text: /****************************************************************************
   *
   * Copyright (c) 2015 Vijay Venkatraman. All rights reserved.
   *
   * 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 PX4 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.
   *
   ****************************************************************************/
  
  #include <px4_defines.h>
  #include <px4_posix.h>
  #include <string.h>
  #include <stdbool.h>
  #include <stdlib.h>
  #include <fcntl.h>
  #include <unistd.h>
  #include <systemlib/err.h>
  #include <errno.h>
  #include <semaphore.h>
  
  #include <sys/stat.h>
  
  #include <drivers/drv_hrt.h>
  #include <sys/mman.h>
  #include <sys/ioctl.h>
  
  #include "systemlib/param/param.h"
  
  #include <shmem.h>
  #include "px4muorb.h"
  
  //#define SHMEM_DEBUG
  void update_to_shmem(param_t param, union param_value_u value);
  int update_from_shmem(param_t param, union param_value_u *value);
  void update_index_from_shmem(void);
  uint64_t update_from_shmem_prev_time = 0, update_from_shmem_current_time = 0;
  extern unsigned char *adsp_changed_index;
  
  struct param_wbuf_s {
  	param_t param;
  	union param_value_u val;
  	bool unsaved;
  };
  
  /*update value and param's change bit in shared memory*/
  void update_to_shmem(param_t param, union param_value_u value)
  {
  	if (px4muorb_param_update_to_shmem(param, (unsigned char *) &value,
  					   sizeof(value))) {
  		PX4_ERR("krait update param %u failed", param);
  	}
  }
  
  void update_index_from_shmem(void)
  {
  	if (!adsp_changed_index) {
  		PX4_ERR("%s no param buffer", __FUNCTION__);
  		return;
  	}
  
  	px4muorb_param_update_index_from_shmem(adsp_changed_index,
  					       PARAM_BUFFER_SIZE);
  }
  
  static void update_value_from_shmem(param_t param, union param_value_u *value)
  {
  	if (px4muorb_param_update_value_from_shmem(param, (unsigned char *) value,
  			sizeof(union param_value_u))) {
  		PX4_ERR("%s get param failed", __FUNCTION__);
  	}
  }
  
  int update_from_shmem(param_t param, union param_value_u *value)
  {
  	unsigned int byte_changed, bit_changed;
  	unsigned int retval = 0;
  
  	if (!adsp_changed_index) {
  		PX4_ERR("%s no param buffer", __FUNCTION__);
  		return 0;
  	}
  
  	update_from_shmem_current_time = hrt_absolute_time();
  
  	if ((update_from_shmem_current_time - update_from_shmem_prev_time)
  	    > 1000000) { //update every 1 second
  		update_from_shmem_prev_time = update_from_shmem_current_time;
  		update_index_from_shmem();
  	}
  
  	byte_changed = param / 8;
  	bit_changed = 1 << param % 8;
  
  	if (adsp_changed_index[byte_changed] & bit_changed) {
  		update_value_from_shmem(param, value);
  		adsp_changed_index[byte_changed] &= ~bit_changed; //clear the bit
  		retval = 1;
  	}
  
  	//else {PX4_INFO("no change to param %s", param_name(param));}
  
  	PX4_DEBUG("%s %d bit on adsp index[%d]",
  		  (retval) ? "cleared" : "unchanged", bit_changed, byte_changed);
  
  	return retval;
  }
  
  