initial commit.
git-svn-id: http://ots.googlecode.com/svn/trunk@2 a4e77c2c-9104-11de-800e-5b313e0d2bf3
diff --git a/tools/ttf-checksum.py b/tools/ttf-checksum.py
new file mode 100755
index 0000000..802e3cc
--- /dev/null
+++ b/tools/ttf-checksum.py
@@ -0,0 +1,44 @@
+import struct
+import sys
+
+def readU32(contents, offset):
+ wordBytes = contents[offset:offset + 4]
+ return struct.unpack('>I', wordBytes)[0]
+
+def readU16(contents, offset):
+ wordBytes = contents[offset:offset + 2]
+ return struct.unpack('>H', wordBytes)[0]
+
+def checkChecksum(infile):
+ contents = infile.read()
+ if len(contents) % 4:
+ print 'File length is not a multiple of 4'
+
+ sum = 0
+ for offset in range(0, len(contents), 4):
+ sum += readU32(contents, offset)
+ while sum >= 2**32:
+ sum -= 2**32
+ print 'Sum of whole file: %x' % sum
+
+ numTables = readU16(contents, 4)
+
+ for offset in range(12, 12 + numTables * 16, 16):
+ tag = contents[offset:offset + 4]
+ chksum = readU32(contents, offset + 4)
+ toffset = readU32(contents, offset + 8)
+ tlength = readU32(contents, offset + 12)
+
+ sum = 0
+ for offset2 in range(toffset, toffset + tlength, 4):
+ sum += readU32(contents, offset2)
+ while sum >= 2**32:
+ sum -= 2**32
+ if sum != chksum:
+ print 'Bad chksum: %s' % tag
+
+if __name__ == '__main__':
+ if len(sys.argv) != 2:
+ print 'Usage: %s <ttf filename>' % sys.argv[0]
+ else:
+ checkChecksum(file(sys.argv[1], 'r'))