40 lines
1.0 KiB
C
40 lines
1.0 KiB
C
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#include <stdint.h>
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#include "env.h"
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#include "psyn.h"
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void env_init(struct envelope_t *env, double attack, double attack_hold, double decay, double sustain, double release)
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{
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env->attack = attack;
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env->attack_hold = attack_hold;
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env->decay = decay;
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env->sustain = sustain;
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env->release = release;
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env->attack_s = env->attack * _sample_rate;
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env->attack_hold_s = env->attack_hold * _sample_rate;
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env->decay_s = env->decay * _sample_rate;
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env->release_s = env->release * _sample_rate;
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}
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double env_getamplitude(struct envelope_t *env, uint32_t sample, uint32_t released)
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{
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double amplitude;
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if (sample < env->attack_s) {
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amplitude = sample / env->attack_s;
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} else if (sample < env->attack_hold_s) {
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amplitude = 1.0;
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} else if (sample < env->decay_s) {
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amplitude = 1.0 - (sample - env->attack_hold_s) / (env->decay_s - env->attack_hold_s) * (1.0 - env->sustain);
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} else {
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amplitude = env->sustain;
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}
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if (released > 0) {
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amplitude *= (1.0 - (sample - released) / env->release_s);
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}
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return amplitude;
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}
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