NodeMCU 9 > 9 = true

bcdrtc.lua

-- -------------------------------------------------------------------
-- FILE:	GIST/bcdrtc.lua
--
-- PURPOSE:	NodeMCU error demo.
--
-- AUTHOR:	Patrick Dorion <dorionpatrick@outlook.com>
--
-- DATE:	November 16, 2019.
--
-- LICENSE: You need permission to use, or reproduce this code.
-- -------------------------------------------------------------------

varlib = {}

function varlib.zeropad ( num, size )

	--[[
			Zero-pads a binary.

			num	    	string		The binary to convert.
			size		number		The chunk size to pad for.

			Returns:	string		Zero-padded binary.
	]]--

    num = tostring ( num )
    if ( size == nil ) then size = 4 end

    while ( #num ) % size ~= 0 do
        num = "0" .. num
    end

    return num

end  --  End of function.

function varlib.dec2base ( int, base )

	--[[
			Converts a decimal integer to any other base.

			int			number		Integer.
			base		number		The base to convert to.

			Returns:	string		Converted value.

			This code is mostly from from Peter Prade <prade@phenomic.net>.
	]]--

	local digits = { }

	for i = 0, 9 do
		digits[i] = string.char ( string.byte ( '0' ) + i )
	end

	for i = 10, 36 do
		digits[i] = string.char ( string.byte ( 'A' ) + i - 10 )
	end

	function convert ( number, base )

		local string = ''

		repeat
			local remainder = number % base
			string = digits[remainder] .. string
			number = ( number - remainder ) / base
		until number == 0

		return string

	end

	return convert ( int, base )

end  --  End of function.


function dec2bcd ( dec )

	--[[
	--		Returns a binary-coded decimal.
	--
	--		It does that this way, and this that way.  Be careful.
	--
	--		dec				number		Number to be converted.
	--
	--		Returns:		string		Binary-coded decimal.
	--
	--		Depends:		module		varlib
	]]--

	--require ( 'varlib' )

	local bcd

	dec = tostring ( dec )

	for i = 1, #dec, 1 do
		if ( i == 1 ) then
			bcd = varlib.zeropad ( varlib.dec2base ( string.sub ( dec, i, i ), 2 ), 4 )
		else
			bcd = bcd .. varlib.zeropad ( varlib.dec2base ( string.sub ( dec, i, i ), 2 ), 4 )
		end
	end

	return bcd

end  --  End of function.


function bin2dec ( bin )

    local dec = 0

    bin = varlib.zeropad ( tostring ( bin ), 4 )

    for i = 1, #bin, 1 do

        if ( string.sub ( bin, i, i ) == '1' ) then
            dec = dec + 2 ^ (#bin - i)
        end

    end

    return dec

end

function bcd2dec ( bcd )

	local dec, digit = '', ''

	bcd = varlib.zeropad ( bcd )

    for i = #bcd, 1, -4 do
        digit = bin2dec ( string.sub ( bcd, i-3, i ) )
		print ( 'digit = ' .. digit )
        if ( tonumber ( digit) > 9 ) then
            print ( "Error: BCD nibble > 9." )
            return 1
        else
            dec = digit .. dec
        end
    end

    return tonumber ( dec )

end

print ( bcd2dec ( '1001' ) )

-- Creates error 'BCD(1001) > 9' on my board.  Runs without error on Lua 5.1.5 on computer.  Board running build September 19, 2019 powered by Lua 5.1.4 on SDK 3.0.1-dev(fce080e)