nuttx-apps/graphics/ft80x/ft80x_ramdl.c

/****************************************************************************
 * apps/graphics/ft80x/ft80x_ramdl.c
 *
 *   Copyright (C) 2018 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name NuttX 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/ioctl.h>
#include <stdint.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>

#include <nuttx/lcd/ft80x.h>

#include "graphics/ft80x.h"
#include "ft80x.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: ft80x_ramdl_rewind
 *
 * Description:
 *   Reset to the start of RAM DL memory
 *
 * Input Parameters:
 *   fd - The file descriptor of the FT80x device.  Opened by the caller
 *        with write access.
 *
 * Returned Value:
 *   Zero (OK) on success.  A negated errno value on failure.
 *
 ****************************************************************************/

int ft80x_ramdl_rewind(int fd)
{
  off_t pos;

  /* Reposition the VFSso that subsequent writes will be to the beginning of
   * the hardware display list.
   */

  pos = lseek(fd, 0, SEEK_SET);
  if (pos < 0)
    {
      int errcode = errno;
      ft80x_err("ERROR: lseek failed: %d\n", errcode);
      return -errcode;
    }

  return OK;
}

/****************************************************************************
 * Name: ft80x_ramdl_append
 *
 * Description:
 *   Append new display list data to RAM DL
 *
 * Input Parameters:
 *   fd     - The file descriptor of the FT80x device.  Opened by the caller
 *            with write access.
 *   data   - A pointer to the start of the data to be written.
 *   len    - The number of bytes to be written.
 *
 * Returned Value:
 *   Zero (OK) on success.  A negated errno value on failure.
 *
 ****************************************************************************/

int ft80x_ramdl_append(int fd, FAR const void *data, size_t len)
{
  size_t nwritten;

  DEBUGASSERT(data != NULL && ((uintptr_t)data & 3) == 0 &&
              len > 0 && (len & 3) == 0);

  /* Write the aligned data directly to the FT80x hardware display list.
   *
   * NOTE:  We have inside knowledge that the write will complete in a
   * single operation so that no piecewise writes will ever be necessary.
   */

  nwritten = write(fd, data, len);
  if (nwritten < 0)
    {
      int errcode = errno;
      ft80x_err("ERROR: write failed: %d\n", errcode);
      return -errcode;
    }

  DEBUGASSERT(nwritten == len);
  return OK;
}