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LEFTONE/util/jukebox/lowpass.c

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#include "./lowpass.h"
#include <assert.h>
#include <stdatomic.h>
#include <stddef.h>
#include "util/math/algorithm.h"
#include "./effect.h"
#include "./format.h"
static void jukebox_lowpass_affect_(
jukebox_effect_t* effect, const jukebox_effect_pcm_t* pcm) {
assert(effect != NULL);
assert(pcm != NULL);
jukebox_lowpass_t* lp = (typeof(lp)) effect;
const size_t ch = lp->format.channels;
const float f = atomic_load(&lp->factor) * JUKEBOX_LOWPASS_FACTOR_UNIT;
assert(ch <= JUKEBOX_LOWPASS_SUPPORT_MAX_CHANNELS);
const size_t pcmlen = pcm->frames * ch;
for (size_t i = 0; i < pcmlen; ++i) {
const float p = (ch+1 <= i? pcm->ptr[i-1-ch]: lp->prev[i]);
pcm->ptr[i] = (1.0f-f)*pcm->ptr[i] + f*p;
}
if (pcmlen < ch) return;
for (size_t i = 0; i < ch; ++i) {
lp->prev[i] = pcm->ptr[pcmlen-ch+i];
}
}
void jukebox_lowpass_initialize(
jukebox_lowpass_t* lowpass, const jukebox_format_t* format, float factor) {
assert(lowpass != NULL);
assert(jukebox_format_valid(format));
assert(MATH_FLOAT_VALID(factor));
*lowpass = (typeof(*lowpass)) {
.super = {
.vtable = {
.affect = jukebox_lowpass_affect_,
},
},
.format = *format,
.factor = factor*10000,
.prev = {0},
};
}
void jukebox_lowpass_deinitialize(jukebox_lowpass_t* lowpass) {
assert(lowpass != NULL);
}