"(x));
216  __asm__("rlwimi %0,%2,8,8,15" : "=&r"(result): "0" (result), "r"(x));
217  __asm__("rlwimi %0,%2,24,0,7" : "=&r"(result): "0" (result), "r"(x));
218  return result;
219 }
220 #elif (defined(__m68k__) && !defined(__mcoldfire__))
223 {
224  __asm__("rorw #8,%0\n\tswap %0\n\trorw #8,%0": "=d"(x): "0"(x):"cc");
225  return x;
226 }
227 #elif defined(__WATCOMC__) && defined(__386__)
228 extern __inline Uint32 SDL_Swap32(Uint32);
229 #pragma aux SDL_Swap32 = \
230  "bswap eax" \
231  parm [eax] \
232  modify [eax];
233 #else
236 {
237  return SDL_static_cast(Uint32, ((x << 24) | ((x << 8) & 0x00FF0000) |
238  ((x >> 8) & 0x0000FF00) | (x >> 24)));
239 }
240 #endif
241 
242 #if HAS_BUILTIN_BSWAP64
243 #define SDL_Swap64(x) __builtin_bswap64(x)
244 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
245 #pragma intrinsic(_byteswap_uint64)
246 #define SDL_Swap64(x) _byteswap_uint64(x)
247 #elif defined(__i386__) && !HAS_BROKEN_BSWAP
250 {
251  union {
252  struct {
253  Uint32 a, b;
254  } s;
255  Uint64 u;
256  } v;
257  v.u = x;
258  __asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1"
259  : "=r"(v.s.a), "=r"(v.s.b)
260  : "0" (v.s.a), "1"(v.s.b));
261  return v.u;
262 }
263 #elif defined(__x86_64__)
266 {
267  __asm__("bswapq %0": "=r"(x):"0"(x));
268  return x;
269 }
270 #elif defined(__WATCOMC__) && defined(__386__)
271 extern __inline Uint64 SDL_Swap64(Uint64);
272 #pragma aux SDL_Swap64 = \
273  "bswap eax" \
274  "bswap edx" \
275  "xchg eax,edx" \
276  parm [eax edx] \
277  modify [eax edx];
278 #else
281 {
282  Uint32 hi, lo;
283 
284  /* Separate into high and low 32-bit values and swap them */
285  lo = SDL_static_cast(Uint32, x & 0xFFFFFFFF);
286  x >>= 32;
287  hi = SDL_static_cast(Uint32, x & 0xFFFFFFFF);
288  x = SDL_Swap32(lo);
289  x <<= 32;
290  x |= SDL_Swap32(hi);
291  return (x);
292 }
293 #endif
294 
295 
296 SDL_FORCE_INLINE float
298 {
299  union {
300  float f;
301  Uint32 ui32;
302  } swapper;
303  swapper.f = x;
304  swapper.ui32 = SDL_Swap32(swapper.ui32);
305  return swapper.f;
306 }
307 
308 /* remove extra macros */
309 #undef HAS_BROKEN_BSWAP
310 #undef HAS_BUILTIN_BSWAP16
311 #undef HAS_BUILTIN_BSWAP32
312 #undef HAS_BUILTIN_BSWAP64
313 
314 /**
315  * \name Swap to native
316  * Byteswap item from the specified endianness to the native endianness.
317  */
318 /* @{ */
319 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
320 #define SDL_SwapLE16(X) (X)
321 #define SDL_SwapLE32(X) (X)
322 #define SDL_SwapLE64(X) (X)
323 #define SDL_SwapFloatLE(X) (X)
324 #define SDL_SwapBE16(X) SDL_Swap16(X)
325 #define SDL_SwapBE32(X) SDL_Swap32(X)
326 #define SDL_SwapBE64(X) SDL_Swap64(X)
327 #define SDL_SwapFloatBE(X) SDL_SwapFloat(X)
328 #else
329 #define SDL_SwapLE16(X) SDL_Swap16(X)
330 #define SDL_SwapLE32(X) SDL_Swap32(X)
331 #define SDL_SwapLE64(X) SDL_Swap64(X)
332 #define SDL_SwapFloatLE(X) SDL_SwapFloat(X)
333 #define SDL_SwapBE16(X) (X)
334 #define SDL_SwapBE32(X) (X)
335 #define SDL_SwapBE64(X) (X)
336 #define SDL_SwapFloatBE(X) (X)
337 #endif
338 /* @} *//* Swap to native */
339 
340 /* Ends C function definitions when using C++ */
341 #ifdef __cplusplus
342 }
343 #endif
344 #include "close_code.h"
345 
346 #endif /* SDL_endian_h_ */
347 
348 /* vi: set ts=4 sw=4 expandtab: */
SDL_FORCE_INLINE Uint32 SDL_Swap32(Uint32 x)
Definition: SDL_endian.h:235
SDL_FORCE_INLINE Uint16 SDL_Swap16(Uint16 x)
Definition: SDL_endian.h:184
SDL_FORCE_INLINE float SDL_SwapFloat(float x)
Definition: SDL_endian.h:297
SDL_FORCE_INLINE Uint64 SDL_Swap64(Uint64 x)
Definition: SDL_endian.h:280
uint16_t Uint16
Definition: SDL_stdinc.h:214
#define SDL_static_cast(type, expression)
Definition: SDL_stdinc.h:161
uint64_t Uint64
Definition: SDL_stdinc.h:239
uint32_t Uint32
Definition: SDL_stdinc.h:226
#define __inline__
Definition: begin_code.h:132
#define SDL_FORCE_INLINE
Definition: begin_code.h:143