1 /* SPDX-License-Identifier: GPL-2.0 */
3 #define _LINUX_MINMAX_H
13  * - Avoid multiple evaluations of the arguments (so side-effects like
14  *   "x++" happen only once) when non-constant.
15  * - Retain result as a constant expressions when called with only
18  * - Perform signed v unsigned type-checking (to generate compile
20  * - Unsigned char/short are always promoted to signed int and can be
21  *   compared against signed or unsigned arguments.
22  * - Unsigned arguments can be compared against non-negative signed constants.
23  * - Comparison of a signed argument against an unsigned constant fails
26 #define __typecheck(x, y) \
30 #define __is_signed(x) 								\
34 /* True for a non-negative signed int constant */
35 #define __is_noneg_int(x)	\
36 	(__builtin_choose_expr(__is_constexpr(x) && __is_signed(x), x, -1) >= 0)
38 #define __types_ok(x, y) 					\
43 #define __cmp_op_min <
44 #define __cmp_op_max >
46 #define __cmp(op, x, y)	((x) __cmp_op_##op (y) ? (x) : (y))
48 #define __cmp_once(op, x, y, unique_x, unique_y) ({	\
52 		#op "(" #x ", " #y ") signedness error, fix types or consider u" #op "() before " #op "_t()"); \
55 #define __careful_cmp(op, x, y)					\
56 	__builtin_choose_expr(__is_constexpr((x) - (y)),	\
60 #define __clamp(val, lo, hi)	\
63 #define __clamp_once(val, lo, hi, unique_val, unique_lo, unique_hi) ({		\
74 #define __careful_clamp(val, lo, hi) ({					\
75 	__builtin_choose_expr(__is_constexpr((val) - (lo) + (hi)),	\
81  * min - return minimum of two values of the same or compatible types
85 #define min(x, y)	__careful_cmp(min, x, y)
88  * max - return maximum of two values of the same or compatible types
92 #define max(x, y)	__careful_cmp(max, x, y)
95  * umin - return minimum of two non-negative values
100 #define umin(x, y)	\
104  * umax - return maximum of two non-negative values
108 #define umax(x, y)	\
112  * min3 - return minimum of three values
117 #define min3(x, y, z) min((typeof(x))min(x, y), z)
120  * max3 - return maximum of three values
125 #define max3(x, y, z) max((typeof(x))max(x, y), z)
128  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
132 #define min_not_zero(x, y) ({			\
138  * clamp - return a value clamped to a given range with strict typechecking
146 #define clamp(val, lo, hi) __careful_clamp(val, lo, hi)
152  * Or not use min/max/clamp at all, of course.
156  * min_t - return minimum of two values, using the specified type
161 #define min_t(type, x, y)	__careful_cmp(min, (type)(x), (type)(y))
164  * max_t - return maximum of two values, using the specified type
169 #define max_t(type, x, y)	__careful_cmp(max, (type)(x), (type)(y))
173  * In the following legit use-case where the "array" passed is a simple pointer,
175  * --- 8< ---
179  * --- 8< ---
188 #define __minmax_array(op, array, len) ({				\  argument
190 	typeof(len) __len = (len);					\
191 	__unqual_scalar_typeof(__array[0]) __element = __array[--__len];\
192 	while (__len--)							\
197  * min_array - return minimum of values present in an array
199  * @len: array length
201  * Note that @len must not be zero (empty array).
203 #define min_array(array, len) __minmax_array(min, array, len)  argument
206  * max_array - return maximum of values present in an array
208  * @len: array length
210  * Note that @len must not be zero (empty array).
212 #define max_array(array, len) __minmax_array(max, array, len)  argument
215  * clamp_t - return a value clamped to a given range using a given type
224 #define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
227  * clamp_val - return a value clamped to a given range using val's type
237 #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
239 static inline bool in_range64(u64 val, u64 start, u64 len)  in in_range64()  argument
241 	return (val - start) < len;  in in_range64()
244 static inline bool in_range32(u32 val, u32 start, u32 len)  in in_range32()  argument
246 	return (val - start) < len;  in in_range32()
250  * in_range - Determine if a value lies within a range.
253  * @len: Number of values in range.
255  * This is more efficient than "if (start <= val && val < (start + len))".
256  * It also gives a different answer if @start + @len overflows the size of
258  * which behaviour you want, or prove that start + len never overflow.
261 #define in_range(val, start, len)					\  argument
262 	((sizeof(start) | sizeof(len) | sizeof(val)) <= sizeof(u32) ?	\
263 		in_range32(val, start, len) : in_range64(val, start, len))
266  * swap - swap values of @a and @b
270 #define swap(a, b) \