C code pre-processor

dgsmith_50 has asked for the wisdom of the Perl Monks concerning the following question:

I work on a large codebase of code written in C for embedded processors. There are many conditionally compiled statements in the code that makes it difficult to read. I would like to know if there exists a perl script that will execute like a C pre-processor to strip away code which is not relavant based on a set of macros. The output from the script would then be used just for reading the code. I want to use PERL because I want to be able to easily modify the script. For example, in the code snippet below, I would want to include the code unmodified if the macro BCS_GFSK_TRACKING_HW_FIX if defined. I would not want to replace BCS_LINKTYPE_ACL_MDR with an actual number because I want to maintain the readability of the code.

    #ifdef BCS_GFSK_TRACKING_HW_FIX
    // The following is HWWA for BR freq tracking    
    switch ( logicalConnInfo )
    {
        case BCS_LINKTYPE_ACL_MDR:
        case BCS_LINKTYPE_ESCO_MDR:
        {
            REG32(dcOffEstCtrl5_adr) &= ~(((UINT32)1) << TRACK_GFSK_FR
+EQ_MASK_OFFSET);
            break;
        }
        default:
        {
            REG32(dcOffEstCtrl5_adr) |= (((UINT32)1) << TRACK_GFSK_FRE
+Q_MASK_OFFSET);
            break;
        }
    }
    #endif
[download]

I found a script at the location below, but it does not appear to handle complex statements such as:

    #if (defined(BCM20702) || defined(BCM20733)) && !defined(FPGA_BD_2
+045)
[download]

http://software.hixie.ch/utilities/unix/preprocessor/

Comment on C code pre-processor Select or Download Code

Replies are listed 'Best First'.
Re: C code pre-processor by educated_foo (Vicar) on Feb 03, 2012 at 17:04 UTC
Why not just use the C preprocessor? If you have C code, you should probably have one lying around on your system. EDIT: I missed the part about not wanting to expand macros in code. Try something like this: `$ perl -pe 'y/A-Za-z/N-ZA-Mn-za-m/ unless /^\s#/' < INPUT \| cpp - \| \ perl -pe 'y/A-Za-z/N-ZA-Mn-za-m/ unless /^\s#/ > OUTPUT'` [download] That should hide the macros in code from CPP unless you choose really weird names.	[reply] [d/l]
Re: C code pre-processor by Khen1950fx (Canon) on Feb 03, 2012 at 18:39 UTC
Try Text::CPP. It's light, fast, and easy to use. `#!/usr/bin/perl use strict; use warnings; use Text::CPP; my $MyData = <DATA>; my $reader = new Text::CPP( Language => 'STDC99', Options => {}, Builtins => { foo => 'this', bar => 'that', }, ); $reader->read('/root/Desktop/file.c'); while (my $token = $reader->token) { print "Token: $token\n"; } $reader->data->{MyKey} = $MyData; __DATA__ #ifdef pathtest 38. This should appear. #else #define pathtest 37. This should appear. #include test.txt 39. This should appear. #undef pathtest #endif` [download]	[reply] [d/l]
Re^2: C code pre-processor by educated_foo (Vicar) on Feb 03, 2012 at 19:52 UTC
It's also XS, so he'll need a C preprocessor to install it in the first place.	[reply]
Re^3: C code pre-processor by dgsmith_50 (Initiate) on Feb 13, 2012 at 19:23 UTC
Hi, I was away for the last few days so I just saw your post. What is XS?	[reply]
Re^4: C code pre-processor by educated_foo (Vicar) on Feb 14, 2012 at 03:15 UTC
Re: C code pre-processor by roboticus (Chancellor) on Feb 03, 2012 at 20:46 UTC
dgsmith_50: The following definitely doesn't do everything you want, as it's a quick knockup. It'll need some tuning, but I think you can tweak it into something useful for you: $ cat C_preprocessor_light.pl #!/usr/bin/perl # # see perlmonks 951682 # use strict; use warnings; my %DEF; my @fl_print = (1); while (<DATA>) { if (/^\s#\sdefine\s+(\w+)/) { $DEF{$1}=1; } elsif (/^\s#\sundef\s+(\w+)/) { delete $DEF{$1}; } elsif (/^\s#\sifdef\s+(\w+)/) { push @fl_print, (exists($DEF{$1}) and $fl_print[-1]); } elsif (/^\s#\sifndef\s+(\w+)/){ push @fl_print, (!exists($DEF{$1}) and $fl_print[-1]); } elsif (/^\s#\sendif/){ pop @fl_print if @fl_print > 1; } print if ($fl_print[-1]); } __DATA__ /* Foo / #ifndef BLARG2 BAR #define BLARG #define GRAK zippy #ifdef BLARG happy #ifndef GRAK lucky #endif puppy #endif #foo #endif bloink [download] It doesn't hide exactly the lines I would want to hide, but it's close... ...roboticus When your only tool is a hammer, all problems look like your thumb.*	[reply] [d/l]