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/*
* Copyright (c) 2021 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* \file ring.h
* \brief Fixed-size pool allocator.
*/
#ifndef UTIL_RING_H
#define UTIL_RING_H
#include <assert.h>
#include <stdint.h>
#include <string.h>
#include <sys/param.h> // MIN
#include <sys/types.h>
#include <stdio.h> // XXX debug
#include "../common.h"
/******************************************************************************/
/* Ring header */
typedef struct
{
size_t roff;
size_t woff;
size_t size;
size_t max_size;
} ring_hdr_t;
/* Make sure elements following the header are aligned */
#define RING_HDRLEN SIZEOF_ALIGNED (ring_hdr_t)
/* This header actually prepends the actual content of the vector */
#define ring_hdr(ring) ((ring_hdr_t *) ((uint8_t *) ring - RING_HDRLEN))
/******************************************************************************/
/* Helpers */
/** Local variable naming macro. */
#define _ring_var(v) _ring_##v
/**
* @brief Allocate and initialize a ring data structure (helper function).
*
* @param[in,out] ring_ptr Ring buffer to allocate and initialize.
* @param[in] elt_size Size of a ring element.
* @param[in] max_size Maximum vector size (O = unlimited).
*/
void _ring_init (void **ring_ptr, size_t elt_size, size_t max_size);
/**
* @brief Free a ring data structure.
*
* @param ring_ptr[in] Pointer to the ring data structure to free.
*/
void _ring_free (void **ring_ptr);
static inline int
_ring_add (void **ring_ptr, size_t elt_size, void *eltp)
{
assert (*ring_ptr);
ring_hdr_t *rh = ring_hdr (*ring_ptr);
/* We always write ! */
memcpy ((uint8_t *) *ring_ptr + rh->woff * elt_size, eltp, elt_size);
rh->woff++;
if (rh->woff == rh->max_size)
rh->woff = 0;
if (rh->size < rh->max_size)
{
rh->size++;
}
else
{
/* One packet was dropped */
rh->roff++;
if (rh->roff == rh->max_size)
rh->roff = 0;
}
return 0;
}
static inline unsigned
_ring_get_fullness (void **ring_ptr)
{
assert (*ring_ptr);
ring_hdr_t *rh = ring_hdr (*ring_ptr);
return (unsigned int) (rh->size * 100 / rh->max_size);
}
static inline unsigned
_ring_is_full (void **ring_ptr)
{
assert (*ring_ptr);
ring_hdr_t *rh = ring_hdr (*ring_ptr);
return rh->size == rh->max_size;
}
static inline size_t
_ring_get_size (void **ring_ptr)
{
assert (*ring_ptr);
ring_hdr_t *rh = ring_hdr (*ring_ptr);
return rh->size;
}
static inline int
_ring_advance (void **ring_ptr, unsigned n)
{
assert (*ring_ptr);
ring_hdr_t *rh = ring_hdr (*ring_ptr);
assert (n <= rh->size);
rh->roff += n;
rh->size -= n;
while (rh->roff >= rh->max_size)
rh->roff -= rh->max_size;
return 0;
}
static inline int
_ring_get (void **ring_ptr, size_t elt_size, unsigned i, void *eltp)
{
assert (*ring_ptr);
ring_hdr_t *rh = ring_hdr (*ring_ptr);
assert (i <= rh->size);
size_t pos = rh->roff + i;
if (pos >= rh->max_size)
pos -= rh->max_size;
memcpy (eltp, (uint8_t *) *ring_ptr + pos * elt_size, elt_size);
return 0;
}
/******************************************************************************/
/* Public API */
/**
* @brief Allocate and initialize a ring data structure.
*
* @param[in,out] ring Ring to allocate and initialize.
* @param[in] max_size Maximum ring size (nonzero).
*
* NOTE:
* - Allocated memory is set to 0 (used by bitmap)
*/
#define ring_init(RING, MAX_SIZE) \
_ring_init ((void **) &(RING), sizeof ((RING)[0]), (MAX_SIZE))
#define ring_free(RING) _ring_free ((void **) &(RING))
#define ring_get_fullness(RING) _ring_get_fullness ((void **) &(RING))
#define ring_is_full(RING) _ring_is_full ((void **) &(RING))
#define ring_get_size(RING) _ring_get_size ((void **) &(RING))
#define ring_add(RING, ELT) \
_ring_add ((void **) &(RING), sizeof (RING[0]), ELT)
#define ring_add_value(RING, VALUE) \
do \
{ \
typeof (VALUE) _ring_var (v) = VALUE; \
_ring_add ((void **) &(RING), sizeof (RING[0]), &_ring_var (v)); \
} \
while (0)
#define ring_advance(RING, N) _ring_advance ((void **) &(RING), (N))
#define ring_get(RING, I, ELTP) \
_ring_get ((void **) &RING, sizeof (RING[0]), (I), (ELTP))
/**
* @brief Helper function used by ring_foreach().
*/
#define ring_enumerate_n(RING, I, ELTP, COUNT, BODY) \
({ \
for ((I) = 0; (I) < MIN (ring_get_size (RING), (COUNT)); (I)++) \
{ \
ring_get ((RING), (I), (ELTP)); \
{ \
BODY; \
} \
} \
})
#define ring_enumerate(ring, i, eltp, BODY) \
ring_enumerate_n ((ring), (i), (eltp), 1, (BODY))
/**
* @brief Iterate over elements in a ring.
*
* @param[in] pool The ring data structure to iterate over
* @param[in, out] eltp A pointer to the element that will be used for
* iteration
* @param[in] BODY Block to execute during iteration
*
* @note Iteration will execute BODY with eltp corresponding successively to
* all elements found in the ring. It is implemented using the more generic
* enumeration function.
*/
#define ring_foreach_n(ring, eltp, count, BODY) \
({ \
unsigned _ring_var (i); \
ring_enumerate_n ((ring), _ring_var (i), (eltp), (count), BODY); \
})
#define ring_foreach(ring, eltp, BODY) \
ring_foreach_n ((ring), (eltp), 1, (BODY))
#endif /* UTIL_RING_H */
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