1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/console.h>
  3#include <linux/types.h>
  4#include <linux/wait.h>
  5
  6#include "speakup.h"
  7#include "spk_priv.h"
  8
  9#define SYNTH_BUF_SIZE 8192	/* currently 8K bytes */
 10
 11static u16 synth_buffer[SYNTH_BUF_SIZE];	/* guess what this is for! */
 12static u16 *buff_in = synth_buffer;
 13static u16 *buff_out = synth_buffer;
 14static u16 *buffer_end = synth_buffer + SYNTH_BUF_SIZE - 1;
 15
 16/* These try to throttle applications by stopping the TTYs
 17 * Note: we need to make sure that we will restart them eventually, which is
 18 * usually not possible to do from the notifiers. TODO: it should be possible
 19 * starting from linux 2.6.26.
 20 *
 21 * So we only stop when we know alive == 1 (else we discard the data anyway),
 22 * and the alive synth will eventually call start_ttys from the thread context.
 23 */
 24void speakup_start_ttys(void)
 25{
 26	int i;
 27
 28	for (i = 0; i < MAX_NR_CONSOLES; i++) {
 29		if (speakup_console[i] && speakup_console[i]->tty_stopped)
 30			continue;
 31		if (vc_cons[i].d && vc_cons[i].d->port.tty)
 32			start_tty(vc_cons[i].d->port.tty);
 33	}
 34}
 35EXPORT_SYMBOL_GPL(speakup_start_ttys);
 36
 37static void speakup_stop_ttys(void)
 38{
 39	int i;
 40
 41	for (i = 0; i < MAX_NR_CONSOLES; i++)
 42		if (vc_cons[i].d && vc_cons[i].d->port.tty)
 43			stop_tty(vc_cons[i].d->port.tty);
 44}
 45
 46static int synth_buffer_free(void)
 47{
 48	int chars_free;
 49
 50	if (buff_in >= buff_out)
 51		chars_free = SYNTH_BUF_SIZE - (buff_in - buff_out);
 52	else
 53		chars_free = buff_out - buff_in;
 54	return chars_free;
 55}
 56
 57int synth_buffer_empty(void)
 58{
 59	return (buff_in == buff_out);
 60}
 61EXPORT_SYMBOL_GPL(synth_buffer_empty);
 62
 63void synth_buffer_add(u16 ch)
 64{
 65	if (!synth->alive) {
 66		/* This makes sure that we won't stop TTYs if there is no synth
 67		 * to restart them
 68		 */
 69		return;
 70	}
 71	if (synth_buffer_free() <= 100) {
 72		synth_start();
 73		speakup_stop_ttys();
 74	}
 75	if (synth_buffer_free() <= 1)
 76		return;
 77	*buff_in++ = ch;
 78	if (buff_in > buffer_end)
 79		buff_in = synth_buffer;
 80	/* We have written something to the speech synthesis, so we are not
 81	 * paused any more.
 82	 */
 83	spk_paused = false;
 84}
 85
 86u16 synth_buffer_getc(void)
 87{
 88	u16 ch;
 89
 90	if (buff_out == buff_in)
 91		return 0;
 92	ch = *buff_out++;
 93	if (buff_out > buffer_end)
 94		buff_out = synth_buffer;
 95	return ch;
 96}
 97EXPORT_SYMBOL_GPL(synth_buffer_getc);
 98
 99u16 synth_buffer_peek(void)
100{
101	if (buff_out == buff_in)
102		return 0;
103	return *buff_out;
104}
105EXPORT_SYMBOL_GPL(synth_buffer_peek);
106
107void synth_buffer_skip_nonlatin1(void)
108{
109	while (buff_out != buff_in) {
110		if (*buff_out < 0x100)
111			return;
112		buff_out++;
113		if (buff_out > buffer_end)
114			buff_out = synth_buffer;
115	}
116}
117EXPORT_SYMBOL_GPL(synth_buffer_skip_nonlatin1);
118
119void synth_buffer_clear(void)
120{
121	buff_in = synth_buffer;
122	buff_out = synth_buffer;
123}
124EXPORT_SYMBOL_GPL(synth_buffer_clear);