Reading files from current directory in assembly

hukka · 06 February 2014, 03:48

Hello EAB!

I'd like to read a file (the filename is known) from the directory the executable was launched from, regardless of whether it's from a floppy or hard drive. I'm using assembly and would like this to work on a plain Amiga 500. This will be my first time coding any sort of file I/O.

Any pointers or even source code to help me get started?

marduk_kurios · 06 February 2014, 04:32

I've just had seen this, it seems it could help you.

Code:

;*******************************************************
;*     Window Example show how to make some basic      *
;*  library calls. And how to use the include files    *
;*                                                     *
;*      ASM-One example coded by Rune Gram-Madsen      *
;*                                                     *
;*       All rights reserved. Copyright (c) 1990       *
;*******************************************************

	INCDIR	df0:include/

;---  Open library  ---

	include	exec/exec_lib.i
	include	libraries/dos_lib.i
	include	libraries/dos.i
	include	intuition/intuition_lib.i

J	LEA	PATH(PC),A0		; Default CLI message
	MOVE.L	A0,-(A7)		; Store CLI message

	BSR.W	DOS_LIBOPEN		; Open dos library
	BSR.L	WINDOW_OPEN		; Open window
	BSR.L	INT_LIBOPEN		; Open intuition library
	BSR.L	WORKBENCH_FRONT		; Put the workbench to front

	MOVE.L	(A7)+,D1		; Path pointer
	MOVEQ	#-2,D2			; Read mode
	CALLDOS	Lock			; Lock
	TST.L	D0
	BEQ.S	.ERROR			; Not found ??
	MOVE.L	D0,D5

	MOVE.L	D5,D1
	MOVE.L	#FILEINFO,D2
	CALLDOS	EXAMINE			; Examine first lock
	TST.L	D0
	BEQ.S	.ERROR

	MOVE.L	#TEXT2,D2
	MOVEQ	#TEXT2_END-TEXT2,D3
	MOVE.L	_WINDOWHANDLE(PC),D1
	CALLDOS	Write

.LOOP	MOVE.L	#FILEINFO+8,D0		; Disk/Dir/File-name ptr
	BSR.W	TEXT_PRINT		; Print name

	MOVE.L	D5,D1
	MOVE.L	#FILEINFO,D2
	CALLDOS	EXNEXT			; Next name on the disk
	TST.L	D0
	BNE.B	.LOOP

.ERROR	CALLDOS	IOERR			; Get message

;--- Close down ---

	MOVE.L	#TEXT1,D2
	MOVEQ	#TEXT1_END-TEXT1,D3
	MOVE.L	_WINDOWHANDLE(PC),D1
	CALLDOS	Write

	MOVE.L	#RETURN,D2
	MOVEQ	#1,D3
	MOVE.L	_WINDOWHANDLE(PC),D1
	CALLDOS	Read

	BSR.L	WORKBENCH_BACK		; workbench back again
	BSR.W	INT_LIBCLOSE		; close intuition lib
	BSR.S	WINDOW_CLOSE		; Close window
	BSR.S	DOS_LIBCLOSE		; close dos
	RTS

;--- Open dos library ---

DOS_LIBOPEN
	LEA.L	_DOSNAME(PC),A1
	MOVEQ	#0,D0
	CALLEXEC OpenLibrary
	MOVE.L	D0,_DOSBASE
	RTS

;--- Close dos library ---

DOS_LIBCLOSE
	MOVE.L	_DOSBASE(PC),A1
	CALLEXEC CloseLibrary
	RTS

;---  Print text  ---

TEXT_PRINT:
	MOVE.L	D0,A0
.LOOP	TST.B	(A0)+
	BNE.S	.LOOP
	SUB.L	D0,A0
	SUBQ.L	#1,A0
	MOVE.L	A0,D3
	MOVE.L	D0,D2
	MOVE.L	_WINDOWHANDLE(PC),D1
	CALLDOS	Write
	MOVE.L	#RETURN,D2
	MOVEQ	#1,D3
	MOVE.L	_WINDOWHANDLE(PC),D1
	CALLDOS	Write
	RTS

;--- Open window ---

WINDOW_OPEN:
	MOVE.L	#_WINDOWNAME,D1
	MOVE.L	#MODE_OLDFILE,D2
	CALLDOS	Open
	MOVE.L	D0,_WINDOWHANDLE
	RTS

;--- Close window ---

WINDOW_CLOSE
	MOVE.L	_WINDOWHANDLE(PC),D1
	CALLDOS	Close
	RTS

;--- Open intuition library ---

INT_LIBOPEN
	LEA.L	_INTNAME(PC),A1
	MOVEQ	#0,D0
	CALLEXEC OpenLibrary
	MOVE.L	D0,_INTUITIONBASE
	RTS

;--- Close intuition library ---

INT_LIBCLOSE
	MOVE.L	_INTUITIONBASE(PC),A1
	CALLEXEC CloseLibrary
	RTS

;--- Workbench to front ---

WORKBENCH_FRONT
	CALLINT	WbenchToFront
	RTS

;--- Workbench to back ---

WORKBENCH_BACK
	CALLINT	WbenchToBack
	RTS

TEXT1:		DC.B	$9B,'3',$6D,'Press <RETURN> : '
TEXT1_END:
TEXT2:		DC.B	$9B,'3',$6D,'Root name : ',$9B,'0',$6D
TEXT2_END:
RETURN:		DC.B	10
_WINDOWNAME	DC.B	'CON:10/10/400/180/Directory',0
	EVEN
_WINDOWHANDLE	DC.L	0
_DOSNAME	DOSNAME
_DOSBASE	DC.L	0
_INTNAME	DC.B	'intuition.library',0
_INTUITIONBASE	DC.L	0

PATH:		DC.B	'DF0:',0,0

	CNOP	0,4

FILEINFO:	DCB.L	260,0

hukka · 06 February 2014, 21:03

Quote:

Originally Posted by marduk_kurios

I've just had seen this, it seems it could help you.

Thanks! That piece of code seems to be hardcoded to load from DF0:, though.

Anyway, I've got my program to load files now, thanks to a piece of code I found on these forums (star4kd.s)! Only problem is, it doesn't try to figure out the current directory, so it seems to only work properly if the files are in the drive root.

Some more Googling finally revealed that apparently the executable's directory is contained in pr_CurrentDir, so I need to figure out how to read and make use of that in assembly. Again, any help would be appreciated!

Asman · 06 February 2014, 22:23

Quote:

Originally Posted by hukka

Hello EAB!

I'd like to read a file (the filename is known) from the directory the executable was launched from, regardless of whether it's from a floppy or hard drive. I'm using assembly and would like this to work on a plain Amiga 500. This will be my first time coding any sort of file I/O.

Any pointers or even source code to help me get started?

I assume that you are in directory for example sys:work/project/
and then you start the executable no matter if this is workbench or cli.
So its very simple to read the file.

1. open dos.library
2. open file ( filename: dc.b "file",0 )
3. read file
4. close file
5. close dos.library

If you need an asm example then I will post one, just give me a sign.

Galahad/FLT · 06 February 2014, 23:14

Quote:

Originally Posted by hukka

Thanks! That piece of code seems to be hardcoded to load from DF0:, though.

Anyway, I've got my program to load files now, thanks to a piece of code I found on these forums (star4kd.s)! Only problem is, it doesn't try to figure out the current directory, so it seems to only work properly if the files are in the drive root.

Some more Googling finally revealed that apparently the executable's directory is contained in pr_CurrentDir, so I need to figure out how to read and make use of that in assembly. Again, any help would be appreciated!

Change 'DF0:' string to 'SYS:' instead

hukka · 07 February 2014, 02:19

Thanks guys! It works now. Turns out my code didn't need any changes, I was just testing it wrong.

While testing, I was running the program from the CLI as "path_to_program/foobar.exe"; to get it to work properly I only needed to first cd to the path and then run the exe. So it's not perfect (since you have to cd to the path first) but good enough for my purposes! (And runs perfectly from Workbench.)

phx · 07 February 2014, 10:44

Since OS2.0 you could use PROGDIR: to access the directory where the program was launched from.

hooverphonique · 07 February 2014, 11:18

Quote:

Originally Posted by hukka

Some more Googling finally revealed that apparently the executable's directory is contained in pr_CurrentDir, so I need to figure out how to read and make use of that in assembly. Again, any help would be appreciated!

that's not entirely true.. pr_CurrentDir contains a lock to the current directory, not the directory of the executable itself.. there is a way to figure out the directory of the executable without using "PROGDIR:", but I can't remember it off the top of my head..

hukka · 07 February 2014, 12:54

Thanks for the replies. Good to know about PROGDIR:! Too bad it doesn't work on 1.2/1.3.

Quote:

Originally Posted by hooverphonique

there is a way to figure out the directory of the executable without using "PROGDIR:", but I can't remember it off the top of my head..

If anyone happens to have this info I'd be very interested in it!

marduk_kurios · 07 February 2014, 17:58

If it's in the path you can use "which". Otherwise I wouldn't know.

Leffmann · 09 February 2014, 18:48

I've looked at it, and unless there's some undocumented method, it seems to me there's only one way:

Find your process with

FindTask(NULL)

, then look at

Process->pr_CLI

to determine if you've been started as a CLI or as a Workbench program.

For Workbench:
Retrieve the WBStartup message sent to you, then simply call

CurrentDir(WBStartup->sm_ArgList[0].wa_Lock)

and you're done.

For CLI:
Look at

Process->pr_CLI->cli_SetName

and

Process->pr_CLI->cli_CommandName

, these fields are the fully qualified path you're currently in, and the command typed on the command line. Together they can form the fully qualified path to your program.

Strip away the name of the program file by working backwards from the end of the command name and removing characters until you hit either "/" or ":", or until the string is empty.

Then search the string for a ":", if you found one then the string is a fully qualified path, and you just call

CurrentDir(Lock( ))

on it and you're done.

If there was no ":" then the command name includes a relative path, and you just concatenate the path you're in, "/", and the command name, in that order, and you have the fully qualified path to call

CurrentDir(Lock( ))

on and you're done.

You can also just prepend your filenames with the path, to avoid locking and changing the directory. Otherwise you must remember to clean up by calling UnLock, and reply to the WBStartup message if you received one. If you ran as a CLI program then you must also call CurrentDir on the previous lock once you're done, or you will confuse the shell.

I think it should work

hooverphonique · 09 February 2014, 19:43

yes.. that's similar to how I've done it in the past on at least one occasion, except that I didn't have to support <2.0, so I used pr_HomeDir instead of cli_SetName.

hukka · 10 February 2014, 21:59

Many thanks, Leffmann! Filing the info for future use.

Leffmann · 11 February 2014, 17:31

Quote:

Originally Posted by Leffmann

I think it should work

I've just written it up and tested it thoroughly, and can now say it works for sure.

Quote:

Originally Posted by hooverphonique

yes.. that's similar to how I've done it in the past on at least one occasion, except that I didn't have to support <2.0, so I used pr_HomeDir instead of cli_SetName.

Yep 2.0 is a lot more convenient than 1.3, but it's still cumbersome to do many things. The AmigaOS APIs have always been very byzantine in this way.

Photon · 10 May 2014, 18:18

ParentDir until you reach :

Leffmann · 17 May 2014, 22:58

Hmm not sure that would work. What file lock would you start from?

Mrs Beanbag · 19 May 2014, 23:08

let me clear this up, it is only necessary to be able to load files from the executable's directory, not to know the actual path, right? If one could get a lock to that directory you can Dos.library::CurrentDir to it and you're done, you can just use relative paths.

Instead of taking Process->pr_CLI->cli_CommandName and looking for '/' in the string, of course we could just get the lock to the file and then ParentDir from that.

Leffmann · 20 May 2014, 21:37

Yes but this is precisely the problem; there is no quick way get the file lock.

Mrs Beanbag · 20 May 2014, 22:20

although taking the title of the thread literally, "Reading files from current directory in assembly" this is easy because when launching from CLI you are already in the current directory (i.e. the current directory of the shell, not the path of the executable).

Photon · 21 May 2014, 00:23

In CLI, I'd just use a relative path to the filename and assume the exe is started from the folder it's in.

I'm very weak on Workbench programming, but for a normal "double click icon" program I don't know what other folder it could be started from.

This gives you a lock on the current folder, though I've seen a lock of 0 is valid in some doc.

Code:

CurrDirLock:
	move.l DosBase(PC),a6
	move.l #DirName,d1
	moveq #-2,d2
	jsr Lock(a6)		;d0=0 or valid lock.
	rts
	
DirName: dc.b 0

09 February 2014, 18:48	#11
Leffmann Join Date: Jul 2008 Location: Sweden Posts: 2,269	I've looked at it, and unless there's some undocumented method, it seems to me there's only one way: Find your process with FindTask(NULL) , then look at Process->pr_CLI to determine if you've been started as a CLI or as a Workbench program. For Workbench: Retrieve the WBStartup message sent to you, then simply call CurrentDir(WBStartup->sm_ArgList[0].wa_Lock) and you're done. For CLI: Look at Process->pr_CLI->cli_SetName and Process->pr_CLI->cli_CommandName , these fields are the fully qualified path you're currently in, and the command typed on the command line. Together they can form the fully qualified path to your program. Strip away the name of the program file by working backwards from the end of the command name and removing characters until you hit either "/" or ":", or until the string is empty. Then search the string for a ":", if you found one then the string is a fully qualified path, and you just call CurrentDir(Lock( )) on it and you're done. If there was no ":" then the command name includes a relative path, and you just concatenate the path you're in, "/", and the command name, in that order, and you have the fully qualified path to call CurrentDir(Lock( )) on and you're done. You can also just prepend your filenames with the path, to avoid locking and changing the directory. Otherwise you must remember to clean up by calling UnLock, and reply to the WBStartup message if you received one. If you ran as a CLI program then you must also call CurrentDir on the previous lock once you're done, or you will confuse the shell. I think it should work Last edited by Leffmann; 09 February 2014 at 19:01.

21 May 2014, 00:23	#20
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	In CLI, I'd just use a relative path to the filename and assume the exe is started from the folder it's in. I'm very weak on Workbench programming, but for a normal "double click icon" program I don't know what other folder it could be started from. This gives you a lock on the current folder, though I've seen a lock of 0 is valid in some doc. Code: CurrDirLock: move.l DosBase(PC),a6 move.l #DirName,d1 moveq #-2,d2 jsr Lock(a6) ;d0=0 or valid lock. rts DirName: dc.b 0

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06 February 2014, 03:48	#1
hukka Wolf-bear thing Join Date: Jan 2014 Location: Finland Age: 41 Posts: 56	Reading files from current directory in assembly Hello EAB! I'd like to read a file (the filename is known) from the directory the executable was launched from, regardless of whether it's from a floppy or hard drive. I'm using assembly and would like this to work on a plain Amiga 500. This will be my first time coding any sort of file I/O. Any pointers or even source code to help me get started?

07 February 2014, 02:19	#6
hukka Wolf-bear thing Join Date: Jan 2014 Location: Finland Age: 41 Posts: 56	Thanks guys! It works now. Turns out my code didn't need any changes, I was just testing it wrong. While testing, I was running the program from the CLI as "path_to_program/foobar.exe"; to get it to work properly I only needed to first cd to the path and then run the exe. So it's not perfect (since you have to cd to the path first) but good enough for my purposes! (And runs perfectly from Workbench.)

07 February 2014, 10:44	#7
phx Natteravn Join Date: Nov 2009 Location: Herford / Germany Posts: 2,496	Since OS2.0 you could use PROGDIR: to access the directory where the program was launched from.

07 February 2014, 17:58	#10
marduk_kurios move $dff006,$dff180 Join Date: Feb 2014 Location: USA Posts: 66	If it's in the path you can use "which". Otherwise I wouldn't know.

09 February 2014, 19:43	#12
hooverphonique ex. demoscener "Bigmama" Join Date: Jun 2012 Location: Fyn / Denmark Posts: 1,624	yes.. that's similar to how I've done it in the past on at least one occasion, except that I didn't have to support <2.0, so I used pr_HomeDir instead of cli_SetName.

10 February 2014, 21:59	#13
hukka Wolf-bear thing Join Date: Jan 2014 Location: Finland Age: 41 Posts: 56	Many thanks, Leffmann! Filing the info for future use.

10 May 2014, 18:18	#15
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	ParentDir until you reach :

17 May 2014, 22:58	#16
Leffmann Join Date: Jul 2008 Location: Sweden Posts: 2,269	Hmm not sure that would work. What file lock would you start from?

19 May 2014, 23:08	#17
Mrs Beanbag Glastonbridge Software Join Date: Jan 2012 Location: Edinburgh/Scotland Posts: 2,243	let me clear this up, it is only necessary to be able to load files from the executable's directory, not to know the actual path, right? If one could get a lock to that directory you can Dos.library::CurrentDir to it and you're done, you can just use relative paths. Instead of taking Process->pr_CLI->cli_CommandName and looking for '/' in the string, of course we could just get the lock to the file and then ParentDir from that.

20 May 2014, 21:37	#18
Leffmann Join Date: Jul 2008 Location: Sweden Posts: 2,269	Yes but this is precisely the problem; there is no quick way get the file lock.

20 May 2014, 22:20	#19
Mrs Beanbag Glastonbridge Software Join Date: Jan 2012 Location: Edinburgh/Scotland Posts: 2,243	although taking the title of the thread literally, "Reading files from current directory in assembly" this is easy because when launching from CLI you are already in the current directory (i.e. the current directory of the shell, not the path of the executable).

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