[PATCH v2 09/12] mos6522: record last_irq_levels in mos6522_set_irq()

[Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>]

To detect edge-triggered IRQs it is necessary to store the last state of each
IRQ in a last_irq_levels bitmap.

Note: this is a migration break for machines which use mos6522 instances which
are g3beige/mac99 (PPC) and q800 (m68k).

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 hw/misc/mos6522.c         | 11 +++++++++--
 include/hw/misc/mos6522.h |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/hw/misc/mos6522.c b/hw/misc/mos6522.c
index 38b5877ffa..60b3b693d0 100644
--- a/hw/misc/mos6522.c
+++ b/hw/misc/mos6522.c
@@ -72,6 +72,12 @@ static void mos6522_set_irq(void *opaque, int n, int level)
     }
 
     mos6522_update_irq(s);
+
+    if (level) {
+        s->last_irq_levels |= 1 << n;
+    } else {
+        s->last_irq_levels &= ~(1 << n);
+    }
 }
 
 static uint64_t get_counter_value(MOS6522State *s, MOS6522Timer *ti)
@@ -544,8 +550,8 @@ static const VMStateDescription vmstate_mos6522_timer = {
 
 const VMStateDescription vmstate_mos6522 = {
     .name = "mos6522",
-    .version_id = 0,
-    .minimum_version_id = 0,
+    .version_id = 1,
+    .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_UINT8(a, MOS6522State),
         VMSTATE_UINT8(b, MOS6522State),
@@ -556,6 +562,7 @@ const VMStateDescription vmstate_mos6522 = {
         VMSTATE_UINT8(pcr, MOS6522State),
         VMSTATE_UINT8(ifr, MOS6522State),
         VMSTATE_UINT8(ier, MOS6522State),
+        VMSTATE_UINT8(last_irq_levels, MOS6522State),
         VMSTATE_STRUCT_ARRAY(timers, MOS6522State, 2, 0,
                              vmstate_mos6522_timer, MOS6522Timer),
         VMSTATE_END_OF_LIST()
diff --git a/include/hw/misc/mos6522.h b/include/hw/misc/mos6522.h
index 846ded64b7..9ec9b57239 100644
--- a/include/hw/misc/mos6522.h
+++ b/include/hw/misc/mos6522.h
@@ -131,6 +131,7 @@ struct MOS6522State {
     uint64_t frequency;
 
     qemu_irq irq;
+    uint8_t last_irq_levels;
 };
 
 #define TYPE_MOS6522 "mos6522"
-- 
2.20.1