corrected copyright notices

[gnutls.git] / devel / perlasm / x86_64-xlate.pl

#!/usr/bin/env perl

# Ascetic x86_64 AT&T to MASM/NASM assembler translator by <appro>.
#
# Why AT&T to MASM and not vice versa? Several reasons. Because AT&T
# format is way easier to parse. Because it's simpler to "gear" from
# Unix ABI to Windows one [see cross-reference "card" at the end of
# file]. Because Linux targets were available first...
#
# In addition the script also "distills" code suitable for GNU
# assembler, so that it can be compiled with more rigid assemblers,
# such as Solaris /usr/ccs/bin/as.
#
# This translator is not designed to convert *arbitrary* assembler
# code from AT&T format to MASM one. It's designed to convert just
# enough to provide for dual-ABI OpenSSL modules development...
# There *are* limitations and you might have to modify your assembler
# code or this script to achieve the desired result...
#
# Currently recognized limitations:
#
# - can't use multiple ops per line;
#
# Dual-ABI styling rules.
#
# 1. Adhere to Unix register and stack layout [see cross-reference
#    ABI "card" at the end for explanation].
# 2. Forget about "red zone," stick to more traditional blended
#    stack frame allocation. If volatile storage is actually required
#    that is. If not, just leave the stack as is.
# 3. Functions tagged with ".type name,@function" get crafted with
#    unified Win64 prologue and epilogue automatically. If you want
#    to take care of ABI differences yourself, tag functions as
#    ".type name,@abi-omnipotent" instead.
# 4. To optimize the Win64 prologue you can specify number of input
#    arguments as ".type name,@function,N." Keep in mind that if N is
#    larger than 6, then you *have to* write "abi-omnipotent" code,
#    because >6 cases can't be addressed with unified prologue.
# 5. Name local labels as .L*, do *not* use dynamic labels such as 1:
#    (sorry about latter).
# 6. Don't use [or hand-code with .byte] "rep ret." "ret" mnemonic is
#    required to identify the spots, where to inject Win64 epilogue!
#    But on the pros, it's then prefixed with rep automatically:-)
# 7. Stick to explicit ip-relative addressing. If you have to use
#    GOTPCREL addressing, stick to mov symbol@GOTPCREL(%rip),%r??.
#    Both are recognized and translated to proper Win64 addressing
#    modes. To support legacy code a synthetic directive, .picmeup,
#    is implemented. It puts address of the *next* instruction into
#    target register, e.g.:
#
#               .picmeup        %rax
#               lea             .Label-.(%rax),%rax
#
# 8. In order to provide for structured exception handling unified
#    Win64 prologue copies %rsp value to %rax. For further details
#    see SEH paragraph at the end.
# 9. .init segment is allowed to contain calls to functions only.
# a. If function accepts more than 4 arguments *and* >4th argument
#    is declared as non 64-bit value, do clear its upper part.
\f
my $flavour = shift;
my $output  = shift;
if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }

{ my ($stddev,$stdino,@junk)=stat(STDOUT);
  my ($outdev,$outino,@junk)=stat($output);

    open STDOUT,">$output" || die "can't open $output: $!"
        if ($stddev!=$outdev || $stdino!=$outino);
}

my $gas=1;      $gas=0 if ($output =~ /\.asm$/);
my $elf=1;      $elf=0 if (!$gas);
my $win64=0;
my $prefix="";
my $decor=".L";

my $masmref=8 + 50727*2**-32;   # 8.00.50727 shipped with VS2005
my $masm=0;
my $PTR=" PTR";

my $nasmref=2.03;
my $nasm=0;

if    ($flavour eq "mingw64")   { $gas=1; $elf=0; $win64=1;
                                  $prefix=`echo __USER_LABEL_PREFIX__ | $ENV{CC} -E -P -`;
                                  chomp($prefix);
                                }
elsif ($flavour eq "macosx")    { $gas=1; $elf=0; $prefix="_"; $decor="L\$"; }
elsif ($flavour eq "masm")      { $gas=0; $elf=0; $masm=$masmref; $win64=1; $decor="\$L\$"; }
elsif ($flavour eq "nasm")      { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $decor="\$L\$"; $PTR=""; }
elsif (!$gas)
{   if ($ENV{ASM} =~ m/nasm/ && `nasm -v` =~ m/version ([0-9]+)\.([0-9]+)/i)
    {   $nasm = $1 + $2*0.01; $PTR="";  }
    elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/)
    {   $masm = $1 + $2*2**-16 + $4*2**-32;   }
    die "no assembler found on %PATH" if (!($nasm || $masm));
    $win64=1;
    $elf=0;
    $decor="\$L\$";
}

my $current_segment;
my $current_function;
my %globals;

{ package opcode;       # pick up opcodes
    sub re {
        my      $self = shift;  # single instance in enough...
        local   *line = shift;
        undef   $ret;

        if ($line =~ /^([a-z][a-z0-9]*)/i) {
            $self->{op} = $1;
            $ret = $self;
            $line = substr($line,@+[0]); $line =~ s/^\s+//;

            undef $self->{sz};
            if ($self->{op} =~ /^(movz)x?([bw]).*/) {   # movz is pain...
                $self->{op} = $1;
                $self->{sz} = $2;
            } elsif ($self->{op} =~ /call|jmp/) {
                $self->{sz} = "";
            } elsif ($self->{op} =~ /^p/ && $' !~ /^(ush|op|insrw)/) { # SSEn
                $self->{sz} = "";
            } elsif ($self->{op} =~ /^v/) { # VEX
                $self->{sz} = "";
            } elsif ($self->{op} =~ /movq/ && $line =~ /%xmm/) {
                $self->{sz} = "";
            } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) {
                $self->{op} = $1;
                $self->{sz} = $2;
            }
        }
        $ret;
    }
    sub size {
        my $self = shift;
        my $sz   = shift;
        $self->{sz} = $sz if (defined($sz) && !defined($self->{sz}));
        $self->{sz};
    }
    sub out {
        my $self = shift;
        if ($gas) {
            if ($self->{op} eq "movz") {        # movz is pain...
                sprintf "%s%s%s",$self->{op},$self->{sz},shift;
            } elsif ($self->{op} =~ /^set/) { 
                "$self->{op}";
            } elsif ($self->{op} eq "ret") {
                my $epilogue = "";
                if ($win64 && $current_function->{abi} eq "svr4") {
                    $epilogue = "movq   8(%rsp),%rdi\n\t" .
                                "movq   16(%rsp),%rsi\n\t";
                }
                $epilogue . ".byte      0xf3,0xc3";
            } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") {
                ".p2align\t3\n\t.quad";
            } else {
                "$self->{op}$self->{sz}";
            }
        } else {
            $self->{op} =~ s/^movz/movzx/;
            if ($self->{op} eq "ret") {
                $self->{op} = "";
                if ($win64 && $current_function->{abi} eq "svr4") {
                    $self->{op} = "mov  rdi,QWORD${PTR}[8+rsp]\t;WIN64 epilogue\n\t".
                                  "mov  rsi,QWORD${PTR}[16+rsp]\n\t";
                }
                $self->{op} .= "DB\t0F3h,0C3h\t\t;repret";
            } elsif ($self->{op} =~ /^(pop|push)f/) {
                $self->{op} .= $self->{sz};
            } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") {
                $self->{op} = "\tDQ";
            } 
            $self->{op};
        }
    }
    sub mnemonic {
        my $self=shift;
        my $op=shift;
        $self->{op}=$op if (defined($op));
        $self->{op};
    }
}
{ package const;        # pick up constants, which start with $
    sub re {
        my      $self = shift;  # single instance in enough...
        local   *line = shift;
        undef   $ret;

        if ($line =~ /^\$([^,]+)/) {
            $self->{value} = $1;
            $ret = $self;
            $line = substr($line,@+[0]); $line =~ s/^\s+//;
        }
        $ret;
    }
    sub out {
        my $self = shift;

        if ($gas) {
            # Solaris /usr/ccs/bin/as can't handle multiplications
            # in $self->{value}
            $self->{value} =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi;
            $self->{value} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg;
            sprintf "\$%s",$self->{value};
        } else {
            $self->{value} =~ s/(0b[0-1]+)/oct($1)/eig;
            $self->{value} =~ s/0x([0-9a-f]+)/0$1h/ig if ($masm);
            sprintf "%s",$self->{value};
        }
    }
}
{ package ea;           # pick up effective addresses: expr(%reg,%reg,scale)
    sub re {
        my      $self = shift;  # single instance in enough...
        local   *line = shift;
        undef   $ret;

        # optional * ---vvv--- appears in indirect jmp/call
        if ($line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)/) {
            $self->{asterisk} = $1;
            $self->{label} = $2;
            ($self->{base},$self->{index},$self->{scale})=split(/,/,$3);
            $self->{scale} = 1 if (!defined($self->{scale}));
            $ret = $self;
            $line = substr($line,@+[0]); $line =~ s/^\s+//;

            if ($win64 && $self->{label} =~ s/\@GOTPCREL//) {
                die if (opcode->mnemonic() ne "mov");
                opcode->mnemonic("lea");
            }
            $self->{base}  =~ s/^%//;
            $self->{index} =~ s/^%// if (defined($self->{index}));
        }
        $ret;
    }
    sub size {}
    sub out {
        my $self = shift;
        my $sz = shift;

        $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
        $self->{label} =~ s/\.L/$decor/g;

        # Silently convert all EAs to 64-bit. This is required for
        # elder GNU assembler and results in more compact code,
        # *but* most importantly AES module depends on this feature!
        $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
        $self->{base}  =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;

        # Solaris /usr/ccs/bin/as can't handle multiplications
        # in $self->{label}, new gas requires sign extension...
        use integer;
        $self->{label} =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi;
        $self->{label} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg;
        $self->{label} =~ s/([0-9]+)/$1<<32>>32/eg;

        if ($gas) {
            $self->{label} =~ s/^___imp_/__imp__/   if ($flavour eq "mingw64");

            if (defined($self->{index})) {
                sprintf "%s%s(%s,%%%s,%d)",$self->{asterisk},
                                        $self->{label},
                                        $self->{base}?"%$self->{base}":"",
                                        $self->{index},$self->{scale};
            } else {
                sprintf "%s%s(%%%s)",   $self->{asterisk},$self->{label},$self->{base};
            }
        } else {
            %szmap = (  b=>"BYTE$PTR", w=>"WORD$PTR", l=>"DWORD$PTR",
                        q=>"QWORD$PTR",o=>"OWORD$PTR",x=>"XMMWORD$PTR" );

            $self->{label} =~ s/\./\$/g;
            $self->{label} =~ s/(?<![\w\$\.])0x([0-9a-f]+)/0$1h/ig;
            $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/);
            $sz="q" if ($self->{asterisk} || opcode->mnemonic() eq "movq");
            $sz="l" if (opcode->mnemonic() eq "movd");

            if (defined($self->{index})) {
                sprintf "%s[%s%s*%d%s]",$szmap{$sz},
                                        $self->{label}?"$self->{label}+":"",
                                        $self->{index},$self->{scale},
                                        $self->{base}?"+$self->{base}":"";
            } elsif ($self->{base} eq "rip") {
                sprintf "%s[%s]",$szmap{$sz},$self->{label};
            } else {
                sprintf "%s[%s%s]",$szmap{$sz},
                                        $self->{label}?"$self->{label}+":"",
                                        $self->{base};
            }
        }
    }
}
{ package register;     # pick up registers, which start with %.
    sub re {
        my      $class = shift; # muliple instances...
        my      $self = {};
        local   *line = shift;
        undef   $ret;

        # optional * ---vvv--- appears in indirect jmp/call
        if ($line =~ /^(\*?)%(\w+)/) {
            bless $self,$class;
            $self->{asterisk} = $1;
            $self->{value} = $2;
            $ret = $self;
            $line = substr($line,@+[0]); $line =~ s/^\s+//;
        }
        $ret;
    }
    sub size {
        my      $self = shift;
        undef   $ret;

        if    ($self->{value} =~ /^r[\d]+b$/i)  { $ret="b"; }
        elsif ($self->{value} =~ /^r[\d]+w$/i)  { $ret="w"; }
        elsif ($self->{value} =~ /^r[\d]+d$/i)  { $ret="l"; }
        elsif ($self->{value} =~ /^r[\w]+$/i)   { $ret="q"; }
        elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; }
        elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; }
        elsif ($self->{value} =~ /^[\w]{2}$/i)  { $ret="w"; }
        elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; }

        $ret;
    }
    sub out {
        my $self = shift;
        if ($gas)       { sprintf "%s%%%s",$self->{asterisk},$self->{value}; }
        else            { $self->{value}; }
    }
}
{ package label;        # pick up labels, which end with :
    sub re {
        my      $self = shift;  # single instance is enough...
        local   *line = shift;
        undef   $ret;

        if ($line =~ /(^[\.\w]+)\:/) {
            $self->{value} = $1;
            $ret = $self;
            $line = substr($line,@+[0]); $line =~ s/^\s+//;

            $self->{value} =~ s/^\.L/$decor/;
        }
        $ret;
    }
    sub out {
        my $self = shift;

        if ($gas) {
            my $func = ($globals{$self->{value}} or $self->{value}) . ":";
            if ($win64  &&
                        $current_function->{name} eq $self->{value} &&
                        $current_function->{abi} eq "svr4") {
                $func .= "\n";
                $func .= "      movq    %rdi,8(%rsp)\n";
                $func .= "      movq    %rsi,16(%rsp)\n";
                $func .= "      movq    %rsp,%rax\n";
                $func .= "${decor}SEH_begin_$current_function->{name}:\n";
                my $narg = $current_function->{narg};
                $narg=6 if (!defined($narg));
                $func .= "      movq    %rcx,%rdi\n" if ($narg>0);
                $func .= "      movq    %rdx,%rsi\n" if ($narg>1);
                $func .= "      movq    %r8,%rdx\n"  if ($narg>2);
                $func .= "      movq    %r9,%rcx\n"  if ($narg>3);
                $func .= "      movq    40(%rsp),%r8\n" if ($narg>4);
                $func .= "      movq    48(%rsp),%r9\n" if ($narg>5);
            }
            $func;
        } elsif ($self->{value} ne "$current_function->{name}") {
            $self->{value} .= ":" if ($masm && $ret!~m/^\$/);
            $self->{value} . ":";
        } elsif ($win64 && $current_function->{abi} eq "svr4") {
            my $func =  "$current_function->{name}" .
                        ($nasm ? ":" : "\tPROC $current_function->{scope}") .
                        "\n";
            $func .= "  mov     QWORD${PTR}[8+rsp],rdi\t;WIN64 prologue\n";
            $func .= "  mov     QWORD${PTR}[16+rsp],rsi\n";
            $func .= "  mov     rax,rsp\n";
            $func .= "${decor}SEH_begin_$current_function->{name}:";
            $func .= ":" if ($masm);
            $func .= "\n";
            my $narg = $current_function->{narg};
            $narg=6 if (!defined($narg));
            $func .= "  mov     rdi,rcx\n" if ($narg>0);
            $func .= "  mov     rsi,rdx\n" if ($narg>1);
            $func .= "  mov     rdx,r8\n"  if ($narg>2);
            $func .= "  mov     rcx,r9\n"  if ($narg>3);
            $func .= "  mov     r8,QWORD${PTR}[40+rsp]\n" if ($narg>4);
            $func .= "  mov     r9,QWORD${PTR}[48+rsp]\n" if ($narg>5);
            $func .= "\n";
        } else {
           "$current_function->{name}".
                        ($nasm ? ":" : "\tPROC $current_function->{scope}");
        }
    }
}
{ package expr;         # pick up expressioins
    sub re {
        my      $self = shift;  # single instance is enough...
        local   *line = shift;
        undef   $ret;

        if ($line =~ /(^[^,]+)/) {
            $self->{value} = $1;
            $ret = $self;
            $line = substr($line,@+[0]); $line =~ s/^\s+//;

            $self->{value} =~ s/\@PLT// if (!$elf);
            $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
            $self->{value} =~ s/\.L/$decor/g;
        }
        $ret;
    }
    sub out {
        my $self = shift;
        if ($nasm && opcode->mnemonic()=~m/^j/) {
            "NEAR ".$self->{value};
        } else {
            $self->{value};
        }
    }
}
{ package directive;    # pick up directives, which start with .
    sub re {
        my      $self = shift;  # single instance is enough...
        local   *line = shift;
        undef   $ret;
        my      $dir;
        my      %opcode =       # lea 2f-1f(%rip),%dst; 1: nop; 2:
                (       "%rax"=>0x01058d48,     "%rcx"=>0x010d8d48,
                        "%rdx"=>0x01158d48,     "%rbx"=>0x011d8d48,
                        "%rsp"=>0x01258d48,     "%rbp"=>0x012d8d48,
                        "%rsi"=>0x01358d48,     "%rdi"=>0x013d8d48,
                        "%r8" =>0x01058d4c,     "%r9" =>0x010d8d4c,
                        "%r10"=>0x01158d4c,     "%r11"=>0x011d8d4c,
                        "%r12"=>0x01258d4c,     "%r13"=>0x012d8d4c,
                        "%r14"=>0x01358d4c,     "%r15"=>0x013d8d4c      );

        if ($line =~ /^\s*(\.\w+)/) {
            $dir = $1;
            $ret = $self;
            undef $self->{value};
            $line = substr($line,@+[0]); $line =~ s/^\s+//;

            SWITCH: for ($dir) {
                /\.picmeup/ && do { if ($line =~ /(%r[\w]+)/i) {
                                        $dir="\t.long";
                                        $line=sprintf "0x%x,0x90000000",$opcode{$1};
                                    }
                                    last;
                                  };
                /\.global|\.globl|\.extern/
                            && do { $globals{$line} = $prefix . $line;
                                    $line = $globals{$line} if ($prefix);
                                    last;
                                  };
                /\.type/    && do { ($sym,$type,$narg) = split(',',$line);
                                    if ($type eq "\@function") {
                                        undef $current_function;
                                        $current_function->{name} = $sym;
                                        $current_function->{abi}  = "svr4";
                                        $current_function->{narg} = $narg;
                                        $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
                                    } elsif ($type eq "\@abi-omnipotent") {
                                        undef $current_function;
                                        $current_function->{name} = $sym;
                                        $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
                                    }
                                    $line =~ s/\@abi\-omnipotent/\@function/;
                                    $line =~ s/\@function.*/\@function/;
                                    last;
                                  };
                /\.asciz/   && do { if ($line =~ /^"(.*)"$/) {
                                        $dir  = ".byte";
                                        $line = join(",",unpack("C*",$1),0);
                                    }
                                    last;
                                  };
                /\.rva|\.long|\.quad/
                            && do { $line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
                                    $line =~ s/\.L/$decor/g;
                                    last;
                                  };
            }

            if ($gas) {
                $self->{value} = $dir . "\t" . $line;

                if ($dir =~ /\.extern/) {
                    $self->{value} = ""; # swallow extern
                } elsif (!$elf && $dir =~ /\.type/) {
                    $self->{value} = "";
                    $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" .
                                (defined($globals{$1})?".scl 2;":".scl 3;") .
                                "\t.type 32;\t.endef"
                                if ($win64 && $line =~ /([^,]+),\@function/);
                } elsif (!$elf && $dir =~ /\.size/) {
                    $self->{value} = "";
                    if (defined($current_function)) {
                        $self->{value} .= "${decor}SEH_end_$current_function->{name}:"
                                if ($win64 && $current_function->{abi} eq "svr4");
                        undef $current_function;
                    }
                } elsif (!$elf && $dir =~ /\.align/) {
                    $self->{value} = ".p2align\t" . (log($line)/log(2));
                } elsif ($dir eq ".section") {
                    $current_segment=$line;
                    if (!$elf && $current_segment eq ".init") {
                        if      ($flavour eq "macosx")  { $self->{value} = ".mod_init_func"; }
                        elsif   ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; }
                    }
                } elsif ($dir =~ /\.(text|data)/) {
                    $current_segment=".$1";
                } elsif ($dir =~ /\.hidden/) {
                    if    ($flavour eq "macosx")  { $self->{value} = ".private_extern\t$prefix$line"; }
                    elsif ($flavour eq "mingw64") { $self->{value} = ""; }
                } elsif ($dir =~ /\.comm/) {
                    $self->{value} = "$dir\t$prefix$line";
                    $self->{value} =~ s|,([0-9]+),([0-9]+)$|",$1,".log($2)/log(2)|e if ($flavour eq "macosx");
                }
                $line = "";
                return $self;
            }

            # non-gas case or nasm/masm
            SWITCH: for ($dir) {
                /\.text/    && do { my $v=undef;
                                    if ($nasm) {
                                        $v="section     .text code align=64\n";
                                    } else {
                                        $v="$current_segment\tENDS\n" if ($current_segment);
                                        $current_segment = ".text\$";
                                        $v.="$current_segment\tSEGMENT ";
                                        $v.=$masm>=$masmref ? "ALIGN(64)" : "PAGE";
                                        $v.=" 'CODE'";
                                    }
                                    $self->{value} = $v;
                                    last;
                                  };
                /\.data/    && do { my $v=undef;
                                    if ($nasm) {
                                        $v="section     .data data align=8\n";
                                    } else {
                                        $v="$current_segment\tENDS\n" if ($current_segment);
                                        $current_segment = "_DATA";
                                        $v.="$current_segment\tSEGMENT";
                                    }
                                    $self->{value} = $v;
                                    last;
                                  };
                /\.section/ && do { my $v=undef;
                                    $line =~ s/([^,]*).*/$1/;
                                    $line = ".CRT\$XCU" if ($line eq ".init");
                                    if ($nasm) {
                                        $v="section     $line";
                                        if ($line=~/\.([px])data/) {
                                            $v.=" rdata align=";
                                            $v.=$1 eq "p"? 4 : 8;
                                        } elsif ($line=~/\.CRT\$/i) {
                                            $v.=" rdata align=8";
                                        }
                                    } else {
                                        $v="$current_segment\tENDS\n" if ($current_segment);
                                        $v.="$line\tSEGMENT";
                                        if ($line=~/\.([px])data/) {
                                            $v.=" READONLY";
                                            $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref);
                                        } elsif ($line=~/\.CRT\$/i) {
                                            $v.=" READONLY ALIGN(8)";
                                        }
                                    }
                                    $current_segment = $line;
                                    $self->{value} = $v;
                                    last;
                                  };
                /\.extern/  && do { $self->{value}  = "EXTERN\t".$line;
                                    $self->{value} .= ":NEAR" if ($masm);
                                    last;
                                  };
                /\.globl|.global/
                            && do { $self->{value}  = $masm?"PUBLIC":"global";
                                    $self->{value} .= "\t".$line;
                                    last;
                                  };
                /\.size/    && do { if (defined($current_function)) {
                                        undef $self->{value};
                                        if ($current_function->{abi} eq "svr4") {
                                            $self->{value}="${decor}SEH_end_$current_function->{name}:";
                                            $self->{value}.=":\n" if($masm);
                                        }
                                        $self->{value}.="$current_function->{name}\tENDP" if($masm && $current_function->{name});
                                        undef $current_function;
                                    }
                                    last;
                                  };
                /\.align/   && do { $self->{value} = "ALIGN\t".$line; last; };
                /\.(value|long|rva|quad)/
                            && do { my $sz  = substr($1,0,1);
                                    my @arr = split(/,\s*/,$line);
                                    my $last = pop(@arr);
                                    my $conv = sub  {   my $var=shift;
                                                        $var=~s/^(0b[0-1]+)/oct($1)/eig;
                                                        $var=~s/^0x([0-9a-f]+)/0$1h/ig if ($masm);
                                                        if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva"))
                                                        { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; }
                                                        $var;
                                                    };  

                                    $sz =~ tr/bvlrq/BWDDQ/;
                                    $self->{value} = "\tD$sz\t";
                                    for (@arr) { $self->{value} .= &$conv($_).","; }
                                    $self->{value} .= &$conv($last);
                                    last;
                                  };
                /\.byte/    && do { my @str=split(/,\s*/,$line);
                                    map(s/(0b[0-1]+)/oct($1)/eig,@str);
                                    map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm);       
                                    while ($#str>15) {
                                        $self->{value}.="DB\t"
                                                .join(",",@str[0..15])."\n";
                                        foreach (0..15) { shift @str; }
                                    }
                                    $self->{value}.="DB\t"
                                                .join(",",@str) if (@str);
                                    last;
                                  };
                /\.comm/    && do { my @str=split(/,\s*/,$line);
                                    my $v=undef;
                                    if ($nasm) {
                                        $v.="common     $prefix@str[0] @str[1]";
                                    } else {
                                        $v="$current_segment\tENDS\n" if ($current_segment);
                                        $current_segment = "_DATA";
                                        $v.="$current_segment\tSEGMENT\n";
                                        $v.="COMM       @str[0]:DWORD:".@str[1]/4;
                                    }
                                    $self->{value} = $v;
                                    last;
                                  };
            }
            $line = "";
        }

        $ret;
    }
    sub out {
        my $self = shift;
        $self->{value};
    }
}

sub rex {
 local *opcode=shift;
 my ($dst,$src,$rex)=@_;

   $rex|=0x04 if($dst>=8);
   $rex|=0x01 if($src>=8);
   push @opcode,($rex|0x40) if ($rex);
}

# older gas and ml64 don't handle SSE>2 instructions
my %regrm = (   "%eax"=>0, "%ecx"=>1, "%edx"=>2, "%ebx"=>3,
                "%esp"=>4, "%ebp"=>5, "%esi"=>6, "%edi"=>7      );

my $movq = sub {        # elderly gas can't handle inter-register movq
  my $arg = shift;
  my @opcode=(0x66);
    if ($arg =~ /%xmm([0-9]+),\s*%r(\w+)/) {
        my ($src,$dst)=($1,$2);
        if ($dst !~ /[0-9]+/)   { $dst = $regrm{"%e$dst"}; }
        rex(\@opcode,$src,$dst,0x8);
        push @opcode,0x0f,0x7e;
        push @opcode,0xc0|(($src&7)<<3)|($dst&7);       # ModR/M
        @opcode;
    } elsif ($arg =~ /%r(\w+),\s*%xmm([0-9]+)/) {
        my ($src,$dst)=($2,$1);
        if ($dst !~ /[0-9]+/)   { $dst = $regrm{"%e$dst"}; }
        rex(\@opcode,$src,$dst,0x8);
        push @opcode,0x0f,0x6e;
        push @opcode,0xc0|(($src&7)<<3)|($dst&7);       # ModR/M
        @opcode;
    } else {
        ();
    }
};

my $pextrd = sub {
    if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*(%\w+)/) {
      my @opcode=(0x66);
        $imm=$1;
        $src=$2;
        $dst=$3;
        if ($dst =~ /%r([0-9]+)d/)      { $dst = $1; }
        elsif ($dst =~ /%e/)            { $dst = $regrm{$dst}; }
        rex(\@opcode,$src,$dst);
        push @opcode,0x0f,0x3a,0x16;
        push @opcode,0xc0|(($src&7)<<3)|($dst&7);       # ModR/M
        push @opcode,$imm;
        @opcode;
    } else {
        ();
    }
};

my $pinsrd = sub {
    if (shift =~ /\$([0-9]+),\s*(%\w+),\s*%xmm([0-9]+)/) {
      my @opcode=(0x66);
        $imm=$1;
        $src=$2;
        $dst=$3;
        if ($src =~ /%r([0-9]+)/)       { $src = $1; }
        elsif ($src =~ /%e/)            { $src = $regrm{$src}; }
        rex(\@opcode,$dst,$src);
        push @opcode,0x0f,0x3a,0x22;
        push @opcode,0xc0|(($dst&7)<<3)|($src&7);       # ModR/M
        push @opcode,$imm;
        @opcode;
    } else {
        ();
    }
};

my $pshufb = sub {
    if (shift =~ /%xmm([0-9]+),\s*%xmm([0-9]+)/) {
      my @opcode=(0x66);
        rex(\@opcode,$2,$1);
        push @opcode,0x0f,0x38,0x00;
        push @opcode,0xc0|($1&7)|(($2&7)<<3);           # ModR/M
        @opcode;
    } else {
        ();
    }
};

my $palignr = sub {
    if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
      my @opcode=(0x66);
        rex(\@opcode,$3,$2);
        push @opcode,0x0f,0x3a,0x0f;
        push @opcode,0xc0|($2&7)|(($3&7)<<3);           # ModR/M
        push @opcode,$1;
        @opcode;
    } else {
        ();
    }
};

my $pclmulqdq = sub {
    if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
      my @opcode=(0x66);
        rex(\@opcode,$3,$2);
        push @opcode,0x0f,0x3a,0x44;
        push @opcode,0xc0|($2&7)|(($3&7)<<3);           # ModR/M
        my $c=$1;
        push @opcode,$c=~/^0/?oct($c):$c;
        @opcode;
    } else {
        ();
    }
};

my $rdrand = sub {
    if (shift =~ /%[er](\w+)/) {
      my @opcode=();
      my $dst=$1;
        if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
        rex(\@opcode,0,$1,8);
        push @opcode,0x0f,0xc7,0xf0|($dst&7);
        @opcode;
    } else {
        ();
    }
};

if ($nasm) {
    print <<___;
default rel
%define XMMWORD
___
} elsif ($masm) {
    print <<___;
OPTION  DOTNAME
___
}
while($line=<>) {

    chomp($line);

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

    undef $label;
    undef $opcode;
    undef @args;

    if ($label=label->re(\$line))       { print $label->out(); }

    if (directive->re(\$line)) {
        printf "%s",directive->out();
    } elsif ($opcode=opcode->re(\$line)) {
        my $asm = eval("\$".$opcode->mnemonic());
        undef @bytes;
        
        if ((ref($asm) eq 'CODE') && scalar(@bytes=&$asm($line))) {
            print $gas?".byte\t":"DB\t",join(',',@bytes),"\n";
            next;
        }

        ARGUMENT: while (1) {
        my $arg;

        if ($arg=register->re(\$line))  { opcode->size($arg->size()); }
        elsif ($arg=const->re(\$line))  { }
        elsif ($arg=ea->re(\$line))     { }
        elsif ($arg=expr->re(\$line))   { }
        else                            { last ARGUMENT; }

        push @args,$arg;

        last ARGUMENT if ($line !~ /^,/);

        $line =~ s/^,\s*//;
        } # ARGUMENT:

        if ($#args>=0) {
            my $insn;
            my $sz=opcode->size();

            if ($gas) {
                $insn = $opcode->out($#args>=1?$args[$#args]->size():$sz);
                @args = map($_->out($sz),@args);
                printf "\t%s\t%s",$insn,join(",",@args);
            } else {
                $insn = $opcode->out();
                foreach (@args) {
                    my $arg = $_->out();
                    # $insn.=$sz compensates for movq, pinsrw, ...
                    if ($arg =~ /^xmm[0-9]+$/) { $insn.=$sz; $sz="x" if(!$sz); last; }
                    if ($arg =~ /^mm[0-9]+$/)  { $insn.=$sz; $sz="q" if(!$sz); last; }
                }
                @args = reverse(@args);
                undef $sz if ($nasm && $opcode->mnemonic() eq "lea");
                printf "\t%s\t%s",$insn,join(",",map($_->out($sz),@args));
            }
        } else {
            printf "\t%s",$opcode->out();
        }
    }

    print $line,"\n";
}

print "\n$current_segment\tENDS\n"      if ($current_segment && $masm);
print "END\n"                           if ($masm);

close STDOUT;

\f#################################################
# Cross-reference x86_64 ABI "card"
#
#               Unix            Win64
# %rax          *               *
# %rbx          -               -
# %rcx          #4              #1
# %rdx          #3              #2
# %rsi          #2              -
# %rdi          #1              -
# %rbp          -               -
# %rsp          -               -
# %r8           #5              #3
# %r9           #6              #4
# %r10          *               *
# %r11          *               *
# %r12          -               -
# %r13          -               -
# %r14          -               -
# %r15          -               -
# 
# (*)   volatile register
# (-)   preserved by callee
# (#)   Nth argument, volatile
#
# In Unix terms top of stack is argument transfer area for arguments
# which could not be accomodated in registers. Or in other words 7th
# [integer] argument resides at 8(%rsp) upon function entry point.
# 128 bytes above %rsp constitute a "red zone" which is not touched
# by signal handlers and can be used as temporal storage without
# allocating a frame.
#
# In Win64 terms N*8 bytes on top of stack is argument transfer area,
# which belongs to/can be overwritten by callee. N is the number of
# arguments passed to callee, *but* not less than 4! This means that
# upon function entry point 5th argument resides at 40(%rsp), as well
# as that 32 bytes from 8(%rsp) can always be used as temporal
# storage [without allocating a frame]. One can actually argue that
# one can assume a "red zone" above stack pointer under Win64 as well.
# Point is that at apparently no occasion Windows kernel would alter
# the area above user stack pointer in true asynchronous manner...
#
# All the above means that if assembler programmer adheres to Unix
# register and stack layout, but disregards the "red zone" existense,
# it's possible to use following prologue and epilogue to "gear" from
# Unix to Win64 ABI in leaf functions with not more than 6 arguments.
#
# omnipotent_function:
# ifdef WIN64
#       movq    %rdi,8(%rsp)
#       movq    %rsi,16(%rsp)
#       movq    %rcx,%rdi       ; if 1st argument is actually present
#       movq    %rdx,%rsi       ; if 2nd argument is actually ...
#       movq    %r8,%rdx        ; if 3rd argument is ...
#       movq    %r9,%rcx        ; if 4th argument ...
#       movq    40(%rsp),%r8    ; if 5th ...
#       movq    48(%rsp),%r9    ; if 6th ...
# endif
#       ...
# ifdef WIN64
#       movq    8(%rsp),%rdi
#       movq    16(%rsp),%rsi
# endif
#       ret
#
\f#################################################
# Win64 SEH, Structured Exception Handling.
#
# Unlike on Unix systems(*) lack of Win64 stack unwinding information
# has undesired side-effect at run-time: if an exception is raised in
# assembler subroutine such as those in question (basically we're
# referring to segmentation violations caused by malformed input
# parameters), the application is briskly terminated without invoking
# any exception handlers, most notably without generating memory dump
# or any user notification whatsoever. This poses a problem. It's
# possible to address it by registering custom language-specific
# handler that would restore processor context to the state at
# subroutine entry point and return "exception is not handled, keep
# unwinding" code. Writing such handler can be a challenge... But it's
# doable, though requires certain coding convention. Consider following
# snippet:
#
# .type function,@function
# function:
#       movq    %rsp,%rax       # copy rsp to volatile register
#       pushq   %r15            # save non-volatile registers
#       pushq   %rbx
#       pushq   %rbp
#       movq    %rsp,%r11
#       subq    %rdi,%r11       # prepare [variable] stack frame
#       andq    $-64,%r11
#       movq    %rax,0(%r11)    # check for exceptions
#       movq    %r11,%rsp       # allocate [variable] stack frame
#       movq    %rax,0(%rsp)    # save original rsp value
# magic_point:
#       ...
#       movq    0(%rsp),%rcx    # pull original rsp value
#       movq    -24(%rcx),%rbp  # restore non-volatile registers
#       movq    -16(%rcx),%rbx
#       movq    -8(%rcx),%r15
#       movq    %rcx,%rsp       # restore original rsp
#       ret
# .size function,.-function
#
# The key is that up to magic_point copy of original rsp value remains
# in chosen volatile register and no non-volatile register, except for
# rsp, is modified. While past magic_point rsp remains constant till
# the very end of the function. In this case custom language-specific
# exception handler would look like this:
#
# EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame,
#               CONTEXT *context,DISPATCHER_CONTEXT *disp)
# {     ULONG64 *rsp = (ULONG64 *)context->Rax;
#       if (context->Rip >= magic_point)
#       {   rsp = ((ULONG64 **)context->Rsp)[0];
#           context->Rbp = rsp[-3];
#           context->Rbx = rsp[-2];
#           context->R15 = rsp[-1];
#       }
#       context->Rsp = (ULONG64)rsp;
#       context->Rdi = rsp[1];
#       context->Rsi = rsp[2];
#
#       memcpy (disp->ContextRecord,context,sizeof(CONTEXT));
#       RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase,
#               dips->ControlPc,disp->FunctionEntry,disp->ContextRecord,
#               &disp->HandlerData,&disp->EstablisherFrame,NULL);
#       return ExceptionContinueSearch;
# }
#
# It's appropriate to implement this handler in assembler, directly in
# function's module. In order to do that one has to know members'
# offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant
# values. Here they are:
#
#       CONTEXT.Rax                             120
#       CONTEXT.Rcx                             128
#       CONTEXT.Rdx                             136
#       CONTEXT.Rbx                             144
#       CONTEXT.Rsp                             152
#       CONTEXT.Rbp                             160
#       CONTEXT.Rsi                             168
#       CONTEXT.Rdi                             176
#       CONTEXT.R8                              184
#       CONTEXT.R9                              192
#       CONTEXT.R10                             200
#       CONTEXT.R11                             208
#       CONTEXT.R12                             216
#       CONTEXT.R13                             224
#       CONTEXT.R14                             232
#       CONTEXT.R15                             240
#       CONTEXT.Rip                             248
#       CONTEXT.Xmm6                            512
#       sizeof(CONTEXT)                         1232
#       DISPATCHER_CONTEXT.ControlPc            0
#       DISPATCHER_CONTEXT.ImageBase            8
#       DISPATCHER_CONTEXT.FunctionEntry        16
#       DISPATCHER_CONTEXT.EstablisherFrame     24
#       DISPATCHER_CONTEXT.TargetIp             32
#       DISPATCHER_CONTEXT.ContextRecord        40
#       DISPATCHER_CONTEXT.LanguageHandler      48
#       DISPATCHER_CONTEXT.HandlerData          56
#       UNW_FLAG_NHANDLER                       0
#       ExceptionContinueSearch                 1
#
# In order to tie the handler to the function one has to compose
# couple of structures: one for .xdata segment and one for .pdata.
#
# UNWIND_INFO structure for .xdata segment would be
#
# function_unwind_info:
#       .byte   9,0,0,0
#       .rva    handler
#
# This structure designates exception handler for a function with
# zero-length prologue, no stack frame or frame register.
#
# To facilitate composing of .pdata structures, auto-generated "gear"
# prologue copies rsp value to rax and denotes next instruction with
# .LSEH_begin_{function_name} label. This essentially defines the SEH
# styling rule mentioned in the beginning. Position of this label is
# chosen in such manner that possible exceptions raised in the "gear"
# prologue would be accounted to caller and unwound from latter's frame.
# End of function is marked with respective .LSEH_end_{function_name}
# label. To summarize, .pdata segment would contain
#
#       .rva    .LSEH_begin_function
#       .rva    .LSEH_end_function
#       .rva    function_unwind_info
#
# Reference to functon_unwind_info from .xdata segment is the anchor.
# In case you wonder why references are 32-bit .rvas and not 64-bit
# .quads. References put into these two segments are required to be
# *relative* to the base address of the current binary module, a.k.a.
# image base. No Win64 module, be it .exe or .dll, can be larger than
# 2GB and thus such relative references can be and are accommodated in
# 32 bits.
#
# Having reviewed the example function code, one can argue that "movq
# %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix
# rax would contain an undefined value. If this "offends" you, use
# another register and refrain from modifying rax till magic_point is
# reached, i.e. as if it was a non-volatile register. If more registers
# are required prior [variable] frame setup is completed, note that
# nobody says that you can have only one "magic point." You can
# "liberate" non-volatile registers by denoting last stack off-load
# instruction and reflecting it in finer grade unwind logic in handler.
# After all, isn't it why it's called *language-specific* handler...
#
# Attentive reader can notice that exceptions would be mishandled in
# auto-generated "gear" epilogue. Well, exception effectively can't
# occur there, because if memory area used by it was subject to
# segmentation violation, then it would be raised upon call to the
# function (and as already mentioned be accounted to caller, which is
# not a problem). If you're still not comfortable, then define tail
# "magic point" just prior ret instruction and have handler treat it...
#
# (*)   Note that we're talking about run-time, not debug-time. Lack of
#       unwind information makes debugging hard on both Windows and
#       Unix. "Unlike" referes to the fact that on Unix signal handler
#       will always be invoked, core dumped and appropriate exit code
#       returned to parent (for user notification).