Re^4: How to convert binary to hexadecimal

hi, I wanted to convert a long binary string to a hexadecimal string. sprintf didn't work because the number was more than 32 bits and thr pack/unpack functions are very complicated for me to understand. hence, I converted it using a truth table. The code is

sub Bin2Hex{
              my %truth_table = ( 
               '0000' => '0' , 
               '0001' => '1' , 
               '0010' => '2' , 
               '0011' => '3' , 
               '0100' => '4' , 
               '0101' => '5' , 
               '0110' => '6' , 
               '0111' => '7' , 
               '1000' => '8' , 
               '1001' => '9' , 
               '1010' => 'A' , 
               '1011' => 'B' , 
               '1100' => 'C' , 
               '1101' => 'D' , 
               '1110' => 'E' , 
               '1111' => 'F' , 
                                );
              
              my $count = 0;
              my $hex_string = ''; 
              my $len = $#_ ; 
              #print "len $len" ;
              my $nibble = '' ; 
              my $abit ; 
              my $hex_len ;
               my $hex_nibble ;
              $hex_len = ceil($len/4)  ;    
              #print "hex len $hex_len \n" ; 
              for(my $i=0; $i < $hex_len ; $i++) {
                     for(my $j= 0 ; $j < 4; $j++){
                              $abit = pop(@_) ;
                              if (defined $abit) {
                                       $nibble = $abit.$nibble;  
                              }
                              else {
                                       $nibble = '0'.$nibble ;

                              }
                     }
                      $hex_nibble = $truth_table{$nibble} ; 
                      $hex_string = $hex_nibble.$hex_string ;     
                      $nibble = '' ;
              }
              #print "the converted hex : $hex_string" ;
              return $hex_string ;
 }
[download]

the input to the function is binary string stored in list.

Comment on Re^4: How to convert binary to hexadecimal Download Code

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Re^5: How to convert binary to hexadecimal by roboticus (Chancellor) on Mar 22, 2013 at 01:14 UTC
Anonymonk: Here's another way to do it: $ cat bin2hex.pl #!/usr/bin/perl use strict; use warnings; for my $b (qw(101101110101001010010100101000101011101010101010101010 1 10 101 1010 10101 101010 11010011 000000000000001 000 +1111 11111 11000011 )) { print "$b --> ", bin2hex($b), "\n"; } sub bin2hex { my $bin = shift; # Make input bit string a multiple of 4 $bin = substr("0000",length($bin)%4) . $bin if length($bin)%4; my ($hex, $nybble) = (""); while (length($bin)) { ($nybble,$bin) = (substr($bin,0,4), substr($bin,4)); $nybble = eval "0b$nybble"; $hex .= substr("0123456789ABCDEF", $nybble, 1); } return $hex; } $ perl bin2hex.pl 101101110101001010010100101000101011101010101010101010 --> 2DD4A528AEA +AAA 1 --> 1 10 --> 2 101 --> 5 1010 --> A 10101 --> 15 101010 --> 2A 11010011 --> D3 000000000000001 --> 0001 0001111 --> 0F 11111 --> 1F 11000011 --> C3 [download] It uses an old^[1] trick: Since each "nybble"^[2] represents a decimal value from 0 to 15, you can build a 16 character string of digits, and use the nybble value as the index of a character. Then, to simplify things, we ensure that the string is a multiple of four characters long. That way, we simply chop off four characters, turn it into a hex digit, repeating until the string is consumed. Notes: [1] How old? It was old when I learned it, roughly 35 years ago. [2] Four bits == half a byte, thus, a nybble. ...roboticus When your only tool is a hammer, all problems look like your thumb.	[reply] [d/l]

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Re^5: How to convert binary to hexadecimal
by roboticus (Chancellor) on Mar 22, 2013 at 01:14 UTC

Anonymonk:

Here's another way to do it:

$ cat bin2hex.pl
#!/usr/bin/perl
use strict; use warnings;

for my $b (qw(101101110101001010010100101000101011101010101010101010
              1  10 101 1010 10101 101010 11010011 000000000000001 000
+1111
              11111 11000011
)) {
    print "$b --> ", bin2hex($b), "\n";
}

sub bin2hex {
    my $bin = shift;

    # Make input bit string a multiple of 4
    $bin = substr("0000",length($bin)%4) . $bin if length($bin)%4;

    my ($hex, $nybble) = ("");
    while (length($bin)) {
        ($nybble,$bin) = (substr($bin,0,4), substr($bin,4));
        $nybble = eval "0b$nybble";
        $hex .= substr("0123456789ABCDEF", $nybble, 1);
    }
    return $hex;
}

$ perl bin2hex.pl
101101110101001010010100101000101011101010101010101010 --> 2DD4A528AEA
+AAA
1 --> 1
10 --> 2
101 --> 5
1010 --> A
10101 --> 15
101010 --> 2A
11010011 --> D3
000000000000001 --> 0001
0001111 --> 0F
11111 --> 1F
11000011 --> C3
[download]

It uses an old^[1] trick: Since each "nybble"^[2] represents a decimal value from 0 to 15, you can build a 16 character string of digits, and use the nybble value as the index of a character.

Then, to simplify things, we ensure that the string is a multiple of four characters long. That way, we simply chop off four characters, turn it into a hex digit, repeating until the string is consumed.

Notes:

[1] How old? It was old when I learned it, roughly 35 years ago.

[2] Four bits == half a byte, thus, a nybble.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[reply]
[d/l]