px4_autopilot/apps/systemlib/mixer/mixer_simple.cpp

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

#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 <ctype.h>

#include "mixer.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),
	_info(mixinfo)
{
}

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

static const char *
findtag(const char *buf, unsigned &buflen, char tag)
{
	while (buflen >= 2) {
		if ((buf[0] == tag) && (buf[1] == ':'))
			return buf;
		buf++;
		buflen--;
	}
	return nullptr;
}

static void
skipline(const char *buf, unsigned &buflen)
{
	const char *p;

	/* if we can find a CR or NL in the buffer, skip up to it */
	if ((p = (const char *)memchr(buf, '\r', buflen)) || (p = (const char *)memchr(buf, '\n', buflen)))
		buflen -= (p - buf);
}

int
SimpleMixer::parse_output_scaler(const char *buf, unsigned &buflen, mixer_scaler_s &scaler)
{
	int ret;
	int s[5];
	
	buf = findtag(buf, buflen, 'O');
	if ((buf == nullptr) || (buflen < 12))
		return -1;

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

	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))
		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;
	}
	skipline(buf, buflen);

	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;

	/* 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;
	}

	buflen -= used;

	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;

	if (parse_output_scaler(end - buflen, buflen, mixinfo->output_scaler))
		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))
			goto out;
	}

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

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

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

out:

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

	return sm;
}

SimpleMixer *
SimpleMixer::pwm_input(Mixer::ControlCallback control_cb, uintptr_t cb_handle, unsigned input, uint16_t min, uint16_t mid, uint16_t max)
{
	SimpleMixer *sm = nullptr;
	mixer_simple_s *mixinfo = nullptr;

	mixinfo = (mixer_simple_s *)malloc(MIXER_SIMPLE_SIZE(1));

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

	mixinfo->control_count = 1;

	/*
	 * Always pull from group 0, with the input value giving the channel.
	 */
	mixinfo->controls[0].control_group = 0;
	mixinfo->controls[0].control_index = input;

	/*
	 * Conversion uses both the input and output side of the mixer.
	 *
	 * The input side is used to slide the control value such that the min argument
	 * results in a value of zero.
	 *
	 * The output side is used to apply the scaling for the min/max values so that
	 * the resulting output is a -1.0 ... 1.0 value for the min...max range.
	 */
	mixinfo->controls[0].scaler.negative_scale = 1.0f;
	mixinfo->controls[0].scaler.positive_scale = 1.0f;
	mixinfo->controls[0].scaler.offset = -mid;
	mixinfo->controls[0].scaler.min_output = -(mid - min);
	mixinfo->controls[0].scaler.max_output = (max - mid);

	mixinfo->output_scaler.negative_scale = 500.0f / (mid - min);
	mixinfo->output_scaler.positive_scale = 500.0f / (max - mid);
	mixinfo->output_scaler.offset = 0.0f;
	mixinfo->output_scaler.min_output = -1.0f;
	mixinfo->output_scaler.max_output = 1.0f;

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

	if (sm != nullptr) {
		mixinfo = nullptr;
		debug("PWM input mixer for %d", input);

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

out:

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

	return sm;
}

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

	if (_info == nullptr)
		return 0;

	if (space < 1)
		return 0;

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

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

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

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

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

int
SimpleMixer::check()
{
	int ret;
	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 (_info->control_count > 32)
		return -2;

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

	if (ret != 0)
		return ret;

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

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

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

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

	return 0;
}