Boot block examples?

[h0ffman]

Was wondering if anyone had any boot block example code? I think the steps i need to do are...

1. Allocate memory
2. Use TrackDisk.Device to load a section off the disk into the allocated memory
3. Kill system
4. Jmp into the data loaded off the disk.

Any pointers would be ACE

Cheers in advance..

Edit - Also, with killing the system, as I'm going to be taking over all of the 1 meg chip ram on an a600 I figured will have to set the stack pointer somewhere else, or will it be at the top of the ram already?

[BippyM]

http://eab.abime.net/showthread.php?t=28001

Further down in that thread

[StingRay]

Originally Posted by h0ffman

Was wondering if anyone had any boot block example code? I think the steps i need to do are...

Here is a small example straight from my Super Cars crack. I guess you're mostly interested in how to load via trackdisk so there is no memory allocation etc. here.

BOOT    dc.l    "DOS"<<8
    dc.l    0
    dc.l    "STR!"

    pea    $60000
    move.l    (a7),a2
    lea    .BOOT(pc),a0
    move.w    #1024/4-1,d7
.copy    move.l    (a0)+,(a2)+
    dbf    d7,.copy
    rts

.BOOT
; disable instruction cache
    cmp.w    #36,$14(a6)
    bcs.b    .nocache
    moveq    #0,d0
    moveq    #1<<0,d1
    move.l    a1,a5
    jsr    -648(a6)    
    move.l    a5,a1
.nocache

    pea    $30000
    move.l    (a7)+,$28(a1)
    move.l    #1636*512,$2c(a1)
    move.l    #74*512,$24(a1)
    jsr    -456(a6)
    movem.l    d0-a6,-(a7)
    jsr    $30000
    movem.l    (a7)+,d0-a6

Originally Posted by h0ffman

1. Allocate memory
2. Use TrackDisk.Device to load a section off the disk into the allocated memory
3. Kill system
4. Jmp into the data loaded off the disk.

Any pointers would be ACE

That's completely correct.

Originally Posted by h0ffman

Also, with killing the system, as I'm going to be taking over all of the 1 meg chip ram on an a600 I figured will have to set the stack pointer somewhere else, or will it be at the top of the ram already?

Since you have complete control over the system you should set the stackpointer yourself to a safe location (preferably either very low or very high in mem).

[h0ffman]

Wicked.. got the boot block working. The music disk engine wasn't working to start with, until I remembered it has all the OS saving calls it does before starting up. They aint gonna work if you destory memory are they!!