Exponential Ramp Generator

Overview

Exponential Ramp

exp_upward_ramp_gen is an exponential upward ramp generator that generates an exponentially increasing amplitude from 0.0 to 1.0, similar to a capacitor charged by a series resistor over time specified by the duration (width) and samples per second (sps), and optional exponential curvature (cv) parameters.

exp_downward_ramp_gen is the inverse of the exponential upward ramp generator. This is similar to a capacitor discherged through a resistor.

The Q DSP library utilizes the exponential ramp generators for generating complex envelopes.

Include

#include <q/synth/exponential_gen.hpp>

Declaration

struct exp_upward_ramp_gen
{
            exp_upward_ramp_gen(duration width, float sps, float cv = 0.95);

   float    operator()();
   void     config(duration width, float sps);
   void     config(duration width, float sps, float cv);
   void     reset();
};

struct exp_downward_ramp_gen : exp_upward_ramp_gen
{
   using exp_upward_ramp_gen::exp_upward_ramp_gen;

   float    operator()();
};

Expressions

exp_upward_ramp_gen and exp_downward_ramp_gen are a models of Ramp. In addition to valid expressions for Ramp, exp_upward_ramp_gen and exp_downward_ramp_gen allow these expressions.

Notation

g

Object of type exp_upward_ramp_gen or exp_downward_ramp_gen.

w

Object of type duration.

sps

Floating point value representing samples per second.

cv

Exponential curvature.

The cv constructor and config parameter determines the curvature of the exponential. Valid cv values range greater than 0.0 to anything less than 1.0. cv is the final value in the exponential curve that will be considered as the peak value that will be scaled up to 1.0. Increasing the cv value leads to more pronounced curves. Lower cv values produce flatter, more linear ramps. The default is 0.95.

Constructor

Expression Semantics

exp_upward_ramp_gen(w, sps, cv)

Construct exp_upward_ramp_gen given width, w, and samples per second, sps, and exponential curvature, cw.

exp_downward_ramp_gen(w, sps, cv)

Construct exp_downward_ramp_gen given width, w, and samples per second, sps, and exponential curvature, cw.
C++ brace initialization may also be used.

Mutators

Expression Semantics

g.config(w, sps, cw)

Set the ramp width, w, with samples per second, sps, and exponential curvature, cw.