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

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