#!/usr/bin/env perl

# PowerPC assembler distiller by <appro>.

my $output = shift;
open STDOUT,">$output" || die "can't open $output: $!";

my $flavour = $output;
my %GLOBALS;
my $dotinlocallabels=0;

################################################################
# directives which need special treatment on different platforms
################################################################
my $globl = sub {
    my $junk = shift;
    my $name = shift;
    my $global = \$GLOBALS{$name};
    my $ret;

    $name =~ s|^[\.\_]||;
 
    SWITCH: for ($flavour) {
	/aix/		&& do { $name = ".$name";
				last;
			      };
	/osx/		&& do { $name = "_$name";
				last;
			      };
	/linux.*32/	&& do {	$ret .= ".globl	$name\n";
				$ret .= ".type	$name,\@function";
				$dotinlocallabels = 1;
				last;
			      };
	/linux.*64/	&& do {	$ret .= ".globl	.$name\n";
				$ret .= ".type	.$name,\@function\n";
				$ret .= ".section	\".opd\",\"aw\"\n";
				$ret .= ".globl	$name\n";
				$ret .= ".align	3\n";
				$ret .= "$name:\n";
				$ret .= ".quad	.$name,.TOC.\@tocbase,0\n";
				$ret .= ".size	$name,24\n";
				$ret .= ".previous\n";

				$name = ".$name";
				$dotinlocallabels = 1;
				last;
			      };
    }

    $ret = ".globl	$name" if (!$ret);
    $$global = $name;
    $ret;
};
my $text = sub {
    ($flavour =~ /aix/) ? ".csect" : ".text";
};
my $machine = sub {
    my $junk = shift;
    my $arch = shift;
    if ($flavour =~ /osx/)
    {	$arch =~ s/\"//g;
	$arch = ($flavour=~/64/) ? "ppc970-64" : "ppc970" if ($arch eq "any");
    }
    ".machine	$arch";
};

################################################################
# simplified mnemonics not handled by at least one assembler
################################################################
my $cmplw = sub {
    my $f = shift;
    my $cr = 0; $cr = shift if ($#_>1);
    # Some out-of-date 32-bit GNU assembler just can't handle cmplw...
    ($flavour =~ /linux.*32/) ?
	"	.long	".sprintf "0x%x",31<<26|$cr<<23|$_[0]<<16|$_[1]<<11|64 :
	"	cmplw	".join(',',$cr,@_);
};
my $bdnz = sub {
    my $f = shift;
    my $bo = $f=~/[\+\-]/ ? 17 : 16;
    "	bc	$bo,0,".shift;
};

while($line=<>) {

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

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

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

    {
	$line =~ s|^\s*(\.?)(\w+)([\.\+\-]?)\s*||;
	my $c = $1; $c = "\t" if ($c eq "");
	my $mnemonic = $2;
	my $f = $3;
	my $opcode = eval("\$$mnemonic");
	$line =~ s|\br([0-9]+)\b|$1|g if ($c ne "." and $flavour !~ /osx/);
	if (ref($opcode) eq 'CODE') { $line = &$opcode($f,split(',',$line)); }
	elsif ($mnemonic)           { $line = $c.$mnemonic.$f."\t".$line; }
    }

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

close STDOUT;