From 93ed9b2f3b12b8b8d1483c5d8265edbd3e1332b4 Mon Sep 17 00:00:00 2001
From: sergystepanov <sergystepanov@gmail.com>
Date: Mon, 6 Jul 2026 17:27:08 +0300
Subject: [PATCH] Add RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK

---
 pkg/worker/caged/libretro/frontend.go          |  2 ++
 pkg/worker/caged/libretro/nanoarch/nanoarch.go | 11 +++++++++++
 pkg/worker/caged/libretro/nanoarch/nanoarch.h  |  5 +++++
 3 files changed, 18 insertions(+)

diff --git a/pkg/worker/caged/libretro/frontend.go b/pkg/worker/caged/libretro/frontend.go
index 6974d590..945a9a29 100644
--- a/pkg/worker/caged/libretro/frontend.go
+++ b/pkg/worker/caged/libretro/frontend.go
@@ -337,6 +337,8 @@ func (f *Frontend) Start() {
 		case <-f.done:
 			return
 		default:
+			f.nano.NotifyFrameTime(targetFrameTimeNs / 1000)
+
 			f.Tick()
 
 			now := os.Nanotime()
diff --git a/pkg/worker/caged/libretro/nanoarch/nanoarch.go b/pkg/worker/caged/libretro/nanoarch/nanoarch.go
index 1319cbd6..9ec2cbdc 100644
--- a/pkg/worker/caged/libretro/nanoarch/nanoarch.go
+++ b/pkg/worker/caged/libretro/nanoarch/nanoarch.go
@@ -40,6 +40,7 @@ type Nanoarch struct {
 	retropad InputState
 
 	keyboardCb    *C.struct_retro_keyboard_callback
+	frameTimeCb   *C.struct_retro_frame_time_callback
 	LastFrameTime time.Time
 	LibCo         bool
 	meta          Metadata
@@ -427,6 +428,12 @@ func (n *Nanoarch) Run() {
 	}
 }
 
+func (n *Nanoarch) NotifyFrameTime(usec int64) {
+	if n.frameTimeCb != nil {
+		C.call_frame_time_cb(n.frameTimeCb, C.retro_usec_t(usec))
+	}
+}
+
 func (n *Nanoarch) IsSupported() error                  { return graphics.RGFWTryInit() }
 func (n *Nanoarch) IsGL() bool                          { return n.Video.gl.enabled }
 func (n *Nanoarch) IsStopped() bool                     { return n.Stopped.Load() }
@@ -876,6 +883,10 @@ func coreEnvironment(cmd C.unsigned, data unsafe.Pointer) C.bool {
 		latency := *(*C.unsigned)(data)
 		Nan0.log.Info().Uint("latency_ms", uint(latency)).Msg("audio latency requested")
 		return true
+	case C.RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK:
+		Nan0.frameTimeCb = (*C.struct_retro_frame_time_callback)(data)
+		Nan0.log.Info().Msg("Frame time callback registered")
+		return true
 	}
 	return false
 }
diff --git a/pkg/worker/caged/libretro/nanoarch/nanoarch.h b/pkg/worker/caged/libretro/nanoarch/nanoarch.h
index 2479d0cf..66a6a879 100644
--- a/pkg/worker/caged/libretro/nanoarch/nanoarch.h
+++ b/pkg/worker/caged/libretro/nanoarch/nanoarch.h
@@ -41,4 +41,9 @@ static inline void call_audio_buffer_status(
 	if (cb && cb->callback) cb->callback(active, occupancy, underrun);
 }
 
+static inline void call_frame_time_cb(
+	struct retro_frame_time_callback *cb, retro_usec_t usec) {
+	if (cb && cb->callback) cb->callback(usec);
+}
+
 #endif