/* Copyright (C) 2021,2022 fef <owo@fef.moe>.  All rights reserved. */

#pragma once

#include <gay/cdefs.h>
#include <gay/types.h>

/**
 * @brief Get the number of elements in a statically allocated array.
 *
 * @param a The array
 * @returns The number of elements
 */
#define ARRAY_SIZE(a) ( sizeof(a) / sizeof((a)[0]) )

#define abs(x) ({		\
	typeof(x) __x = (x);	\
	__x < 0 ? -__x : +__x;	\
})

#define max(a, b) ({		\
	typeof(a) __a = (a);	\
	typeof(b) __b = (b);	\
	__a > __b ? __a : __b;	\
})

#define min(a, b) ({		\
	typeof(a) __a = (a);	\
	typeof(b) __b = (b);	\
	__a < __b ? __a : __b;	\
})

/** @brief Get type type of a structure member. */
#define __typeof_member(type, member) typeof( ((type *)0)->member )

/**
 * @brief Cast a pointer to a struct member out to the containing structure.
 *
 * @param ptr Pointer to the struct member
 * @param type Type of the containing structure
 * @param member Name of the member within the containing structure
 * @returns Pointer to the containing structure
 */
#define container_of(ptr, type, member) ({				\
	/* implicit type check to avoid obvious mistakes */		\
        __typeof_member(type, member) *__membptr = (ptr);		\
	(type *)( (void *)__membptr - offsetof(type, member) );		\
})

/** @brief Determine whether `ptr` is kinda sus. */
static __always_inline bool sus_nil(const void *ptr)
{
	return ptr < (void *)0x1000;
}

static __always_inline uintmax_t _align_floor(uintmax_t ptr, usize size)
{
	return ptr - ptr % size;
}
#define align_floor(ptr, size) ( (typeof(ptr))_align_floor((uintptr_t)(ptr), size) )

static __always_inline uintmax_t _align_ceil(uintmax_t ptr, usize size)
{
	uintmax_t aligned = ptr - ptr % size;
	if (aligned < ptr)
		aligned += size;
	return aligned;
}
#define align_ceil(ptr, size) ( (typeof(ptr))_align_ceil((uintmax_t)(ptr), size) )