06779: Mounting Zenix Floppy Disk crashes MAME with floating point exception error

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06779	Crash/Freeze	Critical (emulator)	Always	Nov 28, 2017, 22:35	Nov 29, 2017, 11:07

Tester	MrGW	View Status	Public	Platform	MAME (Self-compiled)
Assigned To	Duke	Resolution	Fixed	OS	Linux (64-bit)
Status [?]	Resolved			Driver	trs/coco3.cpp
Version	0.191	Fixed in Version	0.193	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06779: Mounting Zenix Floppy Disk crashes MAME with floating point exception error
Description	When you try to mount the floppy disk based game "Zenix" using MAME's built-in UI or the command line, it crashes MAME. Here's the command line I used: ~/.mame $ mame coco3 -flop1 ZENIX.DSK Floating point exception
Steps To Reproduce	Here's the command line I used: ~/.mame $ mame coco3 -flop1 ZENIX.DSK Floating point exception ... or use MAME's UI to browse for the ZENIX.DSK file and mount it on the first floppy drive.
Additional Information	I've tested this same disk image on a real Coco 3 using the CoCoSDC storage device. No issues. I've also tested the same disk image on the VCC 2.01b emulator (for Windows). No issues. I have a self-compiled ARM build of MAME 0.191 (32bit) and it crashes as well. I've attached the disk image for you to test.
Github Commit

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Regression Version
Affected Sets / Systems

Attached Files	ZENIX.zip (46,683 bytes) Nov 28, 2017, 22:35 Uploaded by MrGW Zenix Game Disk image for the Coco 3
Attached Files	zenix.png (32,732 bytes) Nov 29, 2017, 00:36 Uploaded by MrGW

No.14476 Tafoid Administrator Nov 28, 2017, 23:46	This is a JVC formatted disc, apparently. Are we positive the 5 byte header is correct? MAME tends to be pretty exacting when it comes to headers to specific formats and other emulators may simply treat a floppy as a memory dump rather than an specific type of image. I can confirm it doesn't mount without an exception happening, but I'm not sure if it is a shortcoming of the emulation or an issue with the header.
No.14477 Robbbert Senior Tester Nov 28, 2017, 23:56	Exception at EIP=01ffe334 (jvc_format::parse_header(io_generic*, int&, ...)+0x01e4): INTEGER DIVIDE BY ZERO
No.14478 MrGW Tester Nov 29, 2017, 00:37	Hi Tafoid and Robbbert. I did a BACKUP of this disk to a new disk image I created (in Disk Extended Color Basic in VCC). The backup copy caused the same crash in MAME. I created a new blank disk image again (using toolshed) and mounted the ZENIX.DSK as DRIVE 0 and the blank disk in DRIVE 1 in VCC. I did a copy of the 2 files on the disk 0 to disk 1. MAME can mount the new disk and I see the 2 files. When I try to LOADM the game, I get to the following screen (attached). It looks like the ZENIX.DSK image has some sort of copy protection on it (which is probably correct). I got that disk image from the TRS-80 Color Computer Archive.
No.14479 Duke Developer Nov 29, 2017, 09:23	Fixed in commit 5676444d8cf9da4b27ceba2efd0a2d82a343cc57.
No.14480 MrGW Tester Nov 29, 2017, 11:07	Thanks, Duke!