Revert "Hmm"

This reverts commit f17bc0bc8e8ceac6cbfdadb2ade8f877d4eedaca.

Source/DSPSpy/tests/dsp_test.ds

@@ -1,19 +1,25 @@
-incdir "tests"
+incdir  "tests"
 include "dsp_base.inc"
 
-;  Right here we are at a specific predetermined state.
-;  Ideal environment to try instructions.
-        
-;  We can call send_back at any time to send data back to the PowerPC.
-
 test_main:
-  lri $AC0.M, #0x1000
+	CLR $ACC0
-  call send_back
+	CLR $ACC1
 
-  set40
+	LRIS $AX0.H, #1
-  lri $AC0.M, #0x1000
+	CALL send_back
-  set16
-  call send_back
 
-; We're done, DO NOT DELETE THIS LINE
+
-  jmp end_of_test
+	JMP end_of_test
+
+external_irq:
+	INC $ACC0
+	; LRIS $AX0.H, #3
+	; CALL send_back
+	RTI
+
+; Expected output ($AX0.H (send_back num), $AC0.L (interrupt count), and $SR):
+; 1, 0, 3824 (start)
+; 3, 1, 2820 (in interrupt handler)
+; 2, 1, 3820 (back out of interrupt handler)
+; DSPSpy shows "interrupt after 20 ticks / 0 tries" (exact number of ticks varies)
+; ACC1 is 7bb40 or so (also varies, and can vary between steps 2 and 3 if the interrupt happens on the JZ)