Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / isdn / mISDN / dsp_ecdis.h

diff --git a/kernel/drivers/isdn/mISDN/dsp_ecdis.h b/kernel/drivers/isdn/mISDN/dsp_ecdis.h
new file mode 100644 (file)
index 0000000..fed99ac
--- /dev/null
+++ b/kernel/drivers/isdn/mISDN/dsp_ecdis.h
@@ -0,0 +1,110 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * ec_disable_detector.h - A detector which should eventually meet the
+ *                         G.164/G.165 requirements for detecting the
+ *                         2100Hz echo cancellor disable tone.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2001 Steve Underwood
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include "dsp_biquad.h"
+
+struct ec_disable_detector_state {
+       struct biquad2_state notch;
+       int notch_level;
+       int channel_level;
+       int tone_present;
+       int tone_cycle_duration;
+       int good_cycles;
+       int hit;
+};
+
+
+#define FALSE 0
+#define TRUE (!FALSE)
+
+static inline void
+echo_can_disable_detector_init(struct ec_disable_detector_state *det)
+{
+       /* Elliptic notch */
+       /* This is actually centred at 2095Hz, but gets the balance we want, due
+          to the asymmetric walls of the notch */
+       biquad2_init(&det->notch,
+                    (int32_t)(-0.7600000 * 32768.0),
+                    (int32_t)(-0.1183852 * 32768.0),
+                    (int32_t)(-0.5104039 * 32768.0),
+                    (int32_t)(0.1567596 * 32768.0),
+                    (int32_t)(1.0000000 * 32768.0));
+
+       det->channel_level = 0;
+       det->notch_level = 0;
+       det->tone_present = FALSE;
+       det->tone_cycle_duration = 0;
+       det->good_cycles = 0;
+       det->hit = 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+static inline int
+echo_can_disable_detector_update(struct ec_disable_detector_state *det,
+                                int16_t amp)
+{
+       int16_t notched;
+
+       notched = biquad2(&det->notch, amp);
+       /* Estimate the overall energy in the channel, and the energy in
+          the notch (i.e. overall channel energy - tone energy => noise).
+          Use abs instead of multiply for speed (is it really faster?).
+          Damp the overall energy a little more for a stable result.
+          Damp the notch energy a little less, so we don't damp out the
+          blip every time the phase reverses */
+       det->channel_level += ((abs(amp) - det->channel_level) >> 5);
+       det->notch_level += ((abs(notched) - det->notch_level) >> 4);
+       if (det->channel_level > 280) {
+               /* There is adequate energy in the channel.
+                  Is it mostly at 2100Hz? */
+               if (det->notch_level * 6 < det->channel_level) {
+                       /* The notch says yes, so we have the tone. */
+                       if (!det->tone_present) {
+                               /* Do we get a kick every 450+-25ms? */
+                               if (det->tone_cycle_duration >= 425 * 8
+                                   && det->tone_cycle_duration <= 475 * 8) {
+                                       det->good_cycles++;
+                                       if (det->good_cycles > 2)
+                                               det->hit = TRUE;
+                               }
+                               det->tone_cycle_duration = 0;
+                       }
+                       det->tone_present = TRUE;
+               } else
+                       det->tone_present = FALSE;
+               det->tone_cycle_duration++;
+       } else {
+               det->tone_present = FALSE;
+               det->tone_cycle_duration = 0;
+               det->good_cycles = 0;
+       }
+       return det->hit;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/