mfdc.js

// TODO - currently assumed 8 figure grids, expand to 10.
// Mortar flight calculation is pure example.

// V1.0 functionality
// Resection
// Set ML, including temperature and elevation
// Enter target.  
// Shot at target with countdown, and min/max range checks
// Keyboard and screen input, including back button and Run on enter.

// V1.1 Changes:
// Squared up image

// V1.2 Added functionality/fixes:
// Added tooltips for known buttons
// H hour setting/countdown/reset
// Actual time setting (by default uses host time)
// Decimal point enabled (needed for actual time)
// Clear button functionality
// SIM button (within limits of my understanding of its function)
// Back button correctly deals with deleting last digit (i.e. not leaving a minus standing alone)
// WM button - snap shot at range-bearing target
// Blank entry now reports "INPUT REQ'D"

const START_L1="MFDC2-MDP38";
const START_L2="225A-2F4B10A";
const START_L3="L16-L15(4/2)";

const DISPLAY_WIDTH=12;
var on=false;     // Device on
var firston=true; // Cold start message
var firstCountdown=0;
var shift=false;  // Shift key pressed
var timeOffset=0; // Seconds ahead of PC clock
var img;
var offsetX=5;  // Same as padding in img tag
var offsetY=5;
var temperature=21;  // Default.
var defaultText="MK 4 NO ML";
var countdown=0;
var mission1=false;
var mission2=false;

var tgt_grid=-1;
var tgt_alt=-1;
var tgt_desig="";
var tgt_brg=-1;
var tgt_range=-1;

var grid=-1; // Location set by resection
var ml_grid=-1;
var ml_alt=-1;

var h_hrs=-1;
var h_mins=-1;
var h_secs=-1;

// Finite State Machine states
const READY=0;
const STARTING1=100;
const STARTING2=101;
const STARTING3=102;
const RESECTION_GR1=1;
const RESECTION_BR1=2;
const RESECTION_GR2=3;
const RESECTION_BR2=4;
const RESECTION_GR3=5;
const RESECTION_BR3=6;
const RESECTION_CALC=7;
const RESECTION_FOUND=8;
const TEMP_UPDATE=9;
const TGT_GRID=10;
const TGT_ALT=11;
const TGT_NO=12;
const ML_GRID=13;
const ML_ALT=14;
const SHOW_ML_GRID=15;
const SHOW_ML_ALT=16;
const GET_GRID=17;
const GET_ALT=18;
const SOLUTION=19;
const SOLUTION_EL=20;
const COUNTDOWN=21;
const CLEAR_ACTIVE=22;
const CLEAR_CONFIRM=23;
const SET_H_HR=24;
const H_HR_COUNTDOWN=25;
const H_HR_COUNTUP=26;
const GET_TGT_BRG=27;
const GET_TGT_RNG=28;
const SETTING_TIME=29;
const SETTING_MET=30;

var resect_gr1;
var resect_gr2;
var resect_gr3;
var resect_br1;
var resect_br2;
var resect_br3;

var state=STARTING1;
const TOO_NEAR="TGT TOO NEAR";
const OUT_RANGE="OUT OF RANGE";
const INVALID_KEY="INVALID KEY";
var keyboardInput="";

function start() {
  
var disp=document.getElementById('display');
disp.style.visibility='hidden';
shift=false;
on=false;

img = new Image;                          
img.onload = setup;
img.src = 'images/mfdc.webp';

return false;
}
function setup() {
  
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
img.usemap = document.getElementById("buttons");
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
//------------------------------------------------------------------

document.onkeydown= onKeyDown; 
function onKeyDown(evt){   // Give me some keyboard control (Enter, backspace,plus/minus and 0-9.)
  //if (true) { alert(evt.keyCode); }
  if (evt.keyCode==13) {RUN(); return false;}
  if (evt.keyCode==8)  {Back(); return false;}
  else if (evt.keyCode==189){Neg(); return false;}
  else if (evt.keyCode==48) {B0(); return false; }
  else if (evt.keyCode==49) {B1(); return false; }
  else if (evt.keyCode==50) {B2(); return false; }
  else if (evt.keyCode==51) {B3(); return false; }
  else if (evt.keyCode==52) {B4(); return false; }
  else if (evt.keyCode==53) {B5(); return false; }
  else if (evt.keyCode==54) {B6(); return false; }
  else if (evt.keyCode==55) {B7(); return false; }
  else if (evt.keyCode==56) {B8(); return false; }
  else if (evt.keyCode==57) {B9(); return false; }
  else if (evt.keyCode==190) {Bdp(); return false; }
}
//-------------FOLLOWING BLOCK AUTOGENERATED -------------------------
function overOn() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(10,140,100,80);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overGrid() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(38,253,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overWM() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(222,253,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overDATUM() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(314,253,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overTgts() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(38,344,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overSfty() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(130,344,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overMLs() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(222,344,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overMET() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(314,344,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overShift() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(38,435,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overShot() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(406,435,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overNeg() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(222,526,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overML() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(314,526,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overBack() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(406,526,90,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overSIM() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(42,709,88,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overCLEAR() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(42,799,88,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overRESET() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(42,889,88,89);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB0() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(155,889,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB1() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(155,799,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB2() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(277,799,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB3() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(399,799,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB4() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(155,709,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB5() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(277,709,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB6() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(399,709,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB7() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(155,619,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB8() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(277,619,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overB9() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(399,619,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overBdp() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(277,889,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function overRUN() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.rect(399,889,95,90);
ctx.lineWidth=8;
ctx.strokeStyle = '#ff0000';
ctx.stroke();
}
function outOn() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(10,140,100,80);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outGrid() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(38,253,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outWM() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(222,253,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outDATUM() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(314,253,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outTgts() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(38,344,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outSfty() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(130,344,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outMLs() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(222,344,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outMET() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(314,344,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outShift() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(38,435,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outShot() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(406,435,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outNeg() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(222,526,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outML() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(314,526,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outBack() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(406,526,90,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outSIM() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(42,709,88,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outCLEAR() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(42,799,88,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outRESET() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(42,889,88,89);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB0() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(155,889,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB1() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(155,799,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB2() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(277,799,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB3() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(399,799,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB4() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(155,709,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB5() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(277,709,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB6() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(399,709,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB7() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(155,619,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB8() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(277,619,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outB9() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(399,619,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outBdp() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(277,889,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
function outRUN() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.clearRect(399,889,95,90);
ctx.drawImage(img,offsetX,offsetY,540,1000);
}
//-----------------------END AUTOGEN -------------------------------
//------------------------------------------------------------------
function startupMsg() {

if (state==STARTING1) {  
  document.getElementById('maintext').textContent=START_L1; 
  state=STARTING2;
  setTimeout(startupMsg,1000);
  return false;
} else if (state==STARTING2) {  
  document.getElementById('maintext').textContent=START_L2; 
  state=STARTING3;
  setTimeout(startupMsg,1000);
  return false;
} else if (state==STARTING3) {  
  document.getElementById('maintext').textContent=START_L3; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
return false;  
}
//------------------------------------------------------------------
function flightCountdown() {
  
countdown-=1;
if (countdown<0) { // Device seems to use 6s.
  document.getElementById('maintext').textContent="SPLASH"; 
  state=SOLUTION;
  setTimeout(RUN,5000);
} else {
  document.getElementById('maintext').textContent="  "+countdown+" SECS";
  setTimeout(flightCountdown,1000);
}
return false;  
}
//------------------------------------------------------------------
function Hcountdown() {
  
if (state!=H_HR_COUNTDOWN) return;

h_secs-=1;
if (h_secs==0 && h_mins==0 && h_hrs==0) {
  document.getElementById('maintext').textContent="* H HOUR *"; 
  setTimeout(Hcountup,1000);
  state=H_HR_COUNTUP;
  return false;
}
if (h_secs<0) {
  h_mins-=1;
  h_secs=59;
  if (h_mins<0) {
    h_hrs-=1;
    h_mins=59;
  }
}
document.getElementById('maintext').textContent="H-"+h_hrs.toString().padStart(2,'0')+":"+h_mins.toString().padStart(2,'0')+":"+h_secs.toString().padStart(2,'0'); 
setTimeout(Hcountdown,1000);

return false;  
}
//------------------------------------------------------------------
function Hcountup() {
  
if (state!=H_HR_COUNTUP) return;

h_secs+=1;
if (h_secs>59) {
  h_mins+=1;
  h_secs=0;
  if (h_mins>59) {
    h_hrs+=1;
    h_mins=0;
  }
}
document.getElementById('maintext').textContent="H+"+h_hrs.toString().padStart(2,'0')+":"+h_mins.toString().padStart(2,'0')+":"+h_secs.toString().padStart(2,'0'); 
setTimeout(Hcountup,1000);

return false;  
}
//------------------------------------------------------------------
function On() {
  
on=!on; 
  
if (firston) { startupMsg(); firston=false; }
  
var disp=document.getElementById('display');
disp.style.visibility=(on)?'visible':'hidden'; 

var sh=document.getElementById('shift');
sh.style.visibility=(on && shift)?'visible':'hidden';     

return false;
}
//------------------------------------------------------------------
function Shift() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
shift=!shift;  
  
var sh=document.getElementById('shift');
sh.style.visibility=(shift)?'visible':'hidden';  
  
return false;
}
//------------------------------------------------------------------
function Neg() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
   
if (keyboardInput.length<11) {
  if (keyboardInput.substring(0,1)=="-") keyboardInput=keyboardInput.substring(1);
  else keyboardInput="-"+keyboardInput;
  document.getElementById('maintext').textContent=keyboardInput; 
}
  
return false;
}
//------------------------------------------------------------------
function Sfty() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent="NO RECORD"; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (state!=READY) return false;
   
document.getElementById('maintext').textContent="NO SFTY DATA"; // TODO allow setting 
setTimeout(backToReady,1000);
  
return false;
}
//------------------------------------------------------------------
function Back() {
 
if (!on) return false; 
   
if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (keyboardInput.length>0) {
  keyboardInput=keyboardInput.substring(0,keyboardInput.length-1);
  if (keyboardInput=='-') keyboardInput=""; // Special case - don't just leave a minus on display
  document.getElementById('maintext').textContent=keyboardInput;
}
if (keyboardInput.length==0) {
  document.getElementById('maintext').textContent=defaultText;
}
return false;
}
//------------------------------------------------------------------
function Tgts() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent="NO RECORD"; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
   
if (state!=READY) return false;

if (shift) {
  Shift();  // Cancel shift
  keyboardInput=""; // Cleanup
  state=TGT_GRID;  
  document.getElementById('maintext').textContent="STOTGT GRID?"; 
} else {
  if (tgt_grid==-1) {
    document.getElementById('maintext').textContent="NO RECORD";
    setTimeout(backToReady,1000);
    state=READY;
  }
}
return false;
}
//------------------------------------------------------------------
function RESET() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=""; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
   
state=READY;

keyboardInput=""; // Cleanup
document.getElementById('maintext').textContent=defaultText; 
return false;
}
//------------------------------------------------------------------
function SIM() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) { 
  document.getElementById('maintext').textContent="RUN IF SURE"; 
  state=CLEAR_CONFIRM;
  return FALSE;
}
 
// Seems to toggle missions.  If both true, sets to 1
// If neither, does nothing (confirm?)
if      (mission2) { mission2=false; mission1=true; }
else if (mission1) { mission1=false; mission2=true; }
showMissions();

keyboardInput="";
document.getElementById('maintext').textContent="MISSION  "+(mission1?"1":"2"); 
setTimeout(confirmTemp,1000);
state=READY; 

return false;
}
//------------------------------------------------------------------
function DATUM() {
 
if (!on) return false; 
// Shift has no effect

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent="MSN CLEARED"; 
  // TODO - clear something ...
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

keyboardInput="";
document.getElementById('maintext').textContent="NO TARGETS"; 
setTimeout(confirmTemp,1000);
state=READY; 

return false;
}
//------------------------------------------------------------------
function DN() {
 
if (!on) return false; 
 
if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

// TODO - Implement whatever it does ...

return false;
}
//------------------------------------------------------------------
function CLEAR() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) { // Can't press it twice
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
state=CLEAR_ACTIVE; 
keyboardInput="";
document.getElementById('maintext').textContent="CLEAR _"; 

return false;
}//------------------------------------------------------------------
function ML() {
 
if (!on) return false; 

// Shifted = set a new one, unshifted - show current
   
keyboardInput=""; // Cleanup

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (shift) {
  Shift();  // Cancel shift
  if (state==RESECTION_FOUND) {
    ml_grid=grid;
    ml_alt=0; // Seems like a fault in the calculator - doesn't ask for alt after resection
    state=TEMP_UPDATE;  
    defaultText="ML 00 READY";  // In future we show as set
    document.getElementById('maintext').textContent="ACTIVE ML 00"; 

    mission1=true;
    mission2=true;
    showMissions();
    setTimeout(confirmTemp,2000);
  } else if (state==READY) {
    state=ML_GRID;
    document.getElementById('maintext').textContent="ML GRID?"; 
  }
} else {
  if (ml_grid==-1) {
    document.getElementById('maintext').textContent="NO RECORD";
    setTimeout(backToReady,1000);
    state=READY;
  } else {
    state=SHOW_ML_GRID;
    document.getElementById('maintext').textContent="00 "+ml_grid;
  }
}

return false;
}
//------------------------------------------------------------------
function showMissions() { // Not fully understood - the "12" at bottom of display

document.getElementById('one').textContent=(mission1)?"1":""; 
document.getElementById('two').textContent=(mission2)?"2":""; 

return; 
}
//------------------------------------------------------------------
function MLs() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent="NO RECORD"; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

// Shifted = set a new one, unshifted - show current
   
keyboardInput=""; // Cleanup

if (shift) {
  Shift();  // Cancel shift
  if (state==READY) {
    state=ML_GRID;
    document.getElementById('maintext').textContent="ML GRID?"; 
  }
} else {
  if (ml_grid==-1) {
    document.getElementById('maintext').textContent="NO RECORD";
    state=READY;
    setTimeout(backToReady,1000);
  } else {
    state=SHOW_ML_GRID;
    document.getElementById('maintext').textContent="00 "+ml_grid;
  }
}

return false;
}
//------------------------------------------------------------------
function MET() {
 
if (!on) return false; 

keyboardInput=""; // Cleanup

if (shift) {
  Shift();  // Cancel shift
  document.getElementById('maintext').textContent="MET GROUP 3?"; 
  state=SETTING_MET;
} else {
  document.getElementById('maintext').textContent="STANDARD MET"; 
  state=READY;
  setTimeout(backToReady,1000);
}
return false;
}
//------------------------------------------------------------------
function confirmTemp() {
 
if (!on) return false; 

keyboardInput=""; // Cleanup
state=TEMP_UPDATE;  
document.getElementById('maintext').textContent="CH TMP "+temperature+"C?"; 

return false;
}
//------------------------------------------------------------------
function Grid() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent="MSN CLEARED"; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
   
if (state!=READY) return false;

if (ml_grid==-1) {
  document.getElementById('maintext').textContent="NO ML";
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

keyboardInput=""; // Cleanup
state=GET_GRID;  
document.getElementById('maintext').textContent="TGT GRID?"; 
return false;
}
//------------------------------------------------------------------
function WM() { // Seems to be a range-bearing shot from unsurveyed location
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent="MSN CLEARED"; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
   
if (state!=READY) return false;

keyboardInput=""; // Cleanup
state=GET_TGT_BRG;  
document.getElementById('maintext').textContent="ML-TGT BG ?"; 
return false;
}
//------------------------------------------------------------------
function Shot() {
 
if (!on) return false; 

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
   
if (state!=SOLUTION && state!=SOLUTION_EL) {
  document.getElementById('maintext').textContent="INVALID KEY";
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
if (ml_grid==-1 && tgt_brg==-1) {
  document.getElementById('maintext').textContent="NO ML";
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
var distance=Math.sqrt(Math.pow(ml_grid%10000-tgt_grid%10000,2)+Math.pow(ml_grid/10000-tgt_grid/10000,2));
if (tgt_range!=-1) distance=tgt_range;  // the range-brg shot

if (distance>4000) {
  document.getElementById('maintext').textContent="OUT OF RANGE";
  keyboardInput=""; // Cleanup
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
if (distance<100) {  document.getElementById('maintext').textContent="TGT TOO NEAR";
  keyboardInput=""; // Cleanup
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

keyboardInput=""; // Cleanup
state=COUNTDOWN;  
countdown=37;
document.getElementById('maintext').textContent="   "+countdown+" SECS";
setTimeout(flightCountdown,1000);
return false;
}
//------------------------------------------------------------------
function B0() { // Digit 0
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) return false;  // Do nothing if shifted 
  
if (keyboardInput.length<12) {
  keyboardInput+="0";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B1() { // Digit 1
  
if (!on) return false;  
  
if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (shift) return false;  // Do nothing if shifted 
  
if (keyboardInput.length<12) {
  keyboardInput+="1";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B2() { // Digit 2, also, when shifted RESECT
  
if (!on) return false;  
  
if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (state== READY && shift) {
  Shift();  // Cancel shift
  keyboardInput=""; // Cleanup
  state=RESECTION_GR1;  
  document.getElementById('maintext').textContent="PT. 1 GRID?"; 
  return false;
}
if (shift) return false;  // Do nothing if shifted and not ready
  
if (keyboardInput.length<12) {
  keyboardInput+="2";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B3() { // Digit 3
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) return false;  // Do nothing if shifted 
  
if (keyboardInput.length<12) {
  keyboardInput+="3";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B4() { // Digit 4
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) return false;  // Do nothing if shifted 
  
if (keyboardInput.length<12) {
  keyboardInput+="4";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B5() { // Digit 5
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) return false;  // Do nothing if shifted 
  
if (keyboardInput.length<12) {
  keyboardInput+="5";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B6() { // Digit 6
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (state== READY && shift) {
  Shift();  // Cancel shift
  state=TEMP_UPDATE;  
  document.getElementById('maintext').textContent="CH TEMP "+temperature+"C?"; 
  return false;
}
  
if (shift) return false;  // Do nothing if shifted and not ready
  
if (keyboardInput.length<12) {
  keyboardInput+="6";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B7() { // Digit 7
  
if (!on) return false;  
  
if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}

if (shift) { // It is clock setting time
  Shift();  //Unset it
  keyboardInput="";
  document.getElementById('maintext').textContent="TIME? HHMM.SS"; 
  state=SETTING_TIME;


  return false; 
}  

if (keyboardInput.length<12) {
  keyboardInput+="7";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B8() { // Digit 8
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) { // Set H-Hour
  keyboardInput="";
  document.getElementById('maintext').textContent="H HR ? HHMM"; 
  state=SET_H_HR;
  Shift();  // Cancel shift
  return false;
}  
if (keyboardInput.length<12) {
  keyboardInput+="8";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function B9() { // Digit 9
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) return false;  // Do nothing if shifted 
  
if (keyboardInput.length<12) {
  keyboardInput+="9";
  document.getElementById('maintext').textContent=keyboardInput; 
}
return false;
}
//------------------------------------------------------------------
function Bdp() { // Decimal Point
  
if (!on) return false;  

if (state==CLEAR_ACTIVE) {
  document.getElementById('maintext').textContent=INVALID_KEY; 
  state=READY;
  setTimeout(backToReady,1000);
  return false;
}
  
if (shift) return false;  // Do nothing if shifted (would be self test, but pointless)

if (keyboardInput.length<12 && keyboardInput.indexOf(".")<0) {
  keyboardInput+=".";
  document.getElementById('maintext').textContent=keyboardInput;
}
return false;
}
//------------------------------------------------------------------
function RUN() { 
  
if (!on) return false;  
  
shift=false;  // Clear shift if we run
var sh=document.getElementById('shift');
sh.style.visibility='hidden';

if (state==CLEAR_CONFIRM) {
  document.getElementById('maintext').textContent="MSNS CLEARED"; 
  // I should doubtless actually clear something here ...
  state=READY;
  setTimeout(backToReady,1000); 
  return false; 
}

if (keyboardInput.length==0  && state!=TEMP_UPDATE && state!=SHOW_ML_ALT && state!=SHOW_ML_GRID && state!=SOLUTION && state!=SOLUTION_EL && state!=GET_TGT_BRG && state!=GET_TGT_RNG) {
  if (state==RESECTION_GR3) { // Skip 3rd point
    state=RESECTION_CALC;
    resect_gr3=-1; // No 3rd point
    document.getElementById('maintext').textContent="WORKING"; 
    setTimeout(resection,3000);
    return false;
  }
  document.getElementById('maintext').textContent=INVALID_KEY;
  return false;  
}
if (state==READY) {  // There is no valid input for run when READY
  keyboardInput="";
  document.getElementById('maintext').textContent=INVALID_KEY;
  return false;  
}

switch (state) {
  case(TGT_GRID):  tgt_grid=getGrid(); 
    if (tgt_grid==-2)  { defaultText="STOTGT GRID?"; setTimeout(backToReady,1000); break; }
    if (tgt_grid!=-1)  { state=TGT_ALT; document.getElementById('maintext').textContent="STO TGT ALT?"; } break;
  case(TGT_ALT):  tgt_alt=Number(keyboardInput); 
    if (!isNaN(tgt_alt))  { state=TGT_NO; document.getElementById('maintext').textContent="STO TGT NO?"; } break;
  case(TGT_NO):  tgt_no=keyboardInput;
    if (!isNaN(tgt_no))  { state=READY; document.getElementById('maintext').textContent=tgt_no+" STORD"; 
        setTimeout(backToReady,3000); } break;

  case(GET_GRID):  tgt_grid=getGrid();   // Snap shot at a grid
    if (tgt_grid==-2)  { defaultText="TGT GRID?" ; setTimeout(backToReady,1000); break; }
    if (tgt_grid!=-1)  { state=GET_ALT; document.getElementById('maintext').textContent="TGT ALT?"; } break;
  case(GET_ALT):  tgt_alt=Number(keyboardInput); 
    if (!isNaN(tgt_alt))  {
      state=SOLUTION; 
      document.getElementById('maintext').textContent="ML:00 HE/WP4"; // High Explosive/White Phosphorous 4?
      setTimeout(solution,1000);
    }
    break;
  case (SOLUTION):
    document.getElementById('maintext').textContent="EL: 1258 T: 37"; // TODO make based on calculation
    state=SOLUTION_EL;
    break;
  case (SOLUTION_EL):
    document.getElementById('maintext').textContent="BG: 1577 CH: 3"; // TODO make based on calculation
    state=SOLUTION;  // Cycles round awaiting SHOT
    break;

  case(ML_GRID):  ml_grid=getGrid(); 
    if (ml_grid!=-1)  { state=ML_ALT; document.getElementById('maintext').textContent="ML ALT.?"; } break;
  case(ML_ALT):  ml_alt=Number(keyboardInput); 
    if (!isNaN(ml_alt))  {
      state=TEMP_UPDATE; document.getElementById('maintext').textContent="CH TEMP "+temperature+"C?"; 
      defaultText="ML 00 READY" 
    }
    break;

  case (SHOW_ML_GRID):
    state=SHOW_ML_ALT; document.getElementById('maintext').textContent="00 ALT:"+ml_alt; break;
  case (SHOW_ML_ALT):
    state=TEMP_UPDATE; 
    document.getElementById('maintext').textContent="CH TEMP "+temperature+"C?"; 
    defaultText="ML 00 READY";
    break;

  case(RESECTION_GR1):  resect_gr1=getGrid(); 
    if (resect_gr1!=-1)  { state=RESECTION_BR1; document.getElementById('maintext').textContent="PT. 1 BRG?"; } break;
  case(RESECTION_BR1):  resect_br1=getBrg(); 
    if (resect_br1!=-1) { state=RESECTION_GR2; document.getElementById('maintext').textContent="PT. 2 GRID?"; } break;
  case(RESECTION_GR2):  resect_gr2=getGrid(); 
    if (resect_gr2!=-1) { state=RESECTION_BR2; document.getElementById('maintext').textContent="PT. 2 BRG?"; } break;
  case(RESECTION_BR2):  resect_br2=getBrg(); 
    if (resect_br2!=-1) { state=RESECTION_GR3; document.getElementById('maintext').textContent="PT. 3 GRID?"; } break;
  case(RESECTION_GR3):  resect_gr3=getGrid(); 
    if (resect_gr3!=-1) { state=RESECTION_BR3; document.getElementById('maintext').textContent="PT. 3 BRG?"; } break;
  case(RESECTION_BR3):  resect_br3=getBrg(); 
    keyboardInput="";
    document.getElementById('maintext').textContent="WORKING"; 
    if (resect_br3!=-1) state=RESECTION_CALC;
    setTimeout(resection,3000);
    break;
  case (TEMP_UPDATE):
    if (keyboardInput=="") keyboardInput=temperature.toString();  // keep current
    var tmp=Number(keyboardInput);
    if (!isNaN(tmp)) { temperature=tmp; state=READY; document.getElementById('maintext').textContent=defaultText;}
    else { document.getElementById('maintext').textContent=INVALID_KEY; }
    break;
  case (SET_H_HR):
    var tmp=Number(keyboardInput);
    if (keyboardInput.length!=4 || isNaN(tmp) || tmp<0 || ((tmp%100)>59) || 
        (Math.trunc(tmp/100)>23)) { // 24h clock.  Mins<59 Hrs<24
      document.getElementById('maintext').textContent="INPUT ERROR"; 
      setTimeout(backToReady,1000);
      state=READY;
      keyboardInput="";
      return false;
    }
    var tmp_mins=tmp%100;
    var tmp_hrs=Math.trunc(tmp/100);

    var today=new Date(); // Countdown is until next alignment of times, i.e. <=24h 
    var hr=today.getHours();
    var min=today.getMinutes();
    var sec=today.getSeconds();
    var timeNow=hr*3600.0+min*60.0+sec+timeOffset;
    if (timeNow>(24.0*3600)) timeNow-=(24.0*3600);
    sec=Math.trunc(timeNow%60);
    timeNow/=60;
    min=Math.trunc(timeNow%60);
    hr=Math.trunc(timeNow/60);

    h_hrs=tmp_hrs-hr;
    h_mins=tmp_mins-min;
    h_secs=60-sec;
    if (sec==0) { h_secs=0;} else { h_mins-=1; }

    if (h_secs==0 && h_mins==0 && h_hrs==0) { // Corner case
      document.getElementById('maintext').textContent="* H HOUR *"; 
      setTimeout(Hcountup,1000);
      state=H_HR_COUNTUP;
      break;
    }

    if (h_mins<0) { h_hrs-=1; h_mins+=60; }
    if (h_hrs<0) h_hrs+=24;

    keyboardInput="";
    state=H_HR_COUNTDOWN;
    document.getElementById('maintext').textContent="H-"+h_hrs.toString().padStart(2,'0')+":"+h_mins.toString().padStart(2,'0')+":"+h_secs.toString().padStart(2,'0'); 
    setTimeout(Hcountdown,1000);
    break;
  case (SETTING_TIME):
    var tmp=Number(keyboardInput);
    var tmp_secs=(tmp*100)%100;
    var tmp_mins=tmp%100;
    var tmp_hrs=Math.trunc(tmp/100);
    if (keyboardInput.length!=7 || isNaN(tmp) || tmp_secs>59 || tmp_mins>59 || tmp_hrs>24 || tmp<0) { // 24h clock with seconds (HHMM.SS)
      document.getElementById('maintext').textContent="INPUT ERROR"; 
      setTimeout(backToReady,1000);
      state=READY;
      keyboardInput="";
      return false;
    }
    var timeOfDay=tmp_hrs*3600.0+tmp_mins*60.0+tmp_secs;
    var today=new Date(); // Countdown is until next alignment of times, i.e. <=24h 
    var hr=today.getHours();
    var min=today.getMinutes();
    var sec=today.getSeconds();
    var trueTimeOfDay=hr*3600.0+min*60.0+sec;

    timeOffset=(timeOfDay-trueTimeOfDay); // Capped < 24h
    if (timeOffset<0) timeOffset+=24.0*3600.0;

    document.getElementById('maintext').textContent="CLOCK RESET"; 
    setTimeout(backToReady,1000);
    state=READY;
    keyboardInput="";
    return false;

    break;
  case (SETTING_MET):
    var tmp=Number(keyboardInput);
    if (isNaN(tmp) || tmp!=4) { // Strangely anything but 4 is Input Error ...
      document.getElementById('maintext').textContent="INPUT ERROR"; 
      setTimeout(backToReady,1000);
      state=READY;
      keyboardInput="";
      return false;
    }
    document.getElementById('maintext').textContent="NO GROUP 4"; // ... and 4 easn't much good either
    setTimeout(backToReady,1000);
    state=READY;
    keyboardInput="";
    return false;
    break;

  case (GET_TGT_BRG):
    tgt_brg=getBrg();   // Snap shot at a bearing/range
    if (tgt_brg==-2)  { defaultText="ML-TGT BG ?"; setTimeout(backToReady,1000); break; }
    if (tgt_brg!=-1)  { state=GET_TGT_RNG; document.getElementById('maintext').textContent="ML-TGT RNG ?"; } break;
    break;
  case (GET_TGT_RNG):
    tgt_range=getRange();   
    if (tgt_range==-2)  { defaultText="ML-TGT RNG ?"; setTimeout(backToReady,1000); break; }
    if (tgt_range!=-1)  { 
      state=SOLUTION; // Follow same path as GRID key press, except need no ML
      document.getElementById('maintext').textContent="ML:00 HE/WP4"; // High Explosive/White Phosphorous 4?
      setTimeout(solution,1000);
    }
    break;
}
keyboardInput="";
return false;
}

//------------------------------------------------------------------
function backToReady() {
  document.getElementById('maintext').textContent=defaultText;
  return false;
}
//------------------------------------------------------------------
function solution() {
  document.getElementById('maintext').textContent="BG: 1577 CH:4";// TODO make a variable!
  return false;
}
//------------------------------------------------------------------
function getGrid() {

  if (keyboardInput.length==0) {
    document.getElementById('maintext').textContent="INPUT REQ'D";
    return -2;
  }
  if ((keyboardInput.length%2)!=0) { // Grids must be even
    document.getElementById('maintext').textContent=INVALID_KEY;
    return -1;  
  }    
  // TODO - for now assume 8 figure grids only.  Later 6,8,10 should be OK
  if ((keyboardInput.length%2)!=0) {
    document.getElementById('maintext').textContent=INVALID_KEY;
    return -1;  
  }    
  if (keyboardInput.length!=8) {  
    document.getElementById('maintext').textContent=INVALID_KEY;
    return -1;  
  }
   if (Number(keyboardInput)<0) {  
    document.getElementById('maintext').textContent=INVALID_KEY;
    return -1;  
  } 
  
  return (Number(keyboardInput));  
}
//------------------------------------------------------------------
function getBrg() {
  var tmp=Number(keyboardInput); 

  if (keyboardInput.length==0) {
    document.getElementById('maintext').textContent="INPUT REQ'D";
    return -2;
  }

  if (tmp>=0 && tmp<=6400) return tmp;  

  document.getElementById('maintext').textContent=INVALID_KEY;
  return -1;  
}
//------------------------------------------------------------------
function getRange() {

  if (keyboardInput.length==0) {
    document.getElementById('maintext').textContent="INPUT REQ'D";
    return -2;
  }

  var tmp=Number(keyboardInput); 

  if (tmp>=0) return tmp;  

  document.getElementById('maintext').textContent=INVALID_KEY;
  return -1;  
}
//------------------------------------------------------------------
function resection() {
  // Two point resection to determine location from which sightings are made
  // Should be mathematically correct, and matches (within accuracy) the calculator
  // calculation.  Might struggle for special cases (e.g. small denominator)
  // Currently assumes 8 figure grids.
  
  if (resect_br1==resect_br2 || ((resect_br2-resect_br1)%6400)==0) { // Parallel
    document.getElementById('maintext').textContent="NO SOLUTION";
    state=READY;
    setTimeout(backToReady,3000);
    return false;
  }
  var resect_br1_rad=2*Math.PI*(resect_br1/6400.0); // Mils to radians
  var resect_br2_rad=2*Math.PI*(resect_br2/6400.0);
  //var resect_br3=2*Math.PI*(resect_br3/6400.0);  // TODO - third bearing
  var numerator=Math.sin(resect_br1_rad)*((resect_gr2%10000)-(resect_gr1%10000))-
                Math.cos(resect_br1_rad)*((resect_gr2/10000)-(resect_gr1/10000));
  
  var denominator=Math.sin(resect_br2_rad)*Math.cos(resect_br1_rad)-
                  Math.cos(resect_br2_rad)*Math.sin(resect_br1_rad);
  
  if (denominator==0) { // Not sure this is possible or might duplicate parallel test
    document.getElementById('maintext').textContent="NO SOLUTION";
    state=READY;
    setTimeout(backToReady,4000);  // Not quick!
    return false;    
  }
  var length2=numerator/denominator;

  var eastings=Math.round((resect_gr2/10000)+length2*Math.sin(resect_br2_rad));
  var northing=Math.round((resect_gr2%10000)+length2*Math.cos(resect_br2_rad));

  grid=eastings*10000+northing;  // Store for use by ML
  document.getElementById('maintext').textContent="INT: "+eastings%10000+" "+northing%10000;
  state=RESECTION_FOUND;
  keyboardInput="";
  return;  
}
//------------------------------------------------------------------
//------------------------------------------------------------------
//------------------------------------------------------------------
//------------------------------------------------------------------
//------------------------------------------------------------------