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1 | # Assembler.pm |
2 | # |
3 | # Copyright (c) 1996 Malcolm Beattie |
4 | # |
5 | # You may distribute under the terms of either the GNU General Public |
6 | # License or the Artistic License, as specified in the README file. |
7 | package B::Assembler; |
8 | use Exporter; |
9 | use B qw(ppname); |
10 | use B::Asmdata qw(%insn_data @insn_name); |
11 | |
12 | @ISA = qw(Exporter); |
13 | @EXPORT_OK = qw(assemble_fh assemble_insn strip_comments |
14 | parse_statement uncstring); |
15 | |
16 | use strict; |
17 | my %opnumber; |
18 | my ($i, $opname); |
19 | for ($i = 0; defined($opname = ppname($i)); $i++) { |
20 | $opnumber{$opname} = $i; |
21 | } |
22 | |
23 | my ($linenum, $errors); |
24 | |
25 | sub error { |
26 | my $str = shift; |
27 | warn "$linenum: $str\n"; |
28 | $errors++; |
29 | } |
30 | |
31 | my $debug = 0; |
32 | sub debug { $debug = shift } |
33 | |
34 | # |
35 | # First define all the data conversion subs to which Asmdata will refer |
36 | # |
37 | |
38 | sub B::Asmdata::PUT_U8 { |
39 | my $arg = shift; |
40 | my $c = uncstring($arg); |
41 | if (defined($c)) { |
42 | if (length($c) != 1) { |
43 | error "argument for U8 is too long: $c"; |
44 | $c = substr($c, 0, 1); |
45 | } |
46 | } else { |
47 | $c = chr($arg); |
48 | } |
49 | return $c; |
50 | } |
51 | |
52 | sub B::Asmdata::PUT_U16 { pack("n", $_[0]) } |
53 | sub B::Asmdata::PUT_U32 { pack("N", $_[0]) } |
54 | sub B::Asmdata::PUT_I32 { pack("N", $_[0]) } |
55 | sub B::Asmdata::PUT_objindex { pack("N", $_[0]) } # could allow names here |
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56 | sub B::Asmdata::PUT_svindex { &B::Asmdata::PUT_objindex } |
57 | sub B::Asmdata::PUT_opindex { &B::Asmdata::PUT_objindex } |
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58 | |
59 | sub B::Asmdata::PUT_strconst { |
60 | my $arg = shift; |
61 | $arg = uncstring($arg); |
62 | if (!defined($arg)) { |
63 | error "bad string constant: $arg"; |
64 | return ""; |
65 | } |
66 | if ($arg =~ s/\0//g) { |
67 | error "string constant argument contains NUL: $arg"; |
68 | } |
69 | return $arg . "\0"; |
70 | } |
71 | |
72 | sub B::Asmdata::PUT_pvcontents { |
73 | my $arg = shift; |
74 | error "extraneous argument: $arg" if defined $arg; |
75 | return ""; |
76 | } |
77 | sub B::Asmdata::PUT_PV { |
78 | my $arg = shift; |
79 | $arg = uncstring($arg); |
80 | error "bad string argument: $arg" unless defined($arg); |
81 | return pack("N", length($arg)) . $arg; |
82 | } |
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83 | sub B::Asmdata::PUT_comment_t { |
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84 | my $arg = shift; |
85 | $arg = uncstring($arg); |
86 | error "bad string argument: $arg" unless defined($arg); |
87 | if ($arg =~ s/\n//g) { |
88 | error "comment argument contains linefeed: $arg"; |
89 | } |
90 | return $arg . "\n"; |
91 | } |
92 | sub B::Asmdata::PUT_double { sprintf("%s\0", $_[0]) } |
93 | sub B::Asmdata::PUT_none { |
94 | my $arg = shift; |
95 | error "extraneous argument: $arg" if defined $arg; |
96 | return ""; |
97 | } |
98 | sub B::Asmdata::PUT_op_tr_array { |
99 | my $arg = shift; |
100 | my @ary = split(/\s*,\s*/, $arg); |
101 | if (@ary != 256) { |
102 | error "wrong number of arguments to op_tr_array"; |
103 | @ary = (0) x 256; |
104 | } |
105 | return pack("n256", @ary); |
106 | } |
107 | # XXX Check this works |
108 | sub B::Asmdata::PUT_IV64 { |
109 | my $arg = shift; |
110 | return pack("NN", $arg >> 32, $arg & 0xffffffff); |
111 | } |
112 | |
113 | my %unesc = (n => "\n", r => "\r", t => "\t", a => "\a", |
114 | b => "\b", f => "\f", v => "\013"); |
115 | |
116 | sub uncstring { |
117 | my $s = shift; |
118 | $s =~ s/^"// and $s =~ s/"$// or return undef; |
119 | $s =~ s/\\(\d\d\d|.)/length($1) == 3 ? chr(oct($1)) : ($unesc{$1}||$1)/eg; |
120 | return $s; |
121 | } |
122 | |
123 | sub strip_comments { |
124 | my $stmt = shift; |
125 | # Comments only allowed in instructions which don't take string arguments |
126 | $stmt =~ s{ |
127 | (?sx) # Snazzy extended regexp coming up. Also, treat |
128 | # string as a single line so .* eats \n characters. |
129 | ^\s* # Ignore leading whitespace |
130 | ( |
131 | [^"]* # A double quote '"' indicates a string argument. If we |
132 | # find a double quote, the match fails and we strip nothing. |
133 | ) |
134 | \s*\# # Any amount of whitespace plus the comment marker... |
135 | .*$ # ...which carries on to end-of-string. |
136 | }{$1}; # Keep only the instruction and optional argument. |
137 | return $stmt; |
138 | } |
139 | |
140 | sub parse_statement { |
141 | my $stmt = shift; |
142 | my ($insn, $arg) = $stmt =~ m{ |
143 | (?sx) |
144 | ^\s* # allow (but ignore) leading whitespace |
145 | (.*?) # Instruction continues up until... |
146 | (?: # ...an optional whitespace+argument group |
147 | \s+ # first whitespace. |
148 | (.*) # The argument is all the rest (newlines included). |
149 | )?$ # anchor at end-of-line |
150 | }; |
151 | if (defined($arg)) { |
152 | if ($arg =~ s/^0x(?=[0-9a-fA-F]+$)//) { |
153 | $arg = hex($arg); |
154 | } elsif ($arg =~ s/^0(?=[0-7]+$)//) { |
155 | $arg = oct($arg); |
156 | } elsif ($arg =~ /^pp_/) { |
157 | $arg =~ s/\s*$//; # strip trailing whitespace |
158 | my $opnum = $opnumber{$arg}; |
159 | if (defined($opnum)) { |
160 | $arg = $opnum; |
161 | } else { |
162 | error qq(No such op type "$arg"); |
163 | $arg = 0; |
164 | } |
165 | } |
166 | } |
167 | return ($insn, $arg); |
168 | } |
169 | |
170 | sub assemble_insn { |
171 | my ($insn, $arg) = @_; |
172 | my $data = $insn_data{$insn}; |
173 | if (defined($data)) { |
174 | my ($bytecode, $putsub) = @{$data}[0, 1]; |
175 | my $argcode = &$putsub($arg); |
176 | return chr($bytecode).$argcode; |
177 | } else { |
178 | error qq(no such instruction "$insn"); |
179 | return ""; |
180 | } |
181 | } |
182 | |
183 | sub assemble_fh { |
184 | my ($fh, $out) = @_; |
185 | my ($line, $insn, $arg); |
186 | $linenum = 0; |
187 | $errors = 0; |
188 | while ($line = <$fh>) { |
189 | $linenum++; |
190 | chomp $line; |
191 | if ($debug) { |
192 | my $quotedline = $line; |
193 | $quotedline =~ s/\\/\\\\/g; |
194 | $quotedline =~ s/"/\\"/g; |
195 | &$out(assemble_insn("comment", qq("$quotedline"))); |
196 | } |
197 | $line = strip_comments($line) or next; |
198 | ($insn, $arg) = parse_statement($line); |
199 | &$out(assemble_insn($insn, $arg)); |
200 | if ($debug) { |
201 | &$out(assemble_insn("nop", undef)); |
202 | } |
203 | } |
204 | if ($errors) { |
205 | die "Assembly failed with $errors error(s)\n"; |
206 | } |
207 | } |
208 | |
209 | 1; |
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210 | |
211 | __END__ |
212 | |
213 | =head1 NAME |
214 | |
215 | B::Assembler - Assemble Perl bytecode |
216 | |
217 | =head1 SYNOPSIS |
218 | |
219 | use Assembler; |
220 | |
221 | =head1 DESCRIPTION |
222 | |
223 | See F<ext/B/B/Assembler.pm>. |
224 | |
225 | =head1 AUTHOR |
226 | |
227 | Malcolm Beattie, C<mbeattie@sable.ox.ac.uk> |
228 | |
229 | =cut |