linux/drivers/accessibility/speakup/speakup_dtlk.h

/* SPDX-License-Identifier: GPL-2.0 */
/* speakup_dtlk.h - header file for speakups DoubleTalk driver. */

#define SYNTH_IO_EXTENT …
#define SYNTH_CLEAR …
	/* TTS Port Status Flags */
#define TTS_READABLE …
#define TTS_SPEAKING …
#define TTS_SPEAKING2 …
#define TTS_WRITABLE …
#define TTS_ALMOST_FULL …
#define TTS_ALMOST_EMPTY …

				/* data returned by Interrogate command */
struct synth_settings { … };