PX4-Autopilot/src/lib/mixer/SimpleMixer.cpp

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/**
 * @file mixer_simple.cpp
 *
 * Simple summing mixer.
 */

#include "SimpleMixer.hpp"

#include <stdio.h>
#include <stdlib.h>

#define debug(fmt, args...)	do { } while(0)
//#define debug(fmt, args...)	do { printf("[mixer] " fmt "\n", ##args); } while(0)

SimpleMixer::SimpleMixer(ControlCallback control_cb, uintptr_t cb_handle, mixer_simple_s *mixinfo) :
	Mixer(control_cb, cb_handle),
	_pinfo(mixinfo)
{
}

SimpleMixer::~SimpleMixer()
{
	if (_pinfo != nullptr) {
		free(_pinfo);
	}
}

unsigned SimpleMixer::set_trim(float trim)
{
	_pinfo->output_scaler.offset = trim;
	return 1;
}

unsigned SimpleMixer::get_trim(float *trim)
{
	*trim = _pinfo->output_scaler.offset;
	return 1;
}

int
SimpleMixer::parse_output_scaler(const char *buf, unsigned &buflen, mixer_scaler_s &scaler)
{
	int ret;
	int s[5];
	int n = -1;

	buf = findtag(buf, buflen, 'O');

	if ((buf == nullptr) || (buflen < 12)) {
		debug("output parser failed finding tag, ret: '%s'", buf);
		return -1;
	}

	if ((ret = sscanf(buf, "O: %d %d %d %d %d %n",
			  &s[0], &s[1], &s[2], &s[3], &s[4], &n)) != 5) {
		debug("out scaler parse failed on '%s' (got %d, consumed %d)", buf, ret, n);
		return -1;
	}

	buf = skipline(buf, buflen);

	if (buf == nullptr) {
		debug("no line ending, line is incomplete");
		return -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;
}

int
SimpleMixer::parse_control_scaler(const char *buf, unsigned &buflen, mixer_scaler_s &scaler, uint8_t &control_group,
				  uint8_t &control_index)
{
	unsigned u[2];
	int s[5];

	buf = findtag(buf, buflen, 'S');

	if ((buf == nullptr) || (buflen < 16)) {
		debug("control parser failed finding tag, ret: '%s'", buf);
		return -1;
	}

	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) {
		debug("control parse failed on '%s'", buf);
		return -1;
	}

	buf = skipline(buf, buflen);

	if (buf == nullptr) {
		debug("no line ending, line is incomplete");
		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 *
SimpleMixer::from_text(Mixer::ControlCallback control_cb, uintptr_t cb_handle, const char *buf, unsigned &buflen)
{
	SimpleMixer *sm = nullptr;
	mixer_simple_s *mixinfo = nullptr;
	unsigned inputs;
	int used;
	const char *end = buf + buflen;
	char next_tag;

	/* enforce that the mixer ends with a new line */
	if (!string_well_formed(buf, buflen)) {
		return nullptr;
	}

	/* get the base info for the mixer */
	if (sscanf(buf, "M: %u%n", &inputs, &used) != 1) {
		debug("simple parse failed on '%s'", buf);
		goto out;
	}

	/* at least 1 input is required */
	if (inputs == 0) {
		debug("simple parse got 0 inputs");
		goto out;
	}

	buf = skipline(buf, buflen);

	if (buf == nullptr) {
		debug("no line ending, line is incomplete");
		goto out;
	}

	mixinfo = (mixer_simple_s *)malloc(MIXER_SIMPLE_SIZE(inputs));

	if (mixinfo == nullptr) {
		debug("could not allocate memory for mixer info");
		goto out;
	}

	mixinfo->control_count = inputs;

	/* find the next tag */
	next_tag = findnexttag(end - buflen, buflen);

	if (next_tag == 'S') {
		/* No output scalers specified. Use default values.
		 * Corresponds to:
		 * O:      10000  10000      0 -10000  10000
		 */
		mixinfo->output_scaler.negative_scale	= 1.0f;
		mixinfo->output_scaler.positive_scale	= 1.0f;
		mixinfo->output_scaler.offset		= 0.f;
		mixinfo->output_scaler.min_output	= -1.0f;
		mixinfo->output_scaler.max_output	= 1.0f;

	} else {
		if (parse_output_scaler(end - buflen, buflen, mixinfo->output_scaler)) {
			debug("simple mixer parser failed parsing out scaler tag, ret: '%s'", buf);
			goto out;
		}
	}

	for (unsigned i = 0; i < inputs; i++) {
		if (parse_control_scaler(end - buflen, buflen,
					 mixinfo->controls[i].scaler,
					 mixinfo->controls[i].control_group,
					 mixinfo->controls[i].control_index)) {
			debug("simple mixer parser failed parsing ctrl scaler tag, ret: '%s'", buf);
			goto out;
		}
	}

	sm = new SimpleMixer(control_cb, cb_handle, mixinfo);

	if (sm != nullptr) {
		mixinfo = nullptr;
		debug("loaded mixer with %d input(s)", inputs);

	} else {
		debug("could not allocate memory for mixer");
	}

out:

	if (mixinfo != nullptr) {
		free(mixinfo);
	}

	return sm;
}

unsigned
SimpleMixer::mix(float *outputs, unsigned space)
{
	float sum = 0.0f;

	if (_pinfo == nullptr) {
		return 0;
	}

	if (space < 1) {
		return 0;
	}

	for (unsigned i = 0; i < _pinfo->control_count; i++) {
		float input = 0.0f;

		_control_cb(_cb_handle,
			    _pinfo->controls[i].control_group,
			    _pinfo->controls[i].control_index,
			    input);

		sum += scale(_pinfo->controls[i].scaler, input);
	}

	*outputs = scale(_pinfo->output_scaler, sum);
	return 1;
}

void
SimpleMixer::groups_required(uint32_t &groups)
{
	for (unsigned i = 0; i < _pinfo->control_count; i++) {
		groups |= 1 << _pinfo->controls[i].control_group;
	}
}

int
SimpleMixer::check()
{
	float junk;

	/* sanity that presumes that a mixer includes a control no more than once */
	/* max of 32 groups due to groups_required API */
	if (_pinfo->control_count > 32) {
		return -2;
	}

	/* validate the output scaler */
	int ret = scale_check(_pinfo->output_scaler);

	if (ret != 0) {
		return ret;
	}

	/* validate input scalers */
	for (unsigned i = 0; i < _pinfo->control_count; i++) {

		/* verify that we can fetch the control */
		if (_control_cb(_cb_handle,
				_pinfo->controls[i].control_group,
				_pinfo->controls[i].control_index,
				junk) != 0) {
			return -3;
		}

		/* validate the scaler */
		ret = scale_check(_pinfo->controls[i].scaler);

		if (ret != 0) {
			return (10 * i + ret);
		}
	}

	return 0;
}

float
SimpleMixer::scale(const mixer_scaler_s &scaler, float input)
{
	float output;

	if (input < 0.0f) {
		output = (input * scaler.negative_scale) + scaler.offset;

	} else {
		output = (input * scaler.positive_scale) + scaler.offset;
	}

	return math::constrain(output, scaler.min_output, scaler.max_output);
}

int
SimpleMixer::scale_check(mixer_scaler_s &scaler)
{
	if (scaler.offset > 1.001f) {
		return 1;
	}

	if (scaler.offset < -1.001f) {
		return 2;
	}

	if (scaler.min_output > scaler.max_output) {
		return 3;
	}

	if (scaler.min_output < -1.001f) {
		return 4;
	}

	if (scaler.max_output > 1.001f) {
		return 5;
	}

	return 0;
}