#!/usr/bin/perl
#
# Routine to read define'd constants from a Verilog or C header
# If expressions are used, they need to be defined with care to
# be able to evaluate them. Conditionals are NOT processed.
#

use strict;
use Math::BigInt;

sub header_const($) {
    my($file) = @_;

    my %bases = ('d' => 10, 'b' => 2, 'o' => 8, 'q' => 8, 'h' => 16,
		 'x' => 16, '0' => 8, '0x' => 16, '' => 10);

    my %syms = ();
    open(my $f, '<', $file)
	or die "$0: $file: $!\n";

    while (defined(my $l = <$f>)) {
	chomp $l;
	while ($l =~ /\/$/) {
	    my $ll = <$f>;
	    last unless (defined($ll));
	    chomp $ll;
	    $l = substr($l,0,-1) . $ll;
	}

	$l =~ s/\/\/.*$//;
	$l =~ s/\/\*.*?\*\///g;
	if ($l =~ /^\s*[\`\#]\s*define\s+\`?([[:alpha:]_]\w*)\s+(.*?)\s*$/) {
	    $syms{$1} = $2;
	} elsif ($l =~ /^\s*[\`\#]\s*undef\s+\`?([[:alpha:]_]\w*)/) {
	    delete $syms{$1};
	}
    }

    close($f);

    foreach my $s (keys %syms) {
	my $e = $syms{$s};
	my $o = '';

	# Don't try to evaluate if...
	next if ($e =~ /[\"\$\@\[\{\\]/);

	$e =~ s/\`//g;

	while ($e =~ /^(.*?)\b[0-9]*\'([bhod])([0-9a-f_]+)\b(.*)$/i ||
	       $e =~ /^(.*?)\b()(0[0-7_]+|0b[0-1_]+|0x[0-9a-f_]+)\b(.*)$/i) {
	    $e = $4;
	    $o .= $1;

	    my $base = lc($2);
	    my $dig = $3;
	    $dig =~ s/_//g;

	    if ($base ne '') {
		$base = $bases{$base};
	    } elsif ($dig =~ /^0x/i) {
		$base = 16;
	    } elsif ($dig =~ /^0b/i) {
		$base = 2;
	    } elsif ($dig =~ /^0/) {
		$base = 8;
	    }

	    $o .= Math::BigInt::from_base($dig, $base)->bstr();
	}
	$syms{$s} = $o.$e;
    }

    foreach my $s (keys %syms) {
	my $e = $syms{$s};
	my $o = '';

	while ($e =~ /^(.*?)\b\`?([[:alpha:]_]\w*)\b(.*)$/) {
	    $e = $3;
	    $o .= $1;

	    if (defined($syms{$2})) {
		$e = $syms{$2} . $e;
	    } else {
		$o .= $2;
	    }
	}

	$syms{$s} = eval("{ use bigint; return Math::BigInt->new($o$e)->numify(); }");
    }

    return %syms;
}

1;