zephyr/include/sys/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 ZEPHYR_INCLUDE_SYS_UTIL_H_
#define ZEPHYR_INCLUDE_SYS_UTIL_H_

#include <sys/util_macro.h>

/* needs to be outside _ASMLANGUAGE so 'true' and 'false' can turn
 * into '1' and '0' for asm or linker scripts
 */
#include <stdbool.h>

#ifndef _ASMLANGUAGE

#include <zephyr/types.h>
#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @defgroup sys-util Utility Functions
 * @{
 */

/** @brief Cast @p x, a pointer, to an unsigned integer. */
#define POINTER_TO_UINT(x) ((uintptr_t) (x))
/** @brief Cast @p x, an unsigned integer, to a <tt>void*</tt>. */
#define UINT_TO_POINTER(x) ((void *) (uintptr_t) (x))
/** @brief Cast @p x, a pointer, to a signed integer. */
#define POINTER_TO_INT(x)  ((intptr_t) (x))
/** @brief Cast @p x, a signed integer, to a <tt>void*</tt>. */
#define INT_TO_POINTER(x)  ((void *) (intptr_t) (x))

#if !(defined(__CHAR_BIT__) && defined(__SIZEOF_LONG__))
#	error Missing required predefined macros for BITS_PER_LONG calculation
#endif

/** Number of bits in a long int. */
#define BITS_PER_LONG	(__CHAR_BIT__ * __SIZEOF_LONG__)

/**
 * @brief Create a contiguous bitmask starting at bit position @p l
 *        and ending at position @p h.
 */
#define GENMASK(h, l) \
	(((~0UL) - (1UL << (l)) + 1) & (~0UL >> (BITS_PER_LONG - 1 - (h))))

/** @brief 0 if @p cond is true-ish; causes a compile error otherwise. */
#define ZERO_OR_COMPILE_ERROR(cond) ((int) sizeof(char[1 - 2 * !(cond)]) - 1)

#if defined(__cplusplus)

/* The built-in function used below for type checking in C is not
 * supported by GNU C++.
 */
#define ARRAY_SIZE(array) (sizeof(array) / sizeof((array)[0]))

#else /* __cplusplus */

/**
 * @brief Zero if @p array has an array type, a compile error otherwise
 *
 * This macro is available only from C, not C++.
 */
#define IS_ARRAY(array) \
	ZERO_OR_COMPILE_ERROR( \
		!__builtin_types_compatible_p(__typeof__(array), \
					      __typeof__(&(array)[0])))

/**
 * @brief Number of elements in the given @p array
 *
 * In C++, due to language limitations, this will accept as @p array
 * any type that implements <tt>operator[]</tt>. The results may not be
 * particulary meaningful in this case.
 *
 * In C, passing a pointer as @p array causes a compile error.
 */
#define ARRAY_SIZE(array) \
	((long) (IS_ARRAY(array) + (sizeof(array) / sizeof((array)[0]))))

#endif /* __cplusplus */

/**
 * @brief Check if a pointer @p ptr lies within @p array.
 *
 * In C but not C++, this causes a compile error if @p array is not an array
 * (e.g. if @p ptr and @p array are mixed up).
 *
 * @param ptr a pointer
 * @param array an array
 * @return 1 if @p ptr is part of @p array, 0 otherwise
 */
#define PART_OF_ARRAY(array, ptr) \
	((ptr) && ((ptr) >= &array[0] && (ptr) < &array[ARRAY_SIZE(array)]))

/**
 * @brief Get a pointer to a container structure from an element
 *
 * Example:
 *
 *	struct foo {
 *		int bar;
 *	};
 *
 *	struct foo my_foo;
 *	int *ptr = &my_foo.bar;
 *
 *	struct foo *container = CONTAINER_OF(ptr, struct foo, bar);
 *
 * Above, @p container points at @p my_foo.
 *
 * @param ptr pointer to a structure element
 * @param type name of the type that @p ptr is an element of
 * @param field the name of the field within the struct @p ptr points to
 * @return a pointer to the structure that contains @p ptr
 */
#define CONTAINER_OF(ptr, type, field) \
	((type *)(((char *)(ptr)) - offsetof(type, field)))

/**
 * @brief Value of @p x rounded up to the next multiple of @p align,
 *        which must be a power of 2.
 */
#define ROUND_UP(x, align)                                   \
	(((unsigned long)(x) + ((unsigned long)(align) - 1)) & \
	 ~((unsigned long)(align) - 1))

/**
 * @brief Value of @p x rounded down to the previous multiple of @p
 *        align, which must be a power of 2.
 */
#define ROUND_DOWN(x, align)                                 \
	((unsigned long)(x) & ~((unsigned long)(align) - 1))

/** @brief Value of @p x rounded up to the next word boundary. */
#define WB_UP(x) ROUND_UP(x, sizeof(void *))

/** @brief Value of @p x rounded down to the previous word boundary. */
#define WB_DN(x) ROUND_DOWN(x, sizeof(void *))

/**
 * @brief Ceiling function applied to @p numerator / @p divider as a fraction.
 */
#define ceiling_fraction(numerator, divider) \
	(((numerator) + ((divider) - 1)) / (divider))

/**
 * @def MAX
 * @brief The larger value between @p a and @p b.
 * @note Arguments are evaluated twice.
 */
#ifndef MAX
/* Use Z_MAX for a GCC-only, single evaluation version */
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#endif

/**
 * @def MIN
 * @brief The smaller value between @p a and @p b.
 * @note Arguments are evaluated twice.
 */
#ifndef MIN
/* Use Z_MIN for a GCC-only, single evaluation version */
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif

/**
 * @def CLAMP
 * @brief Clamp a value to a given range.
 * @note Arguments are evaluated multiple times.
 */
#ifndef CLAMP
/* Use Z_CLAMP for a GCC-only, single evaluation version */
#define CLAMP(val, low, high) (((val) <= (low)) ? (low) : MIN(val, high))
#endif

/**
 * @brief Is @p x a power of two?
 * @param x value to check
 * @return true if @p x is a power of two, false otherwise
 */
static inline bool is_power_of_two(unsigned int x)
{
	return (x != 0U) && ((x & (x - 1U)) == 0U);
}

/**
 * @brief Arithmetic shift right
 * @param value value to shift
 * @param shift number of bits to shift
 * @return @p value shifted right by @p shift; opened bit positions are
 *         filled with the sign bit
 */
static inline int64_t arithmetic_shift_right(int64_t value, uint8_t shift)
{
	int64_t sign_ext;

	if (shift == 0U) {
		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));
}

/**
 * @brief      Convert a single character into a hexadecimal nibble.
 *
 * @param c     The character to convert
 * @param x     The address of storage for the converted number.
 *
 *  @return Zero on success or (negative) error code otherwise.
 */
int char2hex(char c, uint8_t *x);

/**
 * @brief      Convert a single hexadecimal nibble into a character.
 *
 * @param c     The number to convert
 * @param x     The address of storage for the converted character.
 *
 *  @return Zero on success or (negative) error code otherwise.
 */
int hex2char(uint8_t x, char *c);

/**
 * @brief      Convert a binary array into string representation.
 *
 * @param buf     The binary array to convert
 * @param buflen  The length of the binary array to convert
 * @param hex     Address of where to store the string representation.
 * @param hexlen  Size of the storage area for string representation.
 *
 * @return     The length of the converted string, or 0 if an error occurred.
 */
size_t bin2hex(const uint8_t *buf, size_t buflen, char *hex, size_t hexlen);

/**
 * @brief      Convert a hexadecimal string into a binary array.
 *
 * @param hex     The hexadecimal string to convert
 * @param hexlen  The length of the hexadecimal string to convert.
 * @param buf     Address of where to store the binary data
 * @param buflen  Size of the storage area for binary data
 *
 * @return     The length of the binary array, or 0 if an error occurred.
 */
size_t hex2bin(const char *hex, size_t hexlen, uint8_t *buf, size_t buflen);

/**
 * @brief      Convert a uint8_t into a decimal string representation.
 *
 * Convert a uint8_t value into its ASCII decimal string representation.
 * The string is terminated if there is enough space in buf.
 *
 * @param buf     Address of where to store the string representation.
 * @param buflen  Size of the storage area for string representation.
 * @param value   The value to convert to decimal string
 *
 * @return     The length of the converted string (excluding terminator if
 *             any), or 0 if an error occurred.
 */
uint8_t u8_to_dec(char *buf, uint8_t buflen, uint8_t value);

#ifdef __cplusplus
}
#endif

#endif /* !_ASMLANGUAGE */

/** @brief Number of bytes in @p x kibibytes */
#ifdef _LINKER
/* This is used in linker scripts so need to avoid type casting there */
#define KB(x) ((x) << 10)
#else
#define KB(x) (((size_t)x) << 10)
#endif
/** @brief Number of bytes in @p x mebibytes */
#define MB(x) (KB(x) << 10)
/** @brief Number of bytes in @p x gibibytes */
#define GB(x) (MB(x) << 10)

/** @brief Number of Hz in @p x kHz */
#define KHZ(x) ((x) * 1000)
/** @brief Number of Hz in @p x MHz */
#define MHZ(x) (KHZ(x) * 1000)

#ifndef BIT
#if defined(_ASMLANGUAGE)
#define BIT(n)  (1 << (n))
#else
/**
 * @brief Unsigned integer with bit position @p n set (signed in
 * assembly language).
 */
#define BIT(n)  (1UL << (n))
#endif
#endif

/** @brief 64-bit unsigned integer with bit position @p _n set. */
#define BIT64(_n) (1ULL << (_n))

/**
 * @brief Set or clear a bit depending on a boolean value
 *
 * The argument @p var is a variable whose value is written to as a
 * side effect.
 *
 * @param var Variable to be altered
 * @param bit Bit number
 * @param set if 0, clears @p bit in @p var; any other value sets @p bit
 */
#define WRITE_BIT(var, bit, set) \
	((var) = (set) ? ((var) | BIT(bit)) : ((var) & ~BIT(bit)))

/**
 * @brief Bit mask with bits 0 through <tt>n-1</tt> (inclusive) set,
 * or 0 if @p n is 0.
 */
#define BIT_MASK(n) (BIT(n) - 1UL)

/**
 * @brief 64-bit bit mask with bits 0 through <tt>n-1</tt> (inclusive) set,
 * or 0 if @p n is 0.
 */
#define BIT64_MASK(n) (BIT64(n) - 1ULL)

/**
 * @}
 */

#endif /* ZEPHYR_INCLUDE_SYS_UTIL_H_ */