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/**
* @file Generic control value mixing library.
*
* This library implements a generic mixer function that can be used
* by any driver or subsytem that wants to combine several control signals
* into a single output.
*
* See mixer.h for more details.
*/
#include "mixer.h"
static int
scale_check(struct MixScaler *scale)
{
if (scale->offset > 1.0f)
return -1;
if (scale->offset > 1.0f)
return -1;
if (scale->lower_limit > scale->upper_limit)
return -1;
if (scale->lower_limit < -1.0f)
return -1;
if (scale->upper_limit > 1.0f)
return -1;
return 0;
}
int
mixer_check(struct MixMixer *mixer, unsigned control_count)
{
if (mixer->control_count < 1)
return -1;
if (mixer->control_count > control_count)
return -1;
if (!scale_check(&mixer->output_scaler))
return -1;
for (unsigned i = 0; i < mixer->control_count; i++) {
if (mixer->control_scaler[i].control >= control_count)
return -1;
if (!scale_check(&mixer->control_scaler[i]))
return -1;
}
return 0;
}
static float
scale(struct MixScaler *scaler, float input)
{
float output;
if (input < 0.0f) {
output = (input * scaler->negative_scale) + scaler->offset;
} else {
output = (input * scaler->positive_scale) + scaler->offset;
}
if (output > scaler->upper_limit) {
output = scaler->upper_limit;
} else if (output < scaler->lower_limit) {
output = scaler->lower_limit;
}
return output;
}
float
mixer_mix(struct MixMixer *mixer, float *controls)
{
struct MixScaler *scaler;
float sum = 0.0f;
for (unsigned i = 0; i < mixer->control_count; i++) {
scaler = &mixer->control_scaler[i];
sum += scale(scaler, controls[scaler->control]);
}
return scale(&mixer->output_scaler, sum);
}
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