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Short-circuit gain interpolation if the change is negligibly small

This commit is contained in:
Ben Loftis 2020-07-21 18:37:32 -05:00
parent 3416af3969
commit a2f4521e77
1 changed files with 13 additions and 2 deletions
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15
libs/pbd/pbd/control_math.h
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@ -23,6 +23,9 @@
#include <math.h>
#include <stdint.h>
/* these numbers ar arbitrary; we use them to keep floats well out of the denormal range */
#define TINY_NUMBER (0.0000001) /* (-140dB) */
/* map gain-coeff [0..2] to position [0..1] */
static inline double
gain_to_position (double g)
@ -100,12 +103,20 @@ interpolate_logarithmic (double from, double to, double fraction, double /*lower
}
static inline double
interpolate_gain (double from, double to, double fraction, double upper)
interpolate_gain (double f, double t, double fraction, double upper)
{
double from = f + TINY_NUMBER; //kill denormals before we use them for anything
double to = t + TINY_NUMBER; //kill denormals before we use them for anything
if ( fabs(to-from) < TINY_NUMBER ){
return to;
}
// this is expensive -- optimize
double g0 = gain_to_position (from * 2. / upper);
double g1 = gain_to_position (to * 2. / upper);
return position_to_gain (g0 + fraction * (g1 - g0)) * upper / 2.;
double diff = g1 - g0;
return position_to_gain (g0 + fraction * (diff)) * upper / 2.;
}
#endif