From 681b65aa0b68c9e7a686de2d6ca0c18c61cb444b Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 8 Apr 2016 18:07:45 +0200
Subject: Add a fixed (not de-clicked) multi-buffer audio/midi delayline.

A ringbuffer intended to be used for plugin-thru/bypass
latency compensation.
---
 libs/ardour/fixed_delay.cc | 132 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 libs/ardour/fixed_delay.cc

(limited to 'libs/ardour/fixed_delay.cc')

diff --git a/libs/ardour/fixed_delay.cc b/libs/ardour/fixed_delay.cc
new file mode 100644
index 0000000000..d59619cdf9
--- /dev/null
+++ b/libs/ardour/fixed_delay.cc
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2016 Robin Gareus <robin@gareus.org>
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include "ardour/audio_buffer.h"
+#include "ardour/buffer_set.h"
+#include "ardour/fixed_delay.h"
+#include "ardour/midi_buffer.h"
+
+using namespace ARDOUR;
+
+FixedDelay::FixedDelay ()
+	: _max_delay (0)
+	, _delay (0)
+	, _pending_flush (false)
+{
+	for (size_t i = 0; i < DataType::num_types; ++i) {
+		_buffers.push_back (BufferVec ());
+	}
+	_count.reset ();
+}
+
+FixedDelay::~FixedDelay ()
+{
+	clear ();
+}
+
+void
+FixedDelay::configure (const ChanCount& count, framecnt_t max_delay)
+{
+	if (max_delay <= _max_delay || count <= _count) {
+		return;
+	}
+	_max_delay = std::max (_max_delay, max_delay);
+	for (DataType::iterator i = DataType::begin (); i != DataType::end (); ++i) {
+		ensure_buffers (*i, count.get (*i), _max_delay + 1);
+	}
+}
+
+void
+FixedDelay::set (const ChanCount& count, framecnt_t delay)
+{
+	configure (count, delay);
+	_delay = delay;
+}
+
+void
+FixedDelay::ensure_buffers (DataType type, size_t num_buffers, size_t buffer_capacity)
+{
+	assert (type != DataType::NIL);
+	assert (type < _buffers.size ());
+	if (num_buffers == 0) {
+		return;
+	}
+	BufferVec& bufs = _buffers[type];
+	if (bufs.size () < num_buffers || (bufs.size () > 0 && bufs[0]->buf->capacity () < buffer_capacity)) {
+		for (BufferVec::iterator i = bufs.begin (); i != bufs.end (); ++i) {
+			delete (*i);
+		}
+		bufs.clear ();
+		for (size_t i = 0; i < num_buffers; ++i) {
+			bufs.push_back (new DelayBuffer (type, buffer_capacity));
+		}
+		_count.set (type, num_buffers);
+	}
+}
+
+void
+FixedDelay::clear ()
+{
+	for (std::vector<BufferVec>::iterator i = _buffers.begin (); i != _buffers.end (); ++i) {
+		for (BufferVec::iterator j = (*i).begin (); j != (*i).end (); ++j) {
+			delete *j;
+		}
+		(*i).clear ();
+	}
+	_buffers.clear ();
+	_count.reset ();
+}
+
+void
+FixedDelay::delay (
+		ARDOUR::DataType dt, uint32_t id,
+		Buffer& out, const Buffer& in,
+		pframes_t n_frames,
+		framecnt_t dst_offset, framecnt_t src_offset)
+{
+	if (_delay == 0) {
+		out.read_from (in, n_frames, dst_offset, src_offset);
+		return;
+	}
+
+	assert (dt < _buffers.size ());
+	assert (id < _buffers[dt].size ());
+	DelayBuffer *db = _buffers[dt][id];
+
+	if (db->pos + n_frames > _max_delay) {
+		uint32_t w0 = _max_delay - db->pos;
+		uint32_t w1 = db->pos + n_frames - _max_delay;
+		db->buf->read_from (in, w0, db->pos, src_offset);
+		db->buf->read_from (in, w1, 0, src_offset + w0);
+	} else {
+		db->buf->read_from (in, n_frames, db->pos, src_offset);
+	}
+
+	uint32_t rp = (db->pos + _max_delay - _delay) % _max_delay;
+
+	if (rp + n_frames > _max_delay) {
+		uint32_t r0 = _max_delay - rp;
+		uint32_t r1 = rp + n_frames - _max_delay;
+		out.read_from (*db->buf, r0, dst_offset, rp);
+		out.read_from (*db->buf, r1, dst_offset + r0, 0);
+	} else {
+		out.read_from (*db->buf, n_frames, dst_offset, rp);
+	}
+
+	db->pos = (db->pos + n_frames) % _max_delay;
+}
-- 
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