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);
125