1 /*
2  * Copyright (c) 2011-2014, Wind River Systems, Inc.
3  *
4  * SPDX-License-Identifier: Apache-2.0
5  */
6 
7 /**
8  * @file
9  * @brief Macro utilities
10  *
11  * Macro utilities are the public interface for C/C++ code and device tree
12  * related implementation.  In general, C/C++ will include <sys/util.h>
13  * instead this file directly.  For device tree implementation, this file
14  * should be include instead <sys/util_internal.h>
15  */
16 
17 #ifndef ZEPHYR_INCLUDE_SYS_UTIL_MACROS_H_
18 #define ZEPHYR_INCLUDE_SYS_UTIL_MACROS_H_
19 
20 #ifdef __cplusplus
21 extern "C" {
22 #endif
23 
24 /**
25  * @addtogroup sys-util
26  * @{
27  */
28 
29 /*
30  * Most of the eldritch implementation details for all the macrobatics
31  * below (APIs like IS_ENABLED(), COND_CODE_1(), etc.) are hidden away
32  * in this file.
33  */
34 #include <zephyr/sys/util_internal.h>
35 
36 #ifndef BIT
37 #if defined(_ASMLANGUAGE)
38 #define BIT(n)  (1 << (n))
39 #else
40 /**
41  * @brief Unsigned integer with bit position @p n set (signed in
42  * assembly language).
43  */
44 #define BIT(n)  (1UL << (n))
45 #endif
46 #endif
47 
48 /** @brief 64-bit unsigned integer with bit position @p _n set. */
49 #define BIT64(_n) (1ULL << (_n))
50 
51 /**
52  * @brief Set or clear a bit depending on a boolean value
53  *
54  * The argument @p var is a variable whose value is written to as a
55  * side effect.
56  *
57  * @param var Variable to be altered
58  * @param bit Bit number
59  * @param set if 0, clears @p bit in @p var; any other value sets @p bit
60  */
61 #define WRITE_BIT(var, bit, set) \
62 	((var) = (set) ? ((var) | BIT(bit)) : ((var) & ~BIT(bit)))
63 
64 /**
65  * @brief Bit mask with bits 0 through <tt>n-1</tt> (inclusive) set,
66  * or 0 if @p n is 0.
67  */
68 #define BIT_MASK(n) (BIT(n) - 1UL)
69 
70 /**
71  * @brief 64-bit bit mask with bits 0 through <tt>n-1</tt> (inclusive) set,
72  * or 0 if @p n is 0.
73  */
74 #define BIT64_MASK(n) (BIT64(n) - 1ULL)
75 
76 /** @brief Check if a @p x is a power of two */
77 #define IS_POWER_OF_TWO(x) (((x) != 0U) && (((x) & ((x) - 1U)) == 0U))
78 
79 /**
80  * @brief Check if bits are set continuously from the specified bit
81  *
82  * The macro is not dependent on the bit-width.
83  *
84  * @param m Check whether the bits are set continuously or not.
85  * @param s Specify the lowest bit for that is continuously set bits.
86  */
87 #define IS_SHIFTED_BIT_MASK(m, s) (!(((m) >> (s)) & (((m) >> (s)) + 1U)))
88 
89 /**
90  * @brief Check if bits are set continuously from the LSB.
91  *
92  * @param m Check whether the bits are set continuously from LSB.
93  */
94 #define IS_BIT_MASK(m) IS_SHIFTED_BIT_MASK(m, 0)
95 
96 /**
97  * @brief Check for macro definition in compiler-visible expressions
98  *
99  * This trick was pioneered in Linux as the config_enabled() macro. It
100  * has the effect of taking a macro value that may be defined to "1"
101  * or may not be defined at all and turning it into a literal
102  * expression that can be handled by the C compiler instead of just
103  * the preprocessor. It is often used with a @p CONFIG_FOO macro which
104  * may be defined to 1 via Kconfig, or left undefined.
105  *
106  * That is, it works similarly to <tt>\#if defined(CONFIG_FOO)</tt>
107  * except that its expansion is a C expression. Thus, much <tt>\#ifdef</tt>
108  * usage can be replaced with equivalents like:
109  *
110  *     if (IS_ENABLED(CONFIG_FOO)) {
111  *             do_something_with_foo
112  *     }
113  *
114  * This is cleaner since the compiler can generate errors and warnings
115  * for @p do_something_with_foo even when @p CONFIG_FOO is undefined.
116  *
117  * Note: Use of IS_ENABLED in a <tt>\#if</tt> statement is discouraged
118  *       as it doesn't provide any benefit vs plain <tt>\#if defined()</tt>
119  *
120  * @param config_macro Macro to check
121  * @return 1 if @p config_macro is defined to 1, 0 otherwise (including
122  *         if @p config_macro is not defined)
123  */
124 #define IS_ENABLED(config_macro) Z_IS_ENABLED1(config_macro)
125 /* INTERNAL: the first pass above is just to expand any existing
126  * macros, we need the macro value to be e.g. a literal "1" at
127  * expansion time in the next macro, not "(1)", etc... Standard
128  * recursive expansion does not work.
129  */
130 
131 /**
132  * @brief Insert code depending on whether @p _flag expands to 1 or not.
133  *
134  * This relies on similar tricks as IS_ENABLED(), but as the result of
135  * @p _flag expansion, results in either @p _if_1_code or @p
136  * _else_code is expanded.
137  *
138  * To prevent the preprocessor from treating commas as argument
139  * separators, the @p _if_1_code and @p _else_code expressions must be
140  * inside brackets/parentheses: <tt>()</tt>. These are stripped away
141  * during macro expansion.
142  *
143  * Example:
144  *
145  *     COND_CODE_1(CONFIG_FLAG, (uint32_t x;), (there_is_no_flag();))
146  *
147  * If @p CONFIG_FLAG is defined to 1, this expands to:
148  *
149  *     uint32_t x;
150  *
151  * It expands to <tt>there_is_no_flag();</tt> otherwise.
152  *
153  * This could be used as an alternative to:
154  *
155  *     #if defined(CONFIG_FLAG) && (CONFIG_FLAG == 1)
156  *     #define MAYBE_DECLARE(x) uint32_t x
157  *     #else
158  *     #define MAYBE_DECLARE(x) there_is_no_flag()
159  *     #endif
160  *
161  *     MAYBE_DECLARE(x);
162  *
163  * However, the advantage of COND_CODE_1() is that code is resolved in
164  * place where it is used, while the @p \#if method defines @p
165  * MAYBE_DECLARE on two lines and requires it to be invoked again on a
166  * separate line. This makes COND_CODE_1() more concise and also
167  * sometimes more useful when used within another macro's expansion.
168  *
169  * @note @p _flag can be the result of preprocessor expansion, e.g.
170  *	 an expression involving <tt>NUM_VA_ARGS_LESS_1(...)</tt>.
171  *	 However, @p _if_1_code is only expanded if @p _flag expands
172  *	 to the integer literal 1. Integer expressions that evaluate
173  *	 to 1, e.g. after doing some arithmetic, will not work.
174  *
175  * @param _flag evaluated flag
176  * @param _if_1_code result if @p _flag expands to 1; must be in parentheses
177  * @param _else_code result otherwise; must be in parentheses
178  */
179 #define COND_CODE_1(_flag, _if_1_code, _else_code) \
180 	Z_COND_CODE_1(_flag, _if_1_code, _else_code)
181 
182 /**
183  * @brief Like COND_CODE_1() except tests if @p _flag is 0.
184  *
185  * This is like COND_CODE_1(), except that it tests whether @p _flag
186  * expands to the integer literal 0. It expands to @p _if_0_code if
187  * so, and @p _else_code otherwise; both of these must be enclosed in
188  * parentheses.
189  *
190  * @param _flag evaluated flag
191  * @param _if_0_code result if @p _flag expands to 0; must be in parentheses
192  * @param _else_code result otherwise; must be in parentheses
193  * @see COND_CODE_1()
194  */
195 #define COND_CODE_0(_flag, _if_0_code, _else_code) \
196 	Z_COND_CODE_0(_flag, _if_0_code, _else_code)
197 
198 /**
199  * @brief Insert code if @p _flag is defined and equals 1.
200  *
201  * Like COND_CODE_1(), this expands to @p _code if @p _flag is defined to 1;
202  * it expands to nothing otherwise.
203  *
204  * Example:
205  *
206  *     IF_ENABLED(CONFIG_FLAG, (uint32_t foo;))
207  *
208  * If @p CONFIG_FLAG is defined to 1, this expands to:
209  *
210  *     uint32_t foo;
211  *
212  * and to nothing otherwise.
213  *
214  * It can be considered as a more compact alternative to:
215  *
216  *     #if defined(CONFIG_FLAG) && (CONFIG_FLAG == 1)
217  *     uint32_t foo;
218  *     #endif
219  *
220  * @param _flag evaluated flag
221  * @param _code result if @p _flag expands to 1; must be in parentheses
222  */
223 #define IF_ENABLED(_flag, _code) \
224 	COND_CODE_1(_flag, _code, ())
225 
226 /**
227  * @brief Check if a macro has a replacement expression
228  *
229  * If @p a is a macro defined to a nonempty value, this will return
230  * true, otherwise it will return false. It only works with defined
231  * macros, so an additional @p \#ifdef test may be needed in some cases.
232  *
233  * This macro may be used with COND_CODE_1() and COND_CODE_0() while
234  * processing `__VA_ARGS__` to avoid processing empty arguments.
235  *
236  * Example:
237  *
238  *	#define EMPTY
239  *	#define NON_EMPTY	1
240  *	#undef  UNDEFINED
241  *	IS_EMPTY(EMPTY)
242  *	IS_EMPTY(NON_EMPTY)
243  *	IS_EMPTY(UNDEFINED)
244  *	#if defined(EMPTY) && IS_EMPTY(EMPTY) == true
245  *	some_conditional_code
246  *	#endif
247  *
248  * In above examples, the invocations of IS_EMPTY(...) return @p true,
249  * @p false, and @p true; @p some_conditional_code is included.
250  *
251  * @param ... macro to check for emptiness (may be `__VA_ARGS__`)
252  */
253 #define IS_EMPTY(...) Z_IS_EMPTY_(__VA_ARGS__)
254 
255 /**
256  * @brief Like <tt>a == b</tt>, but does evaluation and
257  * short-circuiting at C preprocessor time.
258  *
259  * This however only works for integer literal from 0 to 4095.
260  *
261  */
262 #define IS_EQ(a, b) Z_IS_EQ(a, b)
263 
264 /**
265  * @brief Remove empty arguments from list.
266  *
267  * During macro expansion, `__VA_ARGS__` and other preprocessor
268  * generated lists may contain empty elements, e.g.:
269  *
270  *	#define LIST ,a,b,,d,
271  *
272  * Using EMPTY to show each empty element, LIST contains:
273  *
274  *      EMPTY, a, b, EMPTY, d
275  *
276  * When processing such lists, e.g. using FOR_EACH(), all empty elements
277  * will be processed, and may require filtering out.
278  * To make that process easier, it is enough to invoke LIST_DROP_EMPTY
279  * which will remove all empty elements.
280  *
281  * Example:
282  *
283  *	LIST_DROP_EMPTY(LIST)
284  *
285  * expands to:
286  *
287  *	a, b, d
288  *
289  * @param ... list to be processed
290  */
291 #define LIST_DROP_EMPTY(...) \
292 	Z_LIST_DROP_FIRST(FOR_EACH(Z_LIST_NO_EMPTIES, (), __VA_ARGS__))
293 
294 /**
295  * @brief Macro with an empty expansion
296  *
297  * This trivial definition is provided for readability when a macro
298  * should expand to an empty result, which e.g. is sometimes needed to
299  * silence checkpatch.
300  *
301  * Example:
302  *
303  *	#define LIST_ITEM(n) , item##n
304  *
305  * The above would cause checkpatch to complain, but:
306  *
307  *	#define LIST_ITEM(n) EMPTY, item##n
308  *
309  * would not.
310  */
311 #define EMPTY
312 
313 /**
314  * @brief Macro that expands to its argument
315  *
316  * This is useful in macros like @c FOR_EACH() when there is no
317  * transformation required on the list elements.
318  *
319  * @param V any value
320  */
321 #define IDENTITY(V) V
322 
323 /**
324  * @brief Get nth argument from argument list.
325  *
326  * @param N Argument index to fetch. Counter from 1.
327  * @param ... Variable list of arguments from which one argument is returned.
328  *
329  * @return Nth argument.
330  */
331 #define GET_ARG_N(N, ...) Z_GET_ARG_##N(__VA_ARGS__)
332 
333 /**
334  * @brief Strips n first arguments from the argument list.
335  *
336  * @param N Number of arguments to discard.
337  * @param ... Variable list of arguments.
338  *
339  * @return argument list without N first arguments.
340  */
341 #define GET_ARGS_LESS_N(N, ...) Z_GET_ARGS_LESS_##N(__VA_ARGS__)
342 
343 /**
344  * @brief Like <tt>a || b</tt>, but does evaluation and
345  * short-circuiting at C preprocessor time.
346  *
347  * This is not the same as the binary @p || operator; in particular,
348  * @p a should expand to an integer literal 0 or 1. However, @p b
349  * can be any value.
350  *
351  * This can be useful when @p b is an expression that would cause a
352  * build error when @p a is 1.
353  */
354 #define UTIL_OR(a, b) COND_CODE_1(UTIL_BOOL(a), (a), (b))
355 
356 /**
357  * @brief Like <tt>a && b</tt>, but does evaluation and
358  * short-circuiting at C preprocessor time.
359  *
360  * This is not the same as the binary @p &&, however; in particular,
361  * @p a should expand to an integer literal 0 or 1. However, @p b
362  * can be any value.
363  *
364  * This can be useful when @p b is an expression that would cause a
365  * build error when @p a is 0.
366  */
367 #define UTIL_AND(a, b) COND_CODE_1(UTIL_BOOL(a), (b), (0))
368 
369 /**
370  * @brief UTIL_INC(x) for an integer literal x from 0 to 4095 expands to an
371  * integer literal whose value is x+1.
372  *
373  * @see UTIL_DEC(x)
374  */
375 #define UTIL_INC(x) UTIL_PRIMITIVE_CAT(Z_UTIL_INC_, x)
376 
377 /**
378  * @brief UTIL_DEC(x) for an integer literal x from 0 to 4095 expands to an
379  * integer literal whose value is x-1.
380  *
381  * @see UTIL_INC(x)
382  */
383 #define UTIL_DEC(x) UTIL_PRIMITIVE_CAT(Z_UTIL_DEC_, x)
384 
385 /**
386  * @brief UTIL_X2(y) for an integer literal y from 0 to 4095 expands to an
387  * integer literal whose value is 2y.
388  */
389 #define UTIL_X2(y) UTIL_PRIMITIVE_CAT(Z_UTIL_X2_, y)
390 
391 
392 /**
393  * @brief Generates a sequence of code with configurable separator.
394  *
395  * Example:
396  *
397  *     #define FOO(i, _) MY_PWM ## i
398  *     { LISTIFY(PWM_COUNT, FOO, (,)) }
399  *
400  * The above two lines expand to:
401  *
402  *    { MY_PWM0 , MY_PWM1 }
403  *
404  * @param LEN The length of the sequence. Must be an integer literal less
405  *            than 4095.
406  * @param F A macro function that accepts at least two arguments:
407  *          <tt>F(i, ...)</tt>. @p F is called repeatedly in the expansion.
408  *          Its first argument @p i is the index in the sequence, and
409  *          the variable list of arguments passed to LISTIFY are passed
410  *          through to @p F.
411  *
412  * @param sep Separator (e.g. comma or semicolon). Must be in parentheses;
413  *            this is required to enable providing a comma as separator.
414  *
415  * @note Calling LISTIFY with undefined arguments has undefined
416  * behavior.
417  */
418 #define LISTIFY(LEN, F, sep, ...) UTIL_CAT(Z_UTIL_LISTIFY_, LEN)(F, sep, __VA_ARGS__)
419 
420 /**
421  * @brief Call a macro @p F on each provided argument with a given
422  *        separator between each call.
423  *
424  * Example:
425  *
426  *     #define F(x) int a##x
427  *     FOR_EACH(F, (;), 4, 5, 6);
428  *
429  * This expands to:
430  *
431  *     int a4;
432  *     int a5;
433  *     int a6;
434  *
435  * @param F Macro to invoke
436  * @param sep Separator (e.g. comma or semicolon). Must be in parentheses;
437  *            this is required to enable providing a comma as separator.
438  * @param ... Variable argument list. The macro @p F is invoked as
439  *            <tt>F(element)</tt> for each element in the list.
440  */
441 #define FOR_EACH(F, sep, ...) \
442 	Z_FOR_EACH(F, sep, REVERSE_ARGS(__VA_ARGS__))
443 
444 /**
445  * @brief Like FOR_EACH(), but with a terminator instead of a separator,
446  *        and drops empty elements from the argument list
447  *
448  * The @p sep argument to <tt>FOR_EACH(F, (sep), a, b)</tt> is a
449  * separator which is placed between calls to @p F, like this:
450  *
451  *     FOR_EACH(F, (sep), a, b) // F(a) sep F(b)
452  *                              //               ^^^ no sep here!
453  *
454  * By contrast, the @p term argument to <tt>FOR_EACH_NONEMPTY_TERM(F, (term),
455  * a, b)</tt> is added after each time @p F appears in the expansion:
456  *
457  *     FOR_EACH_NONEMPTY_TERM(F, (term), a, b) // F(a) term F(b) term
458  *                                             //                ^^^^
459  *
460  * Further, any empty elements are dropped:
461  *
462  *     FOR_EACH_NONEMPTY_TERM(F, (term), a, EMPTY, b) // F(a) term F(b) term
463  *
464  * This is more convenient in some cases, because FOR_EACH_NONEMPTY_TERM()
465  * expands to nothing when given an empty argument list, and it's
466  * often cumbersome to write a macro @p F that does the right thing
467  * even when given an empty argument.
468  *
469  * One example is when `__VA_ARGS__` may or may not be empty,
470  * and the results are embedded in a larger initializer:
471  *
472  *     #define SQUARE(x) ((x)*(x))
473  *
474  *     int my_array[] = {
475  *             FOR_EACH_NONEMPTY_TERM(SQUARE, (,), FOO(...))
476  *             FOR_EACH_NONEMPTY_TERM(SQUARE, (,), BAR(...))
477  *             FOR_EACH_NONEMPTY_TERM(SQUARE, (,), BAZ(...))
478  *     };
479  *
480  * This is more convenient than:
481  *
482  * 1. figuring out whether the @p FOO, @p BAR, and @p BAZ expansions
483  *    are empty and adding a comma manually (or not) between FOR_EACH()
484  *    calls
485  * 2. rewriting SQUARE so it reacts appropriately when "x" is empty
486  *    (which would be necessary if e.g. @p FOO expands to nothing)
487  *
488  * @param F Macro to invoke on each nonempty element of the variable
489  *          arguments
490  * @param term Terminator (e.g. comma or semicolon) placed after each
491  *             invocation of F. Must be in parentheses; this is required
492  *             to enable providing a comma as separator.
493  * @param ... Variable argument list. The macro @p F is invoked as
494  *            <tt>F(element)</tt> for each nonempty element in the list.
495  */
496 #define FOR_EACH_NONEMPTY_TERM(F, term, ...)				\
497 	COND_CODE_0(							\
498 		/* are there zero non-empty arguments ? */		\
499 		NUM_VA_ARGS_LESS_1(LIST_DROP_EMPTY(__VA_ARGS__, _)),	\
500 		/* if so, expand to nothing */				\
501 		(),							\
502 		/* otherwise, expand to: */				\
503 		(/* FOR_EACH() on nonempty elements, */		\
504 			FOR_EACH(F, term, LIST_DROP_EMPTY(__VA_ARGS__))	\
505 			/* plus a final terminator */			\
506 			__DEBRACKET term				\
507 		))
508 
509 /**
510  * @brief Call macro @p F on each provided argument, with the argument's index
511  *        as an additional parameter.
512  *
513  * This is like FOR_EACH(), except @p F should be a macro which takes two
514  * arguments: <tt>F(index, variable_arg)</tt>.
515  *
516  * Example:
517  *
518  *     #define F(idx, x) int a##idx = x
519  *     FOR_EACH_IDX(F, (;), 4, 5, 6);
520  *
521  * This expands to:
522  *
523  *     int a0 = 4;
524  *     int a1 = 5;
525  *     int a2 = 6;
526  *
527  * @param F Macro to invoke
528  * @param sep Separator (e.g. comma or semicolon). Must be in parentheses;
529  *            this is required to enable providing a comma as separator.
530  * @param ... Variable argument list. The macro @p F is invoked as
531  *            <tt>F(index, element)</tt> for each element in the list.
532  */
533 #define FOR_EACH_IDX(F, sep, ...) \
534 	Z_FOR_EACH_IDX(F, sep, REVERSE_ARGS(__VA_ARGS__))
535 
536 /**
537  * @brief Call macro @p F on each provided argument, with an additional fixed
538  *	  argument as a parameter.
539  *
540  * This is like FOR_EACH(), except @p F should be a macro which takes two
541  * arguments: <tt>F(variable_arg, fixed_arg)</tt>.
542  *
543  * Example:
544  *
545  *     static void func(int val, void *dev);
546  *     FOR_EACH_FIXED_ARG(func, (;), dev, 4, 5, 6);
547  *
548  * This expands to:
549  *
550  *     func(4, dev);
551  *     func(5, dev);
552  *     func(6, dev);
553  *
554  * @param F Macro to invoke
555  * @param sep Separator (e.g. comma or semicolon). Must be in parentheses;
556  *            this is required to enable providing a comma as separator.
557  * @param fixed_arg Fixed argument passed to @p F as the second macro parameter.
558  * @param ... Variable argument list. The macro @p F is invoked as
559  *            <tt>F(element, fixed_arg)</tt> for each element in the list.
560  */
561 #define FOR_EACH_FIXED_ARG(F, sep, fixed_arg, ...) \
562 	Z_FOR_EACH_FIXED_ARG(F, sep, fixed_arg, REVERSE_ARGS(__VA_ARGS__))
563 
564 /**
565  * @brief Calls macro @p F for each variable argument with an index and fixed
566  *        argument
567  *
568  * This is like the combination of FOR_EACH_IDX() with FOR_EACH_FIXED_ARG().
569  *
570  * Example:
571  *
572  *     #define F(idx, x, fixed_arg) int fixed_arg##idx = x
573  *     FOR_EACH_IDX_FIXED_ARG(F, (;), a, 4, 5, 6);
574  *
575  * This expands to:
576  *
577  *     int a0 = 4;
578  *     int a1 = 5;
579  *     int a2 = 6;
580  *
581  * @param F Macro to invoke
582  * @param sep Separator (e.g. comma or semicolon). Must be in parentheses;
583  *            This is required to enable providing a comma as separator.
584  * @param fixed_arg Fixed argument passed to @p F as the third macro parameter.
585  * @param ... Variable list of arguments. The macro @p F is invoked as
586  *            <tt>F(index, element, fixed_arg)</tt> for each element in
587  *            the list.
588  */
589 #define FOR_EACH_IDX_FIXED_ARG(F, sep, fixed_arg, ...) \
590 	Z_FOR_EACH_IDX_FIXED_ARG(F, sep, fixed_arg, REVERSE_ARGS(__VA_ARGS__))
591 
592 /** @brief Reverse arguments order.
593  *
594  * @param ... Variable argument list.
595  */
596 #define REVERSE_ARGS(...) \
597 	Z_FOR_EACH_ENGINE(Z_FOR_EACH_EXEC, (,), Z_BYPASS, _, __VA_ARGS__)
598 
599 /**
600  * @brief Number of arguments in the variable arguments list minus one.
601  *
602  * @param ... List of arguments
603  * @return  Number of variadic arguments in the argument list, minus one
604  */
605 #define NUM_VA_ARGS_LESS_1(...) \
606 	NUM_VA_ARGS_LESS_1_IMPL(__VA_ARGS__, 63, 62, 61, \
607 	60, 59, 58, 57, 56, 55, 54, 53, 52, 51,		 \
608 	50, 49, 48, 47, 46, 45, 44, 43, 42, 41,		 \
609 	40, 39, 38, 37, 36, 35, 34, 33, 32, 31,		 \
610 	30, 29, 28, 27, 26, 25, 24, 23, 22, 21,		 \
611 	20, 19, 18, 17, 16, 15, 14, 13, 12, 11,		 \
612 	10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, ~)
613 
614 /**
615  * @brief Mapping macro that pastes results together
616  *
617  * This is similar to FOR_EACH() in that it invokes a macro repeatedly
618  * on each element of `__VA_ARGS__`. However, unlike FOR_EACH(),
619  * MACRO_MAP_CAT() pastes the results together into a single token.
620  *
621  * For example, with this macro FOO:
622  *
623  *     #define FOO(x) item_##x##_
624  *
625  * <tt>MACRO_MAP_CAT(FOO, a, b, c),</tt> expands to the token:
626  *
627  *     item_a_item_b_item_c_
628  *
629  * @param ... Macro to expand on each argument, followed by its
630  *            arguments. (The macro should take exactly one argument.)
631  * @return The results of expanding the macro on each argument, all pasted
632  *         together
633  */
634 #define MACRO_MAP_CAT(...) MACRO_MAP_CAT_(__VA_ARGS__)
635 
636 /**
637  * @brief Mapping macro that pastes a fixed number of results together
638  *
639  * Similar to @ref MACRO_MAP_CAT(), but expects a fixed number of
640  * arguments. If more arguments are given than are expected, the rest
641  * are ignored.
642  *
643  * @param N   Number of arguments to map
644  * @param ... Macro to expand on each argument, followed by its
645  *            arguments. (The macro should take exactly one argument.)
646  * @return The results of expanding the macro on each argument, all pasted
647  *         together
648  */
649 #define MACRO_MAP_CAT_N(N, ...) MACRO_MAP_CAT_N_(N, __VA_ARGS__)
650 
651 /**
652  * @}
653  */
654 
655 #ifdef __cplusplus
656 }
657 #endif
658 
659 #endif /* ZEPHYR_INCLUDE_SYS_UTIL_MACROS_H_ */
660