Move file handling into ChkSum class.

gcksum.py

@@ -5,21 +5,11 @@ from grmn import ChkSum
 import sys
 
 FILE = sys.argv[1]
-BLOCKSIZE = 4 * 1024
-
-print("Reading {} ".format(FILE), end="")
 
 csum = ChkSum()
-
-with open(FILE, "rb") as f:
-    while True:
-        block = f.read(BLOCKSIZE)
-        csum.add(block)
-        print(".", end="", flush=True)
-        if len(block) < BLOCKSIZE:
-            print(" done.")
-            break
-    f.close()
+print("Reading {} ...".format(FILE), end="", flush=True)
+csum.add_from_file(FILE, print_progress=True)
+print(" done.")
 
 print("Sum of all bytes: {:02x}".format(csum.get_sum()))
 print("Last byte: {:02x}".format(csum.get_last_byte()))