[_k_e_r_n] fix order of format/coverage bytes
In OT kern subtable header, the format is the high byte of 'coverage' bit mask (bits 8-15), and the low byte (bits 0-7) is the actual coverage bits. In AAT kern, it's the opposite: the coverage flags are the high byte, whereas the subtable format is the low byte. Also adjusted the test data, and set coverage to 1 for OT kern subtable (which means the usual horizontal kerning).
This commit is contained in:
Cosimo Lupo
parent
5d16828031
commit
d715575794
@ -37,15 +37,14 @@ class table__k_e_r_n(DefaultTable.DefaultTable):
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for i in range(nTables):
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if self.version == 1.0:
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# Apple
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length, coverage = struct.unpack(">LH", data[:6])
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length, coverage, subtableFormat = struct.unpack(">LBB", data[:6])
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else:
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# in OpenType spec the "version" field refers to the common
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# subtable header; the actual subtable format is stored in
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# the last 8 mask bits of "coverage" field.
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# Since this "version" is always 0 (and is not present in the
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# later AAT extensions), we simply ignore it here
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_, length, coverage = struct.unpack(">HHH", data[:6])
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subtableFormat = coverage & 0xff
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_, length, subtableFormat, coverage = struct.unpack(">HHBB", data[:6])
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if subtableFormat not in kern_classes:
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subtable = KernTable_format_unkown(subtableFormat)
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else:
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@ -103,7 +102,8 @@ class KernTable_format_0(object):
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def decompile(self, data, ttFont):
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if not self.apple:
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version, length, coverage = struct.unpack(">HHH", data[:6])
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version, length, subtableFormat, coverage = struct.unpack(
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">HHBB", data[:6])
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if version != 0:
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from fontTools.ttLib import TTLibError
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raise TTLibError(
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@ -112,9 +112,10 @@ class KernTable_format_0(object):
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# Should we also assert length == len(data)?
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data = data[6:]
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else:
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length, coverage, tupleIndex = struct.unpack(">LHH", data[:8])
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length, coverage, subtableFormat, tupleIndex = struct.unpack(
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">LBBH", data[:8])
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data = data[8:]
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assert self.format == coverage & 0xFF, "unsupported format"
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assert self.format == subtableFormat, "unsupported format"
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self.coverage = coverage
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self.tupleIndex = tupleIndex
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@ -168,13 +169,12 @@ class KernTable_format_0(object):
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for left, right, value in kernTable:
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data = data + struct.pack(">HHh", left, right, value)
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# ensure mask bits 8-15 (subtable format) are set to 0
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self.coverage &= ~0xFF
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if not self.apple:
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version = 0
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length = len(data) + 6
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header = struct.pack(">HHH", version, length, self.coverage)
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header = struct.pack(
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">HHBB", version, length, self.format, self.coverage)
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else:
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if self.tupleIndex is None:
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# sensible default when compiling a TTX from an old fonttools
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@ -183,7 +183,8 @@ class KernTable_format_0(object):
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log.warning("'tupleIndex' is None; default to 0")
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self.tupleIndex = 0
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length = len(data) + 8
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header = struct.pack(">LHH", length, self.coverage, self.tupleIndex)
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header = struct.pack(
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">LBBH", length, self.coverage, self.format, self.tupleIndex)
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return header + data
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def toXML(self, writer, ttFont):
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@ -13,7 +13,8 @@ KERN_VER_0_FMT_0_DATA = deHexStr(
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'0001 ' # 2: nTables=1
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'0000 ' # 4: version=0 (bogus field, unused)
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'0020 ' # 6: length=32
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'0000 ' # 8: coverage=0
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'00 ' # 8: format=0
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'01 ' # 9: coverage=1
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'0003 ' # 10: nPairs=3
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'000C ' # 12: searchRange=12
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'0001 ' # 14: entrySelector=1
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@ -26,7 +27,7 @@ assert len(KERN_VER_0_FMT_0_DATA) == 36
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KERN_VER_0_FMT_0_XML = [
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'<version value="0"/>',
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'<kernsubtable coverage="0" format="0">',
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'<kernsubtable coverage="1" format="0">',
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' <pair l="E" r="M" v="-40"/>',
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' <pair l="E" r="c" v="40"/>',
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' <pair l="F" r="o" v="-50"/>',
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@ -37,7 +38,8 @@ KERN_VER_1_FMT_0_DATA = deHexStr(
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'0001 0000 ' # 0: version=1
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'0000 0001 ' # 4: nTables=1
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'0000 0022 ' # 8: length=34
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'0000 ' # 12: coverage=0
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'00 ' # 12: coverage=0
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'00 ' # 13: format=0
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'0000 ' # 14: tupleIndex=0
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'0003 ' # 16: nPairs=3
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'000C ' # 18: searchRange=12
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@ -63,11 +65,13 @@ KERN_VER_0_FMT_UNKNOWN_DATA = deHexStr(
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'0002 ' # 2: nTables=2
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'0000 ' # 4: version=0
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'000A ' # 6: length=10
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'0004 ' # 8: coverage=4 (format 4 doesn't exist)
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'04 ' # 8: format=4 (format 4 doesn't exist)
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'01 ' # 9: coverage=1
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'1234 5678 ' # 10: garbage...
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'0000 ' # 14: version=0
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'000A ' # 16: length=10
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'0005 ' # 18: coverage=5 (format 5 doesn't exist)
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'05 ' # 18: format=5 (format 5 doesn't exist)
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'01 ' # 18: coverage=1
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'9ABC DEF0 ' # 20: garbage...
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)
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assert len(KERN_VER_0_FMT_UNKNOWN_DATA) == 24
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@ -76,11 +80,13 @@ KERN_VER_1_FMT_UNKNOWN_DATA = deHexStr(
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'0001 0000 ' # 0: version=1
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'0000 0002 ' # 4: nTables=2
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'0000 000C ' # 8: length=12
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'0004 ' # 12: coverage=4 (format 4 doesn't exist)
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'00 ' # 12: coverage=0
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'04 ' # 13: format=4 (format 4 doesn't exist)
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'0000 ' # 14: tupleIndex=0
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'1234 5678' # 16: garbage...
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'0000 000C ' # 20: length=12
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'0005 ' # 18: coverage=5 (format 5 doesn't exist)
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'00 ' # 18: coverage=0
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'05 ' # 19: format=5 (format 5 doesn't exist)
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'0000 ' # 20: tupleIndex=0
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'9ABC DEF0 ' # 22: garbage...
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)
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@ -113,7 +119,9 @@ class KernTableTest(object):
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st = kern.kernTables[0]
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assert st.apple is (version == 1.0)
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assert st.format == 0
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assert st.coverage == 0
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# horizontal kerning in OT kern is coverage 0x01, while in
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# AAT kern it's the default (0)
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assert st.coverage == (0 if st.apple else 1)
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assert st.tupleIndex == (0 if st.apple else None)
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assert len(st.kernTable) == 3
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assert st.kernTable == {
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@ -136,7 +144,7 @@ class KernTableTest(object):
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apple = version == 1.0
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st = KernTable_format_0(apple)
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kern.kernTables = [st]
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st.coverage = 0
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st.coverage = (0 if apple else 1)
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st.tupleIndex = 0 if apple else None
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st.kernTable = {
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('E', 'M'): -40,
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@ -165,7 +173,7 @@ class KernTableTest(object):
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st = kern.kernTables[0]
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assert st.apple is (version == 1.0)
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assert st.format == 0
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assert st.coverage == 0
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assert st.coverage == (0 if st.apple else 1)
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assert st.tupleIndex == (0 if st.apple else None)
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assert len(st.kernTable) == 3
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assert st.kernTable == {
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@ -188,7 +196,7 @@ class KernTableTest(object):
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apple = version == 1.0
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st = KernTable_format_0(apple)
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kern.kernTables = [st]
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st.coverage = 0
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st.coverage = 0 if apple else 1
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st.tupleIndex = 0 if apple else None
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st.kernTable = {
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('E', 'M'): -40,
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@ -238,13 +246,15 @@ class KernTableTest(object):
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kern.kernTables = []
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for unknown_fmt, kern_data in zip((4, 5), ("1234 5678", "9ABC DEF0")):
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coverage = unknown_fmt
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if version > 0:
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coverage = 0
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header_fmt = deHexStr(
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"%08X %04X %04X" % (st_length, coverage, 0))
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"%08X %02X %02X %04X" % (
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st_length, coverage, unknown_fmt, 0))
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else:
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coverage = 1
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header_fmt = deHexStr(
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"%04X %04X %04X" % (0, st_length, coverage))
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"%04X %04X %02X %02X" % (0, st_length, unknown_fmt, coverage))
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st = KernTable_format_unkown(unknown_fmt)
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st.data = header_fmt + deHexStr(kern_data)
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kern.kernTables.append(st)
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