New API for force the loading of a specific ROM file from script

input.cpp

@@ -2875,6 +2875,11 @@ void cmd_user_key(char*cmd)
   user_io_kbd(key, press);
 }
 
+void cmd_force_file(char*cmd)
+{
+  user_io_force_file(cmd);
+}
+
 struct cmdentry
 {
   const char * name;
@@ -2895,6 +2900,7 @@ void handle_MiSTer_cmd(char*cmd)
     {"enable_io",    cmd_en_io},
     {"enable_osd",   cmd_en_osd},
     {"fb_cmd",       video_cmd},
+    {"force_file",   cmd_force_file},
     {"fpga_set",     cmd_fpga_set},
     {"load_core",    cmd_load_rbf},
     {"user_joy",     cmd_user_joy},

user_io.cpp

@@ -1779,11 +1779,21 @@ static int process_ss(const char *rom_name)
 	return 1;
 }
 
+static char force_file[1024] = {0};
+int user_io_force_file(const char* name)
+{
+	strncpy(force_file, name, sizeof(force_file));
+	force_file[sizeof(force_file)-1] = '\0';
+	return 0;
+}
+
 int user_io_file_tx(const char* name, unsigned char index, char opensave, char mute, char composite)
 {
 	fileTYPE f = {};
 	static uint8_t buf[4096];
 
+	if (force_file[0] != '\0') name = force_file;
+
 	if (!FileOpen(&f, name, mute)) return 0;
 
 	unsigned long bytes2send = f.size;

user_io.h

@@ -261,6 +261,8 @@ void user_io_check_reset(unsigned short modifiers, char useKeys);
 
 void user_io_rtc_reset();
 
+int user_io_force_file(const char *);
+
 const char* get_rbf_dir();
 const char* get_rbf_name();
 const char* get_rbf_path();