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/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
* University Research and Technology
* Corporation. All rights reserved.
* Copyright (c) 2004-2007 The University of Tennessee and The University
* of Tennessee Research Foundation. All rights
* reserved.
* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 2010 Cisco Systems, Inc. All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "opal_config.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include "opal/class/opal_ring_buffer.h"
#include "opal/constants.h"
#include "opal/util/output.h"
static void opal_ring_buffer_construct(opal_ring_buffer_t *);
static void opal_ring_buffer_destruct(opal_ring_buffer_t *);
OBJ_CLASS_INSTANCE(opal_ring_buffer_t, opal_object_t, opal_ring_buffer_construct,
opal_ring_buffer_destruct);
/*
* opal_ring_buffer constructor
*/
static void opal_ring_buffer_construct(opal_ring_buffer_t *ring)
{
OBJ_CONSTRUCT(&ring->lock, opal_mutex_t);
OBJ_CONSTRUCT(&ring->cond, opal_condition_t);
ring->in_use = false;
ring->head = 0;
ring->tail = -1;
ring->size = 0;
ring->addr = NULL;
}
/*
* opal_ring_buffer destructor
*/
static void opal_ring_buffer_destruct(opal_ring_buffer_t *ring)
{
if (NULL != ring->addr) {
free(ring->addr);
ring->addr = NULL;
}
ring->size = 0;
OBJ_DESTRUCT(&ring->lock);
OBJ_DESTRUCT(&ring->cond);
}
/**
* initialize a ring object
*/
int opal_ring_buffer_init(opal_ring_buffer_t *ring, int size)
{
/* check for errors */
if (NULL == ring) {
return OPAL_ERR_BAD_PARAM;
}
/* Allocate and set the ring to NULL */
ring->addr = (char **) calloc(size * sizeof(char *), 1);
if (NULL == ring->addr) { /* out of memory */
return OPAL_ERR_OUT_OF_RESOURCE;
}
ring->size = size;
return OPAL_SUCCESS;
}
void *opal_ring_buffer_push(opal_ring_buffer_t *ring, void *ptr)
{
char *p = NULL;
OPAL_ACQUIRE_THREAD(&(ring->lock), &(ring->cond), &(ring->in_use));
if (NULL != ring->addr[ring->head]) {
p = (char *) ring->addr[ring->head];
if (ring->tail == ring->size - 1) {
ring->tail = 0;
} else {
ring->tail = ring->head + 1;
}
}
ring->addr[ring->head] = (char *) ptr;
if (ring->tail < 0) {
ring->tail = ring->head;
}
if (ring->head == ring->size - 1) {
ring->head = 0;
} else {
ring->head++;
}
OPAL_RELEASE_THREAD(&(ring->lock), &(ring->cond), &(ring->in_use));
return (void *) p;
}
void *opal_ring_buffer_pop(opal_ring_buffer_t *ring)
{
char *p = NULL;
OPAL_ACQUIRE_THREAD(&(ring->lock), &(ring->cond), &(ring->in_use));
if (-1 == ring->tail) {
/* nothing has been put on the ring yet */
p = NULL;
} else {
p = (char *) ring->addr[ring->tail];
ring->addr[ring->tail] = NULL;
if (ring->tail == ring->size - 1) {
ring->tail = 0;
} else {
ring->tail++;
}
/* see if the ring is empty */
if (ring->tail == ring->head) {
ring->tail = -1;
}
}
OPAL_RELEASE_THREAD(&(ring->lock), &(ring->cond), &(ring->in_use));
return (void *) p;
}
void *opal_ring_buffer_poke(opal_ring_buffer_t *ring, int i)
{
char *p = NULL;
int offset;
OPAL_ACQUIRE_THREAD(&(ring->lock), &(ring->cond), &(ring->in_use));
if (ring->size <= i || -1 == ring->tail) {
p = NULL;
} else if (i < 0) {
/* return the value at the head of the ring */
if (ring->head == 0) {
p = ring->addr[ring->size - 1];
} else {
p = ring->addr[ring->head - 1];
}
} else {
/* calculate the offset of the tail in the ring */
offset = ring->tail + i;
/* correct for wrap-around */
if (ring->size <= offset) {
offset -= ring->size;
}
p = ring->addr[offset];
}
OPAL_RELEASE_THREAD(&(ring->lock), &(ring->cond), &(ring->in_use));
return (void *) p;
}
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