Rework the mixer architecture based on discussions about arbitrary geometry mixing and plugins.

Now the mixer is a C++ library that can be fairly easily bolted into an output driver to provide mixing services.

Teach the FMU driver how to use it as an example.  More testing is still required.

1 files changed, 288 insertions, 0 deletions

diff --git a/apps/systemlib/mixer/mixer_group.cpp b/apps/systemlib/mixer/mixer_group.cpp
new file mode 100644
index 000000000..72a2ff3e5
--- /dev/null
+++ b/apps/systemlib/mixer/mixer_group.cpp
@@ -0,0 +1,288 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file mixer_group.cpp
+ *
+ * Mixer collection.
+ */
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <errno.h>
+#include <stdio.h>
+#include <math.h>
+#include <unistd.h>
+
+#include "mixer.h"
+
+namespace
+{
+
+/**
+ * Effectively fdgets() with some extra smarts.
+ */
+static int
+mixer_getline(int fd, char *line, unsigned maxlen)
+{
+	/* reduce line budget by 1 to account for terminal NUL */
+	maxlen--;
+
+	/* loop looking for a non-comment line */
+	for (;;) {
+		int	ret;
+		char	c;
+		char	*p = line;
+
+		/* loop reading characters for this line */
+		for (;;) {
+			ret = read(fd, &c, 1);
+
+			/* on error or EOF, return same */
+			if (ret <= 0)
+				return ret;
+
+			/* ignore carriage returns */
+			if (c == '\r')
+				continue;
+
+			/* line termination */
+			if (c == '\n') {
+				/* ignore malformed lines */
+				if ((p - line) < 4)
+					break;
+
+				if (line[1] != ':')
+					break;
+
+				/* terminate line as string and return */
+				*p = '\0';
+				return 1;
+			}
+
+			/* if we have space, accumulate the byte and go on */
+			if ((p - line) < maxlen)
+				*p++ = c;
+		}
+	}
+}
+
+/**
+ * Parse a scaler from the buffer.
+ */
+static int
+mixer_parse_scaler(const char *buf, mixer_scaler_s &scaler, uint8_t &control_group, uint8_t &control_index)
+{
+	unsigned u[2];
+	int s[5];
+
+	if (sscanf(buf, "S: %u %u %d %d %d %d %d",
+		   &u[0], &u[1], &s[0], &s[1], &s[2], &s[3], &s[4]) != 7)
+		return -1;
+
+	control_group	= u[0];
+	control_index	= u[1];
+	scaler.negative_scale	= s[0] / 10000.0f;
+	scaler.positive_scale	= s[1] / 10000.0f;
+	scaler.offset		= s[2] / 10000.0f;
+	scaler.min_output	= s[3] / 10000.0f;
+	scaler.max_output	= s[4] / 10000.0f;
+
+	return 0;
+}
+
+SimpleMixer *
+mixer_load_simple(Mixer::ControlCallback control_cb, uintptr_t cb_handle, int fd, unsigned inputs)
+{
+	mixer_simple_s	*mixinfo = nullptr;
+	char		buf[60];
+	uint8_t		control_group, control_index;
+	int		ret;
+
+	/* let's assume we're going to read a simple mixer */
+	mixinfo = (mixer_simple_s *)malloc(MIXER_SIMPLE_SIZE(inputs));
+
+	/* first, get the output scaler */
+	ret = mixer_getline(fd, buf, sizeof(buf));
+	if (ret < 1)
+		goto fail;
+	if (mixer_parse_scaler(buf, mixinfo->output_scaler, control_group, control_index))
+		goto fail;
+
+	/* now get any inputs */
+	for (unsigned i = 0; i < inputs; i++) {
+		ret = mixer_getline(fd, buf, sizeof(buf));
+		if (ret < 1)
+			goto fail;
+		if (mixer_parse_scaler(buf, 
+				       mixinfo->inputs[i].scaler,
+				       mixinfo->inputs[i].control_group,
+				       mixinfo->inputs[i].control_index)) {
+			goto fail;
+		}
+	}
+
+	/* XXX should be a factory that validates the mixinfo ... */
+	return new SimpleMixer(control_cb, cb_handle, mixinfo);
+
+fail:
+	free(mixinfo);
+	return nullptr;
+}
+
+int
+mixer_load(Mixer::ControlCallback control_cb, uintptr_t cb_handle, int fd, Mixer *&mixer)
+{
+	int		ret;
+	char		buf[60];
+	unsigned	scalers;
+
+	ret = mixer_getline(fd, buf, sizeof(buf));
+
+	/* end of file or error ?*/
+	if (ret < 1)
+		return ret;
+
+	/* slot is empty - allocate a null mixer */
+	if (buf[0] == 'Z') {
+		mixer = new NullMixer();
+		return 0;
+	}
+
+	/* is it a simple mixer? */
+	if (sscanf(buf, "M: %u", &scalers) == 1) {
+		mixer = mixer_load_simple(control_cb, cb_handle, fd, scalers);
+		return (mixer == nullptr) ? -1 : 0;
+	}
+
+	/* we don't recognise the mixer type */
+	return -1;
+}
+
+
+} // namespace
+
+MixerGroup::MixerGroup(ControlCallback control_cb, uintptr_t cb_handle) :
+	Mixer(control_cb, cb_handle),
+	_first(nullptr)
+{
+}
+
+MixerGroup::~MixerGroup()
+{
+	Mixer *mixer;
+
+	/* discard sub-mixers */
+	while (_first != nullptr) {
+		mixer = _first;
+		_first = mixer->_next;
+		delete mixer;
+	}
+}
+
+void
+MixerGroup::add_mixer(Mixer *mixer)
+{
+	Mixer **mpp;
+
+	mpp = &_first;
+	while (*mpp != nullptr)
+		mpp = &((*mpp)->_next);
+	*mpp = mixer;
+	mixer->_next = nullptr;
+}
+
+unsigned
+MixerGroup::mix(float *outputs, unsigned space)
+{
+	Mixer	*mixer = _first;
+	unsigned index = 0;
+
+	while ((mixer != nullptr) && (index < space)) {
+		index += mixer->mix(outputs + index, space - index);
+		mixer = mixer->_next;
+	}
+	return index;
+}
+
+void
+MixerGroup::groups_required(uint32_t &groups)
+{
+	Mixer	*mixer = _first;
+
+	while (mixer != nullptr) {
+		mixer->groups_required(groups);
+		mixer = mixer->_next;
+	}
+}
+
+int
+MixerGroup::load_from_file(const char *path)
+{
+	if (_first != nullptr)
+		return -1;
+
+	int fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	for (;;) {
+		int	result;
+		Mixer	*mixer;
+
+		result = mixer_load(_control_cb,
+				    _cb_handle,
+				    fd,
+				    mixer);
+
+		/* error? */
+		if (result < 0)
+			return -1;
+
+		/* EOF or error */
+		if (result < 1)
+			break;
+
+		add_mixer(mixer);
+	}
+
+	close(fd);
+	return 0;
+}