Re: Detect STX and ETX hex in received string

[kcott]

in reply to Detect STX and ETX hex in received string

G'day jagexCoder,

Welcome to the monastery.

This regexp seems to do what you want:

qr{ [$STX] ( [^$ETX]{0,80} ) [^$ETX]* [$ETX] }x

Here's my test:

$ perl -Mstrict -Mwarnings -e '
my ($STX, $ETX) = (chr(2), chr(3));
my $re = qr{ [$STX] ( [^$ETX]{0,80} ) [^$ETX]* [$ETX] }x;
my $empty = $STX . $ETX;
my $short = $STX . "a" x 79 . $ETX;
my $exact = $STX . "a" x 80 . $ETX;
my $long = $STX . "a" x 81 . $ETX;
my $buf = $empty . $short . $exact . $long;
print "1234567890" x 8, "\n";
print "$_\n" for $buf =~ /$re/g;
print "1234567890" x 8, "\n";
'
1234567890123456789012345678901234567890123456789012345678901234567890
[phone]

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+aaaaaaaaaa
1234567890123456789012345678901234567890123456789012345678901234567890
[phone]

[ColonelPanic]

This regex would not match anything unless an ETX was found, while the poster wanted to stop reading as soon as 80 bytes were found.

(Apologies; originally this comment contained a typo such that it made no sense)

[kcott]

I'd say that's a matter of interpretation. I did consider the situation where no ETX existed; however, jagexCoder wrote "... packets of interest that are within STX and ETX endings.". Accordingly, I coded for STX and ETX to always be present. Perhaps wait for the OP to clarify this.

[Aside: You appear to have removed the original typo, so I don't know what you're apologising for. Regardless, I accept your apology. :-) ]

Update: Oh dear! Having posted this, I see I've also introduced a typo such that it made no sense.
s/Perhaps wait for to OP can clarify this./Perhaps wait for the OP to clarify this./

[ColonelPanic]

Fair enough, I suppose it is a matter of interpretation.