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/*-
 *   BSD LICENSE
 * 
 *   Copyright(c) 2010-2012 Intel Corporation. All rights reserved.
 *   All rights reserved.
 * 
 *   Redistribution and use in source and binary forms, with or without 
 *   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 
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */

#ifndef _RTE_LPM_H_
#define _RTE_LPM_H_

/**
 * @file
 * RTE Longest Prefix Match (LPM)
 */

#include <errno.h>
#include <sys/queue.h>
#include <stdint.h>
#include <stdlib.h>
#include <rte_branch_prediction.h>
#include <rte_memory.h>

#ifdef __cplusplus
extern "C" {
#endif

/** Max number of characters in LPM name. */
#define RTE_LPM_NAMESIZE	32

/** Possible location to allocate memory. */
#define RTE_LPM_HEAP	0

/** Possible location to allocate memory. */
#define RTE_LPM_MEMZONE	1

/** Maximum depth value possible for IPv4 LPM. */
#define RTE_LPM_MAX_DEPTH 32

/** Total number of tbl24 entries. */
#define RTE_LPM_TBL24_NUM_ENTRIES (1 << 24)

/** Number of entries in a tbl8 group. */
#define RTE_LPM_TBL8_GROUP_NUM_ENTRIES 256

/** Total number of tbl8 groups in the tbl8. */
#define RTE_LPM_TBL8_NUM_GROUPS 256

/** Total number of tbl8 entries. */
#define RTE_LPM_TBL8_NUM_ENTRIES (RTE_LPM_TBL8_NUM_GROUPS *                   \
					RTE_LPM_TBL8_GROUP_NUM_ENTRIES)

/** Macro to enable/disable run-time checks. */
#if defined(RTE_LIBRTE_LPM_DEBUG)
#define RTE_LPM_RETURN_IF_TRUE(cond, retval) do {                             \
	if (cond) return (retval);                                            \
} while (0)
#else
#define RTE_LPM_RETURN_IF_TRUE(cond, retval)
#endif

/** Tbl24 entry structure. */
struct rte_lpm_tbl24_entry {
	/* Using single uint8_t to store 3 values. */
	uint8_t valid     :1; /**< Validation flag. */
	uint8_t ext_entry :1; /**< External entry. */
	uint8_t depth     :6; /**< Rule depth. */
	/* Stores Next hop or group index (i.e. gindex)into tbl8. */
	union {
		uint8_t next_hop;
		uint8_t tbl8_gindex;
	};
};

/** Tbl8 entry structure. */
struct rte_lpm_tbl8_entry {
	/* Using single uint8_t to store 3 values. */
	uint8_t valid       :1; /**< Validation flag. */
	uint8_t valid_group :1; /**< Group validation flag. */
	uint8_t depth       :6; /**< Rule depth. */
	uint8_t next_hop; /**< next hop. */
};

/** Rule structure. */
struct rte_lpm_rule {
	uint32_t ip; /**< Rule IP address. */
	uint8_t  next_hop; /**< Rule next hop. */
};

/** LPM structure. */
struct rte_lpm {
	TAILQ_ENTRY(rte_lpm) next;      /**< Next in list. */

	/* LPM metadata. */
	char name[RTE_LPM_NAMESIZE];        /**< Name of the lpm. */
	int mem_location; /**< Location of memory to be allocated. */
	uint32_t max_rules_per_depth; /**< Max. balanced rules per lpm. */
	uint32_t used_rules_at_depth[RTE_LPM_MAX_DEPTH]; /**< Rules / depth. */

	/* LPM Tables. */
	struct rte_lpm_tbl24_entry tbl24[RTE_LPM_TBL24_NUM_ENTRIES] \
			__rte_cache_aligned; /**< LPM tbl24 table. */
	struct rte_lpm_tbl8_entry tbl8[RTE_LPM_TBL8_NUM_ENTRIES] \
			__rte_cache_aligned; /**< LPM tbl8 table. */
	struct rte_lpm_rule rules_tbl[0] \
			__rte_cache_aligned; /**< LPM rules. */
};

/**
 * Create an LPM object.
 *
 * @param name
 *   LPM object name
 * @param socket_id
 *   NUMA socket ID for LPM table memory allocation
 * @param max_rules
 *   Maximum number of LPM rules that can be added
 * @param mem_location
 *   Location of memory to be allocated. Can only be RTE_LPM_HEAP or
 *   RTE_LPM_MEMZONE
 * @return
 *   Handle to LPM object on success, NULL otherwise with rte_errno set
 *   to an appropriate values. Possible rte_errno values include:
 *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 *    - E_RTE_SECONDARY - function was called from a secondary process instance
 *    - E_RTE_NO_TAILQ - no tailq list could be got for the lpm object list
 *    - EINVAL - invalid parameter passed to function
 *    - ENOSPC - the maximum number of memzones has already been allocated
 *    - EEXIST - a memzone with the same name already exists
 *    - ENOMEM - no appropriate memory area found in which to create memzone
 */
struct rte_lpm *
rte_lpm_create(const char *name, int socket_id, int max_rules,
		int mem_location);

/**
 * Find an existing LPM object and return a pointer to it.
 *
 * @param name
 *   Name of the lpm object as passed to rte_lpm_create()
 * @return
 *   Pointer to lpm object or NULL if object not found with rte_errno
 *   set appropriately. Possible rte_errno values include:
 *    - ENOENT - required entry not available to return.
 */
struct rte_lpm *
rte_lpm_find_existing(const char *name);

/**
 * Free an LPM object.
 *
 * @param lpm
 *   LPM object handle
 * @return
 *   None
 */
void
rte_lpm_free(struct rte_lpm *lpm);

/**
 * Add a rule to the LPM table.
 *
 * @param lpm
 *   LPM object handle
 * @param ip
 *   IP of the rule to be added to the LPM table
 * @param depth
 *   Depth of the rule to be added to the LPM table
 * @param next_hop
 *   Next hop of the rule to be added to the LPM table
 * @return
 *   0 on success, negative value otherwise
 */
int
rte_lpm_add(struct rte_lpm *lpm, uint32_t ip, uint8_t depth, uint8_t next_hop);

/**
 * Delete a rule from the LPM table.
 *
 * @param lpm
 *   LPM object handle
 * @param ip
 *   IP of the rule to be deleted from the LPM table
 * @param depth
 *   Depth of the rule to be deleted from the LPM table
 * @return
 *   0 on success, negative value otherwise
 */
int
rte_lpm_delete(struct rte_lpm *lpm, uint32_t ip, uint8_t depth);

/**
 * Delete all rules from the LPM table.
 *
 * @param lpm
 *   LPM object handle
 */
void
rte_lpm_delete_all(struct rte_lpm *lpm);

/**
 * Lookup an IP into the LPM table.
 *
 * @param lpm
 *   LPM object handle
 * @param ip
 *   IP to be looked up in the LPM table
 * @param next_hop
 *   Next hop of the most specific rule found for IP (valid on lookup hit only)
 * @return
 *   -EINVAL for incorrect arguments, -ENOENT on lookup miss, 0 on lookup hit
 */
static inline int
rte_lpm_lookup(struct rte_lpm *lpm, uint32_t ip, uint8_t *next_hop)
{
	uint32_t tbl24_index, tbl8_group_index, tbl8_index;

	/* DEBUG: Check user input arguments. */
	RTE_LPM_RETURN_IF_TRUE(((lpm == NULL) || (next_hop == NULL)), -EINVAL);

	/* Calculate index into tbl24. */
	tbl24_index = (ip >> 8);

	/*
	 * Use the tbl24_index to access the required tbl24 entry then check if
	 * the tbl24 entry is INVALID, if so return -ENOENT.
	 */
	if (!lpm->tbl24[tbl24_index].valid){
		return -ENOENT; /* Lookup miss. */
	}
	/*
	 * If tbl24 entry is valid check if it is NOT extended (i.e. it does
	 * not use a tbl8 extension) if so return the next hop.
	 */
	if (likely(lpm->tbl24[tbl24_index].ext_entry == 0)) {
		*next_hop = lpm->tbl24[tbl24_index].next_hop;
		return 0; /* Lookup hit. */
	}

	/*
	 * If tbl24 entry is valid and extended calculate the index into the
	 * tbl8 entry.
	 */
	tbl8_group_index = lpm->tbl24[tbl24_index].tbl8_gindex;
	tbl8_index = (tbl8_group_index * RTE_LPM_TBL8_GROUP_NUM_ENTRIES) +
			(ip & 0xFF);

	/* Check if the tbl8 entry is invalid and if so return -ENOENT. */
	if (!lpm->tbl8[tbl8_index].valid)
		return -ENOENT;/* Lookup miss. */

	/* If the tbl8 entry is valid return return the next_hop. */
	*next_hop = lpm->tbl8[tbl8_index].next_hop;
	return 0; /* Lookup hit. */
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_LPM_H_ */