xref: /dpdk/lib/eal/include/rte_common.h (revision d065725b6fb99bb4ebbcd6ee5fa4628886d7bee3)
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 #ifdef __cplusplus
43 #define __extension__
44 #endif
45 #endif
46 
47 /*
48  * RTE_TOOLCHAIN_GCC is defined if the target is built with GCC,
49  * while a host application (like pmdinfogen) may have another compiler.
50  * RTE_CC_IS_GNU is true if the file is compiled with GCC,
51  * no matter it is a target or host application.
52  */
53 #define RTE_CC_IS_GNU 0
54 #if defined __clang__
55 #define RTE_CC_CLANG
56 #elif defined __INTEL_COMPILER
57 #define RTE_CC_ICC
58 #elif defined __GNUC__
59 #define RTE_CC_GCC
60 #undef RTE_CC_IS_GNU
61 #define RTE_CC_IS_GNU 1
62 #endif
63 #if RTE_CC_IS_GNU
64 #define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 +	\
65 		__GNUC_PATCHLEVEL__)
66 #endif
67 
68 /**
69  * Force type alignment
70  *
71  * This macro should be used when alignment of a struct or union type
72  * is required. For toolchain compatibility it should appear between
73  * the {struct,union} keyword and tag. e.g.
74  *
75  *   struct __rte_aligned(8) tag { ... };
76  *
77  * If alignment of an object/variable is required then this macro should
78  * not be used, instead prefer C11 alignas(a).
79  */
80 #ifdef RTE_TOOLCHAIN_MSVC
81 #define __rte_aligned(a) __declspec(align(a))
82 #else
83 #define __rte_aligned(a) __attribute__((__aligned__(a)))
84 #endif
85 
86 #ifdef RTE_ARCH_STRICT_ALIGN
87 typedef uint64_t unaligned_uint64_t __rte_aligned(1);
88 typedef uint32_t unaligned_uint32_t __rte_aligned(1);
89 typedef uint16_t unaligned_uint16_t __rte_aligned(1);
90 #else
91 typedef uint64_t unaligned_uint64_t;
92 typedef uint32_t unaligned_uint32_t;
93 typedef uint16_t unaligned_uint16_t;
94 #endif
95 
96 /**
97  * Force a structure to be packed
98  */
99 #ifdef RTE_TOOLCHAIN_MSVC
100 #define __rte_packed
101 #else
102 #define __rte_packed __attribute__((__packed__))
103 #endif
104 
105 /**
106  * Macro to mark a type that is not subject to type-based aliasing rules
107  */
108 #ifdef RTE_TOOLCHAIN_MSVC
109 #define __rte_may_alias
110 #else
111 #define __rte_may_alias __attribute__((__may_alias__))
112 #endif
113 
114 /******* Macro to mark functions and fields scheduled for removal *****/
115 #ifdef RTE_TOOLCHAIN_MSVC
116 #define __rte_deprecated
117 #define __rte_deprecated_msg(msg)
118 #else
119 #define __rte_deprecated	__attribute__((__deprecated__))
120 #define __rte_deprecated_msg(msg)	__attribute__((__deprecated__(msg)))
121 #endif
122 
123 /**
124  *  Macro to mark macros and defines scheduled for removal
125  */
126 #if defined(RTE_CC_GCC) || defined(RTE_CC_CLANG)
127 #define RTE_PRAGMA(x)  _Pragma(#x)
128 #define RTE_PRAGMA_WARNING(w) RTE_PRAGMA(GCC warning #w)
129 #define RTE_DEPRECATED(x)  RTE_PRAGMA_WARNING(#x is deprecated)
130 #else
131 #define RTE_DEPRECATED(x)
132 #endif
133 
134 /**
135  * Mark a function or variable to a weak reference.
136  */
137 #define __rte_weak __attribute__((__weak__))
138 
139 /**
140  * Force symbol to be generated even if it appears to be unused.
141  */
142 #ifdef RTE_TOOLCHAIN_MSVC
143 #define __rte_used
144 #else
145 #define __rte_used __attribute__((used))
146 #endif
147 
148 /*********** Macros to eliminate unused variable warnings ********/
149 
150 /**
151  * short definition to mark a function parameter unused
152  */
153 #ifdef RTE_TOOLCHAIN_MSVC
154 #define __rte_unused
155 #else
156 #define __rte_unused __attribute__((__unused__))
157 #endif
158 
159 /**
160  * Mark pointer as restricted with regard to pointer aliasing.
161  */
162 #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L
163 #define __rte_restrict __restrict
164 #else
165 #define __rte_restrict restrict
166 #endif
167 
168 /**
169  * definition to mark a variable or function parameter as used so
170  * as to avoid a compiler warning
171  */
172 #define RTE_SET_USED(x) (void)(x)
173 
174 /**
175  * Check format string and its arguments at compile-time.
176  *
177  * GCC on Windows assumes MS-specific format string by default,
178  * even if the underlying stdio implementation is ANSI-compliant,
179  * so this must be overridden.
180  */
181 #ifdef RTE_TOOLCHAIN_MSVC
182 #define __rte_format_printf(format_index, first_arg)
183 #else
184 #if RTE_CC_IS_GNU
185 #define __rte_format_printf(format_index, first_arg) \
186 	__attribute__((format(gnu_printf, format_index, first_arg)))
187 #else
188 #define __rte_format_printf(format_index, first_arg) \
189 	__attribute__((format(printf, format_index, first_arg)))
190 #endif
191 #endif
192 
193 /**
194  * Specify data or function section/segment.
195  */
196 #ifdef RTE_TOOLCHAIN_MSVC
197 #define __rte_section(name) \
198 	__pragma(data_seg(name)) __declspec(allocate(name))
199 #else
200 #define __rte_section(name) \
201 	__attribute__((section(name)))
202 #endif
203 
204 /**
205  * Tells compiler that the function returns a value that points to
206  * memory, where the size is given by the one or two arguments.
207  * Used by compiler to validate object size.
208  */
209 #if defined(RTE_CC_GCC) || defined(RTE_CC_CLANG)
210 #define __rte_alloc_size(...) \
211 	__attribute__((alloc_size(__VA_ARGS__)))
212 #else
213 #define __rte_alloc_size(...)
214 #endif
215 
216 #define RTE_PRIORITY_LOG 101
217 #define RTE_PRIORITY_BUS 110
218 #define RTE_PRIORITY_CLASS 120
219 #define RTE_PRIORITY_LAST 65535
220 
221 #define RTE_PRIO(prio) \
222 	RTE_PRIORITY_ ## prio
223 
224 /**
225  * Run function before main() with high priority.
226  *
227  * @param func
228  *   Constructor function.
229  * @param prio
230  *   Priority number must be above 100.
231  *   Lowest number is the first to run.
232  */
233 #ifndef RTE_INIT_PRIO /* Allow to override from EAL */
234 #ifndef RTE_TOOLCHAIN_MSVC
235 #define RTE_INIT_PRIO(func, prio) \
236 static void __attribute__((constructor(RTE_PRIO(prio)), used)) func(void)
237 #else
238 /* definition from the Microsoft CRT */
239 typedef int(__cdecl *_PIFV)(void);
240 
241 #define CTOR_SECTION_LOG ".CRT$XIB"
242 #define CTOR_SECTION_BUS ".CRT$XIC"
243 #define CTOR_SECTION_CLASS ".CRT$XID"
244 #define CTOR_SECTION_LAST ".CRT$XIY"
245 
246 #define CTOR_PRIORITY_TO_SECTION(priority) CTOR_SECTION_ ## priority
247 
248 #define RTE_INIT_PRIO(name, priority) \
249 	static void name(void); \
250 	static int __cdecl name ## _thunk(void) { name(); return 0; } \
251 	__pragma(const_seg(CTOR_PRIORITY_TO_SECTION(priority))) \
252 	__declspec(allocate(CTOR_PRIORITY_TO_SECTION(priority))) \
253 	    _PIFV name ## _pointer = &name ## _thunk; \
254 	__pragma(const_seg()) \
255 	static void name(void)
256 #endif
257 #endif
258 
259 /**
260  * Run function before main() with low priority.
261  *
262  * The constructor will be run after prioritized constructors.
263  *
264  * @param func
265  *   Constructor function.
266  */
267 #define RTE_INIT(func) \
268 	RTE_INIT_PRIO(func, LAST)
269 
270 /**
271  * Run after main() with low priority.
272  *
273  * @param func
274  *   Destructor function name.
275  * @param prio
276  *   Priority number must be above 100.
277  *   Lowest number is the last to run.
278  */
279 #ifndef RTE_FINI_PRIO /* Allow to override from EAL */
280 #ifndef RTE_TOOLCHAIN_MSVC
281 #define RTE_FINI_PRIO(func, prio) \
282 static void __attribute__((destructor(RTE_PRIO(prio)), used)) func(void)
283 #else
284 #define DTOR_SECTION_LOG "mydtor$B"
285 #define DTOR_SECTION_BUS "mydtor$C"
286 #define DTOR_SECTION_CLASS "mydtor$D"
287 #define DTOR_SECTION_LAST "mydtor$Y"
288 
289 #define DTOR_PRIORITY_TO_SECTION(priority) DTOR_SECTION_ ## priority
290 
291 #define RTE_FINI_PRIO(name, priority) \
292 	static void name(void); \
293 	__pragma(const_seg(DTOR_PRIORITY_TO_SECTION(priority))) \
294 	__declspec(allocate(DTOR_PRIORITY_TO_SECTION(priority))) name ## _pointer = &name; \
295 	__pragma(const_seg()) \
296 	static void name(void)
297 #endif
298 #endif
299 
300 /**
301  * Run after main() with high priority.
302  *
303  * The destructor will be run *before* prioritized destructors.
304  *
305  * @param func
306  *   Destructor function name.
307  */
308 #define RTE_FINI(func) \
309 	RTE_FINI_PRIO(func, LAST)
310 
311 /**
312  * Hint never returning function
313  */
314 #ifdef RTE_TOOLCHAIN_MSVC
315 #define __rte_noreturn
316 #else
317 #define __rte_noreturn __attribute__((noreturn))
318 #endif
319 
320 /**
321  * Issue a warning in case the function's return value is ignored.
322  *
323  * The use of this attribute should be restricted to cases where
324  * ignoring the marked function's return value is almost always a
325  * bug. With GCC, some effort is required to make clear that ignoring
326  * the return value is intentional. The usual void-casting method to
327  * mark something unused as used does not suppress the warning with
328  * this compiler.
329  *
330  * @code{.c}
331  * __rte_warn_unused_result int foo();
332  *
333  * void ignore_foo_result(void) {
334  *         foo(); // generates a warning with all compilers
335  *
336  *         (void)foo(); // still generates the warning with GCC (but not clang)
337  *
338  *         int unused __rte_unused;
339  *         unused = foo(); // does the trick with all compilers
340  *  }
341  * @endcode
342  */
343 #ifdef RTE_TOOLCHAIN_MSVC
344 #define __rte_warn_unused_result
345 #else
346 #define __rte_warn_unused_result __attribute__((warn_unused_result))
347 #endif
348 
349 /**
350  * Force a function to be inlined
351  */
352 #ifdef RTE_TOOLCHAIN_MSVC
353 #define __rte_always_inline
354 #else
355 #define __rte_always_inline inline __attribute__((always_inline))
356 #endif
357 
358 /**
359  * Force a function to be noinlined
360  */
361 #define __rte_noinline __attribute__((noinline))
362 
363 /**
364  * Hint function in the hot path
365  */
366 #define __rte_hot __attribute__((hot))
367 
368 /**
369  * Hint function in the cold path
370  */
371 #ifdef RTE_TOOLCHAIN_MSVC
372 #define __rte_cold
373 #else
374 #define __rte_cold __attribute__((cold))
375 #endif
376 
377 /**
378  * Disable AddressSanitizer on some code
379  */
380 #ifdef RTE_MALLOC_ASAN
381 #ifdef RTE_CC_CLANG
382 #define __rte_no_asan __attribute__((no_sanitize("address", "hwaddress")))
383 #else
384 #define __rte_no_asan __attribute__((no_sanitize_address))
385 #endif
386 #else /* ! RTE_MALLOC_ASAN */
387 #define __rte_no_asan
388 #endif
389 
390 /*********** Macros for pointer arithmetic ********/
391 
392 /**
393  * add a byte-value offset to a pointer
394  */
395 #define RTE_PTR_ADD(ptr, x) ((void*)((uintptr_t)(ptr) + (x)))
396 
397 /**
398  * subtract a byte-value offset from a pointer
399  */
400 #define RTE_PTR_SUB(ptr, x) ((void *)((uintptr_t)(ptr) - (x)))
401 
402 /**
403  * get the difference between two pointer values, i.e. how far apart
404  * in bytes are the locations they point two. It is assumed that
405  * ptr1 is greater than ptr2.
406  */
407 #define RTE_PTR_DIFF(ptr1, ptr2) ((uintptr_t)(ptr1) - (uintptr_t)(ptr2))
408 
409 /**
410  * Workaround to cast a const field of a structure to non-const type.
411  */
412 #define RTE_CAST_FIELD(var, field, type) \
413 	(*(type *)((uintptr_t)(var) + offsetof(typeof(*(var)), field)))
414 
415 /*********** Macros/static functions for doing alignment ********/
416 
417 
418 /**
419  * Macro to align a pointer to a given power-of-two. The resultant
420  * pointer will be a pointer of the same type as the first parameter, and
421  * point to an address no higher than the first parameter. Second parameter
422  * must be a power-of-two value.
423  */
424 #define RTE_PTR_ALIGN_FLOOR(ptr, align) \
425 	((typeof(ptr))RTE_ALIGN_FLOOR((uintptr_t)(ptr), align))
426 
427 /**
428  * Macro to align a value to a given power-of-two. The resultant value
429  * will be of the same type as the first parameter, and will be no
430  * bigger than the first parameter. Second parameter must be a
431  * power-of-two value.
432  */
433 #define RTE_ALIGN_FLOOR(val, align) \
434 	(typeof(val))((val) & (~((typeof(val))((align) - 1))))
435 
436 /**
437  * Macro to align a pointer to a given power-of-two. The resultant
438  * pointer will be a pointer of the same type as the first parameter, and
439  * point to an address no lower than the first parameter. Second parameter
440  * must be a power-of-two value.
441  */
442 #define RTE_PTR_ALIGN_CEIL(ptr, align) \
443 	RTE_PTR_ALIGN_FLOOR((typeof(ptr))RTE_PTR_ADD(ptr, (align) - 1), align)
444 
445 /**
446  * Macro to align a value to a given power-of-two. The resultant value
447  * will be of the same type as the first parameter, and will be no lower
448  * than the first parameter. Second parameter must be a power-of-two
449  * value.
450  */
451 #define RTE_ALIGN_CEIL(val, align) \
452 	RTE_ALIGN_FLOOR(((val) + ((typeof(val)) (align) - 1)), align)
453 
454 /**
455  * Macro to align a pointer to a given power-of-two. The resultant
456  * pointer will be a pointer of the same type as the first parameter, and
457  * point to an address no lower than the first parameter. Second parameter
458  * must be a power-of-two value.
459  * This function is the same as RTE_PTR_ALIGN_CEIL
460  */
461 #define RTE_PTR_ALIGN(ptr, align) RTE_PTR_ALIGN_CEIL(ptr, align)
462 
463 /**
464  * Macro to align a value to a given power-of-two. The resultant
465  * value will be of the same type as the first parameter, and
466  * will be no lower than the first parameter. Second parameter
467  * must be a power-of-two value.
468  * This function is the same as RTE_ALIGN_CEIL
469  */
470 #define RTE_ALIGN(val, align) RTE_ALIGN_CEIL(val, align)
471 
472 /**
473  * Macro to align a value to the multiple of given value. The resultant
474  * value will be of the same type as the first parameter and will be no lower
475  * than the first parameter.
476  */
477 #define RTE_ALIGN_MUL_CEIL(v, mul) \
478 	((((v) + (typeof(v))(mul) - 1) / ((typeof(v))(mul))) * (typeof(v))(mul))
479 
480 /**
481  * Macro to align a value to the multiple of given value. The resultant
482  * value will be of the same type as the first parameter and will be no higher
483  * than the first parameter.
484  */
485 #define RTE_ALIGN_MUL_FLOOR(v, mul) \
486 	(((v) / ((typeof(v))(mul))) * (typeof(v))(mul))
487 
488 /**
489  * Macro to align value to the nearest multiple of the given value.
490  * The resultant value might be greater than or less than the first parameter
491  * whichever difference is the lowest.
492  */
493 #define RTE_ALIGN_MUL_NEAR(v, mul)				\
494 	__extension__ ({					\
495 		typeof(v) ceil = RTE_ALIGN_MUL_CEIL(v, mul);	\
496 		typeof(v) floor = RTE_ALIGN_MUL_FLOOR(v, mul);	\
497 		(ceil - (v)) > ((v) - floor) ? floor : ceil;	\
498 	})
499 
500 /**
501  * Checks if a pointer is aligned to a given power-of-two value
502  *
503  * @param ptr
504  *   The pointer whose alignment is to be checked
505  * @param align
506  *   The power-of-two value to which the ptr should be aligned
507  *
508  * @return
509  *   True(1) where the pointer is correctly aligned, false(0) otherwise
510  */
511 static inline int
512 rte_is_aligned(const void * const __rte_restrict ptr, const unsigned int align)
513 {
514 	return ((uintptr_t)ptr & (align - 1)) == 0;
515 }
516 
517 /*********** Macros for compile type checks ********/
518 
519 /* Workaround for toolchain issues with missing C11 macro in FreeBSD */
520 #if !defined(static_assert) && !defined(__cplusplus)
521 #define	static_assert	_Static_assert
522 #endif
523 
524 /**
525  * Triggers an error at compilation time if the condition is true.
526  *
527  * The do { } while(0) exists to workaround a bug in clang (#55821)
528  * where it would not handle _Static_assert in a switch case.
529  */
530 #define RTE_BUILD_BUG_ON(condition) do { static_assert(!(condition), #condition); } while (0)
531 
532 /*********** Cache line related macros ********/
533 
534 /** Cache line mask. */
535 #define RTE_CACHE_LINE_MASK (RTE_CACHE_LINE_SIZE-1)
536 
537 /** Return the first cache-aligned value greater or equal to size. */
538 #define RTE_CACHE_LINE_ROUNDUP(size) RTE_ALIGN_CEIL(size, RTE_CACHE_LINE_SIZE)
539 
540 /** Cache line size in terms of log2 */
541 #if RTE_CACHE_LINE_SIZE == 64
542 #define RTE_CACHE_LINE_SIZE_LOG2 6
543 #elif RTE_CACHE_LINE_SIZE == 128
544 #define RTE_CACHE_LINE_SIZE_LOG2 7
545 #else
546 #error "Unsupported cache line size"
547 #endif
548 
549 /** Minimum Cache line size. */
550 #define RTE_CACHE_LINE_MIN_SIZE 64
551 
552 /** Force alignment to cache line. */
553 #define __rte_cache_aligned __rte_aligned(RTE_CACHE_LINE_SIZE)
554 
555 /** Force minimum cache line alignment. */
556 #define __rte_cache_min_aligned __rte_aligned(RTE_CACHE_LINE_MIN_SIZE)
557 
558 #define _RTE_CACHE_GUARD_HELPER2(unique) \
559 	alignas(RTE_CACHE_LINE_SIZE) \
560 	char cache_guard_ ## unique[RTE_CACHE_LINE_SIZE * RTE_CACHE_GUARD_LINES]
561 #define _RTE_CACHE_GUARD_HELPER1(unique) _RTE_CACHE_GUARD_HELPER2(unique)
562 /**
563  * Empty cache lines, to guard against false sharing-like effects
564  * on systems with a next-N-lines hardware prefetcher.
565  *
566  * Use as spacing between data accessed by different lcores,
567  * to prevent cache thrashing on hardware with speculative prefetching.
568  */
569 #define RTE_CACHE_GUARD _RTE_CACHE_GUARD_HELPER1(__COUNTER__)
570 
571 /*********** PA/IOVA type definitions ********/
572 
573 /** Physical address */
574 typedef uint64_t phys_addr_t;
575 #define RTE_BAD_PHYS_ADDR ((phys_addr_t)-1)
576 
577 /**
578  * IO virtual address type.
579  * When the physical addressing mode (IOVA as PA) is in use,
580  * the translation from an IO virtual address (IOVA) to a physical address
581  * is a direct mapping, i.e. the same value.
582  * Otherwise, in virtual mode (IOVA as VA), an IOMMU may do the translation.
583  */
584 typedef uint64_t rte_iova_t;
585 #define RTE_BAD_IOVA ((rte_iova_t)-1)
586 
587 /*********** Structure alignment markers ********/
588 
589 #ifndef RTE_TOOLCHAIN_MSVC
590 
591 /** Generic marker for any place in a structure. */
592 __extension__ typedef void    *RTE_MARKER[0];
593 /** Marker for 1B alignment in a structure. */
594 __extension__ typedef uint8_t  RTE_MARKER8[0];
595 /** Marker for 2B alignment in a structure. */
596 __extension__ typedef uint16_t RTE_MARKER16[0];
597 /** Marker for 4B alignment in a structure. */
598 __extension__ typedef uint32_t RTE_MARKER32[0];
599 /** Marker for 8B alignment in a structure. */
600 __extension__ typedef uint64_t RTE_MARKER64[0];
601 
602 #endif
603 
604 /*********** Macros for calculating min and max **********/
605 
606 /**
607  * Macro to return the minimum of two numbers
608  */
609 #define RTE_MIN(a, b) \
610 	__extension__ ({ \
611 		typeof (a) _a = (a); \
612 		typeof (b) _b = (b); \
613 		_a < _b ? _a : _b; \
614 	})
615 
616 /**
617  * Macro to return the minimum of two numbers
618  *
619  * As opposed to RTE_MIN, it does not use temporary variables so it is not safe
620  * if a or b is an expression. Yet it is guaranteed to be constant for use in
621  * static_assert().
622  */
623 #define RTE_MIN_T(a, b, t) \
624 	((t)(a) < (t)(b) ? (t)(a) : (t)(b))
625 
626 /**
627  * Macro to return the maximum of two numbers
628  */
629 #define RTE_MAX(a, b) \
630 	__extension__ ({ \
631 		typeof (a) _a = (a); \
632 		typeof (b) _b = (b); \
633 		_a > _b ? _a : _b; \
634 	})
635 
636 /**
637  * Macro to return the maximum of two numbers
638  *
639  * As opposed to RTE_MAX, it does not use temporary variables so it is not safe
640  * if a or b is an expression. Yet it is guaranteed to be constant for use in
641  * static_assert().
642  */
643 #define RTE_MAX_T(a, b, t) \
644 	((t)(a) > (t)(b) ? (t)(a) : (t)(b))
645 
646 /*********** Other general functions / macros ********/
647 
648 #ifndef offsetof
649 /** Return the offset of a field in a structure. */
650 #define offsetof(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
651 #endif
652 
653 /**
654  * Return pointer to the wrapping struct instance.
655  *
656  * Example:
657  *
658  *  struct wrapper {
659  *      ...
660  *      struct child c;
661  *      ...
662  *  };
663  *
664  *  struct child *x = obtain(...);
665  *  struct wrapper *w = container_of(x, struct wrapper, c);
666  */
667 #ifndef container_of
668 #ifdef RTE_TOOLCHAIN_MSVC
669 #define container_of(ptr, type, member) \
670 			((type *)((uintptr_t)(ptr) - offsetof(type, member)))
671 #else
672 #define container_of(ptr, type, member)	__extension__ ({		\
673 			const typeof(((type *)0)->member) *_ptr = (ptr); \
674 			__rte_unused type *_target_ptr =	\
675 				(type *)(ptr);				\
676 			(type *)(((uintptr_t)_ptr) - offsetof(type, member)); \
677 		})
678 #endif
679 #endif
680 
681 /** Swap two variables. */
682 #define RTE_SWAP(a, b) \
683 	__extension__ ({ \
684 		typeof (a) _a = a; \
685 		a = b; \
686 		b = _a; \
687 	})
688 
689 /**
690  * Get the size of a field in a structure.
691  *
692  * @param type
693  *   The type of the structure.
694  * @param field
695  *   The field in the structure.
696  * @return
697  *   The size of the field in the structure, in bytes.
698  */
699 #define RTE_SIZEOF_FIELD(type, field) (sizeof(((type *)0)->field))
700 
701 #define _RTE_STR(x) #x
702 /** Take a macro value and get a string version of it */
703 #define RTE_STR(x) _RTE_STR(x)
704 
705 /**
706  * ISO C helpers to modify format strings using variadic macros.
707  * This is a replacement for the ", ## __VA_ARGS__" GNU extension.
708  * An empty %s argument is appended to avoid a dangling comma.
709  */
710 #define RTE_FMT(fmt, ...) fmt "%.0s", __VA_ARGS__ ""
711 #define RTE_FMT_HEAD(fmt, ...) fmt
712 #define RTE_FMT_TAIL(fmt, ...) __VA_ARGS__
713 
714 /** Mask value of type "tp" for the first "ln" bit set. */
715 #define	RTE_LEN2MASK(ln, tp)	\
716 	((tp)((uint64_t)-1 >> (sizeof(uint64_t) * CHAR_BIT - (ln))))
717 
718 /** Number of elements in the array. */
719 #define	RTE_DIM(a)	(sizeof (a) / sizeof ((a)[0]))
720 
721 /**
722  * Converts a numeric string to the equivalent uint64_t value.
723  * As well as straight number conversion, also recognises the suffixes
724  * k, m and g for kilobytes, megabytes and gigabytes respectively.
725  *
726  * If a negative number is passed in  i.e. a string with the first non-black
727  * character being "-", zero is returned. Zero is also returned in the case of
728  * an error with the strtoull call in the function.
729  *
730  * @param str
731  *     String containing number to convert.
732  * @return
733  *     Number.
734  */
735 uint64_t
736 rte_str_to_size(const char *str);
737 
738 /**
739  * Function to terminate the application immediately, printing an error
740  * message and returning the exit_code back to the shell.
741  *
742  * This function never returns
743  *
744  * @param exit_code
745  *     The exit code to be returned by the application
746  * @param format
747  *     The format string to be used for printing the message. This can include
748  *     printf format characters which will be expanded using any further parameters
749  *     to the function.
750  */
751 __rte_noreturn void
752 rte_exit(int exit_code, const char *format, ...)
753 	__rte_format_printf(2, 3);
754 
755 #ifdef __cplusplus
756 }
757 #endif
758 
759 #endif
760