Add rewind granularity. (Faster, but less accurate rewind.)

config.def.h

@@ -153,6 +153,9 @@ static const bool rewind_enable = false;
 // The buffer size for the rewind buffer. This needs to be about 15-20MB per minute. Very game dependant.
 static const unsigned rewind_buffer_size = 20 << 20; // 20MiB
 
+// How many frames to rewind at a time.
+static const unsigned rewind_granularity = 1;
+
 
 
 

general.h

@@ -88,6 +88,7 @@ struct settings
 
    bool rewind_enable;
    unsigned rewind_buffer_size;
+   unsigned rewind_granularity;
 };
 
 enum ssnes_game_type

settings.c

@@ -126,6 +126,7 @@ static void set_defaults(void)
 
    g_settings.rewind_enable = rewind_enable;
    g_settings.rewind_buffer_size = rewind_buffer_size;
+   g_settings.rewind_granularity = rewind_granularity;
 
    assert(sizeof(g_settings.input.binds[0]) >= sizeof(snes_keybinds_1));
    assert(sizeof(g_settings.input.binds[1]) >= sizeof(snes_keybinds_2));
@@ -314,6 +315,7 @@ static void parse_config_file(void)
 
    CONFIG_GET_BOOL(rewind_enable, "rewind_enable");
    CONFIG_GET_INT(rewind_buffer_size, "rewind_buffer_size");
+   CONFIG_GET_INT(rewind_granularity, "rewind_granularity");
 
    read_keybinds(conf);
 

ssnes.c

@@ -826,14 +826,17 @@ static void check_rewind(void)
          g_extern.frame_is_reverse = true;
       }
       else
-      {
          msg_queue_push(g_extern.msg_queue, "Reached end of rewind buffer!", 0, 30);
-      }
    }
    else
    {
-      snes_serialize(g_extern.state_buf, snes_serialize_size());
-      state_manager_push(g_extern.state_manager, g_extern.state_buf);
+      static unsigned cnt = 0;
+      cnt = (cnt + 1) % (g_settings.rewind_granularity ? g_settings.rewind_granularity : 1); // Avoid possible SIGFPE.
+      if (cnt == 0)
+      {
+         snes_serialize(g_extern.state_buf, snes_serialize_size());
+         state_manager_push(g_extern.state_manager, g_extern.state_buf);
+      }
    }
 }
 

ssnes.cfg

@@ -199,6 +199,9 @@
 # The buffer should be approx. 20MB per minute of buffer time.
 # rewind_buffer_size = 20
 
+# Rewind granularity. When rewinding defined number of frames, you can rewind several frames at a time, increasing the rewinding speed.
+# rewind_granularity = 1
+
 # Hold button down to rewind. Rewinding must be enabled.
 # input_rewind = r