drivers/staging/speakup/buffers.c

   1 #include <linux/console.h>
   2 #include <linux/smp_lock.h>
   3 #include <linux/types.h>
   4 #include <linux/wait.h>
   5
   6 #include "speakup.h"
   7 #include "spk_priv.h"
   8
   9 #define synthBufferSize 8192    /* currently 8K bytes */
  10
  11 static u_char synth_buffer[synthBufferSize];    /* guess what this is for! */
  12 static u_char *buff_in = synth_buffer;
  13 static u_char *buff_out = synth_buffer;
  14 static u_char *buffer_end = synth_buffer+synthBufferSize-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  */
  24 void 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 != NULL) && (vc_cons[i].d->port.tty != NULL))
  32                         start_tty(vc_cons[i].d->port.tty);
  33         }
  34 }
  35 EXPORT_SYMBOL_GPL(speakup_start_ttys);
  36
  37 static 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 != NULL) && (vc_cons[i].d->port.tty != NULL))
  43                         stop_tty(vc_cons[i].d->port.tty);
  44 }
  45
  46 static int synth_buffer_free(void)
  47 {
  48         int bytesFree;
  49
  50         if (buff_in >= buff_out)
  51                 bytesFree = synthBufferSize - (buff_in - buff_out);
  52         else
  53                 bytesFree = buff_out - buff_in;
  54         return bytesFree;
  55 }
  56
  57 int synth_buffer_empty(void)
  58 {
  59         return (buff_in == buff_out);
  60 }
  61 EXPORT_SYMBOL_GPL(synth_buffer_empty);
  62
  63 void synth_buffer_add(char 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                 return;
  69         }
  70         if (synth_buffer_free() <= 100) {
  71                 synth_start();
  72                 speakup_stop_ttys();
  73         }
  74         if (synth_buffer_free() <= 1)
  75                 return;
  76         *buff_in++ = ch;
  77         if (buff_in > buffer_end)
  78                 buff_in = synth_buffer;
  79 }
  80
  81 char synth_buffer_getc(void)
  82 {
  83         char ch;
  84
  85         if (buff_out == buff_in)
  86                 return 0;
  87         ch = *buff_out++;
  88         if (buff_out > buffer_end)
  89                 buff_out = synth_buffer;
  90         return ch;
  91 }
  92 EXPORT_SYMBOL_GPL(synth_buffer_getc);
  93
  94 char synth_buffer_peek(void)
  95 {
  96         if (buff_out == buff_in)
  97                 return 0;
  98         return *buff_out;
  99 }
 100 EXPORT_SYMBOL_GPL(synth_buffer_peek);
 101
 102 void synth_buffer_clear(void)
 103 {
 104         buff_in = buff_out = synth_buffer;
 105         return;
 106 }
 107 EXPORT_SYMBOL_GPL(synth_buffer_clear);