-- 04.08.24/AH A2A Bendix-King DME KN62A FREQ (standalone) doesn't work reliable
--
--	A2A Bendix-King DME KN62A, delivered by C172 Trainer and PA28 doesn't work reliable in standalone mode
--  So I created this script that reads Prepar3D offsets of NAV2 (as there is no NAV3) and
--  shows the DME values in a small window
--	
-- to be done:
-- Define button to call script

-- Init
NAVout="- no NAV state -"
DME1out="NAV1 inactive or no DME"
DME2out="NAV2 inactive or no DME"
--
NAV1mask=18							-- NAVstate bit mask : NAV1 good and has DME = 2^1+ 2^5 = 2 + 16 = 18
NAV2mask=36							-- NAVstate bit mask : NAV2 good and has DME = 2^2 + 2^6 = 4 + 32 = 36

-- offset  0x3300 Additional radio and autopilot status indicators (read only access). Allocation by bits which are set when true.:
--					Bit 0 = least significant (value 1), 1 = good NAV1, 2 = good NAV2, 4 = NAV1 has DME, 5 = NAV2 has DME
NAVstate=ipc.readUW(0x3300)
NAV1bits=logic.And(NAVstate,NAV1mask)		-- NAV1 good and has DME = 2^1 + 2^5 = 2 + 16 = 18
NAV2bits=logic.And(NAVstate,NAV2mask)		-- NAV2 good and has DME = 2^2 + 2^6 = 4 + 32 = 36
NAVout="NAV-State: " .. NAVstate .. "      " .. " NAV1bits: " .. NAV1bits .. " NAV2bits: " .. NAV2bits .. "      "

if NAV1bits == NAV1mask then
-- offset  0xc4d NAV1 code flags, bits used as follows: 0 = DME available (bit 3 "No signal available" seems not related to DME)
  DME1byte=ipc.readUB(0xc4d)
  DME1avail=logic.And(DME1byte,1)	-- mask bit 0 "DME avail" = 2^0 = 1. Bit 3 "No signal available" seems related to VOR/OBS only 
  
  if DME1avail == 1 then  
-- offset 0xc29 DME1 distance "DME1 distance as character string, either “nn.n” or “nnn.” (when > 99.9 nm).
--				The 5th character may be a zero or a space. Don’t rely on it."
    DME1dist=ipc.readSTR(0xc29,4)
-- offset 0xc2e DME1 speed as character string, “nnn” followed by either space then zero or just zero
    DME1speed=ipc.readSTR(0xc2E,3)
--	
	DME1out="NAV1 DME  Speed: " .. DME1speed .. " kts   Dist: " .. DME1dist .. " nm       "
  else
    DME1out="NAV1 without DME" .. "                                                           "
  end
end

if NAV2bits == NAV2mask then
 
-- offset  0xc70 NAV2 code flags, bits used as follows: 0 = DME available (bit 3 "No signal available" seems not related to DME)
  DME2byte=ipc.readUB(0xc70)
  DME2avail=logic.And(DME2byte,1)	-- mask bit 0 "DME avail" = 2^0 = 1. Bit 3 "No signal available" seems related to VOR/OBS only 
  
  if DME2avail == 1 then  
-- offset 0xc33 DME2 distance as character string, either “nn.n” or “nnn.” (when > 99.9 nm).
--				The 5th character may be a zero or a space. Don’t rely on it.
    DME2dist=ipc.readSTR(0xc33,4)
-- offset 0xc38 DME2 speed as character string, “nnn” followed by either space then zero or just zero
    DME2speed=ipc.readSTR(0xc38,3)
	DME2out="NAV2 DME  Speed: " .. DME2speed .. " kts   Dist: " .. DME2dist .. " nm       "
  else
    DME2out="NAV2 without DME" .. "                                                           "
  end
 
end
-- DEBUG
-- ipc.lineDisplay(NAVout,1)
-- ipc.lineDisplay(DME1dbg,2)
-- ipc.lineDisplay(DME2dbg,3)

ipc.lineDisplay(DME1out,1)
ipc.lineDisplay(DME2out,2)
ipc.sleep(3000)