jerome@65: local M, plat, bin = {}, require("casc.platform"), require("casc.bin")
jerome@65: local open, tconcat, assert, error = io.open, table.concat, assert, error
jerome@65: local uint32_le, uint32_be = bin.uint32_le, bin.uint32_be
jerome@65: 
jerome@65: local string_cursor do
jerome@65: 	local function read(self, n)
jerome@65: 		local p = self.pos
jerome@65: 		self.pos = p + n
jerome@65: 		return self.str:sub(p, p+n-1)
jerome@65: 	end
jerome@65: 	function string_cursor(s)
jerome@65: 		return {str=s, read=read, pos=1}
jerome@65: 	end
jerome@65: end
jerome@65: 
jerome@65: local function decodeChunk(chunk)
jerome@65: 	local format = chunk:sub(1,1)
jerome@65: 	if format == 'N' then
jerome@65: 		return chunk:sub(2)
jerome@65: 	elseif format == 'Z' then
jerome@65: 		return plat.decompress(chunk:sub(2))
jerome@65: 	else
jerome@65: 		error('Unknown chunk format: ' .. tostring(format))
jerome@65: 	end
jerome@65: end
jerome@65: local function parseBLTE(h, dataSize)
jerome@65: 	local header = h:read(8)
jerome@65: 	assert(header:sub(1,4) == 'BLTE', 'BLTE file magic signature')
jerome@65: 	local ofs = uint32_be(header, 4)
jerome@65: 
jerome@65: 	local chunks, ret = ofs > 0 and {}
jerome@65: 	if ofs > 0 then
jerome@65: 		local n = uint32_be(h:read(4)) % 2^16
jerome@65: 		local buf, p = h:read(n*24), 0
jerome@65: 		for i=1, n do
jerome@65: 			chunks[i], p = uint32_be(buf, p), p + 24
jerome@65: 		end
jerome@65: 		for i=1, #chunks do
jerome@65: 			chunks[i] = decodeChunk(h:read(chunks[i]))
jerome@65: 		end
jerome@65: 		ret = tconcat(chunks, "")
jerome@65: 	else
jerome@65: 		ret = decodeChunk(h:read(dataSize))
jerome@65: 	end
jerome@65: 	return ret
jerome@65: end
jerome@65: 
jerome@65: function M.readArchive(path, offset)
jerome@65: 	assert(type(path) == "string" and type(offset) == "number", 'Syntax: "content" = casc.blte.readArchive("path", offset)')
jerome@65: 
jerome@65: 	local h = open(path, "rb")
jerome@65: 	h:seek("set", offset)
jerome@65: 	local blockHead = h:read(30)
jerome@65: 	local ret = parseBLTE(h, uint32_le(blockHead, 16)-30)
jerome@65: 	h:close()
jerome@65: 	
jerome@65: 	return ret
jerome@65: end
jerome@65: function M.readData(str)
jerome@65: 	assert(type(str) == "string", 'Syntax: "content" = casc.blte.readContent("str")')
jerome@65: 	return parseBLTE(string_cursor(str), #str)
jerome@65: end
jerome@65: 
jerome@65: return M