On Oct 9, 2015 10:36 AM, "Joe Forster/STA" <s...@c64.rulez.org> wrote: > > Hi guys, > > >> A normal DOS app can only access the first 4 GB of a file, or at least it can not seek beyond that, nor can it know about file sizes being beyond that. > > > This came to my mind, too! Where is INT 21h, AX=7142h, the LFN/extended/DOS7+ equivalent of seeking in a file? It could be extended from a 32-bit value to a 64-bit value just like INT 13h, AH=02h was extended to AH=42h for reading disk sectors. > > >> If you extend DOS and / or drivers to support large files, still only software specifically made to use your extended file access interfaces will be able to use large files! > > > You have to do everything on your own under DOS anyway. ;-) > > >> Also, the network redirector API does not support LFN, but I remember that CDEX plus LFN drivers together did provide some support for LFN on DVD and CD filesystems. > > > Newer versions of DOSLFN support long filenames with newer versions of SHSUCDX (but not MSCDEX anymore) if A) SHSUCDX is already loaded or B) the "c+" option is specified on the command line so it can't be that complicated. > > Joe > --
Any foreign filesystem driver for a modern is (e.g. ext# ...) should optionally include support for LFN api. Note that EDR kernel includes extended LFN api for seeking in greater than 4GB files. Assuming a program doesn't seek, and no internal limitations (more likely) files > 4GB can be read/written without changing the abi. I'll try sending the RBIL like snippet later when I'm on my computer. Any extention should follow it to minimize variations for those few DOS programs that may be written to use it. :-) Jeremy
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