xref: /dpdk/lib/eal/include/rte_common.h (revision e9fd1ebf981f361844aea9ec94e17f4bda5e1479)
1 /* SPDX-License-Identifier: BSD-3-Clause
2  * Copyright(c) 2010-2019 Intel Corporation
3  */
4 
5 #ifndef _RTE_COMMON_H_
6 #define _RTE_COMMON_H_
7 
8 /**
9  * @file
10  *
11  * Generic, commonly-used macro and inline function definitions
12  * for DPDK.
13  */
14 
15 #ifdef __cplusplus
16 extern "C" {
17 #endif
18 
19 #include <assert.h>
20 #include <limits.h>
21 #include <stdint.h>
22 #include <stdalign.h>
23 
24 #include <rte_config.h>
25 
26 /* OS specific include */
27 #include <rte_os.h>
28 
29 #ifndef RTE_TOOLCHAIN_MSVC
30 #ifndef typeof
31 #define typeof __typeof__
32 #endif
33 #endif
34 
35 #ifndef __cplusplus
36 #ifndef asm
37 #define asm __asm__
38 #endif
39 #endif
40 
41 #ifdef RTE_TOOLCHAIN_MSVC
42 #define __extension__
43 #endif
44 
45 /*
46  * RTE_TOOLCHAIN_GCC is defined if the target is built with GCC,
47  * while a host application (like pmdinfogen) may have another compiler.
48  * RTE_CC_IS_GNU is true if the file is compiled with GCC,
49  * no matter it is a target or host application.
50  */
51 #define RTE_CC_IS_GNU 0
52 #if defined __clang__
53 #define RTE_CC_CLANG
54 #elif defined __INTEL_COMPILER
55 #define RTE_CC_ICC
56 #elif defined __GNUC__
57 #define RTE_CC_GCC
58 #undef RTE_CC_IS_GNU
59 #define RTE_CC_IS_GNU 1
60 #endif
61 #if RTE_CC_IS_GNU
62 #define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 +	\
63 		__GNUC_PATCHLEVEL__)
64 #endif
65 
66 /**
67  * Force alignment
68  */
69 #ifdef RTE_TOOLCHAIN_MSVC
70 #define __rte_aligned(a)
71 #else
72 #define __rte_aligned(a) __attribute__((__aligned__(a)))
73 #endif
74 
75 #ifdef RTE_ARCH_STRICT_ALIGN
76 typedef uint64_t unaligned_uint64_t __rte_aligned(1);
77 typedef uint32_t unaligned_uint32_t __rte_aligned(1);
78 typedef uint16_t unaligned_uint16_t __rte_aligned(1);
79 #else
80 typedef uint64_t unaligned_uint64_t;
81 typedef uint32_t unaligned_uint32_t;
82 typedef uint16_t unaligned_uint16_t;
83 #endif
84 
85 /**
86  * Force a structure to be packed
87  */
88 #ifdef RTE_TOOLCHAIN_MSVC
89 #define __rte_packed
90 #else
91 #define __rte_packed __attribute__((__packed__))
92 #endif
93 
94 /**
95  * Macro to mark a type that is not subject to type-based aliasing rules
96  */
97 #ifdef RTE_TOOLCHAIN_MSVC
98 #define __rte_may_alias
99 #else
100 #define __rte_may_alias __attribute__((__may_alias__))
101 #endif
102 
103 /******* Macro to mark functions and fields scheduled for removal *****/
104 #ifdef RTE_TOOLCHAIN_MSVC
105 #define __rte_deprecated
106 #define __rte_deprecated_msg(msg)
107 #else
108 #define __rte_deprecated	__attribute__((__deprecated__))
109 #define __rte_deprecated_msg(msg)	__attribute__((__deprecated__(msg)))
110 #endif
111 
112 /**
113  *  Macro to mark macros and defines scheduled for removal
114  */
115 #if defined(RTE_CC_GCC) || defined(RTE_CC_CLANG)
116 #define RTE_PRAGMA(x)  _Pragma(#x)
117 #define RTE_PRAGMA_WARNING(w) RTE_PRAGMA(GCC warning #w)
118 #define RTE_DEPRECATED(x)  RTE_PRAGMA_WARNING(#x is deprecated)
119 #else
120 #define RTE_DEPRECATED(x)
121 #endif
122 
123 /**
124  * Mark a function or variable to a weak reference.
125  */
126 #define __rte_weak __attribute__((__weak__))
127 
128 /**
129  * Force symbol to be generated even if it appears to be unused.
130  */
131 #ifdef RTE_TOOLCHAIN_MSVC
132 #define __rte_used
133 #else
134 #define __rte_used __attribute__((used))
135 #endif
136 
137 /*********** Macros to eliminate unused variable warnings ********/
138 
139 /**
140  * short definition to mark a function parameter unused
141  */
142 #ifdef RTE_TOOLCHAIN_MSVC
143 #define __rte_unused
144 #else
145 #define __rte_unused __attribute__((__unused__))
146 #endif
147 
148 /**
149  * Mark pointer as restricted with regard to pointer aliasing.
150  */
151 #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L
152 #define __rte_restrict __restrict
153 #else
154 #define __rte_restrict restrict
155 #endif
156 
157 /**
158  * definition to mark a variable or function parameter as used so
159  * as to avoid a compiler warning
160  */
161 #define RTE_SET_USED(x) (void)(x)
162 
163 /**
164  * Check format string and its arguments at compile-time.
165  *
166  * GCC on Windows assumes MS-specific format string by default,
167  * even if the underlying stdio implementation is ANSI-compliant,
168  * so this must be overridden.
169  */
170 #ifdef RTE_TOOLCHAIN_MSVC
171 #define __rte_format_printf(format_index, first_arg)
172 #else
173 #if RTE_CC_IS_GNU
174 #define __rte_format_printf(format_index, first_arg) \
175 	__attribute__((format(gnu_printf, format_index, first_arg)))
176 #else
177 #define __rte_format_printf(format_index, first_arg) \
178 	__attribute__((format(printf, format_index, first_arg)))
179 #endif
180 #endif
181 
182 /**
183  * Specify data or function section/segment.
184  */
185 #ifdef RTE_TOOLCHAIN_MSVC
186 #define __rte_section(name) \
187 	__pragma(data_seg(name)) __declspec(allocate(name))
188 #else
189 #define __rte_section(name) \
190 	__attribute__((section(name)))
191 #endif
192 
193 /**
194  * Tells compiler that the function returns a value that points to
195  * memory, where the size is given by the one or two arguments.
196  * Used by compiler to validate object size.
197  */
198 #if defined(RTE_CC_GCC) || defined(RTE_CC_CLANG)
199 #define __rte_alloc_size(...) \
200 	__attribute__((alloc_size(__VA_ARGS__)))
201 #else
202 #define __rte_alloc_size(...)
203 #endif
204 
205 #define RTE_PRIORITY_LOG 101
206 #define RTE_PRIORITY_BUS 110
207 #define RTE_PRIORITY_CLASS 120
208 #define RTE_PRIORITY_LAST 65535
209 
210 #define RTE_PRIO(prio) \
211 	RTE_PRIORITY_ ## prio
212 
213 /**
214  * Run function before main() with high priority.
215  *
216  * @param func
217  *   Constructor function.
218  * @param prio
219  *   Priority number must be above 100.
220  *   Lowest number is the first to run.
221  */
222 #ifndef RTE_INIT_PRIO /* Allow to override from EAL */
223 #ifndef RTE_TOOLCHAIN_MSVC
224 #define RTE_INIT_PRIO(func, prio) \
225 static void __attribute__((constructor(RTE_PRIO(prio)), used)) func(void)
226 #else
227 /* definition from the Microsoft CRT */
228 typedef int(__cdecl *_PIFV)(void);
229 
230 #define CTOR_SECTION_LOG ".CRT$XIB"
231 #define CTOR_SECTION_BUS ".CRT$XIC"
232 #define CTOR_SECTION_CLASS ".CRT$XID"
233 #define CTOR_SECTION_LAST ".CRT$XIY"
234 
235 #define CTOR_PRIORITY_TO_SECTION(priority) CTOR_SECTION_ ## priority
236 
237 #define RTE_INIT_PRIO(name, priority) \
238 	static void name(void); \
239 	static int __cdecl name ## _thunk(void) { name(); return 0; } \
240 	__pragma(const_seg(CTOR_PRIORITY_TO_SECTION(priority))) \
241 	__declspec(allocate(CTOR_PRIORITY_TO_SECTION(priority))) \
242 	    _PIFV name ## _pointer = &name ## _thunk; \
243 	__pragma(const_seg()) \
244 	static void name(void)
245 #endif
246 #endif
247 
248 /**
249  * Run function before main() with low priority.
250  *
251  * The constructor will be run after prioritized constructors.
252  *
253  * @param func
254  *   Constructor function.
255  */
256 #define RTE_INIT(func) \
257 	RTE_INIT_PRIO(func, LAST)
258 
259 /**
260  * Run after main() with low priority.
261  *
262  * @param func
263  *   Destructor function name.
264  * @param prio
265  *   Priority number must be above 100.
266  *   Lowest number is the last to run.
267  */
268 #ifndef RTE_FINI_PRIO /* Allow to override from EAL */
269 #ifndef RTE_TOOLCHAIN_MSVC
270 #define RTE_FINI_PRIO(func, prio) \
271 static void __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
272 #else
273 #define DTOR_SECTION_LOG "mydtor$B"
274 #define DTOR_SECTION_BUS "mydtor$C"
275 #define DTOR_SECTION_CLASS "mydtor$D"
276 #define DTOR_SECTION_LAST "mydtor$Y"
277 
278 #define DTOR_PRIORITY_TO_SECTION(priority) DTOR_SECTION_ ## priority
279 
280 #define RTE_FINI_PRIO(name, priority) \
281 	static void name(void); \
282 	__pragma(const_seg(DTOR_PRIORITY_TO_SECTION(priority))) \
283 	__declspec(allocate(DTOR_PRIORITY_TO_SECTION(priority))) name ## _pointer = &name; \
284 	__pragma(const_seg()) \
285 	static void name(void)
286 #endif
287 #endif
288 
289 /**
290  * Run after main() with high priority.
291  *
292  * The destructor will be run *before* prioritized destructors.
293  *
294  * @param func
295  *   Destructor function name.
296  */
297 #define RTE_FINI(func) \
298 	RTE_FINI_PRIO(func, LAST)
299 
300 /**
301  * Hint never returning function
302  */
303 #ifdef RTE_TOOLCHAIN_MSVC
304 #define __rte_noreturn
305 #else
306 #define __rte_noreturn __attribute__((noreturn))
307 #endif
308 
309 /**
310  * Issue a warning in case the function's return value is ignored.
311  *
312  * The use of this attribute should be restricted to cases where
313  * ignoring the marked function's return value is almost always a
314  * bug. With GCC, some effort is required to make clear that ignoring
315  * the return value is intentional. The usual void-casting method to
316  * mark something unused as used does not suppress the warning with
317  * this compiler.
318  *
319  * @code{.c}
320  * __rte_warn_unused_result int foo();
321  *
322  * void ignore_foo_result(void) {
323  *         foo(); // generates a warning with all compilers
324  *
325  *         (void)foo(); // still generates the warning with GCC (but not clang)
326  *
327  *         int unused __rte_unused;
328  *         unused = foo(); // does the trick with all compilers
329  *  }
330  * @endcode
331  */
332 #ifdef RTE_TOOLCHAIN_MSVC
333 #define __rte_warn_unused_result
334 #else
335 #define __rte_warn_unused_result __attribute__((warn_unused_result))
336 #endif
337 
338 /**
339  * Force a function to be inlined
340  */
341 #ifdef RTE_TOOLCHAIN_MSVC
342 #define __rte_always_inline
343 #else
344 #define __rte_always_inline inline __attribute__((always_inline))
345 #endif
346 
347 /**
348  * Force a function to be noinlined
349  */
350 #define __rte_noinline __attribute__((noinline))
351 
352 /**
353  * Hint function in the hot path
354  */
355 #define __rte_hot __attribute__((hot))
356 
357 /**
358  * Hint function in the cold path
359  */
360 #ifdef RTE_TOOLCHAIN_MSVC
361 #define __rte_cold
362 #else
363 #define __rte_cold __attribute__((cold))
364 #endif
365 
366 /**
367  * Disable AddressSanitizer on some code
368  */
369 #ifdef RTE_MALLOC_ASAN
370 #ifdef RTE_CC_CLANG
371 #define __rte_no_asan __attribute__((no_sanitize("address", "hwaddress")))
372 #else
373 #define __rte_no_asan __attribute__((no_sanitize_address))
374 #endif
375 #else /* ! RTE_MALLOC_ASAN */
376 #define __rte_no_asan
377 #endif
378 
379 /*********** Macros for pointer arithmetic ********/
380 
381 /**
382  * add a byte-value offset to a pointer
383  */
384 #define RTE_PTR_ADD(ptr, x) ((void*)((uintptr_t)(ptr) + (x)))
385 
386 /**
387  * subtract a byte-value offset from a pointer
388  */
389 #define RTE_PTR_SUB(ptr, x) ((void *)((uintptr_t)(ptr) - (x)))
390 
391 /**
392  * get the difference between two pointer values, i.e. how far apart
393  * in bytes are the locations they point two. It is assumed that
394  * ptr1 is greater than ptr2.
395  */
396 #define RTE_PTR_DIFF(ptr1, ptr2) ((uintptr_t)(ptr1) - (uintptr_t)(ptr2))
397 
398 /**
399  * Workaround to cast a const field of a structure to non-const type.
400  */
401 #define RTE_CAST_FIELD(var, field, type) \
402 	(*(type *)((uintptr_t)(var) + offsetof(typeof(*(var)), field)))
403 
404 /*********** Macros/static functions for doing alignment ********/
405 
406 
407 /**
408  * Macro to align a pointer to a given power-of-two. The resultant
409  * pointer will be a pointer of the same type as the first parameter, and
410  * point to an address no higher than the first parameter. Second parameter
411  * must be a power-of-two value.
412  */
413 #define RTE_PTR_ALIGN_FLOOR(ptr, align) \
414 	((typeof(ptr))RTE_ALIGN_FLOOR((uintptr_t)(ptr), align))
415 
416 /**
417  * Macro to align a value to a given power-of-two. The resultant value
418  * will be of the same type as the first parameter, and will be no
419  * bigger than the first parameter. Second parameter must be a
420  * power-of-two value.
421  */
422 #define RTE_ALIGN_FLOOR(val, align) \
423 	(typeof(val))((val) & (~((typeof(val))((align) - 1))))
424 
425 /**
426  * Macro to align a pointer to a given power-of-two. The resultant
427  * pointer will be a pointer of the same type as the first parameter, and
428  * point to an address no lower than the first parameter. Second parameter
429  * must be a power-of-two value.
430  */
431 #define RTE_PTR_ALIGN_CEIL(ptr, align) \
432 	RTE_PTR_ALIGN_FLOOR((typeof(ptr))RTE_PTR_ADD(ptr, (align) - 1), align)
433 
434 /**
435  * Macro to align a value to a given power-of-two. The resultant value
436  * will be of the same type as the first parameter, and will be no lower
437  * than the first parameter. Second parameter must be a power-of-two
438  * value.
439  */
440 #define RTE_ALIGN_CEIL(val, align) \
441 	RTE_ALIGN_FLOOR(((val) + ((typeof(val)) (align) - 1)), align)
442 
443 /**
444  * Macro to align a pointer to a given power-of-two. The resultant
445  * pointer will be a pointer of the same type as the first parameter, and
446  * point to an address no lower than the first parameter. Second parameter
447  * must be a power-of-two value.
448  * This function is the same as RTE_PTR_ALIGN_CEIL
449  */
450 #define RTE_PTR_ALIGN(ptr, align) RTE_PTR_ALIGN_CEIL(ptr, align)
451 
452 /**
453  * Macro to align a value to a given power-of-two. The resultant
454  * value will be of the same type as the first parameter, and
455  * will be no lower than the first parameter. Second parameter
456  * must be a power-of-two value.
457  * This function is the same as RTE_ALIGN_CEIL
458  */
459 #define RTE_ALIGN(val, align) RTE_ALIGN_CEIL(val, align)
460 
461 /**
462  * Macro to align a value to the multiple of given value. The resultant
463  * value will be of the same type as the first parameter and will be no lower
464  * than the first parameter.
465  */
466 #define RTE_ALIGN_MUL_CEIL(v, mul) \
467 	((((v) + (typeof(v))(mul) - 1) / ((typeof(v))(mul))) * (typeof(v))(mul))
468 
469 /**
470  * Macro to align a value to the multiple of given value. The resultant
471  * value will be of the same type as the first parameter and will be no higher
472  * than the first parameter.
473  */
474 #define RTE_ALIGN_MUL_FLOOR(v, mul) \
475 	(((v) / ((typeof(v))(mul))) * (typeof(v))(mul))
476 
477 /**
478  * Macro to align value to the nearest multiple of the given value.
479  * The resultant value might be greater than or less than the first parameter
480  * whichever difference is the lowest.
481  */
482 #define RTE_ALIGN_MUL_NEAR(v, mul)				\
483 	__extension__ ({					\
484 		typeof(v) ceil = RTE_ALIGN_MUL_CEIL(v, mul);	\
485 		typeof(v) floor = RTE_ALIGN_MUL_FLOOR(v, mul);	\
486 		(ceil - (v)) > ((v) - floor) ? floor : ceil;	\
487 	})
488 
489 /**
490  * Checks if a pointer is aligned to a given power-of-two value
491  *
492  * @param ptr
493  *   The pointer whose alignment is to be checked
494  * @param align
495  *   The power-of-two value to which the ptr should be aligned
496  *
497  * @return
498  *   True(1) where the pointer is correctly aligned, false(0) otherwise
499  */
500 static inline int
501 rte_is_aligned(const void * const __rte_restrict ptr, const unsigned int align)
502 {
503 	return ((uintptr_t)ptr & (align - 1)) == 0;
504 }
505 
506 /*********** Macros for compile type checks ********/
507 
508 /* Workaround for toolchain issues with missing C11 macro in FreeBSD */
509 #if !defined(static_assert) && !defined(__cplusplus)
510 #define	static_assert	_Static_assert
511 #endif
512 
513 /**
514  * Triggers an error at compilation time if the condition is true.
515  *
516  * The do { } while(0) exists to workaround a bug in clang (#55821)
517  * where it would not handle _Static_assert in a switch case.
518  */
519 #define RTE_BUILD_BUG_ON(condition) do { static_assert(!(condition), #condition); } while (0)
520 
521 /*********** Cache line related macros ********/
522 
523 /** Cache line mask. */
524 #define RTE_CACHE_LINE_MASK (RTE_CACHE_LINE_SIZE-1)
525 
526 /** Return the first cache-aligned value greater or equal to size. */
527 #define RTE_CACHE_LINE_ROUNDUP(size) RTE_ALIGN_CEIL(size, RTE_CACHE_LINE_SIZE)
528 
529 /** Cache line size in terms of log2 */
530 #if RTE_CACHE_LINE_SIZE == 64
531 #define RTE_CACHE_LINE_SIZE_LOG2 6
532 #elif RTE_CACHE_LINE_SIZE == 128
533 #define RTE_CACHE_LINE_SIZE_LOG2 7
534 #else
535 #error "Unsupported cache line size"
536 #endif
537 
538 /** Minimum Cache line size. */
539 #define RTE_CACHE_LINE_MIN_SIZE 64
540 
541 /** Force alignment to cache line. */
542 #ifdef RTE_TOOLCHAIN_MSVC
543 #define __rte_cache_aligned
544 #else
545 #define __rte_cache_aligned __rte_aligned(RTE_CACHE_LINE_SIZE)
546 #endif
547 
548 /** Force minimum cache line alignment. */
549 #define __rte_cache_min_aligned __rte_aligned(RTE_CACHE_LINE_MIN_SIZE)
550 
551 #define _RTE_CACHE_GUARD_HELPER2(unique) \
552 	alignas(RTE_CACHE_LINE_SIZE) \
553 	char cache_guard_ ## unique[RTE_CACHE_LINE_SIZE * RTE_CACHE_GUARD_LINES]
554 #define _RTE_CACHE_GUARD_HELPER1(unique) _RTE_CACHE_GUARD_HELPER2(unique)
555 /**
556  * Empty cache lines, to guard against false sharing-like effects
557  * on systems with a next-N-lines hardware prefetcher.
558  *
559  * Use as spacing between data accessed by different lcores,
560  * to prevent cache thrashing on hardware with speculative prefetching.
561  */
562 #define RTE_CACHE_GUARD _RTE_CACHE_GUARD_HELPER1(__COUNTER__)
563 
564 /*********** PA/IOVA type definitions ********/
565 
566 /** Physical address */
567 typedef uint64_t phys_addr_t;
568 #define RTE_BAD_PHYS_ADDR ((phys_addr_t)-1)
569 
570 /**
571  * IO virtual address type.
572  * When the physical addressing mode (IOVA as PA) is in use,
573  * the translation from an IO virtual address (IOVA) to a physical address
574  * is a direct mapping, i.e. the same value.
575  * Otherwise, in virtual mode (IOVA as VA), an IOMMU may do the translation.
576  */
577 typedef uint64_t rte_iova_t;
578 #define RTE_BAD_IOVA ((rte_iova_t)-1)
579 
580 /*********** Structure alignment markers ********/
581 
582 #ifndef RTE_TOOLCHAIN_MSVC
583 
584 /** Generic marker for any place in a structure. */
585 __extension__ typedef void    *RTE_MARKER[0];
586 /** Marker for 1B alignment in a structure. */
587 __extension__ typedef uint8_t  RTE_MARKER8[0];
588 /** Marker for 2B alignment in a structure. */
589 __extension__ typedef uint16_t RTE_MARKER16[0];
590 /** Marker for 4B alignment in a structure. */
591 __extension__ typedef uint32_t RTE_MARKER32[0];
592 /** Marker for 8B alignment in a structure. */
593 __extension__ typedef uint64_t RTE_MARKER64[0];
594 
595 #endif
596 
597 /*********** Macros for calculating min and max **********/
598 
599 /**
600  * Macro to return the minimum of two numbers
601  */
602 #define RTE_MIN(a, b) \
603 	__extension__ ({ \
604 		typeof (a) _a = (a); \
605 		typeof (b) _b = (b); \
606 		_a < _b ? _a : _b; \
607 	})
608 
609 /**
610  * Macro to return the minimum of two numbers
611  *
612  * As opposed to RTE_MIN, it does not use temporary variables so it is not safe
613  * if a or b is an expression. Yet it is guaranteed to be constant for use in
614  * static_assert().
615  */
616 #define RTE_MIN_T(a, b, t) \
617 	((t)(a) < (t)(b) ? (t)(a) : (t)(b))
618 
619 /**
620  * Macro to return the maximum of two numbers
621  */
622 #define RTE_MAX(a, b) \
623 	__extension__ ({ \
624 		typeof (a) _a = (a); \
625 		typeof (b) _b = (b); \
626 		_a > _b ? _a : _b; \
627 	})
628 
629 /**
630  * Macro to return the maximum of two numbers
631  *
632  * As opposed to RTE_MAX, it does not use temporary variables so it is not safe
633  * if a or b is an expression. Yet it is guaranteed to be constant for use in
634  * static_assert().
635  */
636 #define RTE_MAX_T(a, b, t) \
637 	((t)(a) > (t)(b) ? (t)(a) : (t)(b))
638 
639 /*********** Other general functions / macros ********/
640 
641 #ifndef offsetof
642 /** Return the offset of a field in a structure. */
643 #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
644 #endif
645 
646 /**
647  * Return pointer to the wrapping struct instance.
648  *
649  * Example:
650  *
651  *  struct wrapper {
652  *      ...
653  *      struct child c;
654  *      ...
655  *  };
656  *
657  *  struct child *x = obtain(...);
658  *  struct wrapper *w = container_of(x, struct wrapper, c);
659  */
660 #ifndef container_of
661 #ifdef RTE_TOOLCHAIN_MSVC
662 #define container_of(ptr, type, member) \
663 			((type *)((uintptr_t)(ptr) - offsetof(type, member)))
664 #else
665 #define container_of(ptr, type, member)	__extension__ ({		\
666 			const typeof(((type *)0)->member) *_ptr = (ptr); \
667 			__rte_unused type *_target_ptr =	\
668 				(type *)(ptr);				\
669 			(type *)(((uintptr_t)_ptr) - offsetof(type, member)); \
670 		})
671 #endif
672 #endif
673 
674 /** Swap two variables. */
675 #define RTE_SWAP(a, b) \
676 	__extension__ ({ \
677 		typeof (a) _a = a; \
678 		a = b; \
679 		b = _a; \
680 	})
681 
682 /**
683  * Get the size of a field in a structure.
684  *
685  * @param type
686  *   The type of the structure.
687  * @param field
688  *   The field in the structure.
689  * @return
690  *   The size of the field in the structure, in bytes.
691  */
692 #define RTE_SIZEOF_FIELD(type, field) (sizeof(((type *)0)->field))
693 
694 #define _RTE_STR(x) #x
695 /** Take a macro value and get a string version of it */
696 #define RTE_STR(x) _RTE_STR(x)
697 
698 /**
699  * ISO C helpers to modify format strings using variadic macros.
700  * This is a replacement for the ", ## __VA_ARGS__" GNU extension.
701  * An empty %s argument is appended to avoid a dangling comma.
702  */
703 #define RTE_FMT(fmt, ...) fmt "%.0s", __VA_ARGS__ ""
704 #define RTE_FMT_HEAD(fmt, ...) fmt
705 #define RTE_FMT_TAIL(fmt, ...) __VA_ARGS__
706 
707 /** Mask value of type "tp" for the first "ln" bit set. */
708 #define	RTE_LEN2MASK(ln, tp)	\
709 	((tp)((uint64_t)-1 >> (sizeof(uint64_t) * CHAR_BIT - (ln))))
710 
711 /** Number of elements in the array. */
712 #define	RTE_DIM(a)	(sizeof (a) / sizeof ((a)[0]))
713 
714 /**
715  * Converts a numeric string to the equivalent uint64_t value.
716  * As well as straight number conversion, also recognises the suffixes
717  * k, m and g for kilobytes, megabytes and gigabytes respectively.
718  *
719  * If a negative number is passed in  i.e. a string with the first non-black
720  * character being "-", zero is returned. Zero is also returned in the case of
721  * an error with the strtoull call in the function.
722  *
723  * @param str
724  *     String containing number to convert.
725  * @return
726  *     Number.
727  */
728 uint64_t
729 rte_str_to_size(const char *str);
730 
731 /**
732  * Function to terminate the application immediately, printing an error
733  * message and returning the exit_code back to the shell.
734  *
735  * This function never returns
736  *
737  * @param exit_code
738  *     The exit code to be returned by the application
739  * @param format
740  *     The format string to be used for printing the message. This can include
741  *     printf format characters which will be expanded using any further parameters
742  *     to the function.
743  */
744 __rte_noreturn void
745 rte_exit(int exit_code, const char *format, ...)
746 	__rte_format_printf(2, 3);
747 
748 #ifdef __cplusplus
749 }
750 #endif
751 
752 #endif
753