Bas2tap

BAS2TAP v2.4                                                (Release 24-07-2005)
Written by Martijn van der Heide of ThunderWare Research Center

This program converts 'BASIC in an ASCII file' to a TAP tape image file, to be
used in a ZX Spectrum emulator. Both 48K and 128K listings are supported.


STANDARD DISCLAIMER
-------------------
This program is provided "as is", without any warranties, nor an indication
that it will fit the purpose.
BAS2TAP has been tested on several systems and OSes, causing no problems.
If you want to use this program, though, you do so at your own risk.
This means that it is extremely unlikely to damage your system, but if the
unthoughtful event DOES happen, you will be on your own.
ThunderWare Research Center can and will accept no claims whatsoever.

This program is neither public domain nor shareware: it's Open Source Software.
This means that anyone is allowed to distribute and use the program, as well as
change the source code. The source code (modified or not) must be included in
any distribution at all time.
You can not request any money from anyone for copying this program, apart from
the expenses made for the media onto which it has been copied.
The package contents may not be changed when distributing it. At least the
following files must be present:

   BAS2TAP.C    source text file
   BAS2TAP.DOC  this documentation file

Remember you can always freely obtain the latest version from
the utilities section of The World of Spectrum, at:
    http://www.worldofspectrum.org/

Or you can try:
    ftp://ftp.worldofspectrum.org/pub/sinclair/tools/pc


REVISION HISTORY
----------------
1.0  26-03-98: First public release
1.1  01-04-98: Changes:
               - Added banner.
               - Switch -q does not suppress warnings, but progress indication.
               - Added switch -w to suppress warnings.
               - Added switch -e on popular demand.
               - Empty lines are skipped and only generate a warning.
               - Lines with only a line number generate an error.
               - Numbers can also start with a decimal point (eg. '.5').
               - Lines no longer require an end-of-line terminator.
               - In-line sequence expansions also remove any trailing
                 spaces unless it was between quotes.
               - The created TAP is made valid (although incomplete) if an error
                 occurs, unless it was a write error.
1.2  11-12-98: Changes:
               - Block graphics were encoded rotated by 1.
               - Added full syntax checking, and
               - Added switch -n to disable the syntax checking again.
               - Added expansion sequences '{CAT}' and '{CODE}' with the sole
                 purpose of being used as channel name in the OPEN # command.
               - Changed the distribution policy from freeware to Open Source
                 Software.
1.3  04-01-99: Changes:
               - Spaces after strings are now skipped (they are not needed).
               - The 'CLS #' command does exist on the Interface 1 after all.
               - Exponential numbers were raised the wrong way around
                 (eg. 25e3 became 0.025 and 25e-3 became 25000). Oooops....
1.4  17-05-99: Changes:
               - UDGs used as 'USR "x"' would result in a crash due to 2
                 bad pointers.
               - Complex expressions between brackets as parameter to other
                 expression types (eg. ATTR or string slicing) would screw
                 up the evaluation.
               - The 'CLS #' command was flagged as being Interface 1
                 specific in the previous version rather than either
                 Interface 1 or Opus Discovery (aaargh!)
1.5  19-05-99: Changes:
               - The 'DIM' command's syntax description was incorrect, so the
                 checker didn't like the variable name before the opening
                 bracket.
1.6  23-06-99: Changes:
               - Several problems with array indices!
               - The 'USR' token only accepted a numerical operand. An
                 exception was made for UDG expressions '"x"' but constructions
                 like 'USR CHR$ a' didn't work.
1.7  02-11-99: Changes:
               - The DEF FN function requires insertion of evaluation room.
1.8  09-11-00: Changes:
               - The DEF FN function only requires insertion of evaluation room
                 in the parameter area before the '=' token.
                 Any bracketed argument would upset the parser.
1.9  08-12-01: Changes:
               - Forgot to skip the ';' colour token separator in class 9.
               - REM statements should be parsed as-is (except for expansion
                 sequences), without taking out multiple spaces or counting
                 quotes.
2.0  11-12-02: Changes:
               - SAVE/LOAD/VERIFY/MERGE DATA didn't work, as the DATA token was
                 set to be allowed as keyword only.
               - ERASE ! didn't work, as ERASE was only allowed from the "m"
                 chennel.
2.1  22-12-02: Changes:
               - Any alphanumerical expression can be sliced, not only
                 variables and direct strings.
               - If the output filename provided on the command line had the
                 extension '.TAP', it shouldn't be forced to '.tap'.
2.2  13-06-03: Changes:
               - Expand sequences PAPER and INK had their codes reversed.
               - Expand sequences BRIGHT and FLASH had their codes reversed.
               - Expand sequences INVERSE and OVER had their codes reversed.
               - Expand sequences {XX} didn't work (missing pointer advance).
               - Expand sequences AT and TAB didn't work and threw a
                 warning instead (missing pointer advance).
2.3  05-07-04: Changes:
               - LET is allowed to write to a substring.
2.4  24-07-05: Changes:
               - BIN is a number format, not an expression token.

SYNTAX
------
  BAS2TAP [-q] [-w] [-e] [-c] [-aX] [-sX] FileIn [FileOut]

-q  goes into quiet mode, suppressing banner and progress indication.
-w  suppress generation of warnings.
-e  write errors to the stdout in stead of the stderr stream.
-c  makes token matching case independant. The drawback is that variables that
    have the same name as a token (eg. 'print') cannot be used, as they will be
    treated as (unexpected) tokens.
-n  disables syntax checking.
-aX sets the auto-start line to line X.
-sX sets the TAP block name to X (max 10 characters).

If no output filename is provided, the same name as the input file will be
used, but with extension `.TAP'.


THE CONVERTOR
-------------
The following rules apply:

1. One BASIC line must be provided in one ASCII line.
2. Keywords must appear in upper case (unless switch -c is used).
3. Keywords that consist of multiple words (eg. `GO TO') must have the space
   in between the words.
4. Spaces between words are not needed, unless this leads to concatenation
   problems - eg. `PRINTVAL"10"' must appear as `PRINT VAL"10"', while
   `PRINT10' is perfectly acceptable.
5. Syntax is fully checked according to
   - the normal Spectrum ROM,
   - Interface 1/Microdrive extension,
   - Opus Discovery extension.

The following sequences are expanded in-line:

   Chars   Expand to

   tab     character 06     ("print '")
   {XX}    XX is 2-digit hex, converts to the Spectrum ASCII value
   {(C)}   character 7F     (copyright sign)
   {-X}    X is 1-8, characters 80-87 (block graphics without shift)
   {+X}    X is 1-8, characters 88-8F (block graphics with shift)
   {X}     X is `A'-`U', converts to the UDG Spectrum ASCII value
   {CODE}  character AF     ('CODE')
   {CAT}   character CF     ('CAT')

Special sequences are (case independant) PAPER, INK, BRIGHT, FLASH, OVER,
INVERSE, AT and TAB control sequences. They may appear as "{PAPER 3}" to convert
to the sequence 0x10,0x03. Note that both AT and TAB take 2 operands, which
should be seperated by a comma (eg. "{AT 1,10}").
Notice that these expansions are identical to what SGD and TAPER create when
saving out BASIC blocks.


RECOMPILING THE SOURCE
----------------------
The source is provided in (almost) fully portable ANSI C, the source text is
written in 132 columns.

If you wish to experiment with different syntax (eg. for a DISCiPLE), you may
find it useful to set the `__DEBUG__' define.

If you make any fundamental change to the source, you are requested - but not
obligated - to send the changed source back to me, so that everyone can benefit
from it. My e-mail address is `mheide()worldofspectrum.org'


Enjoy!

Martijn van der Heide, MSc
Senior Software Developer
ThunderWare Research Center