![]() |
![]() |
#1 |
'Difficult'.
Join Date: May 2006
Location: No fixed abode
Age: 46
Posts: 105
|
mfm/custom regs/track loader
quick question.. if any of you guys could help..
what's the very least amount of mfm data i need to read to seek to any sector on a track?.. (we're talking cutting down to the absolute bare minimum.. saving even $10 bytes would help).. |
![]() |
![]() |
#2 |
Going nowhere
Join Date: Oct 2001
Location: United Kingdom
Age: 50
Posts: 9,035
|
You can't just read a sector, you have to load a track and then decode the relevant sector from there. Well technically, you could read and decode just the first sector, but if you wanted to read the 5th sector in a track, you must load and decode all the previous sectors.
|
![]() |
![]() |
#3 |
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 49
Posts: 26,611
|
You could use DSKBYTR-custom register.. Even unexpanded A500 has enough CPU power to read and decode the data on the fly without need for temporary MFM buffer. (of course you can't have background effects, music etc..)
If I remember correctly, cracked "The Deep"'s loader uses this (really stupid) method. |
![]() |
![]() |
#4 |
'Difficult'.
Join Date: May 2006
Location: No fixed abode
Age: 46
Posts: 105
|
thanks guys..
from this advice i guess i'll try reading one byte at a time and then dumping it in fastmem out of my way. ridiculous as it sounds, i can't spare 3-4k in chipmem with the situation i have. ![]() |
![]() |
![]() |
#5 |
move.w #$4489,$dff07e
Join Date: Sep 2005
Location: Norfolk, UK
Age: 43
Posts: 2,351
|
Could I ask what you are doing? It sounds like something pretty interesting if you are using trackloaders and large amounts of chipram
![]() |
![]() |
![]() |
#6 | |
'Difficult'.
Join Date: May 2006
Location: No fixed abode
Age: 46
Posts: 105
|
Quote:
without adjusting the size of the display (which i really can't do) i need a multiple of $2800 chipram for each bitplane.. i decided to do away with any kind of access to the amiga's o/s libraries and use my own stuff after turning off all the interrupts. so a trackloader makes sense. it's about 80% complete with my w32 version but i want to port it to 680x0.. here's a screenshot if you'd like to see.. point of interest is that the colours cycle, creating the illusion of 'movement' =) Last edited by snyp; 16 November 2010 at 18:55. |
|
![]() |
![]() |
#7 |
move.w #$4489,$dff07e
Join Date: Sep 2005
Location: Norfolk, UK
Age: 43
Posts: 2,351
|
Ahhh
![]() ![]() |
![]() |
![]() |
#8 | |
'Difficult'.
Join Date: May 2006
Location: No fixed abode
Age: 46
Posts: 105
|
Quote:
|
|
![]() |
![]() |
#9 |
move.w #$4489,$dff07e
Join Date: Sep 2005
Location: Norfolk, UK
Age: 43
Posts: 2,351
|
BTW - is that tampon for your avatar?
![]() |
![]() |
![]() |
#10 | |
'Difficult'.
Join Date: May 2006
Location: No fixed abode
Age: 46
Posts: 105
|
Quote:
![]() |
|
![]() |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
ASM: Hardware Track Loader | Vortex | Coders. Tutorials | 175 | 18 October 2022 19:18 |
Game loader stuck on certain track after save state restore | andreas | support.WinUAE | 2 | 26 March 2011 19:59 |
Can't transfer Supaplex cause of CSL track loader ! | Vollldo | support.Games | 4 | 12 March 2011 21:51 |
Custom MFM & Dos tracks | BippyM | Coders. General | 25 | 25 January 2008 19:41 |
understanding the COLORXX regs... | Joe Maroni | Coders. General | 2 | 14 February 2005 07:50 |
|
|