// SPDX-License-Identifier: GPL-2.0#include <linux/console.h>#include <linux/types.h>#include <linux/wait.h> #include "speakup.h"#include "spk_priv.h" #define SYNTH_BUF_SIZE 8192	/* currently 8K bytes */ static u16 synth_buffer[SYNTH_BUF_SIZE];	/* guess what this is for! */static u16 *buff_in = synth_buffer;static u16 *buff_out = synth_buffer;static u16 *buffer_end = synth_buffer + SYNTH_BUF_SIZE - 1; /* These try to throttle applications by stopping the TTYs * Note: we need to make sure that we will restart them eventually, which is * usually not possible to do from the notifiers. TODO: it should be possible * starting from linux 2.6.26. * * So we only stop when we know alive == 1 (else we discard the data anyway), * and the alive synth will eventually call start_ttys from the thread context. */void speakup_start_ttys(void){	int i; 	for (i = 0; i < MAX_NR_CONSOLES; i++) {		if (speakup_console[i] && speakup_console[i]->tty_stopped)			continue;		if (vc_cons[i].d && vc_cons[i].d->port.tty)			start_tty(vc_cons[i].d->port.tty);	}}EXPORT_SYMBOL_GPL(speakup_start_ttys); static void speakup_stop_ttys(void){	int i; 	for (i = 0; i < MAX_NR_CONSOLES; i++)		if (vc_cons[i].d && vc_cons[i].d->port.tty)			stop_tty(vc_cons[i].d->port.tty);} static int synth_buffer_free(void){	int chars_free; 	if (buff_in >= buff_out)		chars_free = SYNTH_BUF_SIZE - (buff_in - buff_out);	else		chars_free = buff_out - buff_in;	return chars_free;} int synth_buffer_empty(void){	return (buff_in == buff_out);}EXPORT_SYMBOL_GPL(synth_buffer_empty); void synth_buffer_add(u16 ch){	if (!synth->alive) {		/* This makes sure that we won't stop TTYs if there is no synth		 * to restart them		 */		return;	}	if (synth_buffer_free() <= 100) {		synth_start();		speakup_stop_ttys();	}	if (synth_buffer_free() <= 1)		return;	*buff_in++ = ch;	if (buff_in > buffer_end)		buff_in = synth_buffer;	/* We have written something to the speech synthesis, so we are not	 * paused any more.	 */	spk_paused = false;} u16 synth_buffer_getc(void){	u16 ch; 	if (buff_out == buff_in)		return 0;	ch = *buff_out++;	if (buff_out > buffer_end)		buff_out = synth_buffer;	return ch;}EXPORT_SYMBOL_GPL(synth_buffer_getc); u16 synth_buffer_peek(void){	if (buff_out == buff_in)		return 0;	return *buff_out;}EXPORT_SYMBOL_GPL(synth_buffer_peek); void synth_buffer_skip_nonlatin1(void){	while (buff_out != buff_in) {		if (*buff_out < 0x100)			return;		buff_out++;		if (buff_out > buffer_end)			buff_out = synth_buffer;	}}EXPORT_SYMBOL_GPL(synth_buffer_skip_nonlatin1); void synth_buffer_clear(void){	buff_in = synth_buffer;	buff_out = synth_buffer;}EXPORT_SYMBOL_GPL(synth_buffer_clear);