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/*-
 *   BSD LICENSE
 * 
 *   Copyright(c) 2010-2013 Intel Corporation. All rights reserved.
 *   All rights reserved.
 * 
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 *   modification, are permitted provided that the following conditions 
 *   are met:
 * 
 *     * Redistributions of source code must retain the above copyright 
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in 
 *       the documentation and/or other materials provided with the 
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its 
 *       contributors may be used to endorse or promote products derived 
 *       from this software without specific prior written permission.
 * 
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
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 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
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 * 
 */

/*
 * Inspired from FreeBSD src/sys/i386/include/atomic.h
 * Copyright (c) 1998 Doug Rabson
 * All rights reserved.
 */

#ifndef _RTE_ATOMIC_H_
#error "don't include this file directly, please include generic <rte_atomic.h>"
#endif

#ifndef _RTE_I686_ATOMIC_H_
#define _RTE_I686_ATOMIC_H_


/**
 * @file
 * Atomic Operations on i686
 */


/*------------------------- 64 bit atomic operations -------------------------*/

/**
 * An atomic compare and set function used by the mutex functions.
 * (atomic) equivalent to:
 *   if (*dst == exp)
 *     *dst = src (all 64-bit words)
 *
 * @param dst
 *   The destination into which the value will be written.
 * @param exp
 *   The expected value.
 * @param src
 *   The new value.
 * @return
 *   Non-zero on success; 0 on failure.
 */
static inline int
rte_atomic64_cmpset(volatile uint64_t *dst, uint64_t exp, uint64_t src)
{
	uint8_t res;
	union {
		struct {
			uint32_t l32;
			uint32_t h32;
		};
		uint64_t u64;
	} _exp, _src;

	_exp.u64 = exp;
	_src.u64 = src;

	asm volatile (
			MPLOCKED
			"cmpxchg8b (%[dst]);"
			"setz %[res];"
			: [res] "=a" (res)      /* result in eax */
			: [dst] "S" (dst),      /* esi */
			  "b" (_src.l32),       /* ebx */
			  "c" (_src.h32),       /* ecx */
			  "a" (_exp.l32),       /* eax */
			  "d" (_exp.h32)        /* edx */
			: "memory" );           /* no-clobber list */

	return res;
}

/**
 * The atomic counter structure.
 */
typedef struct {
	volatile int64_t cnt;  /**< Internal counter value. */
} rte_atomic64_t;

/**
 * Static initializer for an atomic counter.
 */
#define RTE_ATOMIC64_INIT(val) { (val) }

/**
 * Initialize the atomic counter.
 *
 * @param v
 *   A pointer to the atomic counter.
 */
static inline void
rte_atomic64_init(rte_atomic64_t *v)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, 0);
	}
}

/**
 * Atomically read a 64-bit counter.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @return
 *   The value of the counter.
 */
static inline int64_t
rte_atomic64_read(rte_atomic64_t *v)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		/* replace the value by itself */
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, tmp);
	}
	return tmp;
}

/**
 * Atomically set a 64-bit counter.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @param new_value
 *   The new value of the counter.
 */
static inline void
rte_atomic64_set(rte_atomic64_t *v, int64_t new_value)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, new_value);
	}
}

/**
 * Atomically add a 64-bit value to a counter.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @param inc
 *   The value to be added to the counter.
 */
static inline void
rte_atomic64_add(rte_atomic64_t *v, int64_t inc)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, tmp + inc);
	}
}

/**
 * Atomically subtract a 64-bit value from a counter.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @param dec
 *   The value to be substracted from the counter.
 */
static inline void
rte_atomic64_sub(rte_atomic64_t *v, int64_t dec)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, tmp - dec);
	}
}

/**
 * Atomically increment a 64-bit counter by one and test.
 *
 * @param v
 *   A pointer to the atomic counter.
 */
static inline void
rte_atomic64_inc(rte_atomic64_t *v)
{
	rte_atomic64_add(v, 1);
}

/**
 * Atomically decrement a 64-bit counter by one and test.
 *
 * @param v
 *   A pointer to the atomic counter.
 */
static inline void
rte_atomic64_dec(rte_atomic64_t *v)
{
	rte_atomic64_sub(v, 1);
}

/**
 * Add a 64-bit value to an atomic counter and return the result.
 *
 * Atomically adds the 64-bit value (inc) to the atomic counter (v) and
 * returns the value of v after the addition.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @param inc
 *   The value to be added to the counter.
 * @return
 *   The value of v after the addition.
 */
static inline int64_t
rte_atomic64_add_return(rte_atomic64_t *v, int64_t inc)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, tmp + inc);
	}

	return tmp + inc;
}

/**
 * Subtract a 64-bit value from an atomic counter and return the result.
 *
 * Atomically subtracts the 64-bit value (dec) from the atomic counter (v)
 * and returns the value of v after the substraction.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @param dec
 *   The value to be substracted from the counter.
 * @return
 *   The value of v after the substraction.
 */
static inline int64_t
rte_atomic64_sub_return(rte_atomic64_t *v, int64_t dec)
{
	int success = 0;
	uint64_t tmp;

	while (success == 0) {
		tmp = v->cnt;
		success = rte_atomic64_cmpset((volatile uint64_t *)&v->cnt,
		                              tmp, tmp - dec);
	}

	return tmp - dec;
}

/**
 * Atomically increment a 64-bit counter by one and test.
 *
 * Atomically increments the atomic counter (v) by one and returns
 * true if the result is 0, or false in all other cases.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @return
 *   True if the result after the addition is 0; false otherwise.
 */
static inline int rte_atomic64_inc_and_test(rte_atomic64_t *v)
{
	return rte_atomic64_add_return(v, 1) == 0;
}

/**
 * Atomically decrement a 64-bit counter by one and test.
 *
 * Atomically decrements the atomic counter (v) by one and returns true if
 * the result is 0, or false in all other cases.
 *
 * @param v
 *   A pointer to the atomic counter.
 * @return
 *   True if the result after substraction is 0; false otherwise.
 */
static inline int rte_atomic64_dec_and_test(rte_atomic64_t *v)
{
	return rte_atomic64_sub_return(v, 1) == 0;
}

/**
 * Atomically test and set a 64-bit atomic counter.
 *
 * If the counter value is already set, return 0 (failed). Otherwise, set
 * the counter value to 1 and return 1 (success).
 *
 * @param v
 *   A pointer to the atomic counter.
 * @return
 *   0 if failed; else 1, success.
 */
static inline int rte_atomic64_test_and_set(rte_atomic64_t *v)
{
	return rte_atomic64_cmpset((volatile uint64_t *)&v->cnt, 0, 1);
}

/**
 * Atomically set a 64-bit counter to 0.
 *
 * @param v
 *   A pointer to the atomic counter.
 */
static inline void rte_atomic64_clear(rte_atomic64_t *v)
{
	rte_atomic64_set(v, 0);
}

#endif /* _RTE_I686_ATOMIC_H_ */