#!/usr/bin/perl -w
#
# remanence - Simulateur de remanente et remplissage continu
# $Id: remanence.pl,v 1.1.1.1 2004/06/07 13:59:09 felix Exp $
###
# (C) 2004, Félix Hauri - Felix@F-Hauri.CH
#
# This is part of demo ``active background''
# must stay in same directory.
# 
# Files:
#   name    access description
#
#   desired  R     desired temperature
#   current  R/W   current temperature
#   speed    R     desired speed
#   lspeed     W   real speed
#   tank     R/W   tank state 
#

die if defined $ENV{'SERVER_NAME'};

use Time::HiRes qw(ualarm);

$desired=23;
$current=23;

$tank=0;
$oper=1;
$speed=12_000;
$pi=4*atan2(1,1);


sub sign {
    my $val=shift;
    return 0 if $val==0;
    return $val/abs($val);
}

sub onestep {
    # Current temperature follow desired...
    $_=`cat desired`;
    chomp;
    $desired=$1 if /^(\d+.*\d*)$/ and $1 <= 98 and $1 >= 14;

    $_=`cat current`;
    chomp;
    $current=$1 if /^(\d+)$/;

    my $step = sprintf "%.3f", ($desired-$current)/4;
    $step = .5 * sign($desired-$current) if abs($step) >.8;
    $step = .001 * sign($desired-$current) if $step =~ /0.000/ and 
	$current =~ /\.00[12]$|\.99[98]$/;

    unless ($step =~ /^0.000$/) {
	$current=sprintf "%.3f", $current+$step;
	open FH,">current" or die "Can't open current for writting";
	print FH $current;
	close FH;
    }

    # Fill than flush from 0 to 100 at speed 0to20k = 0to4%
    $_=`cat tank`;
    chomp;
    $tank=$1 if /^(\d+)$/;

    $_=`cat speed`;
    chomp;
    $speed=$1 if /^(\d+)$/ and $1 >= 0 and 20_000 >= $1;
    $speed=$speed+500*sin((time % 100)*$pi/50);
    open FH,">lspeed" or die "Can't open lspeed for writting";
    print FH $speed;
    close FH;

    unless ($speed==0) {
	$tank=$tank+$oper*$speed/5000;
	$oper=-$oper if $tank > 100 or $tank < 0;
	$tank=0 if $tank < 0;
	$tank=100 if $tank > 100;
	
	$tank=sprintf "%.3f", $tank;
	open FH,">tank" or die "Can't open tank for writting";
	print FH $tank;
	close FH;
    }
}

ualarm 1,1_000_000;

$SIG{"ALRM"} ="onestep";
print "Pseudo daemon started\n".'hit "quit" to stop it.'."\n";

for (;;) {
    exit if <> =~ /^quit$/;
    };