Difference between revisions of "User talk:FloppusMaximus"
From WikiTI
84plusfreak (Talk | contribs) |
|||
| (One intermediate revision by one other user not shown) | |||
| Line 1: | Line 1: | ||
Can you use [[83Plus:BCALLs:805A|GetFieldSize]] to determine the fieldsize of the fields in an appheader? | Can you use [[83Plus:BCALLs:805A|GetFieldSize]] to determine the fieldsize of the fields in an appheader? | ||
| + | |||
| + | :Yes. Although, GetFieldSize behaves a little oddly on fields with an F size indicator. It wont give you the size of the field (which is a good thing, since if it did, you would end up skipping over the whole app), but it will increment HL to point to the next field in the app header. So you've just got to know it's going to do that, and then go about your business. --[[User:Dan Englender|Dan Englender]] 09:12, 21 Apr 2005 (PDT) | ||
| + | |||
| + | :When I said it behaves very strangely, I wasn't joking. It sets both B and A (note that A is destroyed in this case!) to the MSB of the word, and leaves C=E as the high 4 bits of the second type byte. So it will only "work" when the second type byte is 0F and the MSB of the word is zero; for the "image length" (end of header) field, for instance, it would set BC to the nonsensical value of 70h. I have no idea why they would do this; as far as I know, 800F and 807F in app and OS headers are the only places F-fields are used. [[User:FloppusMaximus|FloppusMaximus]] 14:29, 21 Apr 2005 (PDT) | ||
Latest revision as of 13:29, 21 April 2005
Can you use GetFieldSize to determine the fieldsize of the fields in an appheader?
- Yes. Although, GetFieldSize behaves a little oddly on fields with an F size indicator. It wont give you the size of the field (which is a good thing, since if it did, you would end up skipping over the whole app), but it will increment HL to point to the next field in the app header. So you've just got to know it's going to do that, and then go about your business. --Dan Englender 09:12, 21 Apr 2005 (PDT)
- When I said it behaves very strangely, I wasn't joking. It sets both B and A (note that A is destroyed in this case!) to the MSB of the word, and leaves C=E as the high 4 bits of the second type byte. So it will only "work" when the second type byte is 0F and the MSB of the word is zero; for the "image length" (end of header) field, for instance, it would set BC to the nonsensical value of 70h. I have no idea why they would do this; as far as I know, 800F and 807F in app and OS headers are the only places F-fields are used. FloppusMaximus 14:29, 21 Apr 2005 (PDT)
