berlin_tools/bootloader/customization/as370/FASTLOGO/source/vpp/framequeue.c

/*
 * Copyright (C) 2018 Synaptics Incorporated. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * INFORMATION CONTAINED IN THIS DOCUMENT IS PROVIDED "AS-IS," AND
 * SYNAPTICS EXPRESSLY DISCLAIMS ALL EXPRESS AND IMPLIED WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE, AND ANY WARRANTIES OF NON-INFRINGEMENT OF ANY
 * INTELLECTUAL PROPERTY RIGHTS. IN NO EVENT SHALL SYNAPTICS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, PUNITIVE, OR
 * CONSEQUENTIAL DAMAGES ARISING OUT OF OR IN CONNECTION WITH THE USE
 * OF THE INFORMATION CONTAINED IN THIS DOCUMENT, HOWEVER CAUSED AND
 * BASED ON ANY THEORY OF LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, AND EVEN IF SYNAPTICS WAS
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. IF A TRIBUNAL OF
 * COMPETENT JURISDICTION DOES NOT PERMIT THE DISCLAIMER OF DIRECT
 * DAMAGES OR ANY OTHER DAMAGES, SYNAPTICS' TOTAL CUMULATIVE LIABILITY
 * TO ANY PARTY SHALL NOT EXCEED ONE HUNDRED U.S. DOLLARS.
 */

#define _FRAMEQUEUE_C_

#include "common.h"
#include "framequeue.h"
#include "util.h"

#define WRAPAROUND(a) (((a) >= MAX_NUM_FRAMES) ? 0:(a))

/******************************************************************************
 * FUNCTION: reset frame queue to be empty state
 * PARAMS: *frmq - pionter to a frame queue
 *
 ******************************************************************************/
void frmq_reset(FRAMEQUEUE *frmq)
{
    /* reset read/write pointer of frame queue */
    /* the frame queue is empty when read pointer equals write pointer */
    frmq->shadow_head = 0;
    frmq->head = 0;
    frmq->tail = 0;

    /* reset frame pointers to NULL in frame queue */
    UtilMemSet(frmq->frame_descrs, 0, sizeof(void *)*MAX_NUM_FRAMES);

    return;
}


/******************************************************************************
 * FUNCTION: push a frame descriptor into frame queue
 * PARAMS: *frmq - pointer to frame queue
 *         *frm_descr - pointer to a frame descriptor
 * RETURN: 1 - succeed
 *         0 - fail: frame queue is full
 ******************************************************************************/
int frmq_push(FRAMEQUEUE *frmq, void *frm_descr)
{
    /* first check whether frame queue is full */
    if (WRAPAROUND(frmq->tail+1) == frmq->head)
        return 0;

    /* push frame descriptor into frame queue if not full */
    frmq->frame_descrs[frmq->tail] = frm_descr;

    /* update shadow write pointer */
    frmq->tail = WRAPAROUND(frmq->tail+1);

    return 1;
}

/******************************************************************************
 * FUNCTION: pop a frame descriptor out of a frame queue
 *           but actually without update head pointer.
 * PARAMS: *frmq - pointer to a frame queue
 *         **frm_descr - pointer to the frame descriptor
 * RETURN: 1 - succeed
 *         0 - command queue is empty, no command is available
 * NOTE: use pop_commit to actually update head pointer.
 ******************************************************************************/
int frmq_pop(FRAMEQUEUE *frmq, void **frm_descr)
{
    /* first check whether frame queue is empty */
    if (frmq->head == frmq->tail)
        return 0;

    /* pop a frame descriptor from frame queue if not empty */
    *frm_descr = frmq->frame_descrs[frmq->head];

    /* update shadow read pointer */
    frmq->shadow_head = WRAPAROUND(frmq->head+1);

    return 1;
}

/******************************************************************************
 * FUNCTION: commit previous pop operation
 *           by actually update head pointer.
 * PARAMS: *frmq - pointer to a frame queue
 * RETURN: 1 - succeed
 *         0 - command queue is empty, no command is available
 ******************************************************************************/
int frmq_pop_commit(FRAMEQUEUE *frmq)
{
    /* update shadow read pointer */
    frmq->head = frmq->shadow_head;

    return 1;
}