From 98d1763c34cfe69d53ef490f8cb69085f34e17a9 Mon Sep 17 00:00:00 2001
From: 4am <a2_4am@sent.com>
Date: Tue, 19 Feb 2019 14:31:46 -0500
Subject: [PATCH] don't calculate largest track if there are no tracks

---
 test/valid1.woz | Bin 0 -> 256 bytes
 test/valid2.woz | Bin 0 -> 1536 bytes
 wozardry.py     |   7 +++++--
 3 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 test/valid1.woz
 create mode 100644 test/valid2.woz

diff --git a/test/valid1.woz b/test/valid1.woz
new file mode 100644
index 0000000000000000000000000000000000000000..dfb02800994e39756e1f55f59e0707de3b41e877
GIT binary patch
literal 256
zcmWIdk23tv#miOwG^E$l&&}V4fq{XM5lEEhS0xsu6jdrDRVtVy<|=3y85mmX8W`ys
dT52i)0Z<7x5aR0?umC9We~^QaAn#z1`vG>Nu=M}{

literal 0
HcmV?d00001

diff --git a/test/valid2.woz b/test/valid2.woz
new file mode 100644
index 0000000000000000000000000000000000000000..7054af7f19265a7093fbe3f13906cddaea9848bd
GIT binary patch
literal 1536
zcmWIdk23nt#mkl0(>B}F&&}V4fq{XE5lEEhS0xsu6jdrDRVtVy<|=3y85mmX8W`ys
vT52i)0V9I~P!$FU@pTMX02KW{$U#VucQ6AhhVw@SMnhmU1V%$(#Do9<CP1+2

literal 0
HcmV?d00001

diff --git a/wozardry.py b/wozardry.py
index 039b60a..488032b 100755
--- a/wozardry.py
+++ b/wozardry.py
@@ -545,8 +545,11 @@ class WozWriter(WozDiskImage, WozValidator):
                     compatible_hardware_bitfield |= (1 << offset)
             compatible_hardware_raw = to_uint16(compatible_hardware_bitfield)
             required_ram_raw = to_uint16(self.info["required_ram"])
-            largest_bit_count = max([track.bit_count for track in self.tracks])
-            largest_block_count = (((largest_bit_count+7)//8)+511)//512
+            if self.tracks:
+                largest_bit_count = max([track.bit_count for track in self.tracks])
+                largest_block_count = (((largest_bit_count+7)//8)+511)//512
+            else:
+                largest_block_count = 0
             largest_track_raw = to_uint16(largest_block_count)
             chunk.extend(disk_sides_raw) # 1 byte, 1 or 2
             chunk.extend(boot_sector_format_raw) # 1 byte, 0,1,2,3