Fixed up and made work a PBUF_REF type. Most of the code uses this now

instead of PBUF_ROM. This addition allows support of copy-on-demand where the
lower layers can call pbuf_unref() which tests for any PBUF_REF buffers and
replaces them with PBUF_POOL buffers. This is now used
everywhere. pbuf_unref() is called in ARP queueing and in the coldfire
driver, which puts frames on a DMA queue and frees them later.

Along with this change pbuf_free() now goes through the entire chain of
buffers and tests all the ref counters, not just the first one. Generally now
pbuf_ref_chain() should be called and not pbuf_ref(). This change was made
because it is possible for the head of the pbuf chain to have a different
count than the payload pbuf which might have been passed by the application.

Coldfire ethernet driver also had some minor other updates and STATS was
changed to LWIP_STATS.

ports/coldfire/netif/5272fec.c

@@ -363,7 +363,7 @@ low_level_output(struct netif *netif, struct pbuf *p)
         
     } else {
         /* Increment use count on pbuf */
-        pbuf_ref(p);
+        pbuf_ref_chain(p);
         
         /* Put buffers on descriptor ring, but don't mark them as ready yet */
         tx_insert_eof = tx_insert_sof = mcf5272->tx_insert;
@@ -670,8 +670,8 @@ low_level_init(struct netif *netif)
     
     /* Set the tranceiver interface to MII mode */
     MCF5272_WR_FEC_RCR(imm, 0
-                       | MCF5272_FEC_RCR_MII_MODE);
-    /*  | MCF5272_FEC_RCR_DRT); */      /* half duplex */
+                       | MCF5272_FEC_RCR_MII_MODE
+                       | MCF5272_FEC_RCR_DRT); 	/* half duplex */
 
     /* Only operate in half-duplex, no heart beat control */
     MCF5272_WR_FEC_TCR(imm, 0);

ports/coldfire/proj/lwipopts.h

@@ -183,9 +183,9 @@ a lot of data that needs to be copied, this should be set high. */
 
 
 /* ---------- Statistics options ---------- */
-#define STATS
+#define LWIP_STATS 1
 
-#ifdef STATS
+#ifdef LWIP_STATS
 #define LINK_STATS
 #define IP_STATS
 #define ICMP_STATS

ports/coldfire/sys_arch.c

@@ -62,7 +62,6 @@ static int num_sem = 0;                 // Number of semaphores created
 static int num_mbox = 0;                // Number of mailboxes created
 static int num_thread = 0;              // Number of threads created
 static int num_hisr = 0;                // Number of hisrs created
-static sys_sem_t thread_sem;            // Protect thread structure
 static struct sys_thread *threads = NULL;
 static struct sys_hisr *hisrs = NULL;
 
@@ -78,7 +77,6 @@ static struct sys_hisr *hisrs = NULL;
 void
 sys_init(void)
 {
-    thread_sem = sys_sem_new(1);
     return;
 }
 
@@ -97,18 +95,19 @@ static struct sys_thread *
 introduce_thread(NU_TASK *id, void (*function)(void *arg), void *arg)
 {
   struct sys_thread *thread;
+  sys_prot_t old_level;
   
   thread = (struct sys_thread *) calloc(1,sizeof(struct sys_thread));
     
   if(thread) {
-      sys_arch_sem_wait(thread_sem, 0);         //Wait to obtain the semaphore
+      old_level = sys_arch_protect();
       thread->next = threads;
       thread->timeouts.next = NULL;
       thread->pthread = id;
       thread->function = function;
       thread->arg = arg;
       threads = thread;
-      sys_sem_signal(thread_sem);               //Release semaphore
+      sys_arch_unprotect(old_level);
   }
     
   return thread;
@@ -165,23 +164,22 @@ static struct sys_thread *
 current_thread(void)
 {
     struct sys_thread *st;
+    sys_prot_t old_level;
     NU_TASK *pt;
     
     pt = NU_Current_Task_Pointer();
-    sys_arch_sem_wait(thread_sem, 0);
+    old_level = sys_arch_protect();
     
     for(st = threads; st != NULL; st = st->next)
     {    
         if(st->pthread == pt)
         {
-            sys_sem_signal(thread_sem);
-            
+            sys_arch_unprotect(old_level);
             return st;
         }
     }
 
-    sys_sem_signal(thread_sem);
-
+    sys_arch_unprotect(old_level);
     st = introduce_thread(pt, 0, 0);
     
     if(!st) {

ports/unix/netif/unixif.c

@@ -293,7 +293,7 @@ unixif_output(struct netif *netif, struct pbuf *p, struct ip_addr *ipaddr)
   buf->payload = p->payload;
 
   if(list_elems(unixif->q) == 0) {
-    pbuf_ref(p);
+    pbuf_ref_chain(p);
     list_push(unixif->q, buf);
     sys_timeout((double)p->tot_len * 8000.0 / UNIXIF_BPS, unixif_output_timeout,
 		netif);
@@ -301,7 +301,7 @@ unixif_output(struct netif *netif, struct pbuf *p, struct ip_addr *ipaddr)
     DEBUGF(UNIXIF_DEBUG, ("unixif_output: first on list\n"));
     
   } else {
-    pbuf_ref(p);
+    pbuf_ref_chain(p);
     if(list_push(unixif->q, buf) == 0) {
 #ifdef UNIXIF_DROP_FIRST
       struct unixif_buf *buf2;