English Amiga Board - View Single Post - Hunter's trackloader is driving me bonkers.

ross · 14 October 2018, 09:45

A wrong way to check that the track has been read completely.

You exit from

dbne.w d0,10d8c

in two way:
- if d0 underflow (so when a fixed amount of cycles passed,

mulu

is here to waste cycles)
- if DSKBLK is satisfied from the previous Z flag set by the INTENAR read

On fast processors the track is not completely read because

mulu

is executed faster

EDIT: the funny thing is that this routine could also fail for the opposite situation, that is in for very slow processors
(impossible because there are no 000 Amiga with clock less than 7MHZ, but potentially could happen)

14 October 2018, 09:45	#2
ross Defendit numerus Join Date: Mar 2017 Location: Crossing the Rubicon Age: 54 Posts: 4,483	A wrong way to check that the track has been read completely. You exit from dbne.w d0,10d8c in two way: - if d0 underflow (so when a fixed amount of cycles passed, mulu is here to waste cycles) - if DSKBLK is satisfied from the previous Z flag set by the INTENAR read On fast processors the track is not completely read because mulu is executed faster EDIT: the funny thing is that this routine could also fail for the opposite situation, that is in for very slow processors (impossible because there are no 000 Amiga with clock less than 7MHZ, but potentially could happen) Last edited by ross; 14 October 2018 at 10:54.