sim65 use error codes outside the simulated program's range for non-sim errors

doc/sim65.sgml

@@ -44,6 +44,13 @@ The simulator is called as follows:
           --version             Print the simulator version number
 </verb></tscreen>
 
+sim65 will exit with the error code of the simulated program,
+which is limited to an 8-bit result 0-255.
+
+An error in sim65, like bad arguments or an internal problem will exit with <tt/1/.
+
+A timeout from <tt/-x/ will exist with <tt/2/.
+
 
 <sect1>Command line options in detail<p>
 

src/sim65/error.h

@@ -49,10 +49,12 @@
 
 
 
-#define SIM65_ERROR         0x7F
+#define SIM65_ERROR         -1
-/* Does not use EXIT_FAILURE because it may overlap with test results. */
+/* An error result for errors that are not part of the simulated test.
+** Note that set simulated test can only return 8-bit errors 0-255.
+*/
 
-#define SIM65_ERROR_TIMEOUT 0x7E
+#define SIM65_ERROR_TIMEOUT -2
 /* An error result for max CPU instructions exceeded. */
 
 extern int PrintCycles;

src/sim65/paravirt.c

@@ -124,7 +124,7 @@ static unsigned PopParam (unsigned char Incr)
 static void PVExit (CPURegs* Regs)
 {
     Print (stderr, 1, "PVExit ($%02X)\n", Regs->AC);
-    SimExit (Regs->AC);
+    SimExit (Regs->AC); /* Error code in range 0-255. */
 }