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 <string.h>
  #include <stdbool.h>
  #include <stdlib.h>
  #include <fcntl.h>
  #include <unistd.h>
  #include <errno.h>
  #include <sys/stat.h>
  #include <atomic_ops.h>
  
  #include "systemlib/param/param.h"
  
  #include <shmem.h>
  #include <drivers/drv_hrt.h>
  
  //#define SHMEM_DEBUG
  //#define PARAM_LOCK_DEBUG
  
  int mem_fd;
  unsigned char *map_base, *virt_addr;
  struct shmem_info *shmem_info_p;
  static void *map_memory(off_t target);
  int get_shmem_lock(const char *caller_file_name, int caller_line_number);
  void release_shmem_lock(const char *caller_file_name, int caller_line_number);
  void init_shared_memory(void);
  void copy_params_to_shmem(struct param_info_s *);
  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;
  static unsigned char krait_changed_index[MAX_SHMEM_PARAMS / 8 + 1];
  
  // Small helper to get log2 for ints
  static unsigned log2_for_int(unsigned v)
  {
  	unsigned r = 0;
  
  	while (v >>= 1) {
  		++r;
  	}
  
  	return r;
  }
  
  struct param_wbuf_s {
  	param_t param;
  	union param_value_u val;
  	bool unsaved;
  };
  extern struct param_wbuf_s *param_find_changed(param_t param);
  
  static void *map_memory(off_t target)
  {
  
  	return (void *)(target + LOCK_SIZE);
  
  }
  
  int get_shmem_lock(const char *caller_file_name, int caller_line_number)
  {
  	unsigned char *lock = (unsigned char *)(MAP_ADDRESS + LOCK_OFFSET);
  	unsigned int i = 0;
  
  #ifdef PARAM_LOCK_DEBUG
  	PX4_INFO("lock value %d before get from %s, line: %d\n", *(unsigned int *)0xfbfc000, strrchr(caller_file_name, '/'),
  		 caller_line_number);
  #endif
  
  	while (!atomic_compare_and_set(lock, 1, 0)) {
  		i++;
  		usleep(1000);
  
  		if (i > 100) {
  			break;
  		}
  	}
  
  	if (i > 100) {
  		PX4_INFO("Could not get lock, file name: %s, line number: %d.\n",
  			 strrchr(caller_file_name, '/'), caller_line_number);
  		return -1;
  
  	} else {
  		PX4_DEBUG("Lock acquired, file name: %s, line number: %d\n",
  			  caller_file_name, caller_line_number);
  	}
  
  	return 0; //got the lock
  
  }
  
  void release_shmem_lock(const char *caller_file_name, int caller_line_number)
  {
  	unsigned char *lock = (unsigned char *)(MAP_ADDRESS + LOCK_OFFSET);
  
  	*lock = 1;
  
  #ifdef PARAM_LOCK_DEBUG
  	PX4_INFO("release lock, file name: %s, line number: %d.\n",
  		 strrchr(caller_file_name, '/'), caller_line_number);
  #endif
  
  	return;
  }
  
  void init_shared_memory(void)
  {
  	//PX4_INFO("Value at lock address is %d\n", *(unsigned int*)0xfbfc000);
  	int i;
  
  	if (shmem_info_p) {
  		return;
  	}
  
  	virt_addr = map_memory(MAP_ADDRESS);
  	shmem_info_p = (struct shmem_info *) virt_addr;
  
  	//init lock as 1
  	unsigned char *lock = (unsigned char *)(MAP_ADDRESS + LOCK_OFFSET);
  	*lock = 1;
  
  	for (i = 0; i < MAX_SHMEM_PARAMS / 8 + 1; i++) {
  		shmem_info_p->krait_changed_index[i] = 0;
  	}
  
  	//PX4_INFO("adsp memory mapped\n");
  }
  
  void copy_params_to_shmem(struct param_info_s *param_info_base)
  {
  	param_t param;
  	unsigned int i;
  
  	if (get_shmem_lock(__FILE__, __LINE__) != 0) {
  		PX4_INFO("Could not get shmem lock\n");
  		return;
  	}
  
  	//else PX4_INFO("Got lock\n");
  
  	for (param = 0; param < param_count(); param++) {
  		//{PX4_INFO("writing to offset %d\n", (unsigned char*)(shmem_info_p->adsp_params[param].name)-(unsigned char*)shmem_info_p);}
  		struct param_wbuf_s *s = param_find_changed(param);
  
  		if (s == NULL) {
  			shmem_info_p->params_val[param] = param_info_base[param].val;
  		}
  
  		else {
  			shmem_info_p->params_val[param] = s->val;
  		}
  
  #ifdef SHMEM_DEBUG
  
  		if (param_type(param) == PARAM_TYPE_INT32) {
  			PX4_INFO("%d: written %d for param %s to shared mem", param, shmem_info_p->params_val[param].i, param_name(param));
  
  		} else if (param_type(param) == PARAM_TYPE_FLOAT) {
  			PX4_INFO("%d: written %f for param %s to shared mem", param, shmem_info_p->params_val[param].f, param_name(param));
  		}
  
  #endif
  	}
  
  	for (i = 0; i < MAX_SHMEM_PARAMS / 8 + 1; i++) {
  		shmem_info_p->adsp_changed_index[i] = 0;
  		krait_changed_index[i] = 0;
  	}
  
  	release_shmem_lock(__FILE__, __LINE__);
  	//PX4_INFO("Released lock\n");
  
  }
  
  /*update value and param's change bit in shared memory*/
  void update_to_shmem(param_t param, union param_value_u value)
  {
  	unsigned int byte_changed, bit_changed;
  
  	if (!handle_in_range(param)) {
  		return;
  	}
  
  	if (get_shmem_lock(__FILE__, __LINE__) != 0) {
  		PX4_ERR("Could not get shmem lock\n");
  		return;
  	}
  
  	shmem_info_p->params_val[param] = value;
  
  	byte_changed = param / 8;
  	bit_changed = 1 << param % 8;
  	shmem_info_p->adsp_changed_index[byte_changed] |= bit_changed;
  
  	//PX4_INFO("set %d bit on adsp index[%d] to %d\n", bit_changed, byte_changed, shmem_info_p->adsp_changed_index[byte_changed]);
  
  #ifdef SHMEM_DEBUG
  
  	if (param_type(param) == PARAM_TYPE_INT32) {
  		PX4_INFO("Set value %d for param %s to shmem, set adsp index %d:%d\n", value.i, param_name(param), byte_changed,
  			 bit_changed);
  	}
  
  	else if (param_type(param) == PARAM_TYPE_FLOAT) {
  		PX4_INFO("Set value %f for param %s to shmem, set adsp index %d:%d\n", value.f, param_name(param), byte_changed,
  			 bit_changed);
  	}
  
  #endif
  
  	release_shmem_lock(__FILE__, __LINE__);
  
  }
  
  void update_index_from_shmem(void)
  {
  	unsigned int i;
  	param_t params[MAX_SHMEM_PARAMS / 8 + 1];
  
  	if (get_shmem_lock(__FILE__, __LINE__) != 0) {
  		PX4_ERR("Could not get shmem lock\n");
  		return;
  	}
  
  	for (i = 0; i < MAX_SHMEM_PARAMS / 8 + 1; i++) {
  		// Check if any param has been changed.
  		if (krait_changed_index[i] != shmem_info_p->krait_changed_index[i]) {
  
  			// If a param has changed, we need to find out which one.
  			// From the byte and bit that is different, we can resolve the param number.
  			unsigned bit = log2_for_int(
  					       krait_changed_index[i]
  					       ^ shmem_info_p->krait_changed_index[i]);
  			param_t param_to_get = i * 8 + bit;
  
  			// Update our krait_changed_index as well.
  			krait_changed_index[i] = shmem_info_p->krait_changed_index[i];
  			params[i] = param_to_get;
  
  		} else {
  			params[i] = 0xFFFF;
  		}
  	}
  
  	release_shmem_lock(__FILE__, __LINE__);
  
  	// FIXME: this is a hack but it gets the param so that it gets added
  	// to the local list param_values in param_shmem.c.
  	for (i = 0; i < MAX_SHMEM_PARAMS / 8 + 1; i++) {
  		if (params[i] != 0xFFFF) {
  			int32_t dummy;
  			param_get(params[i], &dummy);
  		}
  	}
  }
  
  static void update_value_from_shmem(param_t param, union param_value_u *value)
  {
  	unsigned int byte_changed, bit_changed;
  
  	if (get_shmem_lock(__FILE__, __LINE__) != 0) {
  		PX4_ERR("Could not get shmem lock\n");
  		return;
  	}
  
  	*value = shmem_info_p->params_val[param];
  
  	/*also clear the index since we are holding the lock*/
  	byte_changed = param / 8;
  	bit_changed = 1 << param % 8;
  	shmem_info_p->krait_changed_index[byte_changed] &= ~bit_changed;
  
  	release_shmem_lock(__FILE__, __LINE__);
  
  #ifdef SHMEM_DEBUG
  
  	if (param_type(param) == PARAM_TYPE_INT32) {
  		PX4_INFO("Got value %d for param %s from shmem, cleared krait index %d:%d\n", value->i, param_name(param), byte_changed,
  			 bit_changed);
  	}
  
  	else if (param_type(param) == PARAM_TYPE_FLOAT) {
  		PX4_INFO("Got value %f for param %s from shmem, cleared krait index %d:%d\n", value->f, param_name(param), byte_changed,
  			 bit_changed);
  	}
  
  #endif
  }
  
  int update_from_shmem(param_t param, union param_value_u *value)
  {
  	unsigned int byte_changed, bit_changed;
  	unsigned int retval = 0;
  
  	if (!handle_in_range(param) || value == NULL) {
  		return retval;
  	}
  
  	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 (krait_changed_index[byte_changed] & bit_changed) {
  		update_value_from_shmem(param, value);
  		krait_changed_index[byte_changed] &= ~bit_changed;
  		retval = 1;
  	}
  
  	//else {PX4_INFO("no change to param %s\n", param_name(param));}
  
  	PX4_DEBUG("%s %d bit on krait changed index[%d]\n",
  		  (retval) ? "cleared" : "unchanged", bit_changed, byte_changed);
  
  	return retval;
  }
  
  