use strict;
use warnings;

while ( my $line = <DATA> ) {

#-- would print lines starting with either 'f' or 'b':
#  if ( $line =~ /^(b|f)/) {
#    print $line;
#  }

  #-- not elegant, like the spec...
  if ( $line =~ /^(b)=(\S+)/ or $line =~ /^(f)\s+(\S+)\s+(\S+)$/ ) {
    print "$1 = '$2' (", $3 // '-' , ")\n";
  }
}


__DATA__
Input file : (to extract for b and f)
b=23 y=0x11 arg=0x70 def=0x1 val=0x234
checking system

b=71 y=0x35 arg=0x87 def=0x3 val=0x76d
h=reg.k2.io.chk 0x2001

b=54 y=0x23 arg=0x78 def=0x2 val=0x65b
f chk.fin.reg.m_cwr 0x213

b=54 y=0x23 arg=0x78 def=0x2 val=0x65b
checking system

b=40 y=0x90 arg=0x34 def=0x5 val=0x2197
f ref.grf.pin.clk_trg 0x0021
 

##</code><code>##

b = '23' (-)
b = '71' (-)
b = '54' (-)
f = 'chk.fin.reg.m_cwr' (0x213)
b = '54' (-)
b = '40' (-)
f = 'ref.grf.pin.clk_trg' (0x0021)