Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / staging / speakup / buffers.c

diff --git a/kernel/drivers/staging/speakup/buffers.c b/kernel/drivers/staging/speakup/buffers.c
new file mode 100644 (file)
index 0000000..d45c8af
--- /dev/null
+++ b/kernel/drivers/staging/speakup/buffers.c
@@ -0,0 +1,105 @@
+#include <linux/console.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include "speakup.h"
+#include "spk_priv.h"
+
+#define SYNTH_BUF_SIZE 8192    /* currently 8K bytes */
+
+static u_char synth_buffer[SYNTH_BUF_SIZE];    /* guess what this is for! */
+static u_char *buff_in = synth_buffer;
+static u_char *buff_out = synth_buffer;
+static u_char *buffer_end = synth_buffer + SYNTH_BUF_SIZE - 1;
+
+/* These try to throttle applications by stopping the TTYs
+ * Note: we need to make sure that we will restart them eventually, which is
+ * usually not possible to do from the notifiers. TODO: it should be possible
+ * starting from linux 2.6.26.
+ *
+ * So we only stop when we know alive == 1 (else we discard the data anyway),
+ * and the alive synth will eventually call start_ttys from the thread context.
+ */
+void speakup_start_ttys(void)
+{
+       int i;
+
+       for (i = 0; i < MAX_NR_CONSOLES; i++) {
+               if (speakup_console[i] && speakup_console[i]->tty_stopped)
+                       continue;
+               if ((vc_cons[i].d != NULL) && (vc_cons[i].d->port.tty != NULL))
+                       start_tty(vc_cons[i].d->port.tty);
+       }
+}
+EXPORT_SYMBOL_GPL(speakup_start_ttys);
+
+static void speakup_stop_ttys(void)
+{
+       int i;
+
+       for (i = 0; i < MAX_NR_CONSOLES; i++)
+               if ((vc_cons[i].d != NULL) && (vc_cons[i].d->port.tty != NULL))
+                       stop_tty(vc_cons[i].d->port.tty);
+}
+
+static int synth_buffer_free(void)
+{
+       int bytes_free;
+
+       if (buff_in >= buff_out)
+               bytes_free = SYNTH_BUF_SIZE - (buff_in - buff_out);
+       else
+               bytes_free = buff_out - buff_in;
+       return bytes_free;
+}
+
+int synth_buffer_empty(void)
+{
+       return (buff_in == buff_out);
+}
+EXPORT_SYMBOL_GPL(synth_buffer_empty);
+
+void synth_buffer_add(char ch)
+{
+       if (!synth->alive) {
+               /* This makes sure that we won't stop TTYs if there is no synth
+                * to restart them */
+               return;
+       }
+       if (synth_buffer_free() <= 100) {
+               synth_start();
+               speakup_stop_ttys();
+       }
+       if (synth_buffer_free() <= 1)
+               return;
+       *buff_in++ = ch;
+       if (buff_in > buffer_end)
+               buff_in = synth_buffer;
+}
+
+char synth_buffer_getc(void)
+{
+       char ch;
+
+       if (buff_out == buff_in)
+               return 0;
+       ch = *buff_out++;
+       if (buff_out > buffer_end)
+               buff_out = synth_buffer;
+       return ch;
+}
+EXPORT_SYMBOL_GPL(synth_buffer_getc);
+
+char synth_buffer_peek(void)
+{
+       if (buff_out == buff_in)
+               return 0;
+       return *buff_out;
+}
+EXPORT_SYMBOL_GPL(synth_buffer_peek);
+
+void synth_buffer_clear(void)
+{
+       buff_in = buff_out = synth_buffer;
+}
+EXPORT_SYMBOL_GPL(synth_buffer_clear);