include/misc/util.h

/*
 * Copyright (c) 2011-2014, Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file
 * @brief Misc utilities
 *
 * Misc utilities usable by the kernel and application code.
 */

#ifndef _UTIL__H_
#define _UTIL__H_

#ifdef __cplusplus
extern "C" {
#endif

#ifndef _ASMLANGUAGE

#include <stdint.h>

/* Helper to pass a int as a pointer or vice-versa.
 * Those are available for 32 bits architectures:
 */
#define POINTER_TO_UINT(x) ((uint32_t) (x))
#define UINT_TO_POINTER(x) ((void *) (x))
#define POINTER_TO_INT(x)  ((int32_t) (x))
#define INT_TO_POINTER(x)  ((void *) (x))

/* Evaluates to 0 if cond is true-ish; compile error otherwise */
#define ZERO_OR_COMPILE_ERROR(cond) ((int) sizeof(char[1 - 2 * !(cond)]) - 1)

/* Evaluates to 0 if array is an array; compile error if not array (e.g.
 * pointer)
 */
#define IS_ARRAY(array) \
	ZERO_OR_COMPILE_ERROR( \
		!__builtin_types_compatible_p(__typeof__(array), \
					      __typeof__(&(array)[0])))

/* Evaluates to number of elements in an array; compile error if not
 * an array (e.g. pointer)
 */
#define ARRAY_SIZE(array) \
	((unsigned long) (IS_ARRAY(array) + \
		(sizeof(array) / sizeof((array)[0]))))

/* Evaluates to 1 if ptr is part of array, 0 otherwise; compile error if
 * "array" argument is not an array (e.g. "ptr" and "array" mixed up)
 */
#define PART_OF_ARRAY(array, ptr) \
	((ptr) && ((ptr) >= &array[0] && (ptr) < &array[ARRAY_SIZE(array)]))

#define CONTAINER_OF(ptr, type, field) \
	((type *)(((char *)(ptr)) - offsetof(type, field)))

/* round "x" up/down to next multiple of "align" (which must be a power of 2) */
#define ROUND_UP(x, align)                                   \
	(((unsigned long)(x) + ((unsigned long)align - 1)) & \
	 ~((unsigned long)align - 1))
#define ROUND_DOWN(x, align) ((unsigned long)(x) & ~((unsigned long)align - 1))

#define ceiling_fraction(numerator, divider) \
	(((numerator) + ((divider) - 1)) / (divider))

#ifdef INLINED
#define INLINE inline
#else
#define INLINE
#endif

#ifndef max
#define max(a, b) (((a) > (b)) ? (a) : (b))
#endif

#ifndef min
#define min(a, b) (((a) < (b)) ? (a) : (b))
#endif

static inline int is_power_of_two(unsigned int x)
{
	return (x != 0) && !(x & (x - 1));
}

static inline int64_t arithmetic_shift_right(int64_t value, uint8_t shift)
{
	int64_t sign_ext;

	if (shift == 0) {
		return value;
	}

	/* extract sign bit */
	sign_ext = (value >> 63) & 1;

	/* make all bits of sign_ext be the same as the value's sign bit */
	sign_ext = -sign_ext;

	/* shift value and fill opened bit positions with sign bit */
	return (value >> shift) | (sign_ext << (64 - shift));
}

#endif /* !_ASMLANGUAGE */

/* KB, MB, GB */
#define KB(x) ((x) << 10)
#define MB(x) (KB(x) << 10)
#define GB(x) (MB(x) << 10)

/* KHZ, MHZ */
#define KHZ(x) ((x) * 1000)
#define MHZ(x) (KHZ(x) * 1000)

#ifndef BIT
#define BIT(n)  (1UL << (n))
#endif

#define BIT_MASK(n) (BIT(n) - 1)

/**
 * @brief Check for macro definition in compiler-visible expressions
 *
 * This trick was pioneered in Linux as the config_enabled() macro.
 * The madness has the effect of taking a macro value that may be
 * defined to "1" (e.g. CONFIG_MYFEATURE), or may not be defined at
 * all and turning it into a literal expression that can be used at
 * "runtime".  That is, it works similarly to
 * "defined(CONFIG_MYFEATURE)" does except that it is an expansion
 * that can exist in a standard expression and be seen by the compiler
 * and optimizer.  Thus much ifdef usage can be replaced with cleaner
 * expressions like:
 *
 *     if (IS_ENABLED(CONFIG_MYFEATURE))
 *             myfeature_enable();
 *
 * INTERNAL
 * First pass just to expand any existing macros, we need the macro
 * value to be e.g. a literal "1" at expansion time in the next macro,
 * not "(1)", etc...  Standard recursive expansion does not work.
 */
#define IS_ENABLED(config_macro) _IS_ENABLED1(config_macro)

/* Now stick on a "_XXXX" prefix, it will now be "_XXXX1" if config_macro
 * is "1", or just "_XXXX" if it's undefined.
 *   ENABLED:   _IS_ENABLED2(_XXXX1)
 *   DISABLED   _IS_ENABLED2(_XXXX)
 */
#define _IS_ENABLED1(config_macro) _IS_ENABLED2(_XXXX##config_macro)

/* Here's the core trick, we map "_XXXX1" to "_YYYY," (i.e. a string
 * with a trailing comma), so it has the effect of making this a
 * two-argument tuple to the preprocessor only in the case where the
 * value is defined to "1"
 *   ENABLED:    _YYYY,    <--- note comma!
 *   DISABLED:   _XXXX
 */
#define _XXXX1 _YYYY,

/* Then we append an extra argument to fool the gcc preprocessor into
 * accepting it as a varargs macro.
 *                         arg1   arg2  arg3
 *   ENABLED:   _IS_ENABLED3(_YYYY,    1,    0)
 *   DISABLED   _IS_ENABLED3(_XXXX 1,  0)
 */
#define _IS_ENABLED2(one_or_two_args) _IS_ENABLED3(one_or_two_args 1, 0)

/* And our second argument is thus now cooked to be 1 in the case
 * where the value is defined to 1, and 0 if not:
 */
#define _IS_ENABLED3(ignore_this, val, ...) val

#ifdef __cplusplus
}
#endif

#endif /* _UTIL__H_ */