component xhc_hb04_util "xhc-hb04 convenience utility";
description """Provides logic for a start/pause button and an interface
to \\fBhalui.program.is_paused\\fR, \\fBis_idle\\fR, \\fBis_running\\fR to generate outputs for \\fBhalui.program.pause\\fR, \\fBresume\\fR, \\fBrun\\fR.

Includes 4 simple lowpass filters with \\fBcoef\\fR and \\fBscale\\fR pins.  The coef value should
be 0 <= coef <=1, smaller coef values slow response.  See the lowpass manpage for
calculating the filter time constant ($ man lowpass).

""";

pin in bit start_or_pause;
pin in bit is_paused;
pin in bit is_idle;
pin in bit is_running;
pin out bit pause;
pin out bit resume;
pin out bit run;

// integer low pass filters (see ilowpass.comp)
pin in s32 in0;
pin in s32 in1;
pin in s32 in2;
pin in s32 in3;
pin out s32 out0;
pin out s32 out1;
pin out s32 out2;
pin out s32 out3;
pin in float scale0 = 1.0;
pin in float scale1 = 1.0;
pin in float scale2 = 1.0;
pin in float scale3 = 1.0;
pin in float coef0 = 1.0;
pin in float coef1 = 1.0;
pin in float coef2 = 1.0;
pin in float coef3 = 1.0;

pin in  float divide_by_k_in;
pin out float divide_by_k_out;
pin in  float k = 1.0;

option data xhc_data;

variable double value0;
variable double value1;
variable double value2;
variable double value3;

function _;
license "GPL";
author "Dewey Garrett";
;;
#include <rtapi_math.h>

typedef struct { int old_start_or_pause; } xhc_data;

FUNCTION(_) {

    if (k == 0) {
      divide_by_k_out = 1e99;
    } else {
      divide_by_k_out = divide_by_k_in / k;
    }

    // protect so that 0 <= coef <= 1
    value0 += (in0 - value0) * (fabs(coef0) < 1 ? fabs(coef0) : 1);
    value1 += (in1 - value1) * (fabs(coef1) < 1 ? fabs(coef1) : 1);
    value2 += (in2 - value2) * (fabs(coef2) < 1 ? fabs(coef2) : 1);
    value3 += (in3 - value3) * (fabs(coef3) < 1 ? fabs(coef3) : 1);

    out0 =  ceil(value0 * scale0 - .5);
    out1 =  ceil(value1 * scale1 - .5);
    out2 =  ceil(value2 * scale2 - .5);
    out3 =  ceil(value3 * scale3 - .5);

    if (data.old_start_or_pause == start_or_pause) return;
    data.old_start_or_pause = start_or_pause;
    if (!start_or_pause) {
        pause = run = resume = 0;
        return;
    }
    if (is_paused)  {pause = 0; run = 0; resume = 1; }
    if (is_running) {pause = 1; run = 0; resume = 0; }
    if (is_idle)    {pause = 0; run = 1; resume = 0; }
}