devintrf.c: add devtag_get_device(machine, type, tag) to retrieve the device_config for (type, tag)

* This is needed, if you need to read a device or device status outside a AM_DEVREAD context.

src/emu/devintrf.c

@@ -590,6 +590,26 @@ void *devtag_get_token(running_machine *machine, device_type type, const char *t
 }
 
 
+/*-------------------------------------------------
+    devtag_get_device - return the device associated
+    with a tag
+-------------------------------------------------*/
+
+const device_config *devtag_get_device(running_machine *machine, device_type type, const char *tag)
+{
+	const device_config *device;
+
+	assert(machine != NULL);
+	assert(type != NULL);
+	assert(tag != NULL);
+
+	device = device_list_find_by_tag(machine->config->devicelist, type, tag);
+	if (device == NULL)
+		fatalerror("devtag_get_device failed to find device: type=%s tag=%s\n", devtype_name(type), tag);
+	return device;
+}
+
+
 /*-------------------------------------------------
     devtag_get_static_config - return a pointer to
     the static configuration for a device based on

src/emu/devintrf.h

@@ -254,6 +254,9 @@ void devtag_reset(running_machine *machine, device_type type, const char *tag);
 
 /* ----- device information getters ----- */
 
+/* return the device associated with a tag */
+const device_config *devtag_get_device(running_machine *machine, device_type type, const char *tag);
+
 /* return the token associated with an allocated device */
 void *devtag_get_token(running_machine *machine, device_type type, const char *tag);