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Old 23 March 2010, 10:55   #81
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Quote:
Originally Posted by StingRay View Post
This is kinda useless (sorry) because load address is not constant.
Life is hard to save some bytes

So another possible size optimization: put $55555555 into some free register ( I guess we can use d7 ) and then do andi.l's in .mfm_decode.
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Old 23 March 2010, 11:00   #82
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@ Asman - Correct but if I remember my own source correctly (bad memory - need to check! ) there are no free regs for the MFM decode mask...
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Old 23 March 2010, 11:02   #83
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Asman, I bow - looks like d7 would be OK.
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Old 23 March 2010, 11:06   #84
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Sting & Asman - legendary work guys.

I already implemented Asman's d7 save, I'll implement Sting's pea save too.

416 byte version of the trackloader to come! \o/

EDIT: Where'd Sting's pea save post just go...? Maybe only a 418 byte version to come...
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Old 23 March 2010, 11:06   #85
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Quote:
Originally Posted by Asman View Post
Life is hard to save some bytes
I know And I edited my post and added some more explanations.
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Old 23 March 2010, 11:08   #86
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Quote:
Originally Posted by pmc View Post
Sting & Asman - legendary work guys.

I already implemented Asman's d7 save, I'll implement Sting's pea save too.

416 byte version of the trackloader to come! \o/

Sorry, I was wrong (and deleted my post). (Didn't have enough coffee yet it seems). But see if you can find a free address register so you can do
lea $8000,a0
...
jmp (a0)

f.e.
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Old 23 March 2010, 11:08   #87
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@StingRay

Awesome

@pmc
Agree, you should put move.l #$5555555,d7 before first bsr.s .mfm_decode.
And please post newest version of source.
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Old 23 March 2010, 11:09   #88
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Sting - after yesterday's shrinking there's two free address regs - a0 and a1 if I remember correctly.

Maybe we might get below 418 yet!
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Old 23 March 2010, 11:13   #89
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Quote:
Originally Posted by pmc View Post
Sting - after yesterday's shrinking there's two free address regs - a0 and a1 if I remember correctly.

Maybe we might get below 418 yet!

Use the pea optimization, easier. ;D Turns out I wasn't wrong and it is indeed 2 bytes smaller. ;D (too stressful to do "fun code" when boss is around ;D)

And since I deleted my original post, I'll post the pea optimization again.

pea $8000
move.l (a7),a4
...
rts

instead of
lea $8000,a4
....
jmp $8000

Last edited by StingRay; 23 March 2010 at 11:23. Reason: added "lost" pea version again :D
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Old 23 March 2010, 12:08   #90
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OK boys, after implementing Sting's and Asman's additional size optimisations here's the 416 byte version!

Anyone who's helped in this is now credited in the source as having done so - thanks guys - much appreciated!

416 byte version removed.

Last edited by pmc; 23 March 2010 at 13:40.
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Old 23 March 2010, 12:28   #91
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So we have one free register a1. Right after comment ; Setup disk controls you should put $4489 into a1 and change a bit source, mean replace all $4489 into a1.

I need some extra coffee. We have also a0 free.

Last edited by Asman; 23 March 2010 at 12:49. Reason: added forget register a0
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Old 23 March 2010, 12:31   #92
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Not tested but:
andi.l #$0000ff00,d1 ;isolate sector number
add.l d1,d1 ;*2 to get byte offset to place this sector in the decode buffer
adda.w d1,a4 ;add the offset to the decode data buffer address

could be done like this:
sf d1
add.w d1,d1
add.w d1,a4
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Old 23 March 2010, 12:54   #93
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Next one (maybe 400 bytes version is possible )

moveq.l #71,d7 ;head settle time
bra.s .wait_timer
.upper_head:
bclr.b #2,(a6) ;select upper disk head
moveq.l #71,d7 ;head sett

can be replaced with:
bra.b .w_timer71
.upper_head:
bclr.b #2,(a6) ;select upper disk head
.w_timer71
moveq.l #71,d7 ;head sett
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Old 23 March 2010, 13:02   #94
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Quote:
Originally Posted by StingRay View Post
Next one (maybe 400 bytes version is possible )

moveq.l #71,d7 ;head settle time
bra.s .wait_timer
.upper_head:
bclr.b #2,(a6) ;select upper disk head
moveq.l #71,d7 ;head sett

can be replaced with:
bra.b .w_timer71
.upper_head:
bclr.b #2,(a6) ;select upper disk head
.w_timer71
moveq.l #71,d7 ;head sett
Damn, I don't catch this ( I'm going to drink coffee ). Could you explain a bit. Thank you.
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Old 23 March 2010, 13:03   #95
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Quote:
Originally Posted by StingRay
Next one (maybe 400 bytes version is possible )
LOL. Smaller than 416 is definitely possivle - not sure 400 is!

Wait 71 timer branch optimisation implemented - trackloader now 414 bytes.

Quote:
Originally Posted by StingRay
Not tested but:
andi.l #$0000ff00,d1 ;isolate sector number
add.l d1,d1 ;*2 to get byte offset to place this sector in the decode buffer
adda.w d1,a4 ;add the offset to the decode data buffer address

could be done like this:
sf d1
add.w d1,d1
add.w d1,a4
Probably being stupid but - sf d1...?
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Old 23 March 2010, 13:04   #96
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Quote:
Originally Posted by Asman
Damn, I don't catch this ( I'm going to drink coffee ). Could you explain a bit. Thank you.
Sting cleverly spotted that you could use the same moveq.l #71 for both head settle times by using a branch to the second one in place of the first one.
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Old 23 March 2010, 13:04   #97
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Probably being stupid but - sf d1...?

s.et f.alse = d1.b = 0.
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Old 23 March 2010, 13:06   #98
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Quote:
Originally Posted by Asman View Post
Damn, I don't catch this ( I'm going to drink coffee ). Could you explain a bit. Thank you.
I explained this in one of my earlier posts.

Quote:
Originally Posted by StingRay
- "chain" your routines, e.g.
move.w #val,d7
bra.w .wait_timer
; some other code
move.w #val,d7
bra.w .wait_timer
; some other code
move.w #val,d7
bra.w .wait_timer


can be changed to:
move.w #val,d7
bra.b .w_timer
; some other code
move.w #val,d7
bra.b .w_timer
; some other code
move.w #val,d7
.w_timer
bra.w .wait_timer
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Old 23 March 2010, 13:10   #99
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Quote:
Originally Posted by StingRay
s.et f.alse = d1.b = 0.
Ah, OK - set false. I'm being dumb though cos I still don't get how that enables replacing the andi that isolates the sector number from the decoded sector header longword.
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Old 23 March 2010, 13:13   #100
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Ah, OK - set false. I'm being dumb though cos I still don't get how that enables replacing the andi that isolates the sector number from the decoded sector header longword.
;d1: $ABCD1234
and.l #$0000ff00,d1 ; d1 = $00001200

;d1: $ABCD1234
sf.b d1 ; d1: $ABCD1200

since we only do .w operations, it doesn't matter what's in the high word of d1

thus: and.l #$0000ff00,d1 = sf.b d1

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