Initial barebones version

src/render_hooks.cpp

@@ -0,0 +1,77 @@
+#include "render_hooks.h"
+#include "d3d_hooks.h"
+
+#include <chrono>
+#include <mutex>
+
+#include <rex/cvar.h>
+
+REXCVAR_DEFINE_BOOL(ac6_unlock_fps, false, "AC6", "Unlock frame rate to 60fps");
+REXCVAR_DEFINE_BOOL(ac6_timing_hooks_enabled, true, "AC6",
+                    "Enable AC6 timing hooks that alter the game's presentation cadence");
+
+using Clock = std::chrono::steady_clock;
+
+namespace {
+
+std::mutex g_frame_mutex;
+double g_frame_time_ms{0.0};
+double g_fps{0.0};
+uint64_t g_frame_count{0};
+Clock::time_point g_frame_start{};
+
+bool AreTimingHooksActive() {
+    return REXCVAR_GET(ac6_timing_hooks_enabled) && REXCVAR_GET(ac6_unlock_fps);
+}
+
+}  // namespace
+
+bool ac6FlipIntervalHook() {
+    return AreTimingHooksActive();
+}
+
+bool ac6PresentIntervalHook(PPCRegister& r10) {
+    if (!AreTimingHooksActive()) {
+        return false;
+    }
+    r10.u64 = 1;
+    return true;
+}
+
+void ac6DeltaDivisorHook(PPCRegister& r29) {
+    if (!AreTimingHooksActive()) {
+        return;
+    }
+    r29.u64 = 30;
+}
+
+void ac6PresentTimingHook(PPCRegister& /*r31*/) {
+    ac6::d3d::OnFrameBoundary();
+
+    const auto now = Clock::now();
+    double frame_time_ms = 0.0;
+    double fps = 0.0;
+    uint64_t frame_count = 0;
+    {
+        std::lock_guard<std::mutex> lock(g_frame_mutex);
+        if (g_frame_start.time_since_epoch().count() != 0) {
+            g_frame_time_ms =
+                std::chrono::duration<double, std::milli>(now - g_frame_start).count();
+            g_fps = g_frame_time_ms > 0.0001 ? (1000.0 / g_frame_time_ms) : 0.0;
+            ++g_frame_count;
+        }
+        g_frame_start = now;
+        frame_time_ms = g_frame_time_ms;
+        fps = g_fps;
+        frame_count = g_frame_count;
+    }
+}
+
+namespace ac6 {
+
+FrameStats GetFrameStats() {
+    std::lock_guard<std::mutex> lock(g_frame_mutex);
+    return FrameStats{g_frame_time_ms, g_fps, g_frame_count};
+}
+
+}  // namespace ac6