From 606015da82fb21ac5e0d8c154ade1114db3a96ce Mon Sep 17 00:00:00 2001
From: Denis <benato.denis96@gmail.com>
Date: Sun, 26 Nov 2023 18:22:31 +0100
Subject: [PATCH] Set the gain to 75% before emitting rumbles

---
 input_dev.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/input_dev.c b/input_dev.c
index 513bbc7..1162794 100644
--- a/input_dev.c
+++ b/input_dev.c
@@ -542,8 +542,6 @@ static void input_udev(
             }
         };
 
-        const int has_ff = libevdev_has_event_type(ctx->dev, EV_FF);
-
         // start the incoming events read thread
         pthread_t incoming_events_thread;
         const int incoming_events_thread_creation = pthread_create(&incoming_events_thread, NULL, input_read_thread_func, (void*)ctx);
@@ -552,6 +550,25 @@ static void input_udev(
             continue;
         }
 
+        const int has_ff = libevdev_has_event_type(ctx->dev, EV_FF);
+
+        if (has_ff) {
+            printf("Setting master gain to 75%%...\n");
+            
+            const struct input_event gain = {
+                .type = EV_FF,
+                .code = FF_GAIN,
+                .value = 0xC000, // [0, 0xFFFF])
+            };
+
+            const int gain_set_res = write(fd, (const void*)&gain, sizeof(gain));
+            if (gain_set_res != sizeof(gain)) {
+                fprintf(stderr, "Unable to adjust gain for force-feedback: %d\n", gain_set_res);
+            }
+        } else {
+            fprintf(stderr, "Unable to adjust gain for force-feedback: EV_FF not supported.\n");
+        }
+
         // while the incoming events thread run...
         while ((ctx->flags & INPUT_CTX_FLAGS_READ_TERMINATED) == 0) {
             if (has_ff) {
@@ -572,7 +589,7 @@ static void input_udev(
                         };
 
                         const int rumble_stop_res = write(fd, (const void*) &rumble_stop, sizeof(rumble_stop));
-                        if (rumble_stop_res < 0) {
+                        if (rumble_stop_res != sizeof(rumble_stop)) {
                             fprintf(stderr, "Unable to stop the previous rumble: %d\n", rumble_stop_res);
                         }
                     }
@@ -580,7 +597,7 @@ static void input_udev(
                     current_effect.u.rumble.strong_magnitude = rumble_msg->strong_magnitude;
                     current_effect.u.rumble.weak_magnitude = rumble_msg->weak_magnitude;
 
-                    printf("Rumble strong_magnitude: %u, weak_magnitude: %u\n", (unsigned)current_effect.u.rumble.strong_magnitude, (unsigned)current_effect.u.rumble.weak_magnitude);
+                    printf("Rumble event received -- strong_magnitude: %u, weak_magnitude: %u\n", (unsigned)current_effect.u.rumble.strong_magnitude, (unsigned)current_effect.u.rumble.weak_magnitude);
 
                     const int effect_upload_res = ioctl(fd, EVIOCSFF, &current_effect);
                     if (effect_upload_res == 0) {
@@ -590,8 +607,10 @@ static void input_udev(
                             .value = 1,
                         };
 
-                        const int effect_start_res = write(fd, (const void*) &rumble_play, sizeof(rumble_play));
-                        if (effect_start_res < 0) {
+                        const int effect_start_res = write(fd, (const void*)&rumble_play, sizeof(rumble_play));
+                        if (effect_start_res == sizeof(rumble_play)) {
+                            printf("Rumble effect play requested to driver\n");
+                        } else {
                             fprintf(stderr, "Unable to write input event starting the rumble: %d\n", effect_start_res);
                         }
                     } else {