1 files changed, 125 insertions, 0 deletions
diff --git a/src/libjitter/jitter.c b/src/libjitter/jitter.c
new file mode 100644
index 0000000..c3af715
--- /dev/null
+++ b/src/libjitter/jitter.c
@@ -0,0 +1,125 @@
+/* Jitter buffering functions
+ *
+ * (C) 2016 by Andreas Eversberg <jolly@eversberg.eu>
+ * All Rights Reserved
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <math.h>
+#include "../libsample/sample.h"
+#include "../libdebug/debug.h"
+#include "jitter.h"
+
+/* create jitter buffer */
+int jitter_create(jitter_t *jitter, int length)
+{
+	memset(jitter, 0, sizeof(*jitter));
+	jitter->spl = malloc(length * sizeof(sample_t));
+	if (!jitter->spl) {
+		PDEBUG(DDSP, DEBUG_ERROR, "No memory for jitter buffer.\n");
+		return -ENOMEM;
+	}
+	jitter->len = length;
+
+	jitter_reset(jitter);
+
+	return 0;
+}
+
+void jitter_reset(jitter_t *jitter)
+{
+	memset(jitter->spl, 0, jitter->len * sizeof(sample_t));
+
+	/* put write pointer ahead by half of the buffer length */
+	jitter->inptr = jitter->len / 2;
+}
+
+void jitter_destroy(jitter_t *jitter)
+{
+	if (jitter->spl) {
+		free(jitter->spl);
+		jitter->spl = NULL;
+	}
+}
+
+/* store audio in jitterbuffer
+ *
+ * stop if buffer is completely filled
+ */
+void jitter_save(jitter_t *jb, sample_t *samples, int length)
+{
+	sample_t *spl;
+	int inptr, outptr, len, space;
+	int i;
+
+	spl = jb->spl;
+	inptr = jb->inptr;
+	outptr = jb->outptr;
+	len = jb->len;
+	space = (outptr - inptr + len - 1) % len;
+
+	if (space < length)
+		length = space;
+	for (i = 0; i < length; i++) {
+		spl[inptr++] = *samples++;
+		if (inptr == len)
+			inptr = 0;
+	}
+
+	jb->inptr = inptr;
+}
+
+/* get audio from jitterbuffer
+ */
+void jitter_load(jitter_t *jb, sample_t *samples, int length)
+{
+	sample_t *spl;
+	int inptr, outptr, len, fill;
+	int i, ii;
+
+	spl = jb->spl;
+	inptr = jb->inptr;
+	outptr = jb->outptr;
+	len = jb->len;
+	fill = (inptr - outptr + len) % len;
+
+	if (fill < length)
+		ii = fill;
+	else
+		ii = length;
+
+	/* fill what we got */
+	for (i = 0; i < ii; i++) {
+		*samples++ = spl[outptr++];
+		if (outptr == len)
+			outptr = 0;
+	}
+	/* on underrun, fill with silence */
+	for (; i < length; i++) {
+		*samples++ = 0;
+	}
+
+	jb->outptr = outptr;
+}
+
+void jitter_clear(jitter_t *jb)
+{
+	jb->inptr = jb->outptr = 0;
+}
+