instance method feed

# File actionmailer/lib/action_mailer/vendor/tmail-1.2.7/tmail/vendor/rchardet-1.3/lib/rchardet/jpcntx.rb, line 136
    def feed(aBuf, aLen)
      return if @_mDone

      # The buffer we got is byte oriented, and a character may span in more than one
      # buffers. In case the last one or two byte in last buffer is not complete, we 
      # record how many byte needed to complete that character and skip these bytes here.
      # We can choose to record those bytes as well and analyse the character once it 
      # is complete, but since a character will not make much difference, by simply skipping
      # this character will simply our logic and improve performance.
      i = @_mNeedToSkipCharNum
      while i < aLen
        order, charLen = get_order(aBuf[i...i+2])
        i += charLen
        if i > aLen
          @_mNeedToSkipCharNum = i - aLen
          @_mLastCharOrder = -1
        else
          if (order != -1) and (@_mLastCharOrder != -1)
            @_mTotalRel += 1
            if @_mTotalRel > MAX_REL_THRESHOLD
              @_mDone = true
              break
            end
            @_mRelSample[jp2CharContext[@_mLastCharOrder][order]] += 1
          end
          @_mLastCharOrder = order
        end
      end
    end