GTick

Overview

The GTick algorithm has but one purpose: take in a gate signal, and return a tick signal.

Gate signals, such as those generated by tgate, are signals that are either off (0) or on (1, or non-zero). Tick signals, such as those generated by metro or phsclk, can be thought of as impulse streams, and produce "tick" values, single-sample non-zero impulses, that can be used as clock sources to trigger things like tenv, trand, or tgate.

In many situations, it can be very difficult to produce a tick signal that is guaranteed to be 1 sample long. Meanwhile, a gate signal is a much more approachable kind of signal to make.

Tangled Files

#ifndef SK_GTICK_H
#define SK_GTICK_H

#ifndef SKFLT
#define SKFLT float
#endif

<<typedefs>>

#ifdef SK_GTICK_PRIV
<<structs>>
#endif

<<funcdefs>>

#endif

#define SK_GTICK_PRIV
#include "gtick.h"
<<funcs>>

Struct

sk_gtick.

typedef struct sk_gtick sk_gtick;

struct sk_gtick {
    SKFLT prev;
};

Init

sk_gtick_init.

void sk_gtick_init(sk_gtick *gt);

void sk_gtick_init(sk_gtick *gt)
{
    gt->prev = 0;
}

Compute

A single sample of gtick is computed with sk_gtick_tick. It expects as an input a gate signal.

SKFLT sk_gtick_tick(sk_gtick *gt, SKFLT in);

A tick signal is only produced what a gate transitions from off to on (in Electrical Engineering terms, they sometimes might say it goes from LOW to HIGH). It does this by keeping track of the previous sample.

A gate signal must transition from on to off before it can be ready to produce another tick again.

SKFLT sk_gtick_tick(sk_gtick *gt, SKFLT gate)
{
    SKFLT out;
    out = 0;

    if (gate > 0 && gt->prev <= 0) {
        out = 1;
    }

    gt->prev = gate;

    return out;
}