--[[
*********************************************
* AYA CHARACTER CONVERTER                   *
                                            *
* for use on nintendo GBA and DS            *
* by suwacrab                               *
*********************************************
--]]

local aya = {}
aya.__index = aya

local printf = function(str,...) print(str:format(...)) end
--|==== lookup tables
aya.pal_formats = {
	-- h == hex,b == binary
	-- > AGB palette formats
	rgb5a1	= 0;		-- | AGGGGGRRRRRBBBBB	: 16-bit	: direct	: 65536-color
	-- > NTR palette formats
	a3i5		= 1;		-- | IIIAAAAA					: 5-bit		: indexed	: 32-color w/ alpha
	a5i3		= 2;		-- | IIIIIAAA					: 3-bit		: indexed	: 8-color w/ alpha
}
aya.clr_formats = {
--								-- | bit format	: bit cnt	: type		: color count
	pal2		= 0;		-- | 76543210		: 1-bit		: indexed	: 2-color
	pal4 		= 1;		-- | 33221100		: 2-bit		: indexed	: 4-color
	pal16 	= 2;		-- | 11110000		: 4-bit		: indexed	: 16-color
	pal256	= 3;		-- | 00000000		: 8-bit		:	indexed	: 256-color
	rgb16 	= 4;		-- | 16-bit RGB	: 16-bit	: direct	: 65536-color
}

local fwrite = function(fname,str,mode)
	assert(str,("attempted to write nil to file %s"):format(fname))
	local f = io.open(fname,mode or "wb")
	f:write(str); f:close();
	printf("\t＊　ＦＷＲＩＴＥ　[%08XH] (%-32s)",#str,fname)
end
--|==== misc functions
local strclamp = function(str,len,fill)
	return (
		#str < len and 
			str..(fill or " "):rep(len-#str)
		or #str > len and
			str:sub(1,len)
		or str
	)
end
local strwrite = function(str,fname,mode)
	fwrite(fname,str,mode)
end
string.clamp = strclamp
string.write = strwrite
--|==== byte functions
local tochr = string.char

local function chrtonum_a16(a,i)
	return a[i] | (a[i+1]<<8)
end
local function chrtonum_a32(a,i)
	return chrtonum_a16(a,i) | (chrtonum_a16(a,i+2)<<16)
end

local tochr_8 = function(n)
	return tochr(n&0xFF) end
local tochr_16 = function(n)
	return tochr_8(n)..tochr_8(n>>8) end
local tochr_32 = function(n)
	return tochr_16(n)..tochr_16(n>>16) end

--|==== read functions
aya.new = function(name)
	local bun = setmetatable({},aya)
	bun:set_name(name)
	return bun
end
aya.set_name = function(bun,name)
	name = name or "sadza"
	bun.name = name:clamp(7,' ').."\0"
	return bun
end
aya.load_new = function(name,fname)
	local bun = aya.new(name)
	bun:load_file(fname)
	return bun
end
aya.load_str = function(bun,str)
	-- read bytes
	local bytes = {} do
		local barray = { str:byte(1,#str) }
		for i = 1,#str do bytes[i-1] = barray[i] end
	end
	-- read bitmap file header
	local header = {} do
		header.type = string.char(bytes[0],bytes[1]) -- 2
		header.size = chrtonum_a32(bytes,0x0002) -- 4
		header.res0 = chrtonum_a16(bytes,0x0006) -- 2
		header.res1 = chrtonum_a16(bytes,0x0008) -- 2
		header.data = chrtonum_a32(bytes,0x000A) -- 2
	end
	-- read DIB header
	local dibheader = {} do
		local dib_offset = 0x000E
		dibheader.headsize = chrtonum_a32(bytes,dib_offset+0x0000) -- 4
		dibheader.width =    chrtonum_a32(bytes,dib_offset+0x0004) -- 4
		dibheader.height =   chrtonum_a32(bytes,dib_offset+0x0008) -- 4
		dibheader.planes =   chrtonum_a16(bytes,dib_offset+0x000C) -- 2
		dibheader.bpp =      chrtonum_a16(bytes,dib_offset+0x000E) -- 2
		dibheader.compress = chrtonum_a32(bytes,dib_offset+0x0010) -- 4
		dibheader.size =     chrtonum_a32(bytes,dib_offset+0x0014) -- 4
		dibheader.resW =     chrtonum_a32(bytes,dib_offset+0x0018) -- 4
		dibheader.resH =     chrtonum_a32(bytes,dib_offset+0x001C) -- 4
		dibheader.clrcnt =   chrtonum_a32(bytes,dib_offset+0x0020) -- 4
		-- > fix dummy 0
		if dibheader.size == 0 then
			local width = dibheader.width
			local height = dibheader.height
			dibheader.size = (dibheader.bpp * width*height)>>3
			print("new size: ",dibheader.size)
		end
	end
	-- read color table
	local palette = {} do
		if dibheader.bpp <= 8 then
			local pal_offset = 0x000E + dibheader.headsize
			for i = 0,(2^dibheader.bpp)-1 do
				local clr = {};
				-- > keep in mind: colors are stored in BGRX format.
				-- > B,G,R,X are 1 byte long, respectively.
				-- > X is unused and is (probably) 0.
				clr[1] = bytes[pal_offset + (i*4) + 0x0002]
				clr[2] = bytes[pal_offset + (i*4) + 0x0001]
				clr[3] = bytes[pal_offset + (i*4) + 0x0000]
				clr[4] = bytes[pal_offset + (i*4) + 0x0003]
				palette[i] = clr
				--print(i,table.unpack(clr))
			end
		end
	end
	-- read pixel data
	local bmpdata_pix = {}
	local bmpdata_chr = {} do
		local bmp_offset = header.data
		local bmp_size = dibheader.size
		-- > write char data
		for i = 0,bmp_size-1 do
			local chr = bytes[bmp_offset + i]
			assert(chr,"BMP character data is nil...")
			bmpdata_chr[i] = chr
		end
		-- read the pixel data
		-- > 1bpp
		if dibheader.bpp == 1 then
			-- > read the (flipped) pixel data
			local pixdat_flip = {} do
				local index = 0
				for i = 0,bmp_size-1 do
					local chr = bmpdata_chr[i]
					for c = 0,7 do
						local p = ((chr>>c)&1)
						pixdat_flip[index] = p; index = index + 1
					end
				end
			end
			-- > read the unflipped pixel data
			local width = dibheader.width
			local height = dibheader.height
			for y = 0,height-1 do
				for x = 0,width-1 do
					-- > read pixel from flipped bitmap
					local py = (height - y)-1
					local pix = pixdat_flip[x + py*width]
					-- > write to real bitmap
					bmpdata_pix[x + y*width] = pix
				end
			end
		end
		-- > 4bpp
		if dibheader.bpp == 4 then
			-- > read the (flipped) pixel data
			local pixdat_flip = {} do
				local index = 0
				for i = 0,bmp_size-1 do
					local chr = bmpdata_chr[i]
					local p0 = chr>>4;  -- 1st pixel is in high nybble, for some reason
					local p1 = chr&0xF; -- 2nd pixel is in low nybble
					pixdat_flip[index] = p0; index = index+1;
					pixdat_flip[index] = p1; index = index+1;
				end
			end
			-- > read the unflipped pixel data
			local width = dibheader.width
			local height = dibheader.height
			for y = 0,height-1 do
				for x = 0,width-1 do
					-- > read pixel from flipped bitmap
					local py = (height - y)-1
					local pix = pixdat_flip[x + py*width]
					-- > write to real bitmap
					bmpdata_pix[x + y*width] = pix
				end
			end
		end
	end
	-- return
	bun.bmpdata_pix = bmpdata_pix
	bun.bmpdata_chr = bmpdata_chr
	bun.palette = palette
	bun.dibheader = dibheader
	bun.header = header
	bun.bmpbytes = bytes
	return bun
end
aya.load_file = function(bun,fname)
	local f = io.open(fname,"rb")
	local str = f:read("*all")
	f:close();
	bun:load_str(str)
	return bun
end

--|==== pixel functions
aya.pix = function(bun,x,y,c)
	local ind = x + y * bun:width()
	if c then bun.bmpdata_pix[ind] = c end
	return bun.bmpdata_pix[ind]
end

aya.width = function(bun) return bun.dibheader.width end
aya.height = function(bun) return bun.dibheader.height end
aya.dimensions = function(bun) return bun:width(),bun:height() end

--|==== write functions
local rgb5a1 = function(r,g,b,a)
	return r | (g<<5) | (b<<10) | (a * 0x8000) end
local rgba4 = function(r,g,b,a)
	return (a<<12) | (r<<8) | (g<<4) | (b) end
local rgba8 = function(r,g,b,a)
	return (a<<24) | (r<<16) | (g<<8) | (b) end

-- > misc saving
aya.pixpack_tile = function(bun,tsize)
	-- vars
	tsize = tsize or 8
	local width = bun:width()
	local height = bun:height()
	-- separate image into [tsize,tsize] tiles
	local tiles = {} do
		for y = 0,(height/tsize)-1 do
			for x = 0,(width/tsize)-1 do
				local tilebuf = {}
				-- > write tile into buffer
				for ty = 0,tsize-1 do
					for tx = 0,tsize-1 do
						local c = bun:pix(tx + x*tsize,ty + y*tsize)
						tilebuf[tx + ty*tsize] = c
					end
				end
				-- > send buffer to tile table
				tiles[#tiles+1] = tilebuf
			end
		end
	end
	
	return tiles
end
aya.save_pal_dat = function(bun,fmt)
	-- to store the converted palette
	local str = {}
	-- accepted palette formats
	local accepted_formats = {
		[aya.pal_formats.rgb5a1]=true,
	}
	-- convert all 15 or so colors
	for i = 0,15 do
		local r,g,b = table.unpack(bun.palette[i])
		local clr = 0;
		-- if the format isn't recognized, error.
		assert(accepted_formats[fmt],"palette format not recognized")
		-- set the color according to the format
		-- > RGB5A1
		if fmt == aya.pal_formats.rgb5a1 then
			clr = (i==0) and rgb5a1(0,0,0,0) or rgb5a1(0,0,0,1)
			clr = clr | rgb5a1(r>>3,g>>3,b>>3,0)
			str[#str+1] = tochr_16(clr)
		-- > RGBA4
		elseif fmt == aya.pal_formats.rgba4 then
			clr = (i==0) and 0x0000 or 0xF000
			clr = clr | rgba4(r>>4,g>>4,b>>4,0)
		-- > RGBA8
		elseif fmt == aya.pal_formats.rgba8 then
			clr = (i==0) and rgba8(0,0,0,0) or rgba8(0,0,0,255)
			clr = clr | rgba8(r,g,b,0)
			str[#str+1] = tochr_32(clr)
		end
	end
	return table.concat(str)
end

-- > 1bpp saving
aya.save_1bpp_tile_dat = function(bun,tsize)
	-- vars
	tsize = tsize or 8
	local width = bun:width()
	local height = bun:height()
	-- separate image into [tsize,tsize] tiles
	local tiles = bun:pixpack_tile(tsize)
	-- write tiles to string
	local str = {}
	for t = 1,#tiles do
		local tile = tiles[t]
		for i = 0,(tsize^2)-1,8 do
			local b = {}
			for c = 0,7 do b[c] = tile[i+c] end
			local chr = 0
			for c = 0,7 do chr = chr | (b[7-c]<<c) end
			str[#str+1] = string.char(chr)
		end
	end
	return table.concat(str)
end
aya.save_1bpp_tile = function(bun,fmt,tsize)
	-- write palette
	print("writing palette...")
	local palette = bun:save_pal_dat(fmt)
	-- write data
	print("writing tiled character data...")
	assert(tsize and tsize>0,"tile size is incorrect.")
	local data = bun:save_1bpp_tile_dat(tsize)
	-- get name
	print("writing image...")
	local name = bun.name or ("SDZACHR")
	name = name:clamp(7," ").."\0"
	-- get dimensions
	-- > new width is going to be the tile size
	-- > new height is (width*height)/tsize
	-- > so 32x32 with tsize 8 is 8x128 
	local width = tsize
	local height = (bun:width()*bun:height())/tsize
	-- write header
	local header = {
		-- > $0000 : name
		name;
		-- > $0008 : size
		tochr_32(width); -- width
		tochr_32(height); -- height
		-- > $0010 : data size
		tochr_32(#data);
		-- > $0014 : color format
		tochr_32(aya.clr_formats.pal2);
		-- > $0018 : palette format
		tochr_32(fmt);
		-- > $001C : character offset
		tochr_32(0x0024 + 0x0000);
		-- > $0020 : palette offset
		tochr_32(0x0024 + #data);
	}
	-- write string
	local str_header = table.concat(header)
	local str_data = data
	local str_palette = palette
	local str_img = str_header..str_data..str_palette
	print(("header size: %04X"):format(#str_header))
	return str_img
end

-- > 2bpp saving
aya.save_2bpp_tile_dat = function(bun,tsize)
	-- vars
	tsize = tsize or 8
	local width = bun:width()
	local height = bun:height()
	-- separate image into [tsize,tsize] tiles
	local tiles = bun:pixpack_tile(tsize)
	-- write tiles to string
	local str = {}
	for t = 1,#tiles do
		local tile = tiles[t]
		for i = 0,(tsize^2)-1,8 do
			local bp = {}
			for p = 0,1 do bp[p] = {} end
			for c = 0,7 do bp[0][c],bp[1][c] = tile[i+c]&1,tile[i+c]>>1 end
			for p = 0,1 do
				local chr = 0
				for c = 0,7 do chr = chr | (bp[p][c]<<(7-c)) end
				str[#str+1] = tochr_8(chr)
			end
		end
	end
	return table.concat(str)
end
aya.save_2bpp_tile = function(bun,fmt,tsize)
	-- write palette
	print("writing palette...")
	local palette = bun:save_pal_dat(fmt)
	-- write data
	print("writing tiled character data...")
	assert(tsize and tsize>0,"tile size is incorrect.")
	local data = bun:save_2bpp_tile_dat(tsize)
	-- get name
	print("writing image...")
	local name = bun.name or ("SDZACHR")
	name = name:clamp(7," ").."\0"
	-- get dimensions
	-- > new width is going to be the tile size
	-- > new height is (width*height)/tsize
	-- > so 32x32 with tsize 8 is 8x128 
	local width = tsize
	local height = (bun:width()*bun:height())/tsize
	-- write header
	local header = {
		-- > $0000 : name
		name;
		-- > $0008 : size
		tochr_32(width); -- width
		tochr_32(height); -- height
		-- > $0010 : data size
		tochr_32(#data);
		-- > $0014 : color format
		tochr_32(aya.clr_formats.pal4);
		-- > $0018 : palette format
		tochr_32(fmt);
		-- > $001C : character offset
		tochr_32(0x0024 + 0x0000);
		-- > $0020 : palette offset
		tochr_32(0x0024 + #data);
	}
	-- write string
	local str_header = table.concat(header)
	local str_data = data
	local str_palette = palette
	local str_img = str_header..str_data..str_palette
	print(("header size: %04X"):format(#str_header))
	return str_img
end

-- > 4bpp saving
aya.save_4bpp_tile_imm = function(bun,tile,tsize)
	local str = {}
	for i = 0,(tsize^2)-1,2 do
		local p0 = tile[i]
		local p1 = tile[i+1]
		str[#str+1] = tochr_8(p0 | (p1<<4))
	end
	return table.concat(str)
end
aya.save_4bpp_tile_dat = function(bun,tsize)
	-- vars
	tsize = tsize or 8
	local width = bun:width()
	local height = bun:height()
	-- separate image into [tsize,tsize] tiles
	local tiles = bun:pixpack_tile(tsize)
	-- write tiles to string
	local str = {}
	for t = 1,#tiles do
		local tile = tiles[t]
		str[#str+1] = bun:save_4bpp_tile_imm(tile,tsize)
	end
	return table.concat(str)
end
aya.save_4bpp_tile_map = function(bun,tsize)
	-- convert image to an array of 8x8px tiles
	local tiles = bun:pixpack_tile(tsize)
	-- vars
	local used = {}		-- | used tiles
	local mapstr = {}	-- | tilemap data
	local datstr = {}	-- | character data
	local swpindx = 0	-- | current tile recycle index
	-- shit loop
	for i = 1,#tiles do
		-- > convert the current 8x8 tile
		local tile = bun:save_4bpp_tile_imm(tiles[i],tsize)
		-- > if tile hasn't been used yet, add it
		if not used[tile] then
			used[tile] = swpindx
			mapstr[#mapstr+1] = tochr_16(swpindx)
			datstr[#datstr+1] = tile
			swpindx = swpindx+1
		-- > otherwise, use the used tile.
		else
			mapstr[#mapstr+1] = tochr_16(used[tile])
		end
	end
	-- > convert map & char data to strings & return
	mapstr = table.concat(mapstr)
	datstr = table.concat(datstr)
	return mapstr,datstr
end
aya.save_4bpp_tile = function(bun,fmt,tsize,map)
	printf("－－－－－－－－　[ SAVING '%-7s' ]　－－－－－－－－",bun.name)
	local dt = os.clock()
	-- write palette
	dt = os.clock()
	io.write("\t＊　writing palette... ")
	local palette = bun:save_pal_dat(fmt)
	printf("(%.8f)",os.clock() - dt)
	dt = os.clock()
	-- write data
	io.write("\t＊　writing tiled character data... ")
	assert(tsize and tsize>0,"tile size is incorrect.")
	local data = bun:save_4bpp_tile_dat(tsize)
	printf("(%.8f)",os.clock() - dt)
	dt = os.clock()
	-- write map
	local map_dat;
	if map then
		io.write("\t＊　writing map... ")
		map_dat,data = bun:save_4bpp_tile_map(tsize)
		printf("(%.8f)",os.clock() - dt)
	end
	-- get name
	dt = os.clock()
	io.write("\t＊　writing image... ")
	bun:set_name(bun.name)
	-- get dimensions
	-- > new width is going to be the tile size
	-- > new height is (width*height)/tsize
	-- > so 32x32 with tsize 8 is 8x128 
	local width = tsize
	local height = (bun:width()*bun:height())/tsize
	-- write header
	local header = {
		-- > $0000 : 0H : name
		bun.name;
		-- > $0008 : 2H : size
		tochr_32(width); -- width
		tochr_32(height); -- height
		tochr_32(map and bun:width()/tsize or 0); -- map width
		tochr_32(map and bun:height()/tsize or 0); -- map height
		-- > $0018 : 7H : data size
		tochr_32(#data);
		-- > $001C : 8H : map size
		tochr_32(map and #map_dat/2 or 0);
		-- > $0020 : 9H : color format,palette format
		tochr_32(aya.clr_formats.pal16 | (fmt<<16));
		-- > $0024 : AH : character offset
		tochr_32(0x0030 + 0x0000);
		-- > $0028 : BH : palette offset
		tochr_32(0x0030 + #data);
		-- > $002C : CH : map offset
		tochr_32(0x0030 + #data + #palette);
	}
	-- write string
	local str_header = table.concat(header)
	local str_data = data
	local str_palette = palette
	local str_map = map_dat or ""
	local str_img = str_header..str_data..str_palette..str_map
	printf("(%.8f)",os.clock() - dt)
	return str_img
end
aya.save_4bpp_dat = function(bun)
	local str = {}
	local width,height = bun:dimensions()
	local bmpdata_pix = bun.bmpdata_pix
	for i = 0,(width*height)-1,2 do
		local p0,p1 = bmpdata_pix[i],bmpdata_pix[i+1]
		str[#str+1] = string.char(p0 | (p1<<4))
	end
	return table.concat(str)
end
aya.save_4bpp = function(bun,fmt)
	-- write palette
	local palette = bun:save_pal_4bpp_dat(fmt)
	-- write data
	local data = bun:save_4bpp_dat()
	-- get name
	bun:set_name(bun.name)
	-- write header
	local header = {
		-- > $0000 : name
		bun.name;
		-- > $0010 : size
		tochr_32(bun:width()); -- width
		tochr_32(bun:height()); -- height
		-- > $0018 : data size
		tochr_32(#data);
		-- > $0014 : color format
		tochr_32(aya.clr_formats.pal16);
		-- > $0018 : palette format
		tochr_32(fmt);
		-- > $001C : character offset
		tochr_32(0x002C + 0x0000);
		-- > $0020 : palette offset
		tochr_32(0x002C + #data);
	}
	-- write string
	local str_header = table.concat(header)
	local str_data = data
	local str_palette = palette
	local str_img = str_header..str_data..str_palette
	return str_img
end

-- > 8bpp saving
aya.save_8bpp_tile_map = function(bun,tsize)
	-- convert image to an array of 8x8px tiles
	local tiles = bun:pixpack_tile(tsize)
	-- vars
	local used = {}		-- | used tiles
	local mapstr = {}	-- | tilemap data
	local datstr = {}	-- | character data
	local swpindx = 0	-- | current tile recycle index
	-- shit loop
	for i = 1,#tiles do
		-- > convert the current tile
		local tile = bun:save_8bpp_tile_imm(tiles[i],tsize)
		-- > if tile hasn't been used yet, add it
		if not used[tile] then
			used[tile] = swpindx
			mapstr[#mapstr+1] = tochr_16(swpindx)
			datstr[#datstr+1] = tile
			swpindx = swpindx+1
		-- > otherwise, use the used tile.
		else
			mapstr[#mapstr+1] = tochr_16(used[tile])
		end
	end
	-- > convert map & char data to strings & return
	mapstr = table.concat(mapstr)
	datstr = table.concat(datstr)
	return mapstr,datstr
end
aya.save_8bpp_tile_imm = function(bun,tile,tsize)
	local str = {}
	for i = 0,(tsize^2)-1,2 do
		str[#str+1] = tochr_8(tile[i])
	end
	return table.concat(str)
end
aya.save_8bpp_tile_dat = function(bun,tsize)
	local tiles = bun:pixpack_tile(tsize)
	local width,height = bun:dimensions()
	-- write tiles to string
	local str = {}
	for t = 1,#tiles do
		local tile = tiles[t]
		str[#str+1] = bun:save_8bpp_tile_imm(tile,tsize)
	end
	return table.concat(str)
end
aya.save_8bpp_tile = function(bun,fmt,tsize,map)
	local dt = os.clock()
	printf("－－－－－－－－　[ SAVING '%-7s' ]　－－－－－－－－",bun.name)
	-- write palette
	io.write("\t＊　writing palette... ")
		local palette = bun:save_pal_dat(fmt)
		printf("(%.8f)",os.clock() - dt)
		dt = os.clock()
	-- write data
	io.write("\t＊　writing tiled character data... ")
		assert(tsize and tsize>0,"tile size is incorrect.")
		local data = bun:save_8bpp_tile_dat(tsize)
		printf("(%.8f)",os.clock() - dt)
		dt = os.clock()
	-- write map
	local map_dat;
	if map then
		-- insert map function here lul
		map_dat,data = bun:save_8bpp_tile_map(tsize)
	end
	-- get name
	bun:set_name(bun.name)
	-- get dimensions
	local width = tsize
	local height = (bun:width()*bun:height())/tsize
	-- write header
	local header = {
		-- > 0000H : name
		bun.name;
		-- > 0008H : image dimensions
		tochr_32(width);
		tochr_32(height);
		tochr_32(map and bun:width()/tsize or 0);
		tochr_32(map and bun:height()/tsize or 0);
		-- > 0018H : data sizes
		tochr_32(#data),tochr_32(map and #map_dat or 0);
		-- > 0020H : color & palette format
		tochr_32(aya.clr_formats.pal16 | (fmt<<16));
		-- > 0024H : character offset
		tochr_32(0x0024 + 0x0000);
		-- > 0028H : palette offset
		tochr_32(0x0024 + #data);
		-- > 002CH : map offset
		tochr_32(0x0024 + #data + #palette);
	}
	-- write string
	local str_header = table.concat(header)
	local str_data = data
	local str_palette = palette
	local str_map = map_dat or ""
	local str_img = str_header..str_data..str_palette..str_map
	return str_img
end
aya.save_8bpp_dat = function(bun)
	local str = {}
	local width,height = bun:dimensions()
	local pixdat = bun.bmpdata_pix
	for i = 0,(width*height)-1 do
		str[#str+1] = tochr_8(pixdat[i])
	end
	return table.concat(str)
end
aya.save_8bpp = function(bun,fmt) 
	-- write palette
	io.write("writing palette... ")
	local palette = bun:save_pal_dat(fmt)
	-- write data
	io.write("writing character data...\n")
	local data = bun:save_8bpp_dat()
	-- get name
	local name = bun.name or ("SDZACHR")
	name = name:clamp(7," ").."\0"
	-- write header
	local header = {
		-- > 0000H : name
		name;
		-- > 0008H : image dimensions
		tochr_32(bun:width());
		tochr_32(bun:height());
		-- > 0010H : data size
		tochr_32(#data);
		-- > 0014H : color format
		tochr_32(aya.clr_formats.pal16);
		-- > 0018H : palette format
		tochr_32(fmt);
		-- > 001CH : character offset
		tochr_32(0x0024 + 0x0000);
		-- > 0020H : palette offset
		tochr_32(0x0024 + #data);
	}
	-- write string
	local str_header = table.concat(header)
	local str_data = data
	local str_palette = palette
	local str_img = str_header..str_data..str_palette
	print(("header size: %04X"):format(#str_header))
	return str_img
end

return aya