LXR linux/drivers/accessibility/speakup/buffers.c

   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