component lincurve "one-dimensional lookup table";
description """Performs a 1-dimensional lookup and interpolation. The x-val
parameters must be monotonic, though identical adjacent values are allowed.
(for example 0,0,0,10) for a 4-element curve. 

For input values less than the x-val-00 breakpoint the y-val-00 is returned. 
For x greater than the largest x-val-NN the yval corresponding to x-max is
returned (ie, no extrapolation is performed.)

Sample usage: loadrt lincurve count=3 personality=4,4,4 
for a set of three 4-element curves.

The axis breakpoints should be set in the lincurve.N.x-val-NN parameters using
"setp", as should the corresponding y values. """;

param rw float x-val-##[16 : personality] "axis breakpoints";
param rw float y-val-##[16 : personality] "output values to be interpolated";

pin in float in_ "The input value";
pin out float out_ "The output value";
pin io float out-io "The output value, compatible with PID gains";

variable unsigned i = 0;

option extra_setup 1;

author "Andy Pugh";
license "GPL";

function _;

;;

FUNCTION(_){
    double f, x;
    x = in_;
    if (x >= x_val(personality-1)) {
        out_ = y_val(personality-1);
        out_io = out_;
        return;
    }
    if (x <= x_val(0)) {
        out_ = y_val(0);
        out_io = out_;
        return;
    }
    while (x > x_val(i+1)) { i++;}
    while (x < (x_val(i))) { i--;}
    
    f = (x - x_val(i))/(x_val(i+1)-x_val(i));
    out_ = y_val(i) + f * (y_val(i+1) - y_val(i));
    out_io = out_;
}

EXTRA_SETUP(){
	if (personality > 16) personality = 16;
	if (personality < 2) personality = 2;
	return 0;
}