removed posix real-time extension timers from cpu

cpu/native/hwtimer_cpu.c

@@ -1,8 +1,11 @@
 /**
  * Native CPU hwtimer_arch.h implementation
  *
- * Uses POSIX real-time extension timers to mimic hardware timers.
+ * Uses POSIX realtime clock and POSIX itimer to mimic hardware.
- * XXX: see hwtimer_isr_timer()
+ * Since there is only 1 itmer per process and RIOT needs several
+ * hardware timers, hwtimers are being multiplexed onto the itimer.
+ *
+ * XXX: does not scale well with number of timers (overhead: O(N)).
  *
  * Copyright (C) 2013 Ludwig Ortmann
  *
@@ -18,6 +21,7 @@
  */
 
 #include <time.h>
+#include <sys/time.h>
 #include <signal.h>
 #include <stdint.h>
 #include <err.h>
@@ -31,17 +35,30 @@
 #include "debug.h"
 
 static unsigned long native_hwtimer_now;
+
 static int native_hwtimer_irq[ARCH_MAXTIMERS];
-static timer_t native_hwtimer_timer[ARCH_MAXTIMERS];
+static struct itimerval native_hwtimer[ARCH_MAXTIMERS];
+static int native_hwtimer_isset[ARCH_MAXTIMERS];
+
+static int next_timer;
 static void (*int_handler)(int);
 
 /**
- * sets timespec to given ticks
+ * sets timeval to given ticks
  */
-void ticks2ts(unsigned long ticks, struct timespec *tp)
+void ticks2tv(unsigned long ticks, struct timeval *tp)
 {
    tp->tv_sec = ticks / HWTIMER_SPEED;
-   tp->tv_nsec = (ticks % HWTIMER_SPEED)*1000 ;
+   tp->tv_usec = (ticks % HWTIMER_SPEED) ;
+}
+
+/**
+ * returns ticks for give timeval
+ */
+unsigned long tv2ticks(struct timeval *tp)
+{
+    /* TODO: check for overflow */
+    return((tp->tv_sec * HWTIMER_SPEED) + (tp->tv_usec));
 }
 
 /**
@@ -54,22 +71,72 @@ unsigned long ts2ticks(struct timespec *tp)
 }
 
 /**
- * native timer signal handler,
+ * set next_timer to the next lowest enabled timer index
+ */
+void schedule_timer(void)
+{
+    int l = next_timer;
+    for (
+            int i = ((next_timer +1) % ARCH_MAXTIMERS);
+            i != next_timer;
+            i = ((i+1) % ARCH_MAXTIMERS)
+        )
+    {
+
+        if ( native_hwtimer_isset[l] != 1 ) {
+            /* make sure we dont compare to garbage in the following
+             * if condition */
+            l = i;
+        }
+
+        if (
+                ( native_hwtimer_isset[i] == 1 ) &&
+                ( tv2ticks(&(native_hwtimer[i].it_value)) < tv2ticks(&(native_hwtimer[l].it_value)) )
+           )
+        {
+            /* set l to the lowest active time */
+            l = i;
+        }
+
+    }
+    next_timer = l;
+    /* l could still point to some unused (garbage) timer if no timers
+     * are set at all */
+    if (native_hwtimer_isset[next_timer] == 1) {
+        if (setitimer(ITIMER_REAL, &native_hwtimer[next_timer], NULL) == -1) {
+            err(1, "schedule_timer");
+        }
+        else {
+            DEBUG("schedule_timer(): set next timer.\n");
+        }
+    }
+    else {
+        DEBUG("schedule_timer(): no next timer!? This looks suspicous.\n");
+        // TODO: unset  timer.
+    }
+}
+
+/**
+ * native timer signal handler
  * 
- * XXX: Calls callback for all timers whenever any timer finishes.
+ * set new system timer, call timer interrupt handler
  */
 void hwtimer_isr_timer()
 {
+    int i;
+
     DEBUG("hwtimer_isr_timer()\n");
 
-    for (int i = 0; i<ARCH_MAXTIMERS; i++) {
+    i = next_timer;
+    native_hwtimer_isset[next_timer] = 0;
+    schedule_timer();
+
     if (native_hwtimer_irq[i] == 1) {
         DEBUG("hwtimer_isr_timer(): calling hwtimer.int_handler(%i)\n", i);
         int_handler(i);
     }
-        if (timer_getoverrun(native_hwtimer_timer[i]) > 0 ) {
+    else {
-            errx(1, "XXX: unhandled hwtimer situation");
+        DEBUG("hwtimer_isr_timer(): this should not have happened");
-        }
     }
 }
 
@@ -93,39 +160,27 @@ void hwtimer_arch_disable_interrupt(void)
 
 void hwtimer_arch_unset(short timer)
 {
-    struct itimerspec its;
-
     DEBUG("hwtimer_arch_unset(%d)\n", timer);
 
     native_hwtimer_irq[timer] = 0;
-
+    native_hwtimer_isset[timer] = 0;
-    its.it_interval.tv_nsec = 0;
+    schedule_timer();
-    its.it_interval.tv_sec = 0;
-    its.it_value.tv_nsec = 0;
-    its.it_value.tv_sec = 0;
-
-    if( (timer_settime(native_hwtimer_timer[timer], 0, &its, NULL)) == -1) {
-        err(1, "hwtimer_arch_unset: timer_settime");
-    }
 
     return;
 }
 
 void hwtimer_arch_set(unsigned long offset, short timer)
 {
-    struct itimerspec its;
-
     DEBUG("hwtimer_arch_set(%li, %i)\n", offset, timer);
     native_hwtimer_irq[timer] = 1;
+    native_hwtimer_isset[timer] = 1;
 
-    ticks2ts(offset, &its.it_value);
+    ticks2tv(offset, &(native_hwtimer[timer].it_value));
-    DEBUG("hwtimer_arch_set(): that is %lis %lins from now\n", its.it_value.tv_sec, its.it_value.tv_nsec);
+    DEBUG("hwtimer_arch_set(): that is %lis %lius from now\n",
+            native_hwtimer[timer].it_value.tv_sec,
+            native_hwtimer[timer].it_value.tv_usec);
 
-    its.it_interval.tv_sec = 0;
+    schedule_timer();
-    its.it_interval.tv_nsec = 0;
-    if (timer_settime(native_hwtimer_timer[timer], 0, &its, NULL) == -1) {
-        err(1, "hwtimer_arch_unset: timer_settime");
-    }
 
     return;
 }
@@ -155,24 +210,18 @@ unsigned long hwtimer_arch_now(void)
 
 void hwtimer_arch_init(void (*handler)(int), uint32_t fcpu)
 {
-    struct sigevent sev;
-
     DEBUG("hwtimer_arch_init()\n");
 
     hwtimer_arch_disable_interrupt();
-
     int_handler = handler;
 
-    sev.sigev_notify = SIGEV_SIGNAL;
     for (int i = 0; i<ARCH_MAXTIMERS; i++) {
         native_hwtimer_irq[i] = 0;
-        //sev.sigev_signo =  _SIG_TIMER + i;;
+        native_hwtimer_isset[i] = 0;
-        sev.sigev_signo =  SIGALRM;
+        native_hwtimer[i].it_interval.tv_sec = 0;
-        //sev.sigev_value.sival_ptr = &native_hwtimer_timer[i];
+        native_hwtimer[i].it_interval.tv_usec = 0;
-        if (timer_create(CLOCK_REALTIME, &sev, &native_hwtimer_timer[i]) == -1) {
-            err(1, "timer_create");
-        }
     }
+
     hwtimer_arch_enable_interrupt();
     return;
 }

cpu/native/include/cpu-conf.h

@@ -24,9 +24,7 @@
 #define KERNEL_CONF_STACKSIZE_IDLE      4096
 #define NATIVE_ISR_STACKSIZE            8192
 
-#define _SIG_UNDEF          SIGRTMIN + 0
+#define _SIG_LTC4150        SIGRTMIN + 0
-#define _SIG_TIMER          SIGRTMIN + 10 // check hwtimer_cpu.h for compliance
-#define _SIG_LTC4150        SIGRTMIN + 20
 
 /* TODO: check for overflow (SIGRTMAX) */