sub expand_line()

in ring/crypto/perlasm/arm-xlate.pl [117:225]

• 84 lines of code
• 25 McCabe index (conditional complexity)

sub expand_line {
  my $line = shift;
  my @ret = ();

    pos($line)=0;

    while ($line =~ m/\G[^@\/\{\"]*/g) {
	if ($line =~ m/\G(@|\/\/|$)/gc) {
	    last;
	}
	elsif ($line =~ m/\G\{/gc) {
	    my $saved_pos = pos($line);
	    $line =~ s/\G([rdqv])([0-9]+)([^\-]*)\-\1([0-9]+)\3/range($1,$3,$2,$4)/e;
	    pos($line) = $saved_pos;
	    $line =~ m/\G[^\}]*\}/g;
	}
	elsif ($line =~ m/\G\"/gc) {
	    $line =~ m/\G[^\"]*\"/g;
	}
    }

    $line =~ s/\b(\w+)/$GLOBALS{$1} or $1/ge;

    return $line;
}

print <<___;
// This file is generated from a similarly-named Perl script in the BoringSSL
// source tree. Do not edit by hand.

#if !defined(__has_feature)
#define __has_feature(x) 0
#endif
#if __has_feature(memory_sanitizer) && !defined(OPENSSL_NO_ASM)
#define OPENSSL_NO_ASM
#endif

#if !defined(OPENSSL_NO_ASM)
___

print "#if defined(__arm__)\n" if ($flavour eq "linux32");
print "#if defined(__aarch64__)\n" if ($flavour eq "linux64");

while(my $line=<>) {

    if ($line =~ m/^\s*(#|@|\/\/)/)	{ print $line; next; }

    $line =~ s|/\*.*\*/||;	# get rid of C-style comments...
    $line =~ s|^\s+||;		# ... and skip white spaces in beginning...
    $line =~ s|\s+$||;		# ... and at the end

    if ($flavour =~ /64/) {
	my $copy = $line;
	# Also remove line comments.
	$copy =~ s|//.*||;
	if ($copy =~ /\b[wx]18\b/) {
	    die "r18 is reserved by the platform and may not be used.";
	}
    }

    {
	$line =~ s|[\b\.]L(\w{2,})|L$1|g;	# common denominator for Locallabel
	$line =~ s|\bL(\w{2,})|\.L$1|g	if ($dotinlocallabels);
    }

    {
	$line =~ s|(^[\.\w]+)\:\s*||;
	my $label = $1;
	if ($label) {
	    printf "%s:",($GLOBALS{$label} or $label);
	}
    }

    if ($line !~ m/^[#@]/) {
	$line =~ s|^\s*(\.?)(\S+)\s*||;
	my $c = $1; $c = "\t" if ($c eq "");
	my $mnemonic = $2;
	my $opcode;
	if ($mnemonic =~ m/([^\.]+)\.([^\.]+)/) {
	    $opcode = eval("\$$1_$2");
	} else {
	    $opcode = eval("\$$mnemonic");
	}

	if ($flavour =~ /ios/) {
	    # Mach-O and ELF use different syntax for these relocations. Note
	    # that we require :pg_hi21: to be explicitly listed. It is normally
	    # optional with adrp instructions.
	    $line =~ s|:pg_hi21:(\w+)|\1\@PAGE|;
	    $line =~ s|:lo12:(\w+)|\1\@PAGEOFF|;
	} else {
	    # Clang's integrated assembly does not support the optional
	    # :pg_hi21: markers, so erase them.
	    $line =~ s|:pg_hi21:||;
	}

	my $arg=expand_line($line);

	if (ref($opcode) eq 'CODE') {
		$line = &$opcode($arg);
	} elsif ($mnemonic)         {
		$line = $c.$mnemonic;
		$line.= "\t$arg" if ($arg ne "");
	}
    }

    print $line if ($line);
    print "\n";
}