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jerome@65
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1 local M, plat, bin = {}, require("casc.platform"), require("casc.bin")
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jerome@65
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2 local open, tconcat, assert, error = io.open, table.concat, assert, error
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jerome@65
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3 local uint32_le, uint32_be = bin.uint32_le, bin.uint32_be
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jerome@65
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4
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jerome@65
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5 local string_cursor do
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jerome@65
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6 local function read(self, n)
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jerome@65
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7 local p = self.pos
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jerome@65
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8 self.pos = p + n
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jerome@65
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9 return self.str:sub(p, p+n-1)
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jerome@65
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10 end
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jerome@65
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11 function string_cursor(s)
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jerome@65
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12 return {str=s, read=read, pos=1}
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jerome@65
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13 end
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jerome@65
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14 end
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jerome@65
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15
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jerome@65
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16 local function decodeChunk(chunk)
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jerome@65
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17 local format = chunk:sub(1,1)
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jerome@65
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18 if format == 'N' then
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jerome@65
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19 return chunk:sub(2)
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jerome@65
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20 elseif format == 'Z' then
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jerome@65
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21 return plat.decompress(chunk:sub(2))
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jerome@65
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22 else
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jerome@65
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23 error('Unknown chunk format: ' .. tostring(format))
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jerome@65
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24 end
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jerome@65
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25 end
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jerome@65
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26 local function parseBLTE(h, dataSize)
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jerome@65
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27 local header = h:read(8)
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jerome@65
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28 assert(header:sub(1,4) == 'BLTE', 'BLTE file magic signature')
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jerome@65
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29 local ofs = uint32_be(header, 4)
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jerome@65
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30
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jerome@65
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31 local chunks, ret = ofs > 0 and {}
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jerome@65
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32 if ofs > 0 then
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jerome@65
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33 local n = uint32_be(h:read(4)) % 2^16
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jerome@65
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34 local buf, p = h:read(n*24), 0
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jerome@65
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35 for i=1, n do
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jerome@65
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36 chunks[i], p = uint32_be(buf, p), p + 24
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jerome@65
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37 end
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jerome@65
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38 for i=1, #chunks do
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jerome@65
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39 chunks[i] = decodeChunk(h:read(chunks[i]))
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jerome@65
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40 end
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jerome@65
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41 ret = tconcat(chunks, "")
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jerome@65
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42 else
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jerome@65
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43 ret = decodeChunk(h:read(dataSize))
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jerome@65
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44 end
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jerome@65
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45 return ret
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jerome@65
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46 end
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jerome@65
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47
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jerome@65
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48 function M.readArchive(path, offset)
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jerome@65
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49 assert(type(path) == "string" and type(offset) == "number", 'Syntax: "content" = casc.blte.readArchive("path", offset)')
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jerome@65
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50
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jerome@65
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51 local h = open(path, "rb")
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jerome@65
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52 h:seek("set", offset)
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jerome@65
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53 local blockHead = h:read(30)
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jerome@65
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54 local ret = parseBLTE(h, uint32_le(blockHead, 16)-30)
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jerome@65
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55 h:close()
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jerome@65
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56
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jerome@65
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57 return ret
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jerome@65
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58 end
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jerome@65
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59 function M.readData(str)
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jerome@65
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60 assert(type(str) == "string", 'Syntax: "content" = casc.blte.readContent("str")')
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jerome@65
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61 return parseBLTE(string_cursor(str), #str)
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jerome@65
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62 end
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jerome@65
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63
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jerome@65
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64 return M |
