diff options
Diffstat (limited to 'dfx-library/lfo.h')
| -rwxr-xr-x | dfx-library/lfo.h | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/dfx-library/lfo.h b/dfx-library/lfo.h new file mode 100755 index 0000000..0c743c7 --- /dev/null +++ b/dfx-library/lfo.h @@ -0,0 +1,150 @@ +/*------------------- by Marc Poirier ][ January 2002 ------------------*/ + +#ifndef __lfo +#define __lfo + +#include <math.h> +#include <stdlib.h> + +#include "dfxmisc.h" +#include "TempoRateTable.h" + + +//------------------------------------------------------------------------------------- +// these are the 8 LFO waveforms: +enum +{ + kSineLFO, + kTriangleLFO, + kSquareLFO, + kSawLFO, + kReverseSawLFO, + kThornLFO, + kRandomLFO, + kRandomInterpolatingLFO, + + numLFOshapes +}; + +//------------------------------------------------------------------------------------- +// constants & macros + +#define LFOshapeScaled(A) (paramSteppedScaled((A), numLFOshapes)) +#define LFOshapeUnscaled(A) (paramSteppedUnscaled((A), numLFOshapes)) + +#define NUM_LFO_POINTS 512 +const float NUM_LFO_POINTS_FLOAT = (float)NUM_LFO_POINTS; // to reduce casting later on +const float LFO_TABLE_STEP = 1.0f / (float)NUM_LFO_POINTS; // to reduce division & encourage multiplication +const long SQUARE_HALF_POINT = NUM_LFO_POINTS / 2; // the point in the table when the square waveform drops to zero + +#define LFO_SMOOTH_DUR 48 +const float LFO_SMOOTH_STEP = 1.0f / (float)LFO_SMOOTH_DUR; + +// this scales the return of processLFO() from 0.0 - 1.0 output to 0.0 - 2.0 (oscillating around 1.0) +#define processLFOzero2two(A) ( ((A)->processLFO() * 2.0f) - (A)->fDepth + 1.0f ); + + +//----------------------------------------------------------------------------- +class LFO +{ +public: + LFO(); + ~LFO(); + + void reset(); + void fillLFOtables(); + + void pickTheLFOwaveform(); + void getShapeName(char *nameString); + + void syncToTheBeat(long samplesToBar); + + // the LFO waveform tables + float *sineTable, *triangleTable, *squareTable, *sawTable, *reverseSawTable, *thornTable; + + // the following are intended to be used as 0.0 - 1.0 VST parameter values: + float fOnOff; // parameter value for turning the LFO on or off + float fTempoSync; // parameter value for toggling tempo sync + float fRate; // parameter value for LFO rate (in Hz) + float fTempoRate; // parameter value for LFO rate (in cycles per beat) + float fDepth; // parameter value LFO depth + float fShape; // parameter value for LFO shape + + bool onOff; // in case it's easier to have a bool version of fOnOff + float position; // this tracks the position in the LFO table + float stepSize; // size of the steps through the LFO table + float *table; // pointer to the LFO table + float randomNumber; // this stores random values for the random LFO waveforms + float oldRandomNumber; // this stores previous random values for the random interpolating LFO waveform + float cycleRate; // the rate in Hz of the LFO (only used for first layer LFOs) + long smoothSamples; // a counter for the position during a smoothing fade + long granularityCounter; // a counter for implementing LFO processing on a block basis + long granularity; // the number of samples to wait before processing + + + //-------------------------------------------------------------------------------------- + // This function wraps around the LFO table position when it passes the cycle end. + // It also sets up the smoothing counter if a discontiguous LFO waveform is being used. + void updatePosition(long numSteps = 1) + { + // increment the LFO position tracker + position += (stepSize * (float)numSteps); + + if (position >= NUM_LFO_POINTS_FLOAT) + { + // wrap around the position tracker if it has made it past the end of the LFO table + position = fmodf(position, NUM_LFO_POINTS_FLOAT); + // get new random LFO values, too + oldRandomNumber = randomNumber; + randomNumber = (float)rand() / (float)RAND_MAX; + // set up the sample smoothing if a discontiguous waveform's cycle just ended + switch (LFOshapeScaled(fShape)) + { + case kSquareLFO : + case kSawLFO : + case kReverseSawLFO : + case kRandomLFO : + smoothSamples = LFO_SMOOTH_DUR; + default: + break; + } + } + + // special check for the square waveform - it also needs smoothing at the half point + else if (LFOshapeScaled(fShape) == kSquareLFO) + { + // check to see if it has just passed the halfway point + if ( ((long)position >= SQUARE_HALF_POINT) && + ((long)(position - stepSize) < SQUARE_HALF_POINT) ) + smoothSamples = LFO_SMOOTH_DUR; + } + } + + //-------------------------------------------------------------------------------------- + // this function gets the current 0.0 - 1.0 output value of the LFO & increments its position + float processLFO() + { + float randiScalar, outValue; + int shape = LFOshapeScaled(fShape); + + if (shape == kRandomInterpolatingLFO) + { + // calculate how far into this LFO cycle we are so far, scaled from 0.0 to 1.0 + randiScalar = position * LFO_TABLE_STEP; + // interpolate between the previous random number & the new one + outValue = (randomNumber * randiScalar) + (oldRandomNumber * (1.0f-randiScalar)); + } + // + else if (shape == kRandomLFO) + outValue = randomNumber; + // + else + outValue = table[(long)position]; + + return (outValue * fDepth); + } + +}; + + +#endif
\ No newline at end of file |