a275@mindlink.UUCP (Travers Naran) (08/05/90)
I have a problem, I was looking at my AmigaDOS Tech Ref. Manual and studying the Filing System. No where does it mention what format is the "Bitmap" or how to get an updated Bitmap if you are altering the Disk block's directly (as in a floppy optimizer). What is the format of the Bitmap or how can I get AmigaDOS to update the Bitmap for me with a new file system structure on the disk? -- ------------------------------------------------------------------- Travers "T'aran" Naran (I am male) Simon Fraser University, Computing Science (Burnaby, B.C., Canada) New Westminster, British Columbia, Canada, North America, etc... Whovian, Prober, Treker, Quantum Leaper.... Mailing addresses: Usenet Travers_Naran@mindlink.UUCP or uunet!van-bc!rsoft!mindlink!Travers_Naran ------------------------------------------------------------------
cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) (08/07/90)
In article <2730@mindlink.UUCP> a275@mindlink.UUCP (Travers Naran) writes: >I have a problem, I was looking at my AmigaDOS Tech Ref. Manual and studying >the Filing System. No where does it mention what format is the "Bitmap" or how >to get an updated Bitmap if you are altering the Disk block's directly (as in a >floppy optimizer). What is the format of the Bitmap or how can I get AmigaDOS >to update the Bitmap for me with a new file system structure on the disk? The format of the bitmap is documented in an AmigaMail article, contact CATS for back issues. It turns out you don't need to know the format for the bitmap because you can just mark it as "bad" in the rootblock when you are done and after uninhibiting the drive the disk-validator will run and write an updated bitmap on the disk for you. Simple as pie. -- --Chuck McManis Sun Microsystems uucp: {anywhere}!sun!cmcmanis BIX: <none> Internet: cmcmanis@Eng.Sun.COM These opinions are my own and no one elses, but you knew that didn't you. "I tell you this parrot is bleeding deceased!"
ewhac@well.sf.ca.us (Leo 'Bols Ewhac' Schwab) (08/09/90)
[ This has been redirected to comp.sys.amiga.tech. ] In article <2729@mindlink.UUCP> a275@mindlink.UUCP (Travers Naran) writes: >I have a problem, I was looking at my AmigaDOS Tech Ref. Manual and studying >the Filing System. No where does it mention what format is the "Bitmap" [ ... ] >What is the format of the Bitmap [ ... ] ? I don't know how to get tell AmigaDOS to update the bitmap short of making it do a full re-validate. The following is a comment in a very old program I wrote called 'dm', which shows sector allocation on an OFS floppy. I can send you the whole program if you like, or you can dig it off one of the older Fish Disks: -------- /* * At this point, we now have the bitmap in the disk buffer. * This is what the first longword in the bitmap represents: * * 333322222222221111111111 * 32109876543210987654321098765432 Sector # * -------------------------------- * 10100101001010010010010001010011 Longword * MSB LSB * * If the bit is set, the sector is free. * * Sectors 0 and 1 contain the boot block. Thus, the DOS is not * allowed to walk on them, and they are permanently allocated. * However, the bitmap does not reflect this i.e. the bitmap starts * at sector 2, which is indicated by bit 0, longword 1. This means * we have to offset everything by two. Can you say "crock?" * * Actually, I suppose this is good, since it prevents some would-be * smart person from un-allocating those sectors and messing things * up badly. * * Bitmap starts at longword 1; longword 0 appears to be some kind * of significant garbage (checksum?) */ -------- I was a lot younger back then... _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ Leo L. Schwab -- The Guy in The Cape INET: well!ewhac@ucbvax.Berkeley.EDU \_ -_ Recumbent Bikes: UUCP: pacbell > !{well,unicom}!ewhac O----^o The Only Way To Fly. hplabs / (pronounced "AE-wack") "Because you never know who might want to sit in your lap."
new@ee.udel.edu (Darren New) (08/09/90)
In article <19479@well.sf.ca.us> ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab) writes: > * However, the bitmap does not reflect this i.e. the bitmap starts > * at sector 2, which is indicated by bit 0, longword 1. This means > * we have to offset everything by two. Can you say "crock?" Actually, it works out quite nicely. It's not 2 sectors, but rather however many sectors happen to be "reserved". For floppies, this is 2; for hard drives, this can vary (altho most programs that worry about such things die if it is not 2, so beware). -- Darren
peterk@cbmger.UUCP (Peter Kittel GERMANY) (08/20/90)
In article <2729@mindlink.UUCP> a275@mindlink.UUCP (Travers Naran) writes: >I have a problem, I was looking at my AmigaDOS Tech Ref. Manual and studying >the Filing System. No where does it mention what format is the "Bitmap" [ ... ] > I don't know how to get tell AmigaDOS to update the bitmap short of >making it do a full re-validate. There is a brute force way to do this: Execute the CLI command DiskChange on the drive, after you have set the BITMAP_VALID flag in the root block to invalid. This causes AmigaDOS to newly read the disk's parameters, find the bitmap invalid and start the validation process (yes, of the WHOLE disk; I don't know about a way to only register the changes). You know you can invoke CLI commands from C language and even from AmigaBasic by use of the dos library function named Execute. -- Best regards, Dr. Peter Kittel // E-Mail to Commodore Frankfurt, Germany \X/ rutgers!cbmvax!cbmger!peterk