1 files changed, 70 insertions, 0 deletions
diff --git a/spa/plugins/audioconvert/crossover.c b/spa/plugins/audioconvert/crossover.c
new file mode 100644
index 0000000..7575833
--- /dev/null
+++ b/spa/plugins/audioconvert/crossover.c
@@ -0,0 +1,70 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <float.h>
+#include <string.h>
+
+#include "crossover.h"
+
+void lr4_set(struct lr4 *lr4, enum biquad_type type, float freq)
+{
+	biquad_set(&lr4->bq, type, freq);
+	lr4->x1 = 0;
+	lr4->x2 = 0;
+	lr4->y1 = 0;
+	lr4->y2 = 0;
+	lr4->z1 = 0;
+	lr4->z2 = 0;
+	lr4->active = true;
+}
+
+void lr4_process(struct lr4 *lr4, float *dst, const float *src, const float vol, int samples)
+{
+	float lx1 = lr4->x1;
+	float lx2 = lr4->x2;
+	float ly1 = lr4->y1;
+	float ly2 = lr4->y2;
+	float lz1 = lr4->z1;
+	float lz2 = lr4->z2;
+	float lb0 = lr4->bq.b0;
+	float lb1 = lr4->bq.b1;
+	float lb2 = lr4->bq.b2;
+	float la1 = lr4->bq.a1;
+	float la2 = lr4->bq.a2;
+	int i;
+
+	if (vol == 0.0f) {
+		memset(dst, 0, samples * sizeof(float));
+		return;
+	} else if (!lr4->active) {
+		if (src != dst || vol != 1.0f) {
+			for (i = 0; i < samples; i++)
+				dst[i] = src[i] * vol;
+		}
+		return;
+	}
+
+	for (i = 0; i < samples; i++) {
+		float x, y, z;
+		x = src[i];
+		y = lb0*x + lb1*lx1 + lb2*lx2 - la1*ly1 - la2*ly2;
+		z = lb0*y + lb1*ly1 + lb2*ly2 - la1*lz1 - la2*lz2;
+		lx2 = lx1;
+		lx1 = x;
+		ly2 = ly1;
+		ly1 = y;
+		lz2 = lz1;
+		lz1 = z;
+		dst[i] = z * vol;
+	}
+#define F(x) (-FLT_MIN < (x) && (x) < FLT_MIN ? 0.0f : (x))
+	lr4->x1 = F(lx1);
+	lr4->x2 = F(lx2);
+	lr4->y1 = F(ly1);
+	lr4->y2 = F(ly2);
+	lr4->z1 = F(lz1);
+	lr4->z2 = F(lz2);
+#undef F
+}