Module:Chessboard mxn

 local p = {}

 function chessboard(args, size, rows, cols, rev, trans, lightdark, altprefix, letters, numbers, header, footer, align, clear)
 function colchar( col )
 return (col <= 26) and ( "abcdefghijklmnopqrstuvwxyz" ):sub( col, col ) 
 	or ( "abcdefghijklmnopqrstuvwxyz" ):sub( math.floor((col-1)/26), math.floor((col-1)/26) ) 
 		.. ( "abcdefghijklmnopqrstuvwxyz" ):sub( col-math.floor((col-1)/26)*26, col-math.floor((col-1)/26)*26)
 end
 function image_square( pc, row, col, size, t, flip, altprefix )
 local colornames = { l = 'white', d = 'black', u = 'unknown color' }
 local piecenames = { 
 p = 'pawn', 
 r = 'rook', 
 n = 'knight', 
 b = 'bishop', 
 q = 'queen', 
 k = 'king', 
 a = 'princess',
 c = 'empress', 
 z = 'champion', 
 w = 'wizard', 
 t = 'fool', 
 h = 'upside-down pawn', 
 m = 'upside-down rook', 
 s = 'upside-down knight', 
 f = 'upside-down king', 
 e = 'upside-down bishop', 
 g = 'upside-down queen',
 G = 'giraffe',
 U = 'unicorn',
 Z = 'zebra'
 }
 local symnames = { 
 xx = 'black cross', 
 ox = 'white cross', 
 xo = 'black circle', 
 oo = 'white circle',
 ul = 'up-left arrow', 
 ua = 'up arrow', 
 ur = 'up-right arrow', 
 la = 'left arrow', 
 ra = 'right arrow',
 dl = 'down-left arrow', 
 da = 'down arrow', 
 dr = 'down-right arrow', 
 lr = 'left-right arrow', 
 ud = 'up-down arrow',
 db = 'up-right and down-left arrow',
 dw = 'up-left and down-right arrow',
 x0 = 'zero', 
 x1 = 'one', 
 x2 = 'two', 
 x3 = 'three', 
 x4 = 'four', 
 x5 = 'five', 
 x6 = 'six', 
 x7 = 'seven', 
 x8 = 'eight', 
 x9 = 'nine'
 }
 local color = mw.ustring.gsub( pc, '^.*(%w)(%w).*$', '%2' ) or ''
 local piece = mw.ustring.gsub( pc, '^.*(%w)(%w).*$', '%1' ) or ''
 local alt = altprefix .. colchar( col ) .. row .. ' '
 if ( colornames[color] and piecenames[piece] ) then
 alt = alt .. colornames[color] .. ' ' .. piecenames[piece]
 else
 alt = alt .. ( symnames[piece .. color] or piece .. ' ' .. color )
 end
 local ld = t and 't' or ((((row + col + flip) % 2) == 0) and 'd' or 'l')
 
 return string.format( '[[File:Chess %s%s%s45.svg|%dx%dpx|alt=%s|%s]]', piece, color, ld, size, size, alt, alt )
 end

 function letters_row( rev, num_lt, num_rt, cols )
 local res = '<tr style="vertical-align:middle">' .. ( num_lt and '<td style="padding:0; vertical-align:inherit"></td>' or '' ) .. '<td style="padding:0; vertical-align:inherit; height:18px">'
 for k = 1, cols do
 res = res .. colchar(rev and (cols - k + 1) or k) .. '</td><td style="padding:0; vertical-align:inherit">'
 end
 res = res .. '</td>' .. ( num_lt and '<td style="padding:0; vertical-align:inherit"></td>' or '' ) .. '</tr>'
 return res
 end
 local letters_tp = letters:match('both') or letters:match('top')
 local letters_bt = letters:match('both') or letters:match('bottom')
 local numbers_lt = numbers:match('both') or numbers:match('left')
 local numbers_rt = numbers:match('both') or numbers:match('right')
 local width = cols * size + 2
 local flip = lightdark and 1 or 0
 if ( numbers_lt ) then width = width + 18 end
 if ( numbers_rt ) then width = width + 18 end

 local b = ''
 local caption = ''

 if ( letters_tp ) then b = b .. letters_row(rev, numbers_lt, numbers_rt, cols) .. '\n' end
 for trow = 1,rows do
 local row = rev and trow or (rows - trow + 1)
 b = b .. '<tr style="vertical-align:middle">'
 if ( numbers_lt ) then b = b .. '<td style="padding:0; vertical-align:inherit; width:18px">' .. row .. '</td>' end
 for tcol = 1,cols do
 local col = rev and (cols - tcol + 1) or tcol
 local idx = cols*(rows - row) + col + 2
 if (args[idx] == nil) then args[idx] = ' ' end
 local img = image_square(args[idx]:match('%w%w') or '', row, col, size, trans, flip, altprefix )
 local bg = (((trow + tcol + flip) % 2) == 0) and '#ffce9e' or '#d18b47'
 b = b .. '<td style="padding:0; vertical-align:inherit; background-color: ' .. bg .. ';">' .. img .. '</td>'
 end
 if ( numbers_rt ) then b = b .. '<td style="padding:0; vertical-align:inherit; width:18px">' .. row .. '</td>' end
 b = b .. '</tr>'
 end
 if ( letters_bt ) then b = b .. letters_row(rev, numbers_lt, numbers_rt, cols) .. '\n' end

 if not footer:match('^%s*$') then
 caption = '<div class="thumbcaption">' .. footer .. '</div>\n'
 end
 b = '<table cellpadding=0 cellspacing=0 class="center noviewer" style="line-height: 0; background:white; font-size:88%; border:1px #c8ccd1 solid;'
 .. 'padding:0; margin:auto">\n' .. b .. '\n</table>'

 if noframe then
 return b
 else
 return '<div class="thumb ' .. align .. '">'
 .. '<div class="center">' .. header .. '</div>' .. '\n<div class="thumbinner" style="width:' .. width .. 'px;">\n' 
 .. b .. '\n' .. caption .. '</div></div>'
 end
 
 end

 function convertFenToArgs( fen )
 -- converts FEN notation to an array of positions, offset by 2
 local res = {' ', ' '}
 -- Loop over rows, which are delimited by /
 for srow in string.gmatch("/" .. fen, "/%w+") do
 srow = srow:gsub("/","") -- clean up row
 -- Loop over all letters and numbers in the row
 -- Since Lua regexes do not have the | operator, we have
 -- to spell things out
 local index = 1
 local piece = "" -- Piece can also be empty squares
 local place = 0
 local pstart = 0
 local pend = 0
 local length = srow:len()
 while index <= length do
 -- Look for a number. Can have multiple digits
 pstart, pend = srow:find("%d+", index)
 if pstart == index then
 piece = srow:sub(pstart, pend)
 index = pend + 1
 for k=1,tonumber(piece) do
 table.insert(res,' ')
 end
 else
 -- If number not found, look for a letter (piece on board)
 pstart = srow:find("%a",index)
 if pstart == index then
 piece = srow:sub(pstart, pstart)
 index = pstart + 1
 -- l: White (light); d: Black (dark)
 local color = piece:match( '%u' ) and 'l' or 'd'
 piece = piece:lower()
 table.insert(res, piece .. color)
 else
 index = length + 1 -- Break loop
 end
 end
 end
 end
 return res
 end

 function p.board(frame)
 local args = frame.args
 local pargs = frame:getParent().args
 local size = (args.size or pargs.size) or '26'
 local reverse = (args.reverse or pargs.reverse or '' ):lower() == "true"
 local trans = (args.transparent or pargs.transparent or '' ):lower() == "true"
 local lightdark = (args.lightdark or pargs.lightdark or '' ):lower() == "swap"
 local altprefix = args.altprefix or pargs.altprefix or ''
 local rows = args.rows or pargs.rows or 8
 local cols = args.cols or pargs.cols or 8
 local letters = ( args.letters or pargs.letters or 'both' ):lower() 
 local numbers = ( args.numbers or pargs.numbers or 'both' ):lower() 
 local header = mw.ustring.gsub( args[2] or pargs[2] or '', '^%s*(.-)%s*$', '%1' )
 local footer = args[3 + rows*cols] or pargs[3 + rows*cols] or ''
 local align = ( args[1] or pargs[1] or 'tright' ):lower()
 local clear = ( args.clear or pargs.clear ) or ( align:match('tright') and 'right' or 'none' )
 local noframe = (args.noframe or pargs.noframe or ''):lower() == "true"
 local fen = args.fen or pargs.fen

 size = mw.ustring.match(size, '[%d]+') or '26' -- remove px from size
 if (fen) then
 align = ( args.align or pargs.align or 'tright' ):lower()
 clear = ( args.clear or pargs.clear ) or ( align:match('tright') and 'right' or 'none' )
 header = args.header or pargs.header or ''
 footer = args.footer or pargs.footer or ''
 return chessboard(convertFenToArgs( fen ), size, rows, cols, reverse, trans, lightdark, altprefix, letters, numbers, header, footer, align, clear, noframe)
 end
 if args[3] then
 return chessboard(args, size, rows, cols, reverse, trans, lightdark, altprefix, letters, numbers, header, footer, align, clear, noframe)
 else
 return chessboard(pargs, size, rows, cols, reverse, trans, lightdark, altprefix, letters, numbers, header, footer, align, clear, noframe)
 end
 
 end

 return p