#!/usr/bin/perl

#
# Pressure / Altitude Table
#
#	This builds a table of input voltage to pressure to altitude
#	The purpose is to either show that one altitude step between
#	pressure sensor readings is adequate, or to build a table
#	to calculate altitude based on pressure.
#


$Vstep=5/1024;	# Volts per A/D step
$p = 0;		# pressure value
$Al=0;

while ( $p < 1024 ) {

#- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
# Pressure - kPa

$Vp=$p * $Vstep;
$Vs=5;

$P = (($Vp/$Vs) + 0.10941) / 0.01059;

#- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
# Altitude - Calculation
#
sub log10 {
   my $n = shift;
 return log($n)/log(10);
}
#
#
#PbP
$Alt1 = -26216 * log($P / 101.325);

#
#ROL / BS2 / Army
#Pa = Po (1 - 6.87535E-06 * Hc)^5.2561
# Hc=(10^(Log(Pa/Po)/5.2561)-1)/-6.87535E-06
#   Pa = pressure at altitude
#   Po = Sea level pressure = 101325 Pa
#   Hc is altitude in feet
#Altitude = (10^(log(P/P_0)/5.2558797)-1)/-6.8755856*10^-6.
#Altitude = (10^(log(P/P_0)/5.2558797)-1)/-6.8755856*10^-6
$Alt2 = (10**(log10($P/101.325)/5.2558797)-1)/(-6.8755856E-6);
#$Alt2 = (10**(log10(($P)/101.325)/5.2558797)-1)/(-6.8755856*10E-6);

$Ad = $Al - $Alt2;

# Home:
#  Pa = Po (1 - 6.87535E-06 * Hc)^5.2561
#  98,072.6328 Pa

# ---------------------------------------------------------------------------

#print "$p $Vp $P $Alt2 $Ad\n";

printf "%.f, /* 0x%x 0x%x %d %.4f V %.4f hpa %.4f ft %.1f delta */\n",
	$Alt2, $Alt2, $p, $p, $Vp, $P, $Alt2, $Ad;

$Al = $Alt2;

$p += 1;
}