#!/usr/local/bin/perl

package x86nasm;

$label="L000";

%lb=(	'eax',	'al',
	'ebx',	'bl',
	'ecx',	'cl',
	'edx',	'dl',
	'ax',	'al',
	'bx',	'bl',
	'cx',	'cl',
	'dx',	'dl',
	);

%hb=(	'eax',	'ah',
	'ebx',	'bh',
	'ecx',	'ch',
	'edx',	'dh',
	'ax',	'ah',
	'bx',	'bh',
	'cx',	'ch',
	'dx',	'dh',
	);

%regs=(	'eax',	'eax',
	'ebx',	'ebx',
	'ecx',	'ecx',
	'edx',	'edx',
	'esi',	'esi',
	'edi',	'edi',
	'ebp',	'ebp',
	'esp',	'esp',
	'mm0',  'mm0',
	'mm1',  'mm1',
	);

sub main::asm_init_output { @out=(); }
sub main::asm_get_output { return(@out); }
sub main::get_labels { return(@labels); }

sub main::external_label
{
	push(@labels,@_);
	foreach (@_) {
		push(@out, "extern\t_$_\n");
	}
}

sub main::LB
	{
	(defined($lb{$_[0]})) || die "$_[0] does not have a 'low byte'\n";
	return($lb{$_[0]});
	}

sub main::HB
	{
	(defined($hb{$_[0]})) || die "$_[0] does not have a 'high byte'\n";
	return($hb{$_[0]});
	}

sub main::BP
	{
	&get_mem("BYTE",@_);
	}

sub main::DWP
	{
	&get_mem("DWORD",@_);
	}

sub main::BC
	{
	return "BYTE @_";
	}

sub main::DWC
	{
	return "DWORD @_";
	}

sub main::stack_push
	{
	my($num)=@_;
	$stack+=$num*4;
	&main::sub("esp",$num*4);
	}

sub main::stack_pop
	{
	my($num)=@_;
	$stack-=$num*4;
	&main::add("esp",$num*4);
	}

sub get_mem
	{
	my($size,$addr,$reg1,$reg2,$idx)=@_;
	my($t,$post);
	my($ret)="[";
	$addr =~ s/^\s+//;
	if ($addr =~ /^(.+)\+(.+)$/)
		{
		if (defined($regs{$reg2})) {
		    $addr=join('+', &conv($1), "_$2");
		} else {
		    $reg2=&conv($1);
		    $addr="_$2";
		}
		}
	elsif ($addr =~ /^[_a-zA-Z]/)
		{
		$addr="_$addr";
		}

	$reg1="$regs{$reg1}" if defined($regs{$reg1});
	$reg2="$regs{$reg2}" if defined($regs{$reg2});
	if (($addr ne "") && ($addr ne 0))
		{
		if ($addr !~ /^-/)
			{ $ret.="${addr}+"; }
		else	{ $post=$addr; }
		}
	if ($reg2 ne "")
		{
		$t="";
		$t="*$idx" if ($idx != 0);
		$reg1="+".$reg1 if ("$reg1$post" ne "");
		$ret.="$reg2$t$reg1$post]";
		}
	else
		{
		$ret.="$reg1$post]"
		}
	return($ret);
	}

sub main::mov	{ &out2("mov",@_); }
sub main::movb	{ &out2("mov",@_); }
sub main::and	{ &out2("and",@_); }
sub main::or	{ &out2("or",@_); }
sub main::shl	{ &out2("shl",@_); }
sub main::shr	{ &out2("shr",@_); }
sub main::xor	{ &out2("xor",@_); }
sub main::xorb	{ &out2("xor",@_); }
sub main::add	{ &out2("add",@_); }
sub main::adc	{ &out2("adc",@_); }
sub main::sub	{ &out2("sub",@_); }
sub main::rotl	{ &out2("rol",@_); }
sub main::rotr	{ &out2("ror",@_); }
sub main::exch	{ &out2("xchg",@_); }
sub main::cmp	{ &out2("cmp",@_); }
sub main::lea	{ &out2("lea",@_); }
sub main::mul	{ &out1("mul",@_); }
sub main::div	{ &out1("div",@_); }
sub main::dec	{ &out1("dec",@_); }
sub main::inc	{ &out1("inc",@_); }
sub main::jmp	{ &out1("jmp",@_); }
sub main::jmp_ptr { &out1p("jmp",@_); }

# This is a bit of a kludge: declare all branches as NEAR.
sub main::je	{ &out1("je NEAR",@_); }
sub main::jle	{ &out1("jle NEAR",@_); }
sub main::jz	{ &out1("jz NEAR",@_); }
sub main::jge	{ &out1("jge NEAR",@_); }
sub main::jl	{ &out1("jl NEAR",@_); }
sub main::jb	{ &out1("jb NEAR",@_); }
sub main::jc	{ &out1("jc NEAR",@_); }
sub main::jnc	{ &out1("jnc NEAR",@_); }
sub main::jnz	{ &out1("jnz NEAR",@_); }
sub main::jne	{ &out1("jne NEAR",@_); }
sub main::jno	{ &out1("jno NEAR",@_); }

sub main::push	{ &out1("push",@_); $stack+=4; }
sub main::pop	{ &out1("pop",@_); $stack-=4; }
sub main::bswap	{ &out1("bswap",@_); &using486(); }
sub main::not	{ &out1("not",@_); }
sub main::call	{ &out1("call",'_'.$_[0]); }
sub main::ret	{ &out0("ret"); }
sub main::nop	{ &out0("nop"); }

sub out2
	{
	my($name,$p1,$p2)=@_;
	my($l,$t);

	push(@out,"\t$name\t");
	$t=&conv($p1).",";
	$l=length($t);
	push(@out,$t);
	$l=4-($l+9)/8;
	push(@out,"\t" x $l);
	push(@out,&conv($p2));
	push(@out,"\n");
	}

sub out0
	{
	my($name)=@_;

	push(@out,"\t$name\n");
	}

sub out1
	{
	my($name,$p1)=@_;
	my($l,$t);
	push(@out,"\t$name\t".&conv($p1)."\n");
	}

sub conv
	{
	my($p)=@_;
	$p =~ s/0x([0-9A-Fa-f]+)/0$1h/;
	return $p;
	}

sub using486
	{
	return if $using486;
	$using486++;
	grep(s/\.386/\.486/,@out);
	}

sub main::file
	{
	push(@out, "segment .text\n");
	}

sub main::function_begin
	{
	my($func,$extra)=@_;

	push(@labels,$func);
	my($tmp)=<<"EOF";
global	_$func
_$func:
	push	ebp
	push	ebx
	push	esi
	push	edi
EOF
	push(@out,$tmp);
	$stack=20;
	}

sub main::function_begin_B
	{
	my($func,$extra)=@_;
	my($tmp)=<<"EOF";
global	_$func
_$func:
EOF
	push(@out,$tmp);
	$stack=4;
	}

sub main::function_end
	{
	my($func)=@_;

	my($tmp)=<<"EOF";
	pop	edi
	pop	esi
	pop	ebx
	pop	ebp
	ret
EOF
	push(@out,$tmp);
	$stack=0;
	%label=();
	}

sub main::function_end_B
	{
	$stack=0;
	%label=();
	}

sub main::function_end_A
	{
	my($func)=@_;

	my($tmp)=<<"EOF";
	pop	edi
	pop	esi
	pop	ebx
	pop	ebp
	ret
EOF
	push(@out,$tmp);
	}

sub main::file_end
	{
	}

sub main::wparam
	{
	my($num)=@_;

	return(&main::DWP($stack+$num*4,"esp","",0));
	}

sub main::swtmp
	{
	return(&main::DWP($_[0]*4,"esp","",0));
	}

# Should use swtmp, which is above esp.  Linix can trash the stack above esp
#sub main::wtmp
#	{
#	my($num)=@_;
#
#	return(&main::DWP(-(($num+1)*4),"esp","",0));
#	}

sub main::comment
	{
	foreach (@_)
		{
		push(@out,"\t; $_\n");
		}
	}

sub main::label
	{
	if (!defined($label{$_[0]}))
		{
		$label{$_[0]}="\$${label}${_[0]}";
		$label++;
		}
	return($label{$_[0]});
	}

sub main::set_label
	{
	if (!defined($label{$_[0]}))
		{
		$label{$_[0]}="${label}${_[0]}";
		$label++;
		}
	push(@out,"$label{$_[0]}:\n");
	}

sub main::data_word
	{
	push(@out,"\tDD\t$_[0]\n");
	}

sub out1p
	{
	my($name,$p1)=@_;
	my($l,$t);

	push(@out,"\t$name\t ".&conv($p1)."\n");
	}

##
## Additional functions required for MMX and other ops
##
sub main::testb { &out2('test', @_) }
sub main::movzx { &out2('movzx', @_) }
sub main::movd { &out2('movd', @_) }
sub main::emms { &out0('emms', @_) }
