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81 lines
2.3 KiB
81 lines
2.3 KiB
/*
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Copyright 2017 Pascal Gauthier.
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Copyright 2012 Google Inc.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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#ifndef __ENV_H
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#define __ENV_H
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#include "synth.h"
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// DX7 envelope generation
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#define ACCURATE_ENVELOPE
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class Env {
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public:
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// The rates and levels arrays are calibrated to match the Dx7 parameters
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// (ie, value 0..99). The outlevel parameter is calibrated in microsteps
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// (ie units of approx .023 dB), with 99 * 32 = nominal full scale. The
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// rate_scaling parameter is in qRate units (ie 0..63).
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void init(const int rates[4], const int levels[4], int outlevel,
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int rate_scaling);
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void update(const int rates[4], const int levels[4], int outlevel,
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int rate_scaling);
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// Result is in Q24/doubling log format. Also, result is subsampled
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// for every N samples.
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// A couple more things need to happen for this to be used as a gain
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// value. First, the # of outputs scaling needs to be applied. Also,
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// modulation.
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// Then, of course, log to linear.
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int32_t getsample();
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void keydown(bool down);
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static int scaleoutlevel(int outlevel);
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void getPosition(char *step);
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static void init_sr(double sample_rate);
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void transfer(Env &src);
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private:
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// PG: This code is normalized to 44100, need to put a multiplier
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// if we are not using 44100.
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static uint32_t sr_multiplier;
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int rates_[4];
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int levels_[4];
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int outlevel_;
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int rate_scaling_;
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// Level is stored so that 2^24 is one doubling, ie 16 more bits than
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// the DX7 itself (fraction is stored in level rather than separate
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// counter)
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int32_t level_;
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int targetlevel_;
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bool rising_;
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int ix_;
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int inc_;
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#ifdef ACCURATE_ENVELOPE
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int staticcount_;
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#endif
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bool down_;
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void advance(int newix);
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};
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#endif // __ENV_H
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