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) \
34  * In particular, statically non-negative signed integer
47  * with sizeof() or __builtin_constant_p() etc).
54 #define __signed_type_use(x,ux) (2+__is_nonneg(x,ux))
55 #define __unsigned_type_use(x,ux) (1+2*(sizeof(ux)<4))
56 #define __sign_use(x,ux) (is_signed_type(typeof(ux))? \
63  * On 64-bit we can just always use 'long', since any
64  * integer or pointer type can just be cast to that.
66  * This does not work for 128-bit signed integers since
75   #define __signed_type(ux) long
77   #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux)>4,1LL,1L))
79 #define __is_nonneg(x,ux) statically_true((__signed_type(ux))(x)>=0)
81 #define __types_ok(x,y,ux,uy) \
84 #define __types_ok3(x,y,z,ux,uy,uz) \
87 #define __cmp_op_min <
88 #define __cmp_op_max >
90 #define __cmp(op, x, y)	((x) __cmp_op_##op (y) ? (x) : (y))
92 #define __cmp_once_unique(op, type, x, y, ux, uy) \
95 #define __cmp_once(op, type, x, y) \
98 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
104 #define __careful_cmp(op, x, y) \
107 #define __clamp(val, lo, hi)	\
110 #define __clamp_once(val, lo, hi, uval, ulo, uhi) ({				\
121 #define __careful_clamp(val, lo, hi) \
125  * min - return minimum of two values of the same or compatible types
129 #define min(x, y)	__careful_cmp(min, x, y)
132  * max - return maximum of two values of the same or compatible types
136 #define max(x, y)	__careful_cmp(max, x, y)
139  * umin - return minimum of two non-negative values
144 #define umin(x, y)	\
148  * umax - return maximum of two non-negative values
152 #define umax(x, y)	\
155 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
162  * min3 - return minimum of three values
167 #define min3(x, y, z) \
171  * max3 - return maximum of three values
176 #define max3(x, y, z) \
180  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
184 #define min_not_zero(x, y) ({			\
190  * clamp - return a value clamped to a given range with strict typechecking
198 #define clamp(val, lo, hi) __careful_clamp(val, lo, hi)
204  * Or not use min/max/clamp at all, of course.
208  * min_t - return minimum of two values, using the specified type
213 #define min_t(type, x, y) __cmp_once(min, type, x, y)
216  * max_t - return maximum of two values, using the specified type
221 #define max_t(type, x, y) __cmp_once(max, type, x, y)
225  * In the following legit use-case where the "array" passed is a simple pointer,
227  * --- 8< ---
231  * --- 8< ---
240 #define __minmax_array(op, array, len) ({				\  argument
242 	typeof(len) __len = (len);					\
243 	__unqual_scalar_typeof(__array[0]) __element = __array[--__len];\
244 	while (__len--)							\
249  * min_array - return minimum of values present in an array
251  * @len: array length
253  * Note that @len must not be zero (empty array).
255 #define min_array(array, len) __minmax_array(min, array, len)  argument
258  * max_array - return maximum of values present in an array
260  * @len: array length
262  * Note that @len must not be zero (empty array).
264 #define max_array(array, len) __minmax_array(max, array, len)  argument
267  * clamp_t - return a value clamped to a given range using a given type
276 #define clamp_t(type, val, lo, hi) __careful_clamp((type)(val), (type)(lo), (type)(hi))
279  * clamp_val - return a value clamped to a given range using val's type
289 #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
291 static inline bool in_range64(u64 val, u64 start, u64 len)  in in_range64()  argument
293 	return (val - start) < len;  in in_range64()
296 static inline bool in_range32(u32 val, u32 start, u32 len)  in in_range32()  argument
298 	return (val - start) < len;  in in_range32()
302  * in_range - Determine if a value lies within a range.
305  * @len: Number of values in range.
307  * This is more efficient than "if (start <= val && val < (start + len))".
308  * It also gives a different answer if @start + @len overflows the size of
310  * which behaviour you want, or prove that start + len never overflow.
313 #define in_range(val, start, len)					\  argument
314 	((sizeof(start) | sizeof(len) | sizeof(val)) <= sizeof(u32) ?	\
315 		in_range32(val, start, len) : in_range64(val, start, len))
318  * swap - swap values of @a and @b
322 #define swap(a, b) \
329 #define MIN(a,b) __cmp(min,a,b)
330 #define MAX(a,b) __cmp(max,a,b)
331 #define MIN_T(type,a,b) __cmp(min,(type)(a),(type)(b))
332 #define MAX_T(type,a,b) __cmp(max,(type)(a),(type)(b))