firmware/heardlist.c at master · PolaricTracker/firmware · GitHub

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/*
 * Heard list for digipeater
 */

#include "kernel/kernel.h"
#include "kernel/stream.h"
#include "defines.h"
#include "config.h"
#include "digipeater.h"


 typedef struct _hitem {
      uint16_t val;
      uint16_t ts;
 } HItem;

 HItem hlist[HEARDLIST_SIZE];
 uint8_t hlist_next = 0;
 uint8_t hlist_length = 0;
 uint16_t time = 0;


/*****************************************************************
 * Must be called periodically with a fixed and known interval
 * It goes through list and removes entries that are older than
 * HEARDLIST_MAX_AGE (in ticks)
 *****************************************************************/

 void hlist_tick()
 {
    time++;
    uint8_t i = hlist_next - hlist_length;
    if (i<0)
        i = HEARDLIST_SIZE-i;

    while (i != hlist_next) {
       if (hlist[i].ts < time - HEARDLIST_MAX_AGE)
          hlist_length--;
       else
          break;
       i = (i+1) % HEARDLIST_SIZE;
    }
 }


 /**************************************************************
  * return true if x exists in list
  **************************************************************/

 bool hlist_exists(uint16_t x)
 {
   uint8_t i = hlist_next - hlist_length;
   if (i<0)
     i = HEARDLIST_SIZE-i;

   while (i != hlist_next) {
     if (hlist[i].val == x)
        return true;
     i = (i+1) % HEARDLIST_SIZE;
   }
   return false;
 }


 /*************************************************
  * Add an entry to the list
  *************************************************/
 void hlist_add(uint16_t x)
 {
   hlist[hlist_next].val = x;
   hlist[hlist_next].ts = time;
   hlist_next = (hlist_next + 1) % HEARDLIST_SIZE;
   if (hlist_length < HEARDLIST_SIZE)
     hlist_length++;
 }