Host GPS with a single PC, instead of 4!

singleGPShost.lua

-- Insert name of 'wireless_modems' (attatched to wired_modems), used for GPS here
-- Remove the already existing onces!
-- EXAMPLE: ["modem_0"] = {x=1, y=2, z=3}
local point = {
    ["modem_0"] = {x=151, y=56, z=-43},
    ["modem_1"] = {x=156, y=56, z=-43},
    ["modem_2"] = {x=151, y=56, z=-38},
    ["modem_3"] = {x=151, y=60, z=-43}
}
local CHANNEL_GPS = gps.CHANNEL_GPS
-----------------------------------------
-- END OF CONFIGURATION
-----------------------------------------

local bRunning = true
local function main()
    local modem = {}
    for name,_ in pairs(point) do
        modem[#modem+1] = {p=peripheral.wrap(name), n=name}
    end

    local function listener(modem)
        modem.p.open(CHANNEL_GPS)
        while bRunning do
            local event, sSide, sChannel, sReplyChannel, sMessage, nDistance = os.pullEvent( "modem_message" )
            if event == "modem_message" then
                if sSide == modem.n and sChannel == CHANNEL_GPS and sMessage == "PING" and nDistance then
                    modem.p.transmit( sReplyChannel, CHANNEL_GPS, { point[modem.n].x, point[modem.n].y, point[modem.n].z } )
                end
            end
        end
        modem.p.close(CHANNEL_GPS)
    end

    parallel.waitForAll(
        function() listener(modem[1]) end,
        function() listener(modem[2]) end,
        function() listener(modem[3]) end,
        function() listener(modem[4]) end
    )
end

main()