forked from Archive/PX4-Autopilot
260 lines
5.9 KiB
C
260 lines
5.9 KiB
C
/****************************************************************************
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*
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* Copyright (C) 2012 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file mixer.c
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*
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* Generic control value mixing library.
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*
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* This library implements a generic mixer function that can be used
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* by any driver or subsytem that wants to combine several control signals
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* into a single output.
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*
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* See mixer.h for more details.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "mixer.h"
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static int
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scale_check(struct MixScaler *scale)
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{
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if (scale->offset > 1.0f)
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return -1;
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if (scale->offset > 1.0f)
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return -1;
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if (scale->lower_limit > scale->upper_limit)
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return -1;
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if (scale->lower_limit < -1.0f)
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return -1;
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if (scale->upper_limit > 1.0f)
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return -1;
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return 0;
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}
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int
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mixer_check(struct MixMixer *mixer, unsigned control_count)
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{
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if (mixer->control_count < 1)
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return -1;
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if (mixer->control_count > control_count)
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return -1;
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if (!scale_check(&mixer->output_scaler))
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return -1;
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for (unsigned i = 0; i < mixer->control_count; i++) {
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if (mixer->control_scaler[i].control >= control_count)
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return -1;
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if (!scale_check(&mixer->control_scaler[i]))
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return -1;
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}
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return 0;
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}
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static float
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scale(struct MixScaler *scaler, float input)
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{
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float output;
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if (input < 0.0f) {
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output = (input * scaler->negative_scale) + scaler->offset;
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} else {
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output = (input * scaler->positive_scale) + scaler->offset;
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}
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if (output > scaler->upper_limit) {
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output = scaler->upper_limit;
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} else if (output < scaler->lower_limit) {
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output = scaler->lower_limit;
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}
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return output;
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}
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float
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mixer_mix(struct MixMixer *mixer, float *controls)
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{
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struct MixScaler *scaler;
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float sum = 0.0f;
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for (unsigned i = 0; i < mixer->control_count; i++) {
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scaler = &mixer->control_scaler[i];
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sum += scale(scaler, controls[scaler->control]);
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}
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return scale(&mixer->output_scaler, sum);
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}
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static int
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mixer_getline(int fd, char *line, unsigned maxlen)
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{
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int ret;
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char c;
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while (--maxlen) {
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ret = read(fd, &c, 1);
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if (ret <= 0)
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return ret;
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if (c == '\r')
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continue;
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if (c == '\n') {
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*line = '\0';
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return 1;
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}
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*line++ = c;
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}
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/* line too long */
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return -1;
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}
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static int
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mixer_load_scaler(const char *buf, struct MixScaler *scaler)
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{
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if (sscanf(buf, "S: %u %f %f %f %f %f",
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&scaler->control, &scaler->negative_scale, &scaler->positive_scale,
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&scaler->offset, &scaler->lower_limit, &scaler->upper_limit) != 6)
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return -1;
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return 0;
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}
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int
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mixer_load(int fd, struct MixMixer **mp)
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{
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int ret, result = -1;
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struct MixMixer *mixer = NULL;
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char buf[100];
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unsigned scalers;
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ret = mixer_getline(fd, buf, sizeof(buf));
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/* end of file? */
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if (ret == 0)
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result = 0;
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/* can't proceed */
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if (ret < 1)
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goto out;
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/* get header */
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if (sscanf(buf, "M: %u", &scalers) != 1)
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goto out;
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/* must have at least one scaler */
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if (scalers < 1)
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goto out;
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/* allocate mixer */
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scalers--;
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mixer = (struct MixMixer *)malloc(MIXER_SIZE(scalers));
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if (mixer == NULL)
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goto out;
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mixer->control_count = scalers;
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ret = mixer_getline(fd, buf, sizeof(buf));
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if (ret < 1)
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goto out;
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if (mixer_load_scaler(buf, &mixer->output_scaler))
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goto out;
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for (unsigned i = 0; i < scalers; i++) {
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if (mixer_getline(fd, buf, sizeof(buf)))
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goto out;
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if (mixer_load_scaler(buf, &mixer->control_scaler[i]))
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goto out;
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}
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result = 1;
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out:
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/* on error, discard allocated mixer */
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if ((result <= 0) && (mixer != NULL))
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free(mixer);
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*mp = mixer;
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return result;
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}
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static int
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mixer_save_scaler(char *buf, struct MixScaler *scaler)
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{
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return sprintf(buf, "S: %u %f %f %f %f %f\n",
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scaler->control, scaler->negative_scale, scaler->positive_scale,
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scaler->offset, scaler->lower_limit, scaler->upper_limit);
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}
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int
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mixer_save(int fd, struct MixMixer *mixer)
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{
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char buf[100];
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int len, ret;
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/* write the mixer header */
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len = sprintf(buf, "M: %u\n", mixer->control_count);
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ret = write(fd, buf, len);
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if (ret != len)
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return -1;
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/* write the output scaler */
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len = mixer_save_scaler(buf, &mixer->output_scaler);
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write(fd, buf, len);
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if (ret != len)
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return -1;
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/* write the control scalers */
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for (unsigned j = 0; j < mixer->control_count; j++) {
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len = mixer_save_scaler(buf, &mixer->control_scaler[j]);
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write(fd, buf, len);
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if (ret != len)
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return -1;
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}
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return 0;
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}
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