1 package App
::Scheme79asm
;
7 use Data
::Dumper qw
/Dumper/;
8 use Data
::SExpression qw
/consp scalarp/;
9 use Scalar
::Util qw
/looks_like_number/;
11 our $VERSION = '0.001001';
39 *consp
= *Data
::SExpression
::consp
;
40 *scalarp
= *Data
::SExpression
::scalarp
;
43 my ($self, $sexp, $location) = @_;
44 die 'Toplevel is not a list: ', Dumper
($sexp), "\n" unless ref $sexp eq 'ARRAY';
45 my ($type, @addrs) = @
$sexp;
48 die 'Type of toplevel is not atom: '. Dumper
($type), "\n" unless scalarp
($type);
51 $addr = $self->{freeptr
} + 1;
52 $self->{freeptr
} += @addrs;
53 $self->process($addrs[$_], $addr + $_) for 0 .. $#addrs;
58 $addr = $self->process($addr) if ref $addr eq 'ARRAY';
59 die 'Addr of toplevel is not atom: ', Dumper
($addr), "\n" unless scalarp
($addr);
61 my ($comment_type, $comment_addr) = ($type, $addr);
63 unless (looks_like_number
$addr) { # is symbol
64 unless (exists $self->{symbols
}{$addr}) {
65 $self->{symbols
}{$addr} = $self->{nsymbols
};
68 $addr = $self->{symbols
}{$addr}
71 die 'Computed addr is not a number: ', Dumper
($addr), "\n" unless looks_like_number
$addr;
73 if (ref $type eq 'Data::SExpression::Symbol') {
74 die "No such type: $type\n" unless exists $TYPES{$type};
75 $type = $TYPES{$type};
76 } elsif (!looks_like_number
$type) {
77 die "Type is not a number or symbol: $type\n"
80 die "Type too large: $type\n" unless $type < (1 << $self->{type_bits
});
81 die "Addr too large: $addr\n" unless $addr < (1 << $self->{addr_bits
});
82 my $result = ($type << $self->{addr_bits
}) + $addr;
85 $location = $self->{freeptr
}
87 $self->{memory
}[$location] = $result;
88 $self->{comment
}[$location] = "$comment_type $comment_addr";
93 my ($self, $string) = @_;
94 my $ds = Data
::SExpression
->new({symbol_case
=> 'up', use_symbol_class
=> 1, fold_lists
=> 1});
98 last if $string =~ /^\s*$/;
99 ($sexp, $string) = $ds->read($string);
100 $self->process($sexp)
106 $self->{memory
}[5] = $self->{memory
}[$self->{freeptr
}];
107 $self->{comment
}[5] = $self->{comment
}[$self->{freeptr
}];
108 $self->{memory
}[4] = $self->{freeptr
};
109 delete $self->{memory
}[$self->{freeptr
}]
113 my ($class, %args) = @_;
114 $args{type_bits
} //= 3;
115 $args{addr_bits
} //= 8;
116 $args{freeptr
} //= 6;
117 $args{memory
} //= [0, 0, (1<<$args{addr_bits
}), (1<<$args{addr_bits
}), 0, 0, 0];
118 $args{symbols
}{NIL
} = 0;
119 $args{symbols
}{T
} = 1;
121 $args{comment
} = ['(cdr part of NIL)', '(car part of NIL)', '(cdr part of T)', '(car part of T)', '(free storage pointer)', '', '(result of computation)'];
126 my ($self, $fh) = @_;
129 my $bits = $self->{type_bits
} + $self->{addr_bits
};
130 my $index_length = length $#{$self->{memory}};
131 my $index_format = '%' . $index_length . 'd';
132 for my $index (0 .. $#{$self->{memory}}) {
133 my $val = $self->{memory
}[$index];
134 my $comment = $self->{comment
}[$index];
136 $val = "${bits}'d$val"
138 $val = $val ?
sprintf "%d'b%0${bits}b", $bits, $val : '0';
140 my $spaces = ' ' x
($bits + 5 - (length $val));
141 $index = sprintf $index_format, $index;
142 say $fh "mem[$index] <= $val;$spaces // $comment"
146 sub parse_and_print
{
147 my ($self, $string, $fh) = @_;
148 $self->parse($string);
160 App::Scheme79asm - assemble sexp to Verilog ROM for SIMPLE processor
164 use App::Scheme79asm;
165 my $asm = App::Scheme79asm->new(type_bits => 3, addr_bits => 5);
166 $asm->parse_and_print('(number 70)');
170 SIMPLE is a LISP processor defined in the 1979
171 B<Design of LISP-Based Processors> paper by Steele and Sussman.
173 The SIMPLE processor expects input in a particular tagged-pointer
174 format. This module takes a string containing a sequence of
175 S-expressions. Each S-expression is a list of one of three types:
177 C<(tag value)>, for example C<(symbol nil)>, represents a value to be
178 put in memory (for example a number, or a symbol, or a variable
181 C<(tag list)>, where C<list> is of one of these three types,
182 represents a tagged pointer. In this case, C<list> is (recursively)
183 laid out in memory as per these rules, and a pointer to that location
184 (and tagged C<tag>) is put somewhere in memory.
186 C<(tag list1 list2)>, where C<list1> and C<list2> are of one of these
187 three types (not necessarily the same type). In this case, C<list1>
188 and C<list2> are (recursively) laid out in memory such that C<list1>
189 is at position X and C<list2> is at position X+1, and a pointer of
190 type tag and value X is put somewhere in memory.
192 After this process the very last pointer placed in memory is moved to
193 the special location 5 (which is where SIMPLE expects to find the
194 expression to be evaluated).
196 In normal use a single S-expression will be supplied, representing an
199 The C<tag> is either a number, a type, or a primitive.
200 The available types are:
206 =item SYMBOL (syn. NUMBER)
208 =item VAR (syn. VARIABLE)
212 =item PROC (syn. PROCEDURE)
214 =item IF (syn. COND, CONDITIONAL)
218 =item QUOTE (syn. QUOTED)
222 The available primitives are:
244 The following methods are available:
248 =item App::Scheme79asm->B<new>([key => value, key => value, ...])
250 Create a new assembler object. Takes a list of keys and values, here
251 are the possible keys:
259 A word is made of a type and an address, with the type occupying the
260 most significant C<type_bits> (default 3) bits, and the address
261 occupying the least significant C<address_bits> (default 8) bits.
262 Therefore the word size is C<type_bits + address_bits> (default 13).
266 A pointer to the last used byte in memory (default 6). The program
267 will be laid out starting with location C<freeptr + 1>.
271 The initial contents of the memory. Note that locations 4, 5, 6 will
272 be overwritten, as will every location larger than the value of
277 The initial comments for memory entries. C<< $comment->[$i] >> is the
278 comment for C<< $memory->[$i] >>.
282 The initial symbol map, as a hashref from symbol name to the index of
283 that symbol. Defaults to C<< {NIL => 0, T => 1} >>.
287 The number of distinct symbols in the initial symbols map (default 2).
291 =item $asm->B<parse>(I<$string>)
293 Parse a sequence of S-expressions and lay it out in memory.
294 Can be called multiple times to lay out multiple sequences of
295 S-expressions one after another.
297 =item $asm->B<finish>
299 Move the last pointer to position 5, and put the free pointer at
300 position 4. After all sequences of S-expressions have been given to
301 B<parse>, this method should be called.
303 =item $asm->B<print>([I<$fh>])
305 Print a block of Verilog code assigning the memory contents to an
306 array named C<mem> to the given filehandle (default STDOUT).
308 =item $asm->B<parse_and_print>(I<$string>[, I<$fh>])
310 Convenience method that calls B<parse>($string), B<finish>, and then
317 L<http://repository.readscheme.org/ftp/papers/ai-lab-pubs/AIM-514.pdf>
321 Marius Gavrilescu, E<lt>marius@ieval.roE<gt>
323 =head1 COPYRIGHT AND LICENSE
325 Copyright (C) 2018 by Marius Gavrilescu
327 This library is free software; you can redistribute it and/or modify
328 it under the same terms as Perl itself, either Perl version 5.24.3 or,
329 at your option, any later version of Perl 5 you may have available.
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