Skip to content

Latest commit

 

History

History
139 lines (92 loc) · 5.79 KB

README.md

File metadata and controls

139 lines (92 loc) · 5.79 KB
Raw

t64fix v0.4.0

New in version 0.4.0

  • Add --create command: create a T64 image and write one or more PRG files to it.
  • Have the option parser properly report a missing argument for string arguments, not just fail silently.
  • Improve make install
  • Add man page.

Introduction

t64fix is a small tool to fix faulty T64 tape images. T64 images are container files used by the old C64S emulator by Miha Peternel. The 'tape' in the name is a misnomer as these files have nothing to do with actual tape dumps, they're used as archives and for storing memory snapshots in C64S.

There are a lot of faulty t64 files out there, mostly created with tools which were written by people who didn't really understand the format.

Usage

Usage is relatively simple: t64fix [OPTIONS] <SOURCE>

When just checking if a t64 file is correct, just issue t64fix <SOURCE>. This will verify the image and show its contents and any warnings on stdout. To fix an image, issue t64fix <SOURCE> -o <DESTINATION>, this will verify and fix <SOURCE> and write it to <DESTINATION>. Using the same for SOURCE and DESTINATION is fine, SOURCE is read into memory and then closed, so using t64fix foo.t64 -o foo.t64 will fix foo.t64 and write it back. But obviously the original file will be lost, so this is not advisable.

More 'advanced' use is available through a few command line switches:

Option Description
-q, --quiet don't output anything to stdout, for use in scripts
-o, --output <fixed-image> write fixed image to filesystem
-e, --extract <index> extract file <index> from image
-x, --extract-all extract all files, except memory snapshots
-c, --create <image> <list-of-files> create t64 image and write on or more files to it
--help show help
--version show version info

The --quiet option tells t64fix to not output any information on stdout, it just returns an exit code (EXIT_SUCCESS or EXIT_FAILURE). See the bash script scripts/verify_multi.sh for an example.

Things that get verified and fixed

There are a few things that get verified and fixed:

Header magic string

There are a few different types of header magic strings out there, the correct one being "C64S image file", padded to 32 bytes with 0x00. This is the string found in t64 files generated by C64S 2.52.

Header tape version number

Version numbers seem to be either 0x100 or 0x101, no information on the difference can be found, so this tool sets the version number to 0x101, which is the version number C64S 2.52 uses.

Number of file records

Many t64 files have the number of available file records and the number of used file records wrong, which can lead to tools not correctly reading files from the container. If either of these numbers is zero, this tools adjusts that number to one since t64 files with more than one record are rare, and seem to have their record counts correct.

End addresses of files

The thing what makes tools and emulators choke on t64 files. Someone wrote a tool called CONV64 which incorrectly writes the end address of any file as 0xc3c6. This causes some tools or emulators to reject the file or silently ignore the incorrect end address, which causes some decrunchers to fail.

This tool corrects the end address by sorting file records on their data offset and then using that information, combined with the file size of the t64 file to determine the correct end address.

C1541 file type

Another thing many images get wrong. File records are supposed to have a C1541 file type byte, which normally should be between 0x80 and 0x84. In reality this is usually something like 0x01 or 0x44. This tool adjusts incorrect values to 0x82 (PRG), since t64 files can really only store PRG files (and C64S' FRZ files)

Building and installing

To build t64fix simply run make. To install run make install as root.

Targets for make:

Target Result
<none> Build t64fix without debugging enabled
all Build t64fix without debugging enabled
clean Remove t64fix and all intermediate objects, delete Doxygen documentation
debug Build t64fix with debugging enabled
dist Generate distribution tarball (t64fix-$(VERSION).tar.gz)
doc Generate Doxygen documentation (in doc/html)
install Install t64fix executable and its man page
install-bin Install t64fix executable
install-man Install t64fix man page
windist Generate Windows distribution zipfile (`t64fix-win[32

Future

I probably won't be adding any more features to this tool, unless specifically asked for them. Any bugs found I will fix, and of course accept patches for them.

TODO

  • d64 support

BUGS

none(?)

Resources