Using VPrintf

[guy lateur]

I'm trying to print a simple string to the shell. I get screens full of HçHçHç.. when I run the code below. Any idea what I'm doing wrong? TIA!

	SECTION TestCLI,CODE

	INCDIR 	"F:\Amiga\_MountHD\dev\include"
	INCLUDE "LVOs.i"

;-- init/startup
init:
	movem.l d1-a6,-(sp)

	move.l 	4.w,a6				;execbase (permanently open lib)
	moveq 	#0,d0 				;return value in d0

	;open dos.library
	move.l 	#dosName,a1
	jsr 	_LVOOldOpenLibrary(a6)
	move.l 	d0,dosBase

test:
	move.l 	dosBase,a6
	move.l 	#text1Format,d1
	move.l 	#text1,d2
	jsr 	_LVOVPrintf(a6)

exit:
	move.l 	4.w,a6				;execbase (permanently open lib)
	moveq 	#0,d0 				;return value in d0

	;close dos.library
	move.l 	dosBase,a1
	jsr 	_LVOCloseLibrary(a6)

	movem.l (sp)+,d1-a6

	moveq 	#0,d0 				;return value in d0
	rts

	SECTION TestCLIData,DATA
	EVEN
text1:
	dc.b 	"Just testing..",0
	EVEN
text1Format:
	dc.b 	"%s",0

	EVEN
dosName:
	dc.b 	"dos.library",0
	EVEN
dosBase:
	ds.l 	1,0

[StingRay]

You are using wrong parameters. d1 is the text to print, d2 is the formatting array.

Change your code like this:

move.l #text1,d1
move.l #text1format,d2


and text1format needs to be changed to look like this:

text1format dc.l arg1 ; ptr to argument 1

arg1 dc.b "%s",0

and your code should work. This is all untested so no guarantees or anything.

[guy lateur]

Originally Posted by StingRay

You are using wrong parameters. d1 is the text to print, d2 is the formatting array.

Yep, that indeed is apparently the case. The code above works as expected when I apply your changes. It's weird, though, because in the docs (http://amigadev.elowar.com/read/ADCD.../node030D.html) it says D1 is the formatting string, and D2 is a pointer to the array of formatting values (ie, values to be formatted, I assumed). Am I reading the wrong docs?

And how about decimals, btw? If I write this:

	EVEN
text1:
	dc.w 	555
	EVEN
argv11:
	dc.b 	"%d",0
	EVEN
text1Format:
	dc.l 	argv11,0

it outputs +33. Quite baffling, I must say..

[Hedeon]

that's weird. How I have learned it, is VPrintf(fmt, argv)
with fmt pointing to something like

dc.b "my address is %08lx",10

and argv pointing to the actual value (argument) you want to be formatted into that string.

so:

move.l DosBase,a6
lea fmt(pc),a1
move.l a1,d1
lea argv(pc),a1
move.l a1,d2
jmp _LVOVPrintf(a6)

fmt dc.b "register d0 = %08lx ; register d1 = %08lx",10
cnop 0,4
argv dc.l $deadbeef,12345678

At least that is how it works for VFPrintF which only adds an fh. Both values in argv will be formatted to a hexidecimal number in above example. (oh, and I like PC relative, don't mind me)

[Hedeon]

Originally Posted by guy lateur

And how about decimals, btw? If I write this:

	EVEN
text1:
	dc.w 	555
	EVEN
argv11:
	dc.b 	"%d",0
	EVEN
text1Format:
	dc.l 	argv11,0

it outputs +33. Quite baffling, I must say..

In my case it would be:

text1:
       dc.b "%d",0
       EVEN
text1format
       dc.w 555

with text1 being pointed to by fmt (STRPTR) and text1format being pointed to by argv (LONG*). fmt to a string with the formatting in it (like %d) the other being the values you want formatted into the string.

[thomas]

Originally Posted by guy lateur

Am I reading the wrong docs?

I would say you read the right docs, but you interpret it wrongly.

The first argument is the string to be printed. It may but does not need to contain format specifiers.

The second argument points to an array. Or rather a list of values. For each format specifier in the first argument, the array has to contain a corresponding value.

For %s the value must be a pointer to a string. Not the string itself.

For %d the value must be a 16bit word.

For %ld the value must be 32bit long word.

If the array does not align with the format specifiers, all values are printed wrong.

Here is a working example:

[guy lateur]

Originally Posted by Hedeon

In my case it would be:

text1:
       dc.b "%d",0
       EVEN
text1format
       dc.w 555

with text1 being pointed to by fmt (STRPTR) and text1format being pointed to by argv (LONG*). fmt to a string with the formatting in it (like %d) the other being the values you want formatted into the string.

Well you're right. I must have done something wrong earlier to make me think those arguments needed to be switched. Which is quite a relief, tbh, or I would have been in for a spell in interpreting the docs from now on. So this works as expected:

test:
	move.l 	dosBase,a6
	move.l 	#text1Format,d1
	move.l 	#text1Values,d2
	jsr 	_LVOVPrintf(a6)

<snip>

	SECTION TestCLIData,DATA
	EVEN
text1Format:
	dc.b 	"%s is %d cm wide and %d cm high",0
text1TestVal:
	dc.b 	"My window",0
	EVEN
text1Values:
	dc.l  	text1TestVal
	dc.w 	288,144

[guy lateur]

Originally Posted by thomas

I would say you read the right docs, but you interpret it wrongly.

The first argument is the string to be printed. It may but does not need to contain format specifiers.

The second argument points to an array. Or rather a list of values. For each format specifier in the first argument, the array has to contain a corresponding value.

For %s the value must be a pointer to a string. Not the string itself.

For %d the value must be a 16bit word.

For %ld the value must be 32bit long word.

If the array does not align with the format specifiers, all values are printed wrong.

Here is a working example:

Oops, I didn't see your post before replying myself, thomas, but thank you for your elaboration and example code, much appreciated!

[Hedeon]

Originally Posted by guy lateur

Well you're right. I must have done something wrong earlier to make me think those arguments needed to be switched. Which is quite a relief, tbh, or I would have been in for a spell in interpreting the docs from now on. So this works as expected:

test:
	move.l 	dosBase,a6
	move.l 	#text1Format,d1
	move.l 	#text1Values,d2
	jsr 	_LVOVPrintf(a6)

<snip>

	SECTION TestCLIData,DATA
	EVEN
text1Format:
	dc.b 	"%s is %d cm wide and %d cm high",0
text1TestVal:
	dc.b 	"My window",0
	EVEN
text1Values:
	dc.l  	text1TestVal
	dc.w 	288,144

Great!