fix machine_external_ints test

testbench/asm/machine_external_ints.s

@@ -1,7 +1,9 @@
 #include "common.s"
 
 machine_software_interrupt:
+    // put expected mcause in x4
     la x4, 0x80000003
+    // put expected mscause in x5
     li x5, 0x0
     // enable software interrupt
     li x2, 0x8
@@ -10,6 +12,7 @@ machine_software_interrupt:
     li x2, TRIGGER_SOFT_INT
     li x3, STDOUT
     sw x2, 0(x3)
+    li x12, 0x8
     j fail_if_not_serviced
 
 machine_timer_interrupt:
@@ -27,4 +30,4 @@ machine_timer_interrupt:
 main:
     call machine_software_interrupt
     call machine_timer_interrupt
-    j _finish
+    j _finish

testbench/asm/tb.h

@@ -1,9 +1,20 @@
 #define STDOUT 0xd0580000
 
-#define TRIGGER_NMI 0x80
+/* TODO remove this. It's not supported by the testbench mailbox logic */
 #define LOAD_NMI_ADDR 0x81
-#define TRIGGER_DBUS_FAULT 0x82
-#define TRIGGER_IBUS_FAULT 0x83
-#define TRIGGER_SOFT_INT 0x84
-#define TRIGGER_TIMER_INT 0x85
-#define TRIGGER_EXT_INT1 0x86
+/* helper macros that define messages to be written to `STDOUT` to trigger and clear interrupts */
+
+#define CLEAR 0x82
+#define TRIGGER 0x83
+
+#define NMI_INT (1<<8)
+#define TIMER_INT (1<<9)
+#define SOFT_INT (1<<10)
+
+#define TRIGGER_NMI_INT (TRIGGER | NMI_INT)
+#define TRIGGER_TIMER_INT (TRIGGER | TIMER_INT)
+#define TRIGGER_SOFT_INT (TRIGGER | SOFT_INT)
+
+#define CLEAR_NMI_INT (CLEAR | NMI_INT)
+#define CLEAR_TIMER_INT (CLEAR | TIMER_INT)
+#define CLEAR_SOFT_INT (CLEAR | SOFT_INT)