I'm almost embarrassed to ask this, but I can't figure out a simple way to
construct a switch ('given') statement where the 'when' clauses involve
bit-testing.
Here's the only way I've figured out to build a switch statement that does the
trick. It seems unusually wordy, which makes me think there must be a simpler
way to test for certain bit combinations. Any suggestions?
Thanks,
Chap
#!/usr/bin/perl
use strict;
use warnings;
use feature ":5.10";
# Here are masks for various bit combos of interest:
my $one_three = 0b00001010; # bits 1 and 3 (counting from 0, right to
left)
my $zero_four = 0b00010001; # bits 0 and 4
my $five = 0b00100000; # bit 5
# Here we will test several bit fields for bit combos of interest:
for my $flags ( 0b10111010, 0b10111000, 0b10010010) {
my $asbits = sprintf("0b%08b", $flags); # prepare bits for pretty-printing
given ( $flags ) {
when ( ($_ & $one_three) == $one_three ) { # bits one and three are on
say "$asbits has bits 1 and 3";
}
when ( ($_ & $zero_four) == $zero_four ) { # bits zero and four are on
say "$asbits has bits 0 and 4";
}
when ( ($_ & $five) == $five ) { # bit five is on
say "$asbits has bit 5";
}
default {
say "$asbits has no interesting bit patterns.";
}
}
}
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