Some small tricks I have done, working with development tools and interesting code I have written. It is not a tutorial site as much just an interesting place to shuffle around. I do have a tiny software collection available (all of which are an order of magnitude larger than anything here).
This site really only uses a little PHP at the moment and in three ways; to include common files/data, a feedback form, and a search form. Including files is pretty straightforward, but I found two articles on a feedback and search form thatI thought would be nice to put in the examples.
My form is similar to this one:
<?php
if ($_POST) {
$subject = $_POST['subject'];
$email = $_POST['email'];
$comments = $_POST['comments'];
$message = Message from $name ($email)\n\nComments:\n\n$comments
;
mail(jay.fink@gmail.com
, Feedback
, $message);
echo "<h2>Thank you!</h2>\n";
echo "<p>Your feedback has been sent.</p>\n";
} else {
?>
<h2>Send Feedback</h2>
<form method = post
action=<?= $PHP_SELF ?>
>
Email Address:<br />
<input type=text
name=email
/> <br />
Subject:<br />
<input type=text
name=subject
/> <br />
<br />Subject:<br />
<textarea name=comments
rows=5
cols=50
>
</textarea><br /><br />
<input type=submit
value=Send Feedback
/>
The search PHP script while clever has one slight drawback, it is using
a non portable grep syntax. Generally speaking, on
any Open Source OS grep -r is supported. I found this
method right here:
<Search> <form action=<?=$PHP_SELF;?gt;method=post<input type=textname=searchstrvalue=<?php echosize=$searchstr; ?>20maxlength=30/> <input type=submitvalue=Search/> </form> <?php $cmdstr =grep -ir $searchstr dir1/* dir2/*.html about/*; $fp = popen( $cmdstr,r); $myresult = array(); echo (<h3>Search Results</h3>\n); while( $buffer = fgetss ( $fp, 4096 )) { list( $fname, $fline ) = split(:, $buffer, 2 ); if ( !defined( $myresult[$fname] )) $myresult[$fname] = $fline; } if ( count( $myresult )) { echo<ul>\n; while ( list( $fname, $fline ) = each( $myresult)) echo<li><a href=\; } else { echo$fname\>$fname</a> : $fline </li>\n<p>Sorry. Search on <b>$searchstr</b> returned no results.</p>\n; } pclose( $fp ); } ?>
Note how the feedback uses a reverse logic, if we have not done a post then print the form yet the search just replaces part of the page on the fly.
I didn't believe it so I had to try it for myself; Perl has four states of nothing. When I have time I will definitely play around with other languages and the nefarious nothing.
my $darkman;
if ($darkman == 0) { print "Darkman is a numerical 0\n";}
if ($darkman == NULL) { print "Darkman is a NULL but not \'NULL\'\n";}
if (!$darkman) { print "Darkman is not !defined\n";}
if ($darkman eq '') { print "Darkman has nothing inside of any quotes\n";}
die $darkman;
Apparently, nothing can die...
While trying to troubleshoot a BIOS problem, I found this and made some minor modifications to it.
; read from a floppy to boot up
[ORG 0]
jmp 07C0h:start ; Goto segment 07C0
; message string
msg db 'Booting....'
start:
; Update the segment registers
mov ax, cs
mov ds, ax
mov es, ax
mov si, msg ; put the message string into si
reset: ; Reset the floppy drive
mov ax, 0 ;
mov dl, 0 ; Drive=0 (=A)
int 13h ;
jc reset ; ERROR => reset again
read:
mov ax, 1000h ; ES:BX = 1000:0000
mov es, ax ;
mov bx, 0 ;
mov ah, 2 ; Load disk data to ES:BX
mov al, 5 ; Load 5 sectors
mov ch, 0 ; Cylinder=0
mov cl, 2 ; Sector=2
mov dh, 0 ; Head=0
mov dl, 0 ; Drive=0
int 13h ; Read!
jc read ; ERROR => Try again
jmp 1000h:0000 ; Jump to the program
times 510-($-$$) db 0
dw 0AA55h
Basically, we init nasm, update the registers,
stick the message string in then reset and read. Not much but
another good starting point.
This is about as small as it gets for inline assembly using the gnu assembler.
/* Simplistic example */
int
main(void)
{
__asm__ (" mov %ah,5");
return 0;
}
NASM is the netwide assembler.
This is a very small demo file in nasm that has a lot of comments regarding x86 based systems (there is some conjecture in there too...):
; For 16 bit machines ; bit: 1 or 0 ; nibble: 4 bits ; byte: 8 bits ; word: 2 bytes (16 bit) ; dword: 2 words (32 bit) ; ; word is dependent on the bus width, e.g a 32 bit processoer has a 32bit ; word and a dword is 64bit....
First, some functions:
; stackplay
; What we are doing is using a stack to swap out the contents of
; two general purpose registers.
stackplay:
push cx ; put cx contents on the stack, aka BP or SP, or Stack Pointer
push ax ; put ax contents on the stack on top of cx
pop cx ; put value from stack (the last item which would have been from
; ax into the cx register
pop ax ; put the value from the stack (the last item whih would've been
; from the cx rgister 3 lines up) into the ax register
; zerogp
; zero out the general purpose registers
zerogp:
mov ax,00
mov bx,00
mov cx,00
mov dx,00
Now onto the main where we shuffle more stuff around and print a message.
message db "hello world!$" ; array byte that is stored using offsets ; Move some stuff around ; NOTES: ; the AX register is actually bits 0-7 of AL and 7-15 ; of AH 8 bit registers. mov ax,10 ; put 10 in general purpose ax register mov bx,20 ; put 20 in general purpose bx register mov cx,30 ; put 30 in general purpose cx register mov dx,40 ; put 40 in general purpose dx register ; move stuff from one GP register to another mov ax,dx ; move the contents from dx into ax jmp stackplay jmp zerogp
Elementry numerical congruence says m and n
are integers and m!=0. Using the division algorithm
n can be expressed as:
n = qm + r, where 0 <= r < |m|
q is the quotient, r the remainder and
|m| is absolute m. To prove this statement,
a simple python session can help out:
>>>q = 3 >>>m = 9 >>>r = 7 >>>q * m + r >>>34
A really small example of some inline C in perl, but it is pretty obvious that it is easy to go from here if you wished to (provided you have the Inline Perl module).
#!/usr/pkg/bin/perl
use Inline C => <<'END_C';
void greet() {
printf("Hello World\n");
}
END_C
greet;
This is an extract from an article I wrote a few years ago that I found interesting (and at the time actually was quite useful to me for some reason ... ).
An ISBN is built using four sets of numbers:
In this example, I will use the same one as I used in the article:
0-673-38582-5
The check digit has 11 possible values:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, X(10)
The final digit is determined by multiplying the first 9 digits by
10, 9, 8, 7, 6, 5, 4, 3, 2 respectively then add them (in our example
we will call this y). The check digit is then chosen so that
y+check_digit is divisible by 11.
[6]> (setq y-first (+ (* 10 0) (* 9 6) (* 8 7) (* 7 3) (* 6 3))) 149 [7]> (setq y-second (+ (* 5 8) (* 4 5) (* 3 8) (* 2 2))) 88 [8]> (setq y (+ y-first y-second)) 237 [9]> (setq check-digit 5) 5 [10]> (setq mod 11) 11 [11]> (+ y check-digit) 242 [12]> (/ 242 mod) 22
From Matt's Script Archive, this little script is a classic for getting rid of pesky ^Ms in a file:
#!/usr/bin/perl
while (<>) {
$_ =~ s/\cM\n/\n/g;
print $_;
}
In this example;
mmwis the project dir name:
cd ~mmw/ cd .. cvs rtag mmw-MAJOR_NUMBER-MINOR_NUMBER-NEXT_NUMBER mmw/
Since it uses MAJOR.MINOR, for the 1.9 release ....
cd ~src/mmw cd .. cvs rtag mmw-1-9 mmw/
Of course,
$CVSROOThas to be set (might be a good idea to make sure
$CVS_RSHis set as well).
This is really a migration since svn move never works right...
server_from: svanadmin dump /path/to/repo > /path/to/repo.dump server_to: svnadmin create /path/to/newrepo scp /path/to/repo.dump server_to:/path/to/newrepo.dump (on server_to) svnadmin load < /path/to/newrepo /path/to/newrepo.dump
(based on last 2 months log reports)
