Streamlined avr_irq subsystem

[simavr] / simavr / sim / sim_irq.c

diff --git a/simavr/sim/sim_irq.c b/simavr/sim/sim_irq.c
index f3377fd..8faff3f 100644 (file)
--- a/simavr/sim/sim_irq.c
+++ b/simavr/sim/sim_irq.c
@@ -37,9 +37,37 @@ avr_irq_t * avr_alloc_irq(uint32_t base, uint32_t count)
 {
        avr_irq_t * irq = (avr_irq_t*)malloc(sizeof(avr_irq_t) * count);
        avr_init_irq(irq, base, count);
+       for (int i = 0; i < count; i++)
+               irq[i].flags |= IRQ_FLAG_ALLOC; 
        return irq;
 }
 
+static avr_irq_hook_t * _avr_alloc_irq_hook(avr_irq_t * irq)
+{
+       avr_irq_hook_t *hook = malloc(sizeof(avr_irq_hook_t));
+       memset(hook, 0, sizeof(avr_irq_hook_t));
+       hook->next = irq->hook;
+       irq->hook = hook;
+       return hook;
+}
+
+void avr_free_irq(avr_irq_t * irq, uint32_t count)
+{
+       for (int i = 0; i < count; i++) {
+               // purge hooks
+               avr_irq_hook_t *hook = irq->hook;
+               while (hook) {
+                       avr_irq_hook_t * next = hook->next;
+                       free(hook);
+                       hook = next;
+               }
+               irq->hook = NULL;
+       }
+       // if that irq list was allocated by us, free it
+       if (irq->flags & IRQ_FLAG_ALLOC)
+               free(irq);
+}
+
 void avr_irq_register_notify(avr_irq_t * irq, avr_irq_notify_t notify, void * param)
 {
        if (!irq || !notify)
@@ -51,44 +79,50 @@ void avr_irq_register_notify(avr_irq_t * irq, avr_irq_notify_t notify, void * pa
                        return; // already there
                hook = hook->next;
        }
-       hook = malloc(sizeof(avr_irq_hook_t));
-       memset(hook, 0, sizeof(avr_irq_hook_t));
-       hook->next = irq->hook;
+       hook = _avr_alloc_irq_hook(irq);
        hook->notify = notify;
        hook->param = param;
-       irq->hook = hook;
 }
 
 void avr_raise_irq(avr_irq_t * irq, uint32_t value)
 {
-       if (!irq || irq->value == value)
+       if (!irq)
                return ;
+       uint32_t output = (irq->flags & IRQ_FLAG_NOT) ? !value : value;
+       if (irq->value == output && (irq->flags & IRQ_FLAG_FILTERED))
+               return;
        avr_irq_hook_t *hook = irq->hook;
        while (hook) {
-               if (hook->notify) {     
+               avr_irq_hook_t * next = hook->next;
                        // prevents reentrance / endless calling loops
-                       if (hook->busy == 0) {
-                               hook->busy++;
-                               hook->notify(irq, value, hook->param);
-                               hook->busy--;
-                       }
-               }
-               hook = hook->next;
+               if (hook->busy == 0) {
+                       hook->busy++;
+                       if (hook->notify)
+                               hook->notify(irq, output,  hook->param);
+                       if (hook->chain)
+                               avr_raise_irq(hook->chain, output);
+                       hook->busy--;
+               }                       
+               hook = next;
        }
-       irq->value = value;
-}
-
-static void _avr_irq_connect(avr_irq_t * irq, uint32_t value, void * param)
-{
-       avr_irq_t * dst = (avr_irq_t*)param;
-       avr_raise_irq(dst, value);
+       // the value is set after the callbacks are called, so the callbacks
+       // can themselves compare for old/new values between their parameter
+       // they are passed (new value) and the previous irq->value
+       irq->value = output;
 }
 
 void avr_connect_irq(avr_irq_t * src, avr_irq_t * dst)
 {
-       if (!src || !dst) {
+       if (!src || !dst || src == dst) {
                printf("avr_connect_irq invalid irq %p/%p", src, dst);
                return;
        }
-       avr_irq_register_notify(src, _avr_irq_connect, dst);
+       avr_irq_hook_t *hook = src->hook;
+       while (hook) {
+               if (hook->chain == dst)
+                       return; // already there
+               hook = hook->next;
+       }
+       hook = _avr_alloc_irq_hook(src);
+       hook->chain = dst;
 }