src_frescan/frescan_packets.c

   1 /*!
   2  * @file frescan_packets.h
   3  *
   4  * @brief FRESCAN packets definition and pool
   5  *
   6  * @version 0.01
   7  *
   8  * @date 27-Feb-2008
   9  *
  10  * @author
  11  *      Daniel Sangorrin
  12  *
  13  * @comments
  14  *
  15  * This file contains the FRESCAN packets definition and functions to
  16  * allocate and free them from a global pool of packets statically
  17  * preallocated.
  18  *
  19  * @license
  20  *
  21  * See MaRTE OS license
  22  *
  23  */
  24
  25 #include "frescan_packets.h"
  26 #include "frescan_debug.h"
  27 #include "frescan_config.h"
  28 #include <misc/freelist.h>
  29
  30 /**
  31  * the_packet_pool - pool of frescan packets
  32  *
  33  * Like in the CAN driver, in FRESCAN we have a statically preallocated pool
  34  * of packets that we will manage through a freelist in O(1) time.
  35  */
  36
  37 static frescan_packet_t the_packet_pool[FRESCAN_MX_PACKETS];
  38 static freelist_t the_packet_pool_freelist;
  39
  40 #ifdef FRESCAN_PACKETPOOL_ENABLE_DEBUG
  41         static int allocated_total = 0;
  42 #endif
  43
  44 /**
  45  * frescan_packets_init
  46  *
  47  * Initializes a pool of packets that will be managed internally
  48  * TODO: initalization flag
  49  */
  50
  51 int frescan_packets_init() {
  52         DEBUG(FRESCAN_PACKETPOOL_ENABLE_DEBUG, "initialize freelist\n");
  53         return freelist_init(&the_packet_pool_freelist, FRESCAN_MX_PACKETS);
  54 }
  55
  56 /**
  57  * frescan_packets_alloc
  58  *
  59  * Allocates a frame from the pool of packets. On error it returns NULL
  60  */
  61
  62 frescan_packet_t *frescan_packets_alloc() {
  63         int pos;
  64
  65         pos = freelist_alloc(&the_packet_pool_freelist);
  66         if (pos == -1) {
  67                 ERROR("could not allocate packet\n");
  68                 return NULL;
  69         }
  70
  71 #ifdef FRESCAN_PACKETPOOL_ENABLE_DEBUG
  72         allocated_total++;
  73 #endif
  74
  75         DEBUG(FRESCAN_PACKETPOOL_ENABLE_DEBUG,
  76               "allocating packet, pos:%d, total:%d\n", pos, allocated_total);
  77
  78         the_packet_pool[pos].pool_pos = pos; // to know how to free it
  79         return &the_packet_pool[pos];
  80 }
  81
  82 /**
  83  * frescan_packets_free
  84  *
  85  * Frees a frame and returns it to the pool of packets.
  86  */
  87
  88 int frescan_packets_free(frescan_packet_t *packet)
  89 {
  90 #ifdef FRESCAN_PACKETPOOL_ENABLE_DEBUG
  91         allocated_total--;
  92 #endif
  93         DEBUG(FRESCAN_PACKETPOOL_ENABLE_DEBUG,
  94               "freeing packet, pos:%d, total:%d\n",
  95               packet->pool_pos, allocated_total);
  96
  97         return freelist_free(&the_packet_pool_freelist, packet->pool_pos);
  98 }