ioport: Restore PIN to PORT values when DDR is set to output

[simavr] / simavr / sim / avr_ioport.c

diff --git a/simavr/sim/avr_ioport.c b/simavr/sim/avr_ioport.c
index 3966996..24a8a9b 100644 (file)
--- a/simavr/sim/avr_ioport.c
+++ b/simavr/sim/avr_ioport.c
@@ -38,19 +38,14 @@ static uint8_t avr_ioport_read(struct avr_t * avr, avr_io_addr_t addr, void * pa
 static void avr_ioport_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, void * param)
 {
        avr_ioport_t * p = (avr_ioport_t *)param;
-       uint8_t oldv = avr->data[addr];
 
        avr_core_watch_write(avr, addr, v);
-       if (v != oldv) {
-               //      printf("PORT%c(%02x) = %02x (was %02x)\n", p->name, addr, v, oldv);
-               int mask = v ^ oldv;
-
-               // raise the internal IRQ callbacks
-               for (int i = 0; i < 8; i++)
-                       if (mask & (1 << i))
-                               avr_raise_irq(p->io.irq + i, (v >> i) & 1);
-               avr_raise_irq(p->io.irq + IOPORT_IRQ_PIN_ALL, v);
-       }
+       //      printf("PORT%c(%02x) = %02x (was %02x)\n", p->name, addr, v, oldv);
+
+       // raise the internal IRQ callbacks
+       for (int i = 0; i < 8; i++)
+               avr_raise_irq(p->io.irq + i, (v >> i) & 1);
+       avr_raise_irq(p->io.irq + IOPORT_IRQ_PIN_ALL, v);
 }
 
 /*
@@ -66,7 +61,8 @@ static void avr_ioport_pin_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t
 
 /*
  * This is a the callback for the DDR register. There is nothing much to do here, apart
- * from triggering an IRQ in case any 'client' code is interested in the information.
+ * from triggering an IRQ in case any 'client' code is interested in the information,
+ * and restoring all PIN bits marked as output to PORT values.
  */
 static void avr_ioport_ddr_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, void * param)
 {
@@ -74,6 +70,14 @@ static void avr_ioport_ddr_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t
 
        avr_raise_irq(p->io.irq + IOPORT_IRQ_DIRECTION_ALL, v);
        avr_core_watch_write(avr, addr, v);
+
+       const uint8_t oldpin = avr->data[p->r_pin];
+       const uint8_t pin = (oldpin & ~v) | (avr->data[p->r_port] & v);
+       avr_core_watch_write(avr, p->r_pin, pin);
+       for (int i = 0; i < 8; i++)
+               if (((oldpin ^ pin) >> i) & 1)
+                       avr_raise_irq(p->io.irq + i, (pin >> i) & 1);
+       avr_raise_irq(p->io.irq + IOPORT_IRQ_PIN_ALL, pin);
 }
 
 /*
@@ -192,6 +196,9 @@ void avr_ioport_init(avr_t * avr, avr_ioport_t * p)
        // allocate this module's IRQ
        avr_io_setirqs(&p->io, AVR_IOCTL_IOPORT_GETIRQ(p->name), IOPORT_IRQ_COUNT, NULL);
 
+       for (int i = 0; i < IOPORT_IRQ_COUNT; i++)
+               p->io.irq[i].flags |= IRQ_FLAG_FILTERED;
+
        avr_register_io_write(avr, p->r_port, avr_ioport_write, p);
        avr_register_io_read(avr, p->r_pin, avr_ioport_read, p);
        avr_register_io_write(avr, p->r_pin, avr_ioport_pin_write, p);