--- a/cutils/treesum.py	Sun Feb 16 09:46:41 2025 +0100
+++ b/cutils/treesum.py	Sun Feb 16 11:07:04 2025 +0100
@@ -24,13 +24,13 @@
 import stat
 import sys
 import time
-import zlib
 
 from . import (__version__, __revision__)
 from . import util
 from .util import cm
 from .util import digest
 from .util import walk
+from .util.crc32 import crc32
 
 
 def main(argv=None):
@@ -937,14 +937,14 @@
 
     def write(self, what):
         self._fp.write(what)
-        self._crc32 = zlib.crc32(what, self._crc32)
+        self._crc32.update(what)
 
     def flush(self):
         self._fp.flush()
 
     def resetdigest(self):
         """Reset the current CRC digest"""
-        self._crc32 = zlib.crc32(b"")
+        self._crc32 = crc32()
 
     def hexcrcdigest(self):
         """
@@ -952,22 +952,7 @@
         :rtype: str
 
         """
-        return (hex(self.crcdigest())[2:]).upper()
-
-    def crcdigest(self):
-        """
-
-        :rtype: int
-
-        """
-        if util.PY2:
-            if self._crc32 < 0:
-                # Return the bitpattern as unsigned 32-bit number
-                return (~self._crc32 ^ 0xFFFFFFFF)
-            else:
-                return self._crc32
-        else:
-            return self._crc32
+        return self._crc32.hexdigest()
 
 
 def normalized_compatible_mode_str(mode):
@@ -1196,31 +1181,13 @@
         return line
 
     def _reset_crc(self):
-        self._crc32 = zlib.crc32(b"")
+        self._crc32 = crc32()
 
     def _update_crc(self, data):
-        self._crc32 = zlib.crc32(data, self._crc32)
+        self._crc32.update(data)
 
     def _hex_crc(self):
-        return (hex(self._get_crc())[2:]).upper()
-
-    def _get_crc(self):
-        """Get the current CRC always as positive number with the same bit#
-        pattern because Python2 yields negative numbers also.
-
-        :return: The current CRC value as positive  number on all Python
-                 versions
-        :rtype: int
-
-        """
-        if util.PY2:
-            if self._crc32 < 0:
-                # Return the bitpattern as unsigned 32-bit number
-                return (~self._crc32 ^ 0xFFFFFFFF)
-            else:
-                return self._crc32
-        else:
-            return self._crc32
+        return self._crc32.hexdigest()
 
     def _get_digest_size(self, algo_name):
         if self._current_algo_name == algo_name: