eg.cpp

00001 #include "signal_processing.h"
00002 
00003 EG::EG ( int32_t a_block_size )
00004 {
00005     this->block_size = a_block_size;
00006     
00007     this->state = release;
00008     this->set_sustain( 0.0f );
00009     this->current_level = 0.0f;
00010     this->set_attack( 0.999 );
00011     this->set_decay( 0.999 );
00012     this->set_release( 0.999 );
00013 
00014 }
00015 
00016 void EG::run( float32_t *pEnvelope )
00017 {
00018     if ( this->state == release )
00019         for ( int i= 0; i< this->block_size; i++ )
00020             pEnvelope[i] = this->current_level = 
00021                 this->current_level * this->release_time_constant;
00022     else if ( this->state == decay )
00023         for ( int i= 0; i< this->block_size; i++ )
00024             pEnvelope[i] = this->current_level = 
00025                 ( this->current_level - this->sustain_level ) * this->decay_time_constant
00026                 + this->sustain_level;
00027     else // attack
00028     {
00029         for ( int i= 0; i< this->block_size; i++ )
00030             pEnvelope[i] = this->current_level = 
00031                 1.5f - 
00032                 ( 1.5f - this->current_level ) * this->attack_time_constant;
00033         if ( this->current_level >= 1.0f )
00034             this->state = decay;
00035      }               
00036     
00037 }
00038 
00039 void EG::on(void)
00040 {
00041     this->state = attack;
00042 }
00043 
00044 void EG::off(void)
00045 {
00046     this->state = release;
00047 }
00048 
00049 void EG::set_sustain( float32_t sustain )
00050 {
00051     this->sustain_level = sustain;
00052 }
00053 
00054 void EG::set_attack( float32_t attack )
00055 {
00056     this->attack_time_constant = 1.0f - (1.0f-attack) * 0.001f;
00057 }
00058 
00059 void EG::set_decay( float32_t decay )
00060 {
00061     this->decay_time_constant = 1.0f - (1.0f-decay) * 0.001f;
00062 }
00063 
00064 void EG::set_release( float32_t release )
00065 {
00066     this->release_time_constant = 1.0f - (1.0f-release) * 0.001f;
00067 }
00068 
00069