sim64 universal 64-bit cycle count support:

MaxCycleCount is accounted by countdown, eliminating the 1-instruction-overhead issue, and removing the need to compare against a growing TotalCycles.
Makes main.c responsible for counting total cycles, instead of 6502.c, so the size of MaxCycleCount etc. is fully determined in one location.
Makes error.c responsible for PrintCycles instead of paravirt.c, so that it can be treated globally instead of
Return value of main() should be SIM65_ERROR because it is unreachable by design.

src/sim65/main.c

@@ -36,7 +36,6 @@
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
-#include <limits.h>
 
 /* common */
 #include "abend.h"
@@ -61,14 +60,14 @@
 /* Name of program file */
 const char* ProgramFile;
 
-/* exit simulator after MaxCycles Cycles */
-unsigned long MaxCycles;
+/* count of total cycles executed */
+unsigned long long TotalCycles = 0;
 
-/* maximum number of cycles that can be tested,
-** requires overhead for longest possible instruction,
-** which should be 7, using 16 for safety.
-*/
-#define MAXCYCLES_LIMIT (ULONG_MAX-16)
+/* exit simulator after MaxCycles Cccles */
+unsigned long long MaxCycles = 0;
+
+/* countdown from MaxCycles */
+unsigned long long RemainCycles;
 
 /* Header signature 'sim65' */
 static const unsigned char HeaderSignature[] = {
@@ -145,11 +144,7 @@ static void OptQuitXIns (const char* Opt attribute ((unused)),
                         const char* Arg attribute ((unused)))
 /* quit after MaxCycles cycles */
 {
-    MaxCycles = strtoul(Arg, NULL, 0);
-    /* Guard against overflow. */
-    if (MaxCycles >= MAXCYCLES_LIMIT) {
-        Error("'-x parameter out of range. Max: %lu",MAXCYCLES_LIMIT);
-    }
+    MaxCycles = strtoull(Arg, NULL, 0);
 }
 
 static unsigned char ReadProgramFile (void)
@@ -247,6 +242,7 @@ int main (int argc, char* argv[])
 
     unsigned I;
     unsigned char SPAddr;
+    unsigned int Cycles;
 
     /* Initialize the cmdline module */
     InitCmdLine (&argc, &argv, "sim65");
@@ -309,18 +305,24 @@ int main (int argc, char* argv[])
     MemInit ();
 
     SPAddr = ReadProgramFile ();
-
     ParaVirtInit (I, SPAddr);
 
     Reset ();
 
+    RemainCycles = MaxCycles;
     while (1) {
-        ExecuteInsn ();
-        if (MaxCycles && (GetCycles () >= MaxCycles)) {
-            ErrorCode (SIM65_ERROR_TIMEOUT, "Maximum number of cycles reached.");
+        Cycles = ExecuteInsn ();
+        TotalCycles += Cycles;
+        if (MaxCycles) {
+            if (Cycles > RemainCycles) {
+                ErrorCode (SIM65_ERROR_TIMEOUT, "Maximum number of cycles (%llu) reached.", MaxCycles);
+            }
+            RemainCycles -= Cycles;
         }
     }
 
-    /* Return an apropriate exit code */
-    return EXIT_SUCCESS;
+    /* Unreachable. sim65 program must exit through paravirtual PVExit
+    ** or timeout from MaxCycles producing an error.
+    */
+    return SIM65_ERROR;
 }