1 /* SPDX-License-Identifier: GPL-2.0 */
11  * min()/max()/clamp() macros must accomplish several things:
13  * - Avoid multiple evaluations of the arguments (so side-effects like
14  *   "x++" happen only once) when non-constant.
15  * - Perform signed v unsigned type-checking (to generate compile
17  * - Unsigned char/short are always promoted to signed int and can be
19  * - Unsigned arguments can be compared against non-negative signed constants.
20  * - Comparison of a signed argument against an unsigned constant fails
31  * In particular, statically non-negative signed integer expressions
53  * Check whether a signed value is always non-negative.
58  * On 64-bit any integer or pointer type can safely be cast to 'long long'.
59  * But on 32-bit we need to avoid warnings about casting pointers to integers
60  * of different sizes without truncating 64-bit values so 'long' or 'long long'
63  * This does not work for 128-bit signed integers since the cast would truncate
101  * min - return minimum of two values of the same or compatible types
108  * max - return maximum of two values of the same or compatible types
112 #define max(x, y)	__careful_cmp(max, x, y)  macro
115  * umin - return minimum of two non-negative values
124  * umax - return maximum of two non-negative values
129 	__careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
138  * min3 - return minimum of three values
147  * max3 - return maximum of three values
153 	__careful_op3(max, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
156  * min_t - return minimum of two values, using the specified type
164  * max_t - return maximum of two values, using the specified type
169 #define max_t(type, x, y) __cmp_once(max, type, x, y)
172  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
198  * clamp - return a value clamped to a given range with typechecking
209  * clamp_t - return a value clamped to a given range using a given type
221  * clamp_val - return a value clamped to a given range using val's type
235  * In the following legit use-case where the "array" passed is a simple pointer,
237  * --- 8< ---
241  * --- 8< ---
250 #define __minmax_array(op, array, len) ({				\  argument
252 	typeof(len) __len = (len);					\
253 	__unqual_scalar_typeof(__array[0]) __element = __array[--__len];\
254 	while (__len--)							\
259  * min_array - return minimum of values present in an array
261  * @len: array length
263  * Note that @len must not be zero (empty array).
265 #define min_array(array, len) __minmax_array(min, array, len)  argument
268  * max_array - return maximum of values present in an array
270  * @len: array length
272  * Note that @len must not be zero (empty array).
274 #define max_array(array, len) __minmax_array(max, array, len)  argument
276 static inline bool in_range64(u64 val, u64 start, u64 len)  in in_range64()  argument
278 	return (val - start) < len;  in in_range64()
281 static inline bool in_range32(u32 val, u32 start, u32 len)  in in_range32()  argument
283 	return (val - start) < len;  in in_range32()
287  * in_range - Determine if a value lies within a range.
290  * @len: Number of values in range.
292  * This is more efficient than "if (start <= val && val < (start + len))".
293  * It also gives a different answer if @start + @len overflows the size of
295  * which behaviour you want, or prove that start + len never overflow.
298 #define in_range(val, start, len)					\  argument
299 	((sizeof(start) | sizeof(len) | sizeof(val)) <= sizeof(u32) ?	\
300 		in_range32(val, start, len) : in_range64(val, start, len))
303  * swap - swap values of @a and @b
315 #define MAX(a, b) __cmp(max, a, b)  macro
317 #define MAX_T(type, a, b) __cmp(max, (type)(a), (type)(b))