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141 lines
3.6 KiB
141 lines
3.6 KiB
/*
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* Copyright 2017 Pascal Gauthier.
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* Copyright 2012 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <math.h>
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#include "synth.h"
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#include "env.h"
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//using namespace std;
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uint32_t Env::sr_multiplier = (1<<24);
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const int levellut[] = {
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0, 5, 9, 13, 17, 20, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 42, 43, 45, 46
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};
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void Env::init_sr(double sampleRate) {
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sr_multiplier = (44100.0 / sampleRate) * (1<<24);
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}
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void Env::init(const int r[4], const int l[4], int32_t ol, int rate_scaling) {
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for (int i = 0; i < 4; i++) {
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rates_[i] = r[i];
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levels_[i] = l[i];
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}
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outlevel_ = ol;
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rate_scaling_ = rate_scaling;
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level_ = 0;
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down_ = true;
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advance(0);
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}
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int32_t Env::getsample() {
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if (ix_ < 3 || ((ix_ < 4) && !down_)) {
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if (rising_) {
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const int jumptarget = 1716;
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if (level_ < (jumptarget << 16)) {
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level_ = jumptarget << 16;
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}
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level_ += (((17 << 24) - level_) >> 24) * inc_;
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// TODO: should probably be more accurate when inc is large
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if (level_ >= targetlevel_) {
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level_ = targetlevel_;
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advance(ix_ + 1);
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}
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} else { // !rising
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level_ -= inc_;
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if (level_ <= targetlevel_) {
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level_ = targetlevel_;
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advance(ix_ + 1);
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}
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}
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}
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// TODO: this would be a good place to set level to 0 when under threshold
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return level_;
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}
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void Env::keydown(bool d) {
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if (down_ != d) {
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down_ = d;
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advance(d ? 0 : 3);
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}
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}
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int Env::scaleoutlevel(int outlevel) {
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return outlevel >= 20 ? 28 + outlevel : levellut[outlevel];
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}
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void Env::advance(int newix) {
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ix_ = newix;
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if (ix_ < 4) {
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int newlevel = levels_[ix_];
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int actuallevel = scaleoutlevel(newlevel) >> 1;
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actuallevel = (actuallevel << 6) + outlevel_ - 4256;
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actuallevel = actuallevel < 16 ? 16 : actuallevel;
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// level here is same as Java impl
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targetlevel_ = actuallevel << 16;
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rising_ = (targetlevel_ > level_);
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// rate
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int qrate = (rates_[ix_] * 41) >> 6;
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qrate += rate_scaling_;
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qrate = min(qrate, 63);
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inc_ = (4 + (qrate & 3)) << (2 + LG_N + (qrate >> 2));
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// meh, this should be fixed elsewhere
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inc_ = ((int64_t)inc_ * (int64_t)sr_multiplier) >> 24;
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}
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}
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void Env::update(const int r[4], const int l[4], int32_t ol, int rate_scaling) {
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for (int i = 0; i < 4; i++) {
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rates_[i] = r[i];
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levels_[i] = l[i];
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}
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outlevel_ = ol;
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rate_scaling_ = rate_scaling;
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if ( down_ ) {
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// for now we simply reset ourselve at level 3
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int newlevel = levels_[2];
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int actuallevel = scaleoutlevel(newlevel) >> 1;
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actuallevel = (actuallevel << 6) - 4256;
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actuallevel = actuallevel < 16 ? 16 : actuallevel;
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targetlevel_ = actuallevel << 16;
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advance(2);
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}
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}
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void Env::getPosition(char *step) {
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*step = ix_;
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}
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void Env::transfer(Env &src) {
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for(int i=0;i<4;i++) {
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rates_[i] = src.rates_[i];
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levels_[i] = src.levels_[i];
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}
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outlevel_ = src.outlevel_;
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rate_scaling_ = src.rate_scaling_;
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level_ = src.level_;
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targetlevel_ = src.targetlevel_;
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rising_= src.rising_;
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ix_ = src.ix_;
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inc_ = src.inc_;
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down_ = src.down_;
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}
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