1 /* SPDX-License-Identifier: GPL-2.0 */
11  * min()/max()/clamp() macros must accomplish three things:
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
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) \  argument
27 	(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
34  * In particular, statically non-negative signed integer
63  * On 64-bit we can just always use 'long', since any
66  * This does not work for 128-bit signed integers since
81 #define __types_ok(x,y,ux,uy) \  argument
82 	(__sign_use(x,ux) & __sign_use(y,uy))
84 #define __types_ok3(x,y,z,ux,uy,uz) \  argument
85 	(__sign_use(x,ux) & __sign_use(y,uy) & __sign_use(z,uz))
90 #define __cmp(op, x, y)	((x) __cmp_op_##op (y) ? (x) : (y))  argument
92 #define __cmp_once_unique(op, type, x, y, ux, uy) \  argument
93 	({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
95 #define __cmp_once(op, type, x, y) \  argument
96 	__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
98 #define __careful_cmp_once(op, x, y, ux, uy) ({		\  argument
99 	__auto_type ux = (x); __auto_type uy = (y);	\
100 	BUILD_BUG_ON_MSG(!__types_ok(x,y,ux,uy),	\
101 		#op"("#x", "#y") signedness error");	\
104 #define __careful_cmp(op, x, y) \  argument
105 	__careful_cmp_once(op, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
125  * min - return minimum of two values of the same or compatible types
127  * @y: second value
129 #define min(x, y)	__careful_cmp(min, x, y)  argument
132  * max - return maximum of two values of the same or compatible types
134  * @y: second value
136 #define max(x, y)	__careful_cmp(max, x, y)  macro
139  * umin - return minimum of two non-negative values
142  * @y: second value
144 #define umin(x, y)	\  argument
145 	__careful_cmp(min, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
148  * umax - return maximum of two non-negative values
150  * @y: second value
152 #define umax(x, y)	\  argument
153 	__careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
155 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\  argument
156 	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
157 	BUILD_BUG_ON_MSG(!__types_ok3(x,y,z,ux,uy,uz),			\
158 		#op"3("#x", "#y", "#z") signedness error");		\
162  * min3 - return minimum of three values
164  * @y: second value
167 #define min3(x, y, z) \  argument
168 	__careful_op3(min, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
171  * max3 - return maximum of three values
173  * @y: second value
176 #define max3(x, y, z) \  argument
177 	__careful_op3(max, x, y, z, __UNIQUE_ID(x_), __UNIQUE_ID(y_), __UNIQUE_ID(z_))
180  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
182  * @y: value2
184 #define min_not_zero(x, y) ({			\  argument
186 	typeof(y) __y = (y);			\
190  * clamp - return a value clamped to a given range with strict typechecking
204  * Or not use min/max/clamp at all, of course.
208  * min_t - return minimum of two values, using the specified type
211  * @y: second value
213 #define min_t(type, x, y) __cmp_once(min, type, x, y)  argument
216  * max_t - return maximum of two values, using the specified type
219  * @y: second value
221 #define max_t(type, x, y) __cmp_once(max, type, x, y)  argument
225  * In the following legit use-case where the "array" passed is a simple pointer,
227  * --- 8< ---
231  * --- 8< ---
243 	__unqual_scalar_typeof(__array[0]) __element = __array[--__len];\
244 	while (__len--)							\
249  * min_array - return minimum of values present in an array
258  * max_array - return maximum of values present in an array
264 #define max_array(array, len) __minmax_array(max, array, len)
267  * clamp_t - return a value clamped to a given range using a given type
279  * clamp_val - return a value clamped to a given range using val's type
293 	return (val - start) < len;  in in_range64()
298 	return (val - start) < len;  in in_range32()
302  * in_range - Determine if a value lies within a range.
318  * swap - swap values of @a and @b
330 #define MAX(a,b) __cmp(max,a,b)  macro
332 #define MAX_T(type,a,b) __cmp(max,(type)(a),(type)(b))