Make the cycle limit optional

3 files changed, 11 insertions, 5 deletions

diff --git a/sim/gdbstub.py b/sim/gdbstub.py
index 75c15cb..c01a4a7 100644
--- a/sim/gdbstub.py
+++ b/sim/gdbstub.py
@@ -1,5 +1,6 @@
 import sys, socket
 
+cycles = None
 start_halted = True
 
 def init():
diff --git a/sim/sim.py b/sim/sim.py
index be846fb..b0a194a 100755
--- a/sim/sim.py
+++ b/sim/sim.py
@@ -275,13 +275,16 @@ prelude.update({k: v for k, v in all_regs})
 module.__dict__.update(prelude)
 spec.loader.exec_module(module)
 
-cycles = module_get('cycles', 1024)
 mem_dumps = module_get('mem_dumps', [])
 
 if init := module_get('init'):
     init()
 
-exec_args = [verilated, '--headless', '--no-tty', '--cycles', str(cycles), '--dump-regs']
+exec_args = [verilated, '--headless', '--no-tty', '--dump-regs']
+
+cycles = module_get('cycles', 1024)
+if cycles is not None:
+    exec_args.extend(['--cycles', str(cycles)])
 
 for rng in mem_dumps:
     length = rng.stop - rng.start
diff --git a/tb/top/conspiracion.cpp b/tb/top/conspiracion.cpp
index bd1086a..f222e54 100644
--- a/tb/top/conspiracion.cpp
+++ b/tb/top/conspiracion.cpp
@@ -1,3 +1,4 @@
+#include <climits>
 #include <cstdio>
 #include <cstdint>
 #include <cstdlib>
@@ -204,7 +205,7 @@ int main(int argc, char **argv)
 
 	args::ValueFlag<unsigned> cycles
 	(
-		parser, "cycles", "Number of core cycles to run", {"cycles"}, 256
+		parser, "cycles", "Max number of core cycles to run", {"cycles"}, UINT_MAX
 	);
 
 	args::ValueFlag<int> control_fd
@@ -446,9 +447,10 @@ int main(int argc, char **argv)
 	};
 
 	unsigned i = 0;
-	while(!failed && i < *cycles)
+	// Abuse unsigned overflow (cycles is UINT_MAX by default)
+	while(!failed && i + 1 <= *cycles)
 	{
-		for(; i < *cycles; ++i)
+		for(; i + 1 <= *cycles; ++i)
 		{
 			cycle();
 			if(failed || top.cpu_halted) [[unlikely]]