Clemens Valens
This is a part of the Kinetiszer project.
Diff: lfo.c
- Revision:
- 0:cb80470434eb
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/lfo.c Tue Oct 28 12:19:42 2014 +0000
@@ -0,0 +1,126 @@
+/*
+Copyright 2013 Paul Soulsby www.soulsbysynths.com
+ This file is part of Atmegatron.
+
+ Atmegatron is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Atmegatron is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Atmegatron. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//**********Bipolar LFO. 16 waveforms, each 64 samples long.***************
+
+#include "atmegatron.h"
+
+//lfo waveforms store in PROGMEM
+const signed char lfo_store[16][LFO_LEN] =
+{
+ {0,12,25,37,49,60,71,81,90,98,106,112,117,122,125,126,127,126,125,122,117,112,106,98,90,81,71,60,49,37,25,12,0,-12,-25,-37,-49,-60,-71,-81,-90,-98,-106,-112,-117,-122,-125,-126,-127,-126,-125,-122,-117,-112,-106,-98,-90,-81,-71,-60,-49,-37,-25,-12}, //sine
+ {0,8,16,24,32,40,48,56,64,71,79,87,95,103,111,119,127,119,111,103,95,87,79,71,64,56,48,40,32,24,16,8,0,-8,-16,-24,-32,-40,-48,-56,-64,-71,-79,-87,-95,-103,-111,-119,-127,-119,-111,-103,-95,-87,-79,-71,-64,-56,-48,-40,-32,-24,-16,-8}, //triangle
+ {127,123,119,115,111,107,103,99,95,91,87,83,79,75,71,67,64,60,56,52,48,44,40,36,32,28,24,20,16,12,8,4,0,-4,-8,-12,-16,-20,-24,-28,-32,-36,-40,-44,-48,-52,-56,-60,-64,-67,-71,-75,-79,-83,-87,-91,-95,-99,-103,-107,-111,-115,-119,-123}, //saw down
+ {-127,-127,-127,-127,-127,-126,-126,-126,-126,-126,-126,-125,-125,-125,-125,-124,-124,-124,-123,-123,-122,-122,-121,-121,-120,-119,-118,-118,-117,-116,-115,-113,-112,-111,-109,-107,-105,-103,-101,-99,-96,-93,-90,-87,-83,-79,-74,-69,-64,-58,-52,-45,-37,-29,-20,-11,0,12,24,38,53,69,87,107}, //Exponential ramp up
+ {0,25,48,70,88,102,112,118,120,118,114,108,101,95,89,86,85,86,89,95,101,108,114,118,120,118,112,102,88,70,48,25,0,-25,-48,-70,-88,-102,-112,-118,-120,-118,-114,-108,-101,-95,-89,-86,-85,-86,-89,-95,-101,-108,-114,-118,-120,-118,-112,-102,-88,-70,-48,-25}, //3rd sine harmonics
+ {127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127}, //5%
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127}, //25%
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127}, //50%
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127}, //75%
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,-127,-127,-127,-127}, //95%
+ {0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,67,71,75,79,83,87,91,95,99,103,107,111,115,119,123,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127}, //Ramp up and hold
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,123,119,115,111,107,103,99,95,91,87,83,79,75,71,67,64,60,56,52,48,44,40,36,32,28,24,20,16,12,8,4}, //Hold and ramp down
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,-127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127}, //duh dugga
+ {127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,-127,-127,-127,-127,-127,-127,-127,-127}, //dugga duh
+ {-104,-72,-14,91,-35,38,-20,-21,83,47,22,-73,-111,-104,-28,27,79,25,34,-112,-45,20,36,-30,-124,-74,-95,56,63,-91,94,78,-121,-27,49,-110,-25,24,-9,11,-80,65,-10,-56,-101,116,105,58,-67,-108,-127,95,-71,88,54,-2,83,109,-37,59,40,-77,84,-28}, //noise
+ {127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127} //DC offset //95%
+};
+unsigned long lfo_ticklen = 500; //ticks per LFO cycle. only used when MIDI clock not present. default = 500 ticks, therefore 1 cycle per beat
+unsigned long lfo_clockticklen = 24; //clock ticks per LFO cylcle. only used when MIDI clock present. 24 ticks per beat, therefore 1 cycle per beat
+unsigned long lfo_starttick = 0; //tick lfo starts oscillating at
+unsigned long lfo_curtick = 0; //cur tick of lfo
+
+//lets and gets
+unsigned int lfo_speed = 8191; //speed of lfo. not actual ticks, just a reference in a lookup table that is then divided to equal actual ticks.
+byte lfo_curtable = 0; //current lfo waveform
+boolean lfo_invert = false; //lfo invert mode
+signed char lfo_level = 0; //lfo output (-127 - 127)
+
+//lets and gets
+//LFO speed. Stored as a lookup table of multipliers, not actual ticks
+void LFO_Let_Speed(unsigned int newspeed)
+{
+ lfo_speed = newspeed;
+ lfo_ticklen = ((unsigned long)lfo_speed+1) * MASTER_BEATTICK >> 13; //Calculate lfo tick length. This method is a way of calculating ticks without using slow (and memory consuming) floating point maths. e.g. 1 cycle per beat = 8192 * 500 >> 13 = 500
+ if (lfo_ticklen<2){
+ lfo_ticklen = 2; //Speed must be 2 or great otherwise divide by 0 in LFO_calcval
+ }
+ lfo_clockticklen = ((unsigned long)lfo_speed+1) * 24 >> 13; //same as above, this time for when MIDI clock is present
+ if (lfo_clockticklen<2){
+ lfo_clockticklen = 2; //Speed must be 2 or great otherwise divide by 0 in LFO_calcval
+ }
+}
+unsigned int LFO_Get_Speed(void)
+{
+ return lfo_speed;
+}
+//set and get lfo waveform
+void LFO_Let_Type(byte newtable)
+{
+ lfo_curtable = newtable;
+}
+byte LFO_Get_Type(void)
+{
+ return lfo_curtable;
+}
+//set and get invert mode
+void LFO_Let_Invert(boolean newinv)
+{
+ lfo_invert = newinv;
+}
+boolean LFO_Get_Invert(void)
+{
+ return lfo_invert;
+}
+//return current lfo level (-127 - 127)
+signed char LFO_Get_Level(void)
+{
+ if (lfo_invert==true){
+ return -lfo_level; //invert output if invert mode on
+ }
+ else{
+ return lfo_level;
+ }
+}
+
+//LFO meat
+//reset lfo start tick. lfo is reset when first key is pressed
+void LFO_Reset(void)
+{
+ if (MIDI_Get_ClockPresent()==false){
+ lfo_starttick = master_tick;
+ }
+}
+//calculate the current output of the lfo
+void LFO_CalcVal(void)
+{
+ unsigned long pos;
+ int index;
+ //char lfoval;
+ if (MIDI_Get_ClockPresent()==false){ //if midi clock not used:
+ lfo_curtick = master_tick - lfo_starttick; //get ticks since lfo started
+ pos = lfo_curtick % lfo_ticklen; //calculate position within cycle in ticks
+ index = (pos * LFO_LEN) / lfo_ticklen; //convert to position within wavetable array
+ }
+ else{
+ pos = MIDI_Get_ClockTick() % lfo_clockticklen; //calculate position within cycle in clock ticks
+ index = (pos * LFO_LEN) / lfo_clockticklen; //convert to position within wavetable array
+ }
+ lfo_level = lfo_store[lfo_curtable][index]; //set lfo level
+}
+