--------------------------------------------------------------------
    -- Copyright (C) 2002  Allen Brown
    -- 
    -- This program is free software; you can redistribute it and/or modify
    -- it under the terms of the GNU General Public License version 2 as
    -- published by the Free Software Foundation.
    -- 
    -- This program is distributed in the hope that it will be useful,
    -- but WITHOUT ANY WARRANTY; without even the implied warranty of
    -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    -- GNU General Public License for more details.
    -- 
    -- You should have received a copy of the GNU General Public License
    -- along with this program; if not, write to the
    --   Free Software Foundation, Inc.
    --   59 Temple Place, Suite 330
    --   Boston, MA  02111-1307  USA
    -- 
    -- To contact the author of this software:
    --   Allen Brown
    --   PO Box J
    --   Corvallis, OR
    -- 
    --   http://brown.armoredpenguin.com/~abrown/contact.html
    --------------------------------------------------------------------

Pbasic simulation translator:


Pbasic is case insensitive.
Translate all variables and addresses to lower case.

Use the following shorthand:
  define $an = \([a-z][a-z0-9_]+\)
  define $nu = \(-?[0-9].?[0-9]+\)

from pbasic		to C				comment
------------		-----				----------------
'\(.*\)			//\1				PBasic comments are
							directly converted
							to C comments.
$an var byte		pbword8_t \1_w8;		Original var name
			#define \1 \1_w8,pbword8	will be expanded to
							new var followed by
							width/point (negative).
$an var $an.$an		#define \1 \2_w8,\3		Bit fields are the
							base var followed by
							the bit pointer.
							Note that this notation
							only works for bit
							fields and if larger
							fields are to be
							supported, a new
							notation will be
							required.
$an con $nu		#define \1 pbconst(\2)		Constants also expanded
							to value followed by
							width/point.

output			pboutput();			Currently stubbed.
input			pbinput();			"
high			pbhigh();			"
low			pblow();			"

$an = <expr>		pblet(&\1,<expr>);		$an may be expanded by
							its define to either a
							pbword8_t or a bit
							pointer.
if <expr1> = <expr2> then $an:
			if( pbeq(<expr1>,<expr2>) ) goto \3;
put $nu,$nu		pbput(pbconst(\1),pbconst(\2);
put $nu,$an		pbput(pbconst(\1),\2);
get $nu,$an		pbget(&\2,pbconst(\1));
gosub $an:						Complex.  See the code.
return			goto gosubreturnc;		Unwind the stack that
							was pushed at the
							gosub call.
goto $an:		goto \1

serin			pbserin				Complex.  See the code.
serout			pbserout			"
shiftout		pbshiftout			"
lookup							Complex.  See the code.

----------------------------------------------------------
		Parts of Expressions

abs(<expr>)		pbabs(<expr>),pbword8
not(<expr>)		pbnot(<expr>),pbword8

<expr> MAX <expr>	pbmax(<expr>,<expr>),pbword8
<expr> MIN <expr>	pbmin(<expr>,<expr>),pbword8
<expr> + <expr>		pbadd(<expr>,<expr>),pbword8
<expr> - <expr>		pbsub(<expr>,<expr>),pbword8
<expr> * <expr>		pbmul(<expr>,<expr>),pbword8
<expr> / <expr>		pbdiv(<expr>,<expr>),pbword8
<expr> \ <expr>		pbmod(<expr>,<expr>),pbword8
<expr> << <expr>	pbshl(<expr>,<expr>),pbword8	shift left
<expr> >> <expr>	pbshr(<expr>,<expr>),pbword8	shift right
<expr> = <expr>		pbeq(<expr>,<expr>),pbword8
<expr> <> <expr>	pbne(<expr>,<expr>),pbword8
<expr> > <expr>		pbgt(<expr>,<expr>),pbword8
<expr> < <expr>		pblt(<expr>,<expr>),pbword8
<expr> >= <expr>	pbge(<expr>,<expr>),pbword8
<expr> <= <expr>	pble(<expr>,<expr>),pbword8
<expr> and <expr>	pbland(<expr>,<expr>),pbword8	Logical
<expr> or <expr>	pblor(<expr>,<expr>),pbword8
<expr> xor <expr>	pblxor(<expr>,<expr>),pbword8
<expr> & <expr>		pbband(<expr>,<expr>),pbword8	Bitwise
<expr> | <expr>		pbbor(<expr>,<expr>),pbword8
<expr> ^ <expr>		pbbxor(<expr>,<expr>),pbword8


----------------------------------------------------------
	Not implemented

debug			Syntax is messy
[]			Brackets don't seem to provide useful information.
<variable> var nibble
<variable> var nib
out$nu = value		Variables connected directly to pins of the
			Basic Stamp are not implemented.

Also, full syntax checking of the .bsx source file is not done.
It is possible to write code that works on this simulator but
which is not valid .bsx.

And we have discovered that it is possible to have code which
passes the bsx syntax checker and simulates but which will not
load.  This is an unsolved problem.

OTOH, some valid .bsx will not compile.  In particular, .bsx
is cavalier about where variables may be declared.  C is far
more restrictive.  If you place all of your declarations at
the beginning of the .bsx file, you will not have trouble with
either the simulator or the Basic Stamp.  (This issue is why
varsboxed.bsx and DefaultProgram1stick.bsx will not translate.)

----------------------------------------------------------