1 files changed, 11 insertions, 16 deletions
diff --git a/scripts/signrom.py b/scripts/signrom.py
index 5629bca222..d1dabe0240 100644
--- a/scripts/signrom.py
+++ b/scripts/signrom.py
@@ -23,26 +23,21 @@ if magic != '\x55\xaa':
 
 size_byte = ord(fin.read(1))
 fin.seek(0)
+data = fin.read()
 
-if size_byte == 0:
-    # If the caller left the size field blank then we will fill it in,
-    # also rounding the whole input to a multiple of 512 bytes.
-    data = fin.read()
-    # +1 because we need a byte to store the checksum.
-    size = len(data) + 1
-    # Round up to next multiple of 512.
-    size += 511
-    size -= size % 512
-    if size >= 65536:
-        sys.exit("%s: option ROM size too large" % sys.argv[1])
+size = size_byte * 512
+if len(data) > size:
+    sys.stderr.write('error: ROM is too large (%d > %d)\n' % (len(data), size))
+    sys.exit(1)
+elif len(data) < size:
+    # Add padding if necessary, rounding the whole input to a multiple of
+    # 512 bytes according to the third byte of the input.
     # size-1 because a final byte is added below to store the checksum.
     data = data.ljust(size-1, '\0')
-    data = data[:2] + chr(size/512) + data[3:]
 else:
-    # Otherwise the input file specifies the size so use it.
-    # -1 because we overwrite the last byte of the file with the checksum.
-    size = size_byte * 512 - 1
-    data = fin.read(size)
+    if ord(data[-1:]) != 0:
+        sys.stderr.write('WARNING: ROM includes nonzero checksum\n')
+    data = data[:size-1]
 
 fout.write(data)