After rename, before performance testing.

Makefile

@@ -15,13 +15,13 @@ debug_build:
 	meson compile -j 4 -C builddir
 
 run: build
-	./builddir/chip8.exe 1 1 ./roms/test_opcode.ch8
+	./builddir/b8rk.exe 1 1 ./roms/test_opcode.ch8
 
 debug: build
 	gdb --nx -x .gdbinit --ex run --args builddir/runtests.exe
 
 debug_run: build
-	gdb --nx -x .gdbinit --batch --ex run --ex bt --ex q --args builddir/chip8.exe 1 1 ./roms/test_opcode.ch8
+	gdb --nx -x .gdbinit --batch --ex run --ex bt --ex q --args builddir/b8rk.exe 1 1 ./roms/test_opcode.ch8
 
 clean:
 	meson compile --clean -C builddir

meson.build

@@ -1,4 +1,4 @@
-project('chip8', 'cpp',
+project('b8rk', 'cpp',
   version: '0.1.0',
   default_options: [
     'cpp_std=c++23',
@@ -83,9 +83,10 @@ dependencies += [
 sources = [
   'src/dbc.cpp',
   'src/chip8.cpp',
+  'src/stats.cpp',
 ]
 
-executable('chip8',
+executable('b8rk',
   sources + [ 'src/main.cpp' ],
   cpp_args: cpp_args,
   link_args: link_args,

src/chip8.cpp

@@ -106,9 +106,6 @@ void Chip8::Cycle() {
   if(soundTimer > 0) {
     --soundTimer;
   }
-
-  fmt::println("opcode: {}, delay: {}, sound: {}, pc: {}",
-      opcode, delayTimer, soundTimer, pc);
 }
 
 

src/main.cpp

@@ -10,7 +10,7 @@
 #include <SFML/Graphics/RectangleShape.hpp>
 #include "dbc.hpp"
 #include "chip8.hpp"
-
+#include "stats.hpp"
 
 struct Display {
   sf::RenderWindow& window;
@@ -92,10 +92,27 @@ int main(int argc, char* argv[]) {
   window.setVerticalSyncEnabled(true);
 
   Display display{window, {0, 0}, {1000, 1000}};
+  Stats cycle_stats;
+  Stats render_stats;
+
+  while (display.active()) {
+    auto currentTime = std::chrono::high_resolution_clock::now();
+    float dt = std::chrono::duration<float, std::chrono::milliseconds::period>(currentTime - lastCycleTime).count();
+
+    if (dt > cycleDelay)
+    {
+        lastCycleTime = currentTime;
+        auto t = cycle_stats.time_start();
+        chip8.Cycle();
+        cycle_stats.sample_time(t);
+    }
 
-  while (true) {
+    auto t = render_stats.time_start();
-    chip8.Cycle();
     display.update(chip8);
     display.render();
+    render_stats.sample_time(t);
   }
+
+  cycle_stats.dump("cycle times");
+  render_stats.dump("render times");
 }

src/stats.cpp

@@ -0,0 +1,11 @@
+#include "stats.hpp"
+#include <fmt/core.h>
+#include "dbc.hpp"
+
+void Stats::dump(std::string msg)
+{
+  dbc::log($F("{}: sum: {}, sumsq: {}, n: {}, "
+            "min: {}, max: {}, mean: {}, stddev: {}",
+            msg, sum, sumsq, n, min, max, mean(),
+            stddev()));
+}

src/stats.hpp

@@ -0,0 +1,59 @@
+#pragma once
+#include <cmath>
+#include <chrono>
+
+struct Stats {
+  using TimeBullshit = std::chrono::time_point<std::chrono::high_resolution_clock>;
+
+  double sum = 0.0;
+  double sumsq = 0.0;
+  double n = 0.0;
+  double min = 0.0;
+  double max = 0.0;
+
+  inline void reset() {
+    sum = 0.0;
+    sumsq = 0.0;
+    n = 0.0;
+    min = 0.0;
+    max = 0.0;
+  }
+
+  inline double mean() {
+    return sum / n;
+  }
+
+  inline double stddev() {
+    return std::sqrt((sumsq - (sum * sum / n)) / (n - 1));
+  }
+
+  inline void sample(double s) {
+    sum += s;
+    sumsq += s * s;
+
+    if (n == 0) {
+      min = s;
+      max = s;
+    } else {
+      if (min > s) min = s;
+      if (max < s) max = s;
+    }
+
+    n += 1;
+  }
+
+  inline TimeBullshit time_start() {
+    return std::chrono::high_resolution_clock::now();
+  }
+
+  inline void sample_time(TimeBullshit start) {
+    auto end = std::chrono::high_resolution_clock::now();
+    auto elapsed = std::chrono::duration<double>(end - start);
+
+    if(elapsed.count() > 0.0) {
+      sample(1.0/elapsed.count());
+    }
+  }
+
+  void dump(std::string msg="");
+};