accessing ROM/libraries from Assembler

[Yulquen74]

I have an assembler book which explains well how to use some parts of

DOS and intuition, but what about other libraries and devices?


Meaning which arguments a function takes and where to put them,
what you get in return and how that data is formatted?


Theres a lot of information out there which is useful if you are using C language, including official ROM kernals, but where do you look if you
want to do it in assembler?

[kamelito]

Have a look at the autodocs
http://amigadev.elowar.com/
The RKM examples have also been reworked in ASM, this could help.
http://aminet.net/search?query=Rkm+asm

[Thomas Richter]

Originally Posted by Yulquen74

Meaning which arguments a function takes and where to put them,
what you get in return and how that data is formatted?

That information is all included in the autodocs which come with the official NDK. You can also use tools like FD2PRAGMA (In Aminet) to convert the fd files containing the function definitions to assembler includes.

[kamelito]

There is also this forum for help etc
https://developer.amigaos3.net/forum

[Yulquen74]

While the NDK contains lots of useful information, I still struggle with getting all the pieces.

I wish to open the timer.device to use the GetSysTime function.

The code below was written by alkis in another thread on EAB, and parts of it does what I need prior to running GetSysTime.

Can someone please explain the stuff I added as comments to the above? I just want to understand what is going on.

       incdir  /opt/amiga/gcc6/m68k-amigaos/ndk-include/
        include devices/timer.i
        include exec/execbase.i ;for ThisTask
        include dos/dosextens.i ;for pr_Result2
        include lvo/exec_lib.i
        include lvo/timer_lib.i

; Create message Port
	move.l	$4.w,a6
        move.l  ThisTask(a6),a5  ; what is this? arg for CreateMsgPort? ndk does not mention a5.
	jsr	_LVOCreateMsgPort(a6)

; Create IORequest
        move.l  d0,d7
	move.l	d0,a0
	moveq	#IOTV_SIZE,d0
	jsr	_LVOCreateIORequest(a6)
	move.l	d0,a4   ; pointer to iorequest structure?

; Open timer.device
	move.l	d0,a1
	lea	tdname(pc),a0
	moveq	#0,d0
	moveq	#0,d1
	jsr	_LVOOpenDevice(a6)

        move.l	IO_DEVICE(a4),a6  ; is this the base address for timer library? what is IO_DEVICE def, and does a4 still contain pointer to iorequest?
	lea	eval(pc),a0
        lea	eval2(pc),a3
        jsr	_LVOReadEClock(a6)
        move.l  a3,a0
        jsr	_LVOReadEClock(a6)
        move.l  d0,d6
        move.l  $4.w,a6
;Close device
        move.l a4,a1
        jsr     _LVOCloseDevice(a6)


;Free IORequest
        move.l  a4,a0
        jsr     _LVODeleteIORequest(a6)

;Free MsgPort
        move.l  d7,a0
        jsr     _LVODeleteMsgPort(a6)

        move.l  eval+4,d1
        move.l  eval2+4,d3
        move.l  eval,d0
        move.l  eval2,d2
        sub.l   d1,d3
        subx.l  d0,d2
        move.l  d6,pr_Result2(a5)
        move.l  d3,d0
        rts


eval:
        dc.l 0,0
eval2:  dc.l 0,0
tdname: TIMERNAME

[a/b]

1. a5=ThisTask, probably a leftover. Typically used to check if started from WB or CLI (task->pr_CLI != 0?), but this is not done here.
2. ptr to IORequest struct, yes.
3. timer device (not library) base, yes. Since a device is *not* opened the same way you open a library, it's done via IORequest and OpenDevice() instead (it's filled in upon success).

[alkis]

1. a5 is used to save E_freq at pr_Result2(a5) near the end

[Minuous]

The NDK alone is not ideal; you should also get the RKRMs if you want complete tutorial-style documentation, the autodocs are more of a quick reference.

[Yulquen74]

Thanks!

[a/b]

Originally Posted by alkis

1. a5 is used to save E_freq at pr_Result2(a5) near the end

Thanks for correction, not sure how I missed that. Could play my too old for this card, or go for eye recalibration needed after watching a full screen of weird scrollers for too long .

[alkis]

Originally Posted by a/b

Thanks for correction, not sure how I missed that. Could play my too old for this card, or go for eye recalibration needed after watching a full screen of weird scrollers for too long .

Bro, if we are playing the too old card, then I needed way more time than I'll admit to understand my code.