kern/include/ros/common.h

#pragma once

#ifndef __ASSEMBLER__

#include <stddef.h>
#include <stdint.h>
#include <sys/types.h>
#include <stdbool.h>
#include <string.h>

typedef uintptr_t physaddr_t;
typedef long intreg_t;
typedef unsigned long uintreg_t;

#ifndef NULL
#define NULL ((void*) 0)
#endif

#ifndef TRUE
#define TRUE	1
#endif

#ifndef FALSE
#define FALSE	0
#endif

#define FOR_CIRC_BUFFER(next, size, var) \
	for (int _var = 0, var = (next); _var < (size); _var++, var = (var + 1) % (size))

#define STRINGIFY(s) __STRINGIFY(s)
#define __STRINGIFY(s) #s

/* A macro for testing if another macro has been #defined or not.  Can be used
 * wherever you need a boolean defined.  Returns 0 or 1. */
#define is_defined(macro) is_defined_(macro)
#define is_defined_test_1 ,
#define is_defined_(value) is_defined__(is_defined_test_##value, value)
#define is_defined__(comma, value) is_defined___(comma 1, 0)
#define is_defined___(_, v, ...) v

#define COUNT_OF(x) (sizeof((x))/sizeof((x)[0]))

#define ZERO_DATA(s) memset(&(s), 0, sizeof(s))

/* Rounding operations (efficient when n is a power of 2)
 * Round down to the nearest multiple of n.
 * The compiler should compile out the branch.  This is needed for 32 bit, so
 * that we can round down uint64_t, without chopping off the top 32 bits. */
#define ROUNDDOWN(a, n)                                                        \
({                                                                             \
	typeof(a) __b;                                                         \
	if (sizeof(a) == 8) {                                                  \
		uint64_t __a = (uint64_t) (a);                                 \
		__b = (typeof(a)) (__a - __a % (n));                           \
	} else {                                                               \
		uintptr_t __a = (uintptr_t) (a);                               \
		__b = (typeof(a)) (__a - __a % (n));                           \
	}                                                                      \
	__b;                                                                   \
})

/* Round up to the nearest multiple of n */
#define ROUNDUP(a, n)                                                          \
({                                                                             \
	typeof(a) __b;                                                         \
	if (sizeof(a) == 8) {                                                  \
		uint64_t __n = (uint64_t) (n);                                 \
		__b = (typeof(a)) (ROUNDDOWN((uint64_t) (a) + __n - 1, __n));  \
	} else {                                                               \
		uintptr_t __n = (uintptr_t) (n);                               \
		__b = (typeof(a)) (ROUNDDOWN((uintptr_t) (a) + __n - 1, __n)); \
	}                                                                      \
	__b;                                                                   \
})

#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))

// Return the integer logarithm of the value provided rounded down
static inline uintptr_t LOG2_DOWN(uintptr_t value)
{
	value |= 1;  // clz(0) is undefined, just or in a 1 bit and define it
	// intrinsic __builtin_clz supported by both > gcc4.6 and LLVM > 1.5
	return (sizeof(value) == 8) ? 63 - __builtin_clzll(value)
	                            : 31 - __builtin_clz(value);
}

// Return the integer logarithm of the value provided rounded up
static inline uintptr_t LOG2_UP(uintptr_t value)
{
	uintptr_t ret = LOG2_DOWN(value);

	// Add 1 if a lower bit set
	ret += 0 != (value ^ ((uintptr_t) 1 << ret));
	return ret;
}

static inline uintptr_t ROUNDUPPWR2(uintptr_t value)
{
	return 1 << LOG2_UP(value);
}

static inline uintptr_t ROUNDDOWNPWR2(uintptr_t value)
{
	return 1 << LOG2_DOWN(value);
}

/* We wraparound if UINT_MAX < a * b, which is also UINT_MAX / a < b. */
static inline bool mult_will_overflow_u64(uint64_t a, uint64_t b)
{
	if (!a)
		return FALSE;
	return (uint64_t)(-1) / a < b;
}

// Return the offset of 'member' relative to the beginning of a struct type
#ifndef offsetof
#define offsetof(type, member)  ((size_t) (&((type*)0)->member))
#endif

/* Return the container/struct holding the object 'ptr' points to */
#define container_of(ptr, type, member) ({                                     \
	(type*)((char*)ptr - offsetof(type, member));                         \
})

/* Makes sure func is run exactly once.  Can handle concurrent callers, and
 * other callers spin til the func is complete. */
#define run_once(func)                                                         \
do {                                                                           \
	static bool ran_once = FALSE;                                          \
	static bool is_running = FALSE;                                        \
	if (!ran_once) {                                                       \
		/* fetch and set TRUE, w/o a header or test_and_set weirdness*/\
		if (!__sync_fetch_and_or(&is_running, TRUE)) {                 \
			/* we won the race and get to run the func */          \
			func;                                                  \
			/* don't let the ran_once write pass previous writes */\
			wmb();                                                 \
			ran_once = TRUE;                                       \
		} else {                                                       \
			/* someone else woni */                                \
			while (!ran_once)                                      \
				cpu_relax();                                   \
		}                                                              \
	}                                                                      \
} while (0)

/* Unprotected, single-threaded version, makes sure func is run exactly once */
#define run_once_racy(func)                                                    \
do {                                                                           \
	static bool ran_once = FALSE;                                          \
	if (!ran_once) {                                                       \
		func;                                                          \
		ran_once = TRUE;                                               \
	}                                                                      \
} while (0)

#ifdef ROS_KERNEL
#include <compiler.h>
#else
/* Force the reading/writing exactly once of x.  You may still need mbs().  See
 * http://lwn.net/Articles/508991/ for more info. */
#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
#define READ_ONCE(x) ACCESS_ONCE(x)
#define WRITE_ONCE(x, val) ((*(volatile typeof(x) *)&(x)) = val)
#endif

#endif /* __ASSEMBLER__ */