# Source code for fontTools.ttLib.tables.T_S_I__0

    """ TSI{0,1,2,3,5} are private tables used by Microsoft Visual TrueType (VTT)
    tool to store its hinting source data.

    TSI0 is the index table containing the lengths and offsets for the glyph
    programs and 'extra' programs ('fpgm', 'prep', and 'cvt') that are contained
    in the TSI1 table.
    """
    from . import DefaultTable
    import struct

    tsi0Format = '>HHL'

    def fixlongs(glyphID, textLength, textOffset):
    	return int(glyphID), int(textLength), textOffset

    class table_T_S_I__0(DefaultTable.DefaultTable):

    	dependencies = ["TSI1"]

    	def decompile(self, data, ttFont):
    		numGlyphs = ttFont['maxp'].numGlyphs
    		indices = []
    		size = struct.calcsize(tsi0Format)
    		for i in range(numGlyphs + 5):
    			glyphID, textLength, textOffset = fixlongs(*struct.unpack(tsi0Format, data[:size]))
    			indices.append((glyphID, textLength, textOffset))
    			data = data[size:]
    		assert len(data) == 0
    		assert indices[-5] == (0XFFFE, 0, 0xABFC1F34), "bad magic number"
    		self.indices = indices[:-5]
    		self.extra_indices = indices[-4:]

    	def compile(self, ttFont):
    		if not hasattr(self, "indices"):
    			# We have no corresponding table (TSI1 or TSI3); let's return
    			# no data, which effectively means "ignore us".
    			return b""
    		data = b""
    		for index, textLength, textOffset in self.indices:
    			data = data + struct.pack(tsi0Format, index, textLength, textOffset)
    		data = data + struct.pack(tsi0Format, 0XFFFE, 0, 0xABFC1F34)
    		for index, textLength, textOffset in self.extra_indices:
    			data = data + struct.pack(tsi0Format, index, textLength, textOffset)
    		return data

    	def set(self, indices, extra_indices):
    		# gets called by 'TSI1' or 'TSI3'
    		self.indices = indices
    		self.extra_indices = extra_indices

    	def toXML(self, writer, ttFont):
    		writer.comment("This table will be calculated by the compiler")
    		writer.newline()