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brlib/include/br.h

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/* br.h - misc macros.
*
* Copyright (C) 2021-2024 Bruno Raoult ("br")
* Licensed under the GNU General Public License v3.0 or later.
* Some rights reserved. See COPYING.
*
* You should have received a copy of the GNU General Public License along with this
* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
*
* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
*
* Some parts are taken from Linux's kernel <linux/kernel.h> and others, and are :
* SPDX-License-Identifier: GPL-2.0
*
* This header contains generic stuff.
*/
#ifndef _BR_H
#define _BR_H
#include <stdint.h>
#include <stdbool.h>
#include <bits/wordsize.h> /* defines __WORDSIZE: 32 or 64 */
#include "struct-group.h"
/* fixed-size types
*/
typedef int64_t s64;
typedef int32_t s32;
typedef int16_t s16;
typedef int8_t s8;
typedef uint64_t u64;
typedef uint32_t u32;
typedef uint16_t u16;
typedef uint8_t u8;
/* convenience types
*/
typedef long long llong;
typedef unsigned long long ullong;
typedef unsigned long int ulong;
typedef unsigned int uint;
typedef unsigned short ushort;
typedef unsigned char uchar;
/* char is a special case, as it can be signed or unsigned
*/
typedef signed char schar;
/* define common types sizes
*/
#define BITS_PER_CHAR 8
#ifndef BITS_PER_SHORT
#define BITS_PER_SHORT (BITS_PER_CHAR * sizeof (short))
#endif
#ifndef BITS_PER_INT
#define BITS_PER_INT (BITS_PER_CHAR * sizeof (int))
#endif
#ifndef BITS_PER_LONG
#define BITS_PER_LONG (BITS_PER_CHAR * sizeof (long))
#endif
#ifndef BITS_PER_LLONG
#define BITS_PER_LLONG (BITS_PER_CHAR * sizeof (long long))
#endif
/* Indirect stringification. Doing two levels allows the parameter to be a
* macro itself. For example, compile with -DFOO=bar, __stringify(FOO)
* converts to "bar".
*/
#define __stringify_1(x...) #x
#define __stringify(x...) __stringify_1(x)
/* generate a (maybe) unique id.
*/
#define ___PASTE(x, y) x##y
#define __PASTE(x, y) ___PASTE(x, y)
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
/* unused/used parameters/functions
* https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute
* https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute
* https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute
* https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute
* https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute
* https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute
*/
#define __unused __attribute__((__unused__))
#define __used __attribute__((__used__))
#define __const __attribute__((__const__))
/* see https://lkml.org/lkml/2018/3/20/845 for explanation of this monster
*/
#define __is_constexpr(x) \
(sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
/*
* min()/max()/clamp() macros must accomplish three things:
*
* - avoid multiple evaluations of the arguments (so side-effects like
* "x++" happen only once) when non-constant.
* - perform strict type-checking (to generate warnings instead of
* nasty runtime surprises). See the "unnecessary" pointer comparison
* in __typecheck().
* - retain result as a constant expressions when called with only
* constant expressions (to avoid tripping VLA warnings in stack
* allocation usage).
*/
#define __typecheck(x, y) \
(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
#define __no_side_effects(x, y) \
(__is_constexpr(x) && __is_constexpr(y))
#define __safe_cmp(x, y) \
(__typecheck(x, y) && __no_side_effects(x, y))
#define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
#define __cmp_once(x, y, unique_x, unique_y, op) ({ \
typeof(x) unique_x = (x); \
typeof(y) unique_y = (y); \
__cmp(unique_x, unique_y, op); })
#define __careful_cmp(x, y, op) \
__builtin_choose_expr(__safe_cmp(x, y), \
__cmp(x, y, op), \
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
#define __pure __attribute__((__pure__))
/**
* min - return minimum of two values of the same or compatible types
* @x: first value
* @y: second value
*/
#define min(x, y) __careful_cmp(x, y, <)
/**
* max - return maximum of two values of the same or compatible types
* @x: first value
* @y: second value
*/
#define max(x, y) __careful_cmp(x, y, >)
/**
* min3 - return minimum of three values
* @x: first value
* @y: second value
* @z: third value
*/
#define min3(x, y, z) min((typeof(x))min(x, y), z)
/**
* max3 - return maximum of three values
* @x: first value
* @y: second value
* @z: third value
*/
#define max3(x, y, z) max((typeof(x))max(x, y), z)
/**
* min_not_zero - return the minimum that is _not_ zero, unless both are zero
* @x: value1
* @y: value2
*/
#define min_not_zero(x, y) ({ \
typeof(x) __x = (x); \
typeof(y) __y = (y); \
__x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
/**
* clamp - return a value clamped to a given range with strict typechecking
* @val: current value
* @lo: lowest allowable value
* @hi: highest allowable value
*
* This macro does strict typechecking of @lo/@hi to make sure they are of the
* same type as @val. See the unnecessary pointer comparisons.
*/
#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
/*
* ..and if you can't take the strict
* types, you can specify one yourself.
*
* Or not use min/max/clamp at all, of course.
*/
/**
* min_t - return minimum of two values, using the specified type
* @type: data type to use
* @x: first value
* @y: second value
*/
#define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <)
/**
* max_t - return maximum of two values, using the specified type
* @type: data type to use
* @x: first value
* @y: second value
*/
#define max_t(type, x, y) __careful_cmp((type)(x), (type)(y), >)
/**
* clamp_t - return a value clamped to a given range using a given type
* @type: the type of variable to use
* @val: current value
* @lo: minimum allowable value
* @hi: maximum allowable value
*
* This macro does no typechecking and uses temporary variables of type
* @type to make all the comparisons.
*/
#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
/**
* clamp_val - return a value clamped to a given range using val's type
* @val: current value
* @lo: minimum allowable value
* @hi: maximum allowable value
*
* This macro does no typechecking and uses temporary variables of whatever
* type the input argument @val is. This is useful when @val is an unsigned
* type and @lo and @hi are literals that will otherwise be assigned a signed
* integer type.
*/
#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
/**
* swap - swap values of @a and @b
* @a: first value
* @b: second value
*/
#define swap(a, b) \
do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
/**
* ARRAY_SIZE - get the number of elements in array @arr
* @arr: array to be sized
*/
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
/**
* abs - return absolute value of an argument
* @x: the value. If it is unsigned type, it is converted to signed type first.
* char is treated as if it was signed (regardless of whether it really is)
* but the macro's return type is preserved as char.
*
* Return: an absolute value of x.
*/
#define abs(x) __abs_choose_expr(x, long long, \
__abs_choose_expr(x, long, \
__abs_choose_expr(x, int, \
__abs_choose_expr(x, short, \
__abs_choose_expr(x, char, \
__builtin_choose_expr( \
__builtin_types_compatible_p(typeof(x), char), \
(char)({ signed char __x = (x); __x<0?-__x:__x; }), \
((void)0)))))))
#define __abs_choose_expr(x, type, other) __builtin_choose_expr( \
__builtin_types_compatible_p(typeof(x), signed type) || \
__builtin_types_compatible_p(typeof(x), unsigned type), \
({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
#endif /* _BR_H */
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