1 files changed, 71 insertions, 0 deletions
diff --git a/third_party/pipewire/spa/utils/dll.h b/third_party/pipewire/spa/utils/dll.h
new file mode 100644
index 0000000000..65d8cd61de
--- /dev/null
+++ b/third_party/pipewire/spa/utils/dll.h
@@ -0,0 +1,71 @@
+/* Simple DLL
+ *
+ * Copyright © 2019 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef SPA_DLL_H
+#define SPA_DLL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stddef.h>
+#include <math.h>
+
+#define SPA_DLL_BW_MAX		0.128
+#define SPA_DLL_BW_MIN		0.016
+
+struct spa_dll {
+	double bw;
+	double z1, z2, z3;
+	double w0, w1, w2;
+};
+
+static inline void spa_dll_init(struct spa_dll *dll)
+{
+	dll->bw = 0.0;
+	dll->z1 = dll->z2 = dll->z3 = 0.0;
+}
+
+static inline void spa_dll_set_bw(struct spa_dll *dll, double bw, unsigned period, unsigned rate)
+{
+	double w = 2 * M_PI * bw * period / rate;
+	dll->w0 = 1.0 - exp (-20.0 * w);
+	dll->w1 = w * 1.5 / period;
+	dll->w2 = w / 1.5;
+	dll->bw = bw;
+}
+
+static inline double spa_dll_update(struct spa_dll *dll, double err)
+{
+	dll->z1 += dll->w0 * (dll->w1 * err - dll->z1);
+	dll->z2 += dll->w0 * (dll->z1 - dll->z2);
+	dll->z3 += dll->w2 * dll->z2;
+	return 1.0 - (dll->z2 + dll->z3);
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* SPA_DLL_H */