X-Git-Url: http://git.ieval.ro/?a=blobdiff_plain;f=lib%2FApp%2FScheme79asm.pm;h=5aebe08689da7b303fc85016d414f0a16d8ae910;hb=0edb4b34e85aceb436bfc91748338a4155c881e5;hp=c971c2cd2930905b25f284aef796d6934a135b6c;hpb=34073a4a81787bd2934f5a82ab6ef7ed261c9451;p=app-scheme79asm.git

diff --git a/lib/App/Scheme79asm.pm b/lib/App/Scheme79asm.pm
index c971c2c..5aebe08 100644
--- a/lib/App/Scheme79asm.pm
+++ b/lib/App/Scheme79asm.pm
@@ -8,7 +8,7 @@ use Data::Dumper qw/Dumper/;
 use Data::SExpression qw/consp scalarp/;
 use Scalar::Util qw/looks_like_number/;
 
-our $VERSION = '0.001';
+our $VERSION = '0.002';
 
 our %TYPES = (
 	LIST => 0,
@@ -163,25 +163,154 @@ App::Scheme79asm - assemble sexp to Verilog ROM for SIMPLE processor
 
   use App::Scheme79asm;
   my $asm = App::Scheme79asm->new(type_bits => 3, addr_bits => 5);
-  $asm->parse_and_print('(number . 70)');
+  $asm->parse_and_print('(number 70)');
 
 =head1 DESCRIPTION
 
-B<NOTE:> this module does not do much at the moment.
-
 SIMPLE is a LISP processor defined in the 1979
 B<Design of LISP-Based Processors> paper by Steele and Sussman.
 
 The SIMPLE processor expects input in a particular tagged-pointer
 format. This module takes a string containing a sequence of
-S-expressions of the form C<(tag . value)> representing a tagged
-pointer. Here the tag is either a number or one of several predefined
-values (see the source for a full list), and the value is either a
-number or another tagged pointer. These values are laid out in memory
-and a block of verilog code assigning the memory contents to an array
-named C<mem> is printed.
-
-More documentation and features to follow.
+S-expressions. Each S-expression is a list of one of three types:
+
+C<(tag value)>, for example C<(symbol nil)>, represents a value to be
+put in memory (for example a number, or a symbol, or a variable
+reference).
+
+C<(tag list)>, where C<list> is of one of these three types,
+represents a tagged pointer. In this case, C<list> is (recursively)
+laid out in memory as per these rules, and a pointer to that location
+(and tagged C<tag>) is put somewhere in memory.
+
+C<(tag list1 list2)>, where C<list1> and C<list2> are of one of these
+three types (not necessarily the same type). In this case, C<list1>
+and C<list2> are (recursively) laid out in memory such that C<list1>
+is at position X and C<list2> is at position X+1, and a pointer of
+type tag and value X is put somewhere in memory.
+
+After this process the very last pointer placed in memory is moved to
+the special location 5 (which is where SIMPLE expects to find the
+expression to be evaluated).
+
+In normal use a single S-expression will be supplied, representing an
+entire program.
+
+The C<tag> is either a number, a type, or a primitive.
+The available types are:
+
+=over
+
+=item LIST
+
+=item SYMBOL (syn. NUMBER)
+
+=item VAR (syn. VARIABLE)
+
+=item CLOSURE
+
+=item PROC (syn. PROCEDURE)
+
+=item IF (syn. COND, CONDITIONAL)
+
+=item CALL
+
+=item QUOTE (syn. QUOTED)
+
+=back
+
+The available primitives are:
+
+=over
+
+=item MORE
+
+=item CAR
+
+=item CDR
+
+=item CONS
+
+=item ATOM
+
+=item PROGN
+
+=item MAKELIST
+
+=item FUNCALL
+
+=back
+
+The following methods are available:
+
+=over
+
+=item App::Scheme79asm->B<new>([key => value, key => value, ...])
+
+Create a new assembler object. Takes a list of keys and values, here
+are the possible keys:
+
+=over
+
+=item type_bits
+
+=item address_bits
+
+A word is made of a type and an address, with the type occupying the
+most significant C<type_bits> (default 3) bits, and the address
+occupying the least significant C<address_bits> (default 8) bits.
+Therefore the word size is C<type_bits + address_bits> (default 13).
+
+=item freeptr
+
+A pointer to the last used byte in memory (default 6). The program
+will be laid out starting with location C<freeptr + 1>.
+
+=item memory
+
+The initial contents of the memory. Note that locations 4, 5, 6 will
+be overwritten, as will every location larger than the value of
+C<freeptr>.
+
+=item comment
+
+The initial comments for memory entries. C<< $comment->[$i] >> is the
+comment for C<< $memory->[$i] >>.
+
+=item symbols
+
+The initial symbol map, as a hashref from symbol name to the index of
+that symbol. Defaults to C<< {NIL => 0, T => 1} >>.
+
+=item nsymbols
+
+The number of distinct symbols in the initial symbols map (default 2).
+
+=back
+
+=item $asm->B<parse>(I<$string>)
+
+Parse a sequence of S-expressions and lay it out in memory.
+Can be called multiple times to lay out multiple sequences of
+S-expressions one after another.
+
+=item $asm->B<finish>
+
+Move the last pointer to position 5, and put the free pointer at
+position 4. After all sequences of S-expressions have been given to
+B<parse>, this method should be called.
+
+=item $asm->B<print>([I<$fh>])
+
+Print a block of Verilog code assigning the memory contents to an
+array named C<mem> to the given filehandle (default STDOUT).
+
+=item $asm->B<parse_and_print>(I<$string>[, I<$fh>])
+
+Convenience method that calls B<parse>($string), B<finish>, and then
+B<print>($fh).
+
+=back
 
 =head1 SEE ALSO