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path: root/drivers/accessibility/speakup/buffers.c
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-rw-r--r--drivers/accessibility/speakup/buffers.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/drivers/accessibility/speakup/buffers.c b/drivers/accessibility/speakup/buffers.c
new file mode 100644
index 0000000000..1371ced2f5
--- /dev/null
+++ b/drivers/accessibility/speakup/buffers.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+#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 u16 synth_buffer[SYNTH_BUF_SIZE]; /* guess what this is for! */
+static u16 *buff_in = synth_buffer;
+static u16 *buff_out = synth_buffer;
+static u16 *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 && vc_cons[i].d->port.tty)
+ 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 && vc_cons[i].d->port.tty)
+ stop_tty(vc_cons[i].d->port.tty);
+}
+
+static int synth_buffer_free(void)
+{
+ int chars_free;
+
+ if (buff_in >= buff_out)
+ chars_free = SYNTH_BUF_SIZE - (buff_in - buff_out);
+ else
+ chars_free = buff_out - buff_in;
+ return chars_free;
+}
+
+int synth_buffer_empty(void)
+{
+ return (buff_in == buff_out);
+}
+EXPORT_SYMBOL_GPL(synth_buffer_empty);
+
+void synth_buffer_add(u16 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;
+ /* We have written something to the speech synthesis, so we are not
+ * paused any more.
+ */
+ spk_paused = false;
+}
+
+u16 synth_buffer_getc(void)
+{
+ u16 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);
+
+u16 synth_buffer_peek(void)
+{
+ if (buff_out == buff_in)
+ return 0;
+ return *buff_out;
+}
+EXPORT_SYMBOL_GPL(synth_buffer_peek);
+
+void synth_buffer_skip_nonlatin1(void)
+{
+ while (buff_out != buff_in) {
+ if (*buff_out < 0x100)
+ return;
+ buff_out++;
+ if (buff_out > buffer_end)
+ buff_out = synth_buffer;
+ }
+}
+EXPORT_SYMBOL_GPL(synth_buffer_skip_nonlatin1);
+
+void synth_buffer_clear(void)
+{
+ buff_in = synth_buffer;
+ buff_out = synth_buffer;
+}
+EXPORT_SYMBOL_GPL(synth_buffer_clear);