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<liquidengineer> Hello
<liquidengineer> I'm programming in x86 asm
<liquidengineer> and wondering if, given a character I'm storing in an 8-bit register (AL), if there's a simple way I can test to see if that character is a digit
<wcstok> check if it's >='0 and <='9'
<liquidengineer> Oh
<liquidengineer> yes
<liquidengineer> that would do it
<liquidengineer> but I didn't think I could do that with a single cmp and jump pair
<liquidengineer> i.e.: I want to jle 9 AND jge 0
<liquidengineer> I don't quite understand how to do a multi-conditional jump
<liquidengineer> I could test for one and if it's true jump to a block where I test the other and jump if THAT one's true/not true, but that seems overcomplicated
<pireau> liquidengineer: i got a program here
<pireau> for DOS, but you could easily port it..
<pireau> it prints a X bytes
<pireau> mov dx,XXXXh ; contains the value to be printed
<pireau> mov cx,XXh ; contains the number of bytes to be printed.
<pireau> would you like it ?
<pireau> it has the the part where I convert the numerical value to it's ASCII value.
<liquidengineer> Hmm....thanks, but I'm not sure I need it...
<liquidengineer> Or maybe I do need to do that
<pireau> http://rafb.net/paste/results/YqGvvm65.html
<liquidengineer> I'm confused
<pireau> just check, it's commented ;)
<liquidengineer> is it legal to compare like this?
<liquidengineer> cmp inputBit, '0'
<liquidengineer> and then do a jge statement?
<pireau> jae
<pireau> jge is for signed numbers...
<liquidengineer> jae does what, then?
<pireau> it actually the same, but it's better for you when you'll read this code in 5 years
<liquidengineer> jmp if alpha equal?
<pireau> Jump Above or Equal
<pireau> Jump Greater or Equal
<pireau> same.
<pireau> 1st, what are you trying to do ?
<liquidengineer> I have an input
<liquidengineer> I need to know if the input character (stored in AL) is alpha
<liquidengineer> if it's a character that's not a digit, I just need to output it
<liquidengineer> if it's a digit between 0 and 9, I need to xlatb it
<pireau> you could mod hte code to work...
<pireau> where i add 30h, you could just output it
<pireau> oh no
<pireau> you already have it's ASCII value
<pireau> numbers are between 30h and 39h.
<pireau> alpha are 41h + 1Ch
<liquidengineer> yeah
<liquidengineer> I already have the ascii value
<liquidengineer> so...
<liquidengineer> I'm looking at this
<pireau> if <=39h AND >=30h -> out put
<liquidengineer> cmp dx,0Fh ; If num is <=0Fh AND >=0
<pireau> else -> xlatb
<pireau> but first you cheack that the value is between 30h and 5Ch
<pireau> yeah
<pireau> cmp dx,0Fh ; If num is <=0Fh AND >=0
<pireau> ja EndIfDetAffiche;
<pireau> cmp dx,0 ;
<pireau> jb EndIfDetAffiche;
<pireau> if it's higher than F jump to EndIf
<pireau> else it executes the other cmp
<liquidengineer> yeah, I was looking at that part
<pireau> it it's below than 0 jump to end if...
<liquidengineer> what's F?
<pireau> 0Fh
<pireau> 1111 ?
<pireau> 15 ?
<liquidengineer> oh
<pireau> 17 in octal ?
<pireau> because here i print a numerical value.
<pireau> so it's between 0 and 9 and A and F
<liquidengineer> yeah
<liquidengineer> so since I'm working in base 10....
<pireau> but i have to know it's its a number or a letter to add ghe right value to it to get it's ASCII value... then print it.
<pireau> work in base 16 ;)
<liquidengineer> I'd rather not... :P
<liquidengineer> but I might end up having to
<pireau> yu
<pireau> yup*
<liquidengineer> I have a question about this:
<liquidengineer> cmp dx,0Fh ; If num is <=0Fh AND >=0
<pireau> yeah ?
<liquidengineer> how does it test BOTH those conditions?
<pireau> the if is accomplished with the 2 compares...
<liquidengineer> how do you know it's greater than 0?
<liquidengineer> OH
<liquidengineer> yaeh
<liquidengineer> so you DO need two compares
<liquidengineer> well then
<liquidengineer> poo
<pireau> yah
<liquidengineer> I was hoping I could do it with one
<pireau> nah
<pireau> i'd be glad to code a part with you
<liquidengineer> I'm hoping I can get this to work with my decimal implementation, since I've already got like 80 lines written
<liquidengineer> so, first I would do something like this, right?
<pireau> first
<liquidengineer> cmp AL,9
<liquidengineer> ?
<pireau> nein
<liquidengineer> oops
<liquidengineer> okay then. :)
<liquidengineer> what should I do first?
<pireau> first test if it's between 30h and 7Ah
<pireau> since you could have a 'A' or a 'a'
<liquidengineer> actually, I was hoping not to test for letters
<liquidengineer> as it is, my program essentially ignores alphanumeric input
<liquidengineer> it just gets echoed out
<liquidengineer> *alpha input
<liquidengineer> I was hoping just to test for 0-9
<eedy31> yellow
<pireau> okay
<liquidengineer> those 10 are the ones I need to take action on
<pireau> then only test if the value is between 48 and 57.
<pireau> if it's not... it's an alpha or a control code or anything else.
<pireau> cmp al,57
<pireau> ja EndIfNum
<pireau> cmp al,38
<pireau> jb EndIfNum
<pireau> ;treatement here
<pireau> EndIfNum
<pireau> like so.
<pireau> you need a ':' after EndIfNum
<liquidengineer> Where EndIfNum is run if it's NOT a number, right?
<pireau> yeah
<pireau> so you place your "treatement code" between the comment and the label.
<liquidengineer> I think I got it, thanks!
<liquidengineer> but you were right
<liquidengineer> I just looked at the what I already had written
<liquidengineer> I have the xlatb instruction inside a labeled codeblock called encrypt
<liquidengineer> it is better to test for alphas and just jump OVER the xlatb if I don't need it
<pireau> cool
<pireau> glad I could help
<liquidengineer> so in the example you gave me I just substitute cmp al,57 for 30h and so forth, right?
<pireau> yeah
<pireau> that;s what I did.
<liquidengineer> thanks
<liquidengineer> I'm sure listening ot me restate things is frustrating, but I have trouble understanding sometimes. :)
<liquidengineer> crud
<liquidengineer> gotta go
<liquidengineer> later
<liquidengineer> :d
<CaffeiniaNervosa> Hello.
<Nomius> What does the cwd instruction in x86?
<wcstok> convert word to doubleword
<Nomius> Thanks
<prolific> What is actually converted with that instruction?
<libero> if you just copy the word into a dw, it copies the least significant 8 bytes only
<libero> and doesn't make sure that the most sig. bytes are managed correctly
<libero> cwd will do that
<prolific> So if you have 10000101000000000 and movl that into a dw, you get 0000[16 0's]0001000010100000000, right?
<prolific> Well, something like that
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