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 ------------------------------------------------------------------
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."