collect_bitstream.lua

   1 QuestHelper_File["collect_bitstream.lua"] = "Development Version"
   2 QuestHelper_Loadtime["collect_bitstream.lua"] = GetTime()
   3
   4 local Merger
   5
   6 local function Output(outbits)
   7   return {
   8     r = {},
   9     cbits = 0,
  10     cval = 0,
  11
  12     append = function (self, value, bits)
  13       self.cbits = self.cbits + bits
  14       self.cval = bit.lshift(self.cval, bits)
  15       self.cval = self.cval + value
  16       while self.cbits >= outbits do
  17         Merger.Add(self.r, strchar(bit.rshift(self.cval, self.cbits - outbits)))
  18         self.cbits = self.cbits - outbits
  19         self.cval = bit.band(self.cval, bit.lshift(1, self.cbits) - 1)
  20       end
  21     end,
  22     finish = function (self)
  23       if self.cbits > 0 then self:append(0, outbits - self.cbits) end
  24       return Merger.Finish(self.r)
  25     end,
  26   }
  27 end
  28
  29 local function Input(indata, outbits)
  30   return {
  31     cbits = 0,
  32     cval = 0,
  33     coffset = 1,
  34
  35     depend = function (self, bits)
  36       while self.cbits < bits do
  37         self.cbits = self.cbits + outbits
  38         self.cval = bit.lshift(self.cval, outbits) + strbyte(indata, self.coffset)
  39         self.coffset = self.coffset + 1
  40       end
  41       local rv = bit.rshift(self.cval, self.cbits - bits)
  42       self.cbits = self.cbits - bits;
  43       self.cval = bit.band(self.cval, bit.lshift(1, self.cbits) - 1)
  44       return rv
  45     end,
  46   }
  47 end
  48
  49 function QH_Collect_Bitstream_Init(_, API)
  50   Merger = API.Utility_Merger
  51   QuestHelper: Assert(Merger)
  52
  53   API.Utility_Bitstream = {Input = Input, Output = Output}
  54 end