ddave@pnet02.cts.com (David Donley) (03/14/89)
HELP! I am trying to write a mountlist writing program. Could somebody
please tell me
1. How can you tell if a BSTR or BPTR is NULL?
2. What has changed in the FileSysStartupMsg, DeviceNode, and fssm_Environ
since 1.2?
Thanks!
Call my BBS at (213) 372-4494
Disclaimer: If it doesn't work, you did something wrong.
ddave@pnet02.CTS.COM ddave@pnet.gryphon.COM killer!gryphon!pnet02!ddavedaveh@cbmvax.UUCP (Dave Haynie) (03/15/89)
in article <13291@gryphon.COM>, ddave@pnet02.cts.com (David Donley) says: > HELP! I am trying to write a mountlist writing program. Could somebody > please tell me > 1. How can you tell if a BSTR or BPTR is NULL? Well, start with the BPTR. Based on the definition: BPTR = CPTR >> 2; One would expect a BPTR NULL to be 0>>2, which magically turns out to be the same as the CPTR NULL. Imagine that. A BCPL string (once de-referenced, of course) is empty is the first byte is 0. You may also note that again, in this one case, that's the same way you tell if a C string is empty. Of course, before de-referencing a BCPL string pointer, you'll have to check that it's non-NULL, and probably shift it's pointer into a CPTR, as most BCPL strings are pointed to by BPTRs. > 2. What has changed in the FileSysStartupMsg, DeviceNode, and fssm_Environ > since 1.2? The only thing I know of is that the environment is longer. The first longword of the environment tells you it's length. Under 1.2, DE_MEMBUFTYPE is the last word of the environment. Under 1.3, you can also have the following environment vector members (in order): ULONG DE_MAXTRANSFER The maximum number of bytes to transfer at a time. ULONG DE_MASK Address mask used to block out certain areas of memory. LONG DE_BOOTPRI Autoboot priority. ULONG DE_DOSTYPE Indicates the file system, SFS = 'DOS\0', FFS = 'DOS\1' > ddave@pnet02.CTS.COM ddave@pnet.gryphon.COM killer!gryphon!pnet02!ddave -- Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy Amiga -- It's not just a job, it's an obsession
ddave@pnet02.cts.com (David Donley) (03/16/89)
daveh@cbmvax.UUCP (Dave Haynie) writes: >in article <13291@gryphon.COM>, ddave@pnet02.cts.com (David Donley) says: > >> HELP! I am trying to write a mountlist writing program. Could somebody >> please tell me > >> 1. How can you tell if a BSTR or BPTR is NULL? > >Well, start with the BPTR. Based on the definition: > > BPTR = CPTR >> 2; > >One would expect a BPTR NULL to be 0>>2, which magically turns out to be >the same as the CPTR NULL. Imagine that. > >A BCPL string (once de-referenced, of course) is empty is the first byte >is 0. You may also note that again, in this one case, that's the same >way you tell if a C string is empty. Of course, before de-referencing a >BCPL string pointer, you'll have to check that it's non-NULL, and probably >shift it's pointer into a CPTR, as most BCPL strings are pointed to by >BPTRs. > >> 2. What has changed in the FileSysStartupMsg, DeviceNode, and fssm_Environ >> since 1.2? > >The only thing I know of is that the environment is longer. The first longword >of the environment tells you it's length. Under 1.2, DE_MEMBUFTYPE is the >last word of the environment. Under 1.3, you can also have the following >environment vector members (in order): > > ULONG DE_MAXTRANSFER The maximum number of bytes to transfer > at a time. > ULONG DE_MASK Address mask used to block out certain > areas of memory. > LONG DE_BOOTPRI Autoboot priority. > ULONG DE_DOSTYPE Indicates the file system, SFS = 'DOS\0', > FFS = 'DOS\1' > >> ddave@pnet02.CTS.COM ddave@pnet.gryphon.COM killer!gryphon!pnet02!ddave >-- >Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" > {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy > Amiga -- It's not just a job, it's an obsession Thanks for the help, I just had some probabems with dn_Handler asd several other things (like dn_GlobVec) being set to 0xFFFFFFFF when they weren't being used. Is this true, or am I realy screwed up here? Call my BBS at (213) 372-4494 Disclaimer: If it doesn't work, you did something wrong. ddave@pnet02.CTS.COM ddave@pnet.gryphon.COM killer!gryphon!pnet02!ddave
daveh@cbmvax.UUCP (Dave Haynie) (03/17/89)
in article <13361@gryphon.COM>, ddave@pnet02.cts.com (David Donley) says: > Thanks for the help, I just had some probabems with dn_Handler asd several > other things (like dn_GlobVec) being set to 0xFFFFFFFF when they weren't being > used. Is this true, or am I realy screwed up here? It's certainly true. I'm not sure about dn_GlobVec, but there are two specific "nothing there" values possible for some BCPL-ish things. Often a NULL pointer in a field somewhere is taken to mean "I don't have my own THING, use the default", whereas the 0xFFFFFFFF == -1L value is saying "don't use THING at all". > Call my BBS at (213) 372-4494 -- Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy Amiga -- It's not just a job, it's an obsession