From 3952d93bb08323e8473d50d2a6b7cd9299f9d97e Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Thu, 2 Jan 2025 17:10:00 +0000
Subject: [PATCH] Add CMake option to enable/disable performance monitoring

---
 CMakeLists.txt        |  1 +
 engine/CMakeLists.txt |  3 +++
 engine/engine.c       | 22 ++++++++++++++++------
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0ab86ab..72027c2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,7 @@ project(epec-mcu-emulator LANGUAGES C)
 
 option(WERROR "Treat warnings as errors" OFF)
 option(SANITIZERS "Enable memory and undefined behaviour sanitizers" OFF)
+option(PERFMON "Monitor performance of game code" ON)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
diff --git a/engine/CMakeLists.txt b/engine/CMakeLists.txt
index dc63058..7248276 100644
--- a/engine/CMakeLists.txt
+++ b/engine/CMakeLists.txt
@@ -1,3 +1,6 @@
 add_library(engine engine.c)
 set_default_target_options(engine)
 target_include_directories(engine PUBLIC include)
+if(${PERFMON})
+  target_compile_definitions(engine PRIVATE PERFMON)
+endif()
diff --git a/engine/engine.c b/engine/engine.c
index d111910..adf86f9 100644
--- a/engine/engine.c
+++ b/engine/engine.c
@@ -13,6 +13,12 @@
 #define VT100_CURSORTOPLEFT "\33[H"
 #define VT100_CLEAR "\33[2J"
 
+#ifdef PERFMON
+#define GETPERF(x) x = SDL_GetPerformanceCounter()
+#else
+#define GETPERF(x)
+#endif
+
 typedef struct {
 	double freq;
 	uint64_t start, evt, update, render;
@@ -39,10 +45,12 @@ int main(int argc, char *argv[])
 	void *gamemem = calloc(1, game_conf.memsize);
 	game_init(argc, argv, gamemem, renderer);
 
+#ifdef PERFMON
 	perf_t perf = { .freq = SDL_GetPerformanceFrequency() / 1000000.0 };
 	uint64_t frame = 0;
+#endif
 	while (1) {
-		perf.start = SDL_GetPerformanceCounter();
+		GETPERF(perf.start);
 
 		// Handle all events currently in queue
 		SDL_Event evt;
@@ -50,18 +58,19 @@ int main(int argc, char *argv[])
 			if (game_evthandle(gamemem, &evt) != GAMESTATUS_OK)
 				goto quit;
 		}
-		perf.evt = SDL_GetPerformanceCounter();
+		GETPERF(perf.evt);
 
 		// Update game state
 		if (game_update(gamemem, interval) != GAMESTATUS_OK)
 			goto quit;
-		perf.update = SDL_GetPerformanceCounter();
+		GETPERF(perf.update);
 
 		// Render frame
 		SDL_RenderClear(renderer);
 		game_render(gamemem, renderer, SDL_GetTicks64());
-		perf.render = SDL_GetPerformanceCounter();
+		GETPERF(perf.render);
 
+#ifdef PERFMON
 		// Print performance analysis every 16 frames
 		if ((frame & 15) == 0) {
 			const double evt = (perf.evt - perf.start) / perf.freq;
@@ -75,9 +84,10 @@ int main(int argc, char *argv[])
 			    "%10.3f μs\ntotal\t%10.3f μs (%05.2f%%)\n",
 			    evt, update, render, total, total_pc);
 		}
-
-		// Increment frame counter and present frame
 		++frame;
+#endif
+
+		// Present frame
 		SDL_RenderPresent(renderer);
 	}