tbas

BASIC interpreter

Introduction
Documentation
Installation
Download tbas

Introduction

Welcome to tbas, a console interpreter for the BASIC language, in a structured version (no need for line numbers even if it can deal with them), complete with many math functions and many many features!

Documentation

Available documentation (which is contained into the downloadable package and is linked here for your convenience):

• The tbas manual for current version in pdf format.

Installation

The tbas executable, before use, must be compiled and installed. I suggest the following very easy procedure in 4 steps (use the terminal):

1) Copy the package somewhere, and unpack it; it will unpack into a directory named tbas.1.0.XXX.src;

2) Now, choose a directory in your path, where executables will be saved; let's assume it's ~/bin (that is the sub-directory /bin in your Home directory, but you can choose any). Edit the Makefile to customize addresses for tbas (e.g., among the rest, change the install directory to ~/bin, commenting the undesired destinations and leaving un-commented ONE ONLY valid destination) using the destination directory you chose.

3) get into tbas source directory and type the following (be sure to have gcc installed):

$ make
$ make install

(the latter may require root privileges if you try to install tbas into system directories, as suggested by default in the Makefile).

For Mac Users: in case you want to install tbas into some system directory (e.g. /user/local/bin), remember that root privileges are not required, as long as you can access an administrative login: in this case, after make, login as an administrator with

$ su

(being the username of the administrator) - you will be requested of a password - and then install the software with

$ sudo make install

$ exit

4) now type the following to test the correct installation:

$ tbas –help

This shows the basic features of tbas and you're done!

Download tbas

Well, this new release requested a quite endless turn of changes, and for all the new features and corrections I thank Bruce Axtens and Tom Lake who, along with my friend Ian Jones, helped me to release this Beta version... Thanks also to Marcus Cruz, who suggested a couple of interesting improvements

You can download tbas Beta sources here.

The Windows binaries (gently provided by Bruce) can be found here:

Windows 32bit binary

Windows 64bit binary

The introduction of the interactive session (suggested by Tom) led to a number of problems (mainly the error detection system and the insertion/deletion/substitution of lines), problems that Bruce, Tom and Ian signaled in great quantity during the development phase, and that I finally manage to solve. I mean most of them. This required rewriting part of the code to adapt it to the interactive session. In any case now it's time to let you use it and test it.

WARNING: I removed all differences from Unix and not-Unix systems; tbas can now be compiled under Linux only, or under Windows with CygWin/MinGW installed and run from there (though not every feature is guaranteed to work). It's too onerous and overwhelming treating more than one Operating System...

New additions:

• added the interactive session (enabled by option -i) . This is the main innovation with respect to the Alpha (build 3) version
• added ON and OFF as synonyms to TRUE and FALSE
• added FREE/FREE$
• added functions ALN/ALN() and ELN/ELN() to return the number of the line where an interrupt/error occurred
• The introduction of the interactive session, to let the user adopt options from there, forced me to separate the Header and Timing features in the starting option;  now -H enables the header only, and -T enables the timing (this was asked by Tom)
• added the ? command synonym of PRINT
• added the command PIPE that stores in an internal buffer the output of the execution of the bash command contained in its string argument and coming from a pipe source, and the string function PIPE$ that returns the content of the PIPE buffer, as a whole or as one slice of it. Bruce was the one who proposed this
• added # as the equivalent operator of <>
• added the LTRIM$ and RTRIM$ string functions
• added option -D, that disables the inversion of colors in debugging (asked by Bruce)
• added the EXEC statement to execute the string argument as a BASIC statement, an ideal companion of COMMAND$
• added UNTRACE as synonym of TRACE OFF; also added to TRACE the ability to print the variable content if TRACE is followed by the variable index, or print the variable content when it changes if TRACE is followed by the variable name
• added the numeric functions NUMBER(A$), PICT(A$) and ALPHA(A$), with string arguments
• added the PROGRAM/TITLE/_TITLE statements
• added option -L to list the program indented rather than executing it
• added option -N, to print eleven spaces enclosed in quotes in place of a void string when a MAT PRINT is used to print a string array; in ALpha (build 3) that token was printed by default, but now you can choose whether use it or not by using option N; the default behavior is now to print the 'real' empty string. Correspondingly, I added the OPTION NULLS ON/OFF to change the behavior during run-time.
• added the AS STRING and the AS REAL specifiers in DECLARE; they are simply ignored (apart for some check) because the two types are the default types in BASIC, but they help in writing clearer definitions, and make programs compatible with other dialects.
• added the SWAP statement, by a precise request by Tom
• added the COPY statement, that copies one array onto another
• added the REM PRAGMA statement, to pass to program some console options; PRAGMA does not execute in the interactive sessions. This statement (which is invisible for other BASICs) lets declare options in the PRAGMA line and avoid the need to specify which options must be invoked in the command line to execute the program you're deploying
• added the REAL() function, which is simply ignored, because all numbers in tbas are real (in the math sense). Again, this makes the program clearer and maybe compatible with other dialects
• added the two system variables LASTCHANNEL and FREECHANNEL that return respectively the last successfully opened channel number and the first available (i.e. not opened with OPEN, FILE or FILES) channel number. This is a Bruce request. These variables, like CLK or DATE, cannot be instantiated by the user, but their content can be assigned to normal variables
• added the statements ERRPRINT, OPTION ERRORSTREAM ON|OFF and the system variable STREAM (requested by Bruce)
• added PROGRAM$, a system string variable that returns the name of the current file under execution; in the interactive session, reports the file loaded/saved as last. (requested by Bruce)
• added the passing of arrays to SUBs, specified by the name and the () token
• added MONTH$ and WEEKDAY$ as synonyms of MONTH$(0) and WEEKDAY$(0)
• added the new options -e and --exec that execute immediately the loaded program (it must be used with option -i). If no program is given as argument to be loaded, the empty program is run (i.e., the empty lines separating the running before and after execution are printed, and nothing more). If -i is not used, -e alone is ignored
• added option --interactive as a synonym for -i
• added the INCLUDE statement (from the MTS tradition), to change the standard input to the file given as an argument string (the default is that the input is expected from keyboard); only INPUT and MATINPUT are influenced by this statement; INKEY$ and INPUT$ (which require a keyboard input) continue with their standard behavior
• added OPTION WARNINGS ON|OFF
• added to LINEINPUT# (and LINPUT#) the ability to consider also void lines in reading from files (required by Ian)
• added the USING statement, that fixes a default format for all subsequent prints of the same type. USING or USING OFF can be used to disable this features also a PRINT USING disables the features. Use with care, the format establishes the things that must be printed (if you set USING "###.###" you cannot print strings until you disable USING!)
• many other minor additions were applied. The manual is updated, so check it for further notices.

Solved bugs:

• completed the recognizing of variables names, making it case-insensitive, and thus accepting 'a' as 'A' identifying the same variable. SUBs were already made this way (CALC and calc already referred to the same sub)
• Revolutionized the syntax: now in the source the statements DECLARE, SUB, HANDLER, WHILE, UNTIL, IF must be followed by a blank. Also SELECT and DO, if followed by something. The keywords THEN (when followed by something), TO, STEP, BY, AS, OTHERWISE, IN must be written surrounded by blanks. The commands FOR, GOTO, GOSUB, ELSE, USE, when not used  as statements, must also be surrounded by blanks
  
• modified ONDEBUG and OFFDEBUG to be used with ON and OFF, and thus the command is ON DEBUG and OFF DEBUG
• solved a bug in SYSTEM that, if the user hit CTRL-C during the session, when SYSTEM/BYE is typed, the interrupt error appeared without need
• after a comment in comp.lang.basic by Marcus Cruz, I realized that the two comments @ (stop) and & (suspend) are redundant. So, accepting his suggestion, I chose to use @ only, both for suspend and stop (in practice, 'stop' is a 'suspend' that is not terminated). This seems reasonable and technically good. There shouldn't be much code around with the & comment, but if you've used it, change & to @ and that's done
• solved a bug in the numeric functions MIN and MAX, that in some cases didn't return the correct value. The same for VMAX and VMIN. The problem was signaled by TOM
• Modified and simplified the string printing, because there were too much limitations that came from the DEC version (decb). These limits were removed and now tbas prints full strings (up to the maximum string length). Maintained the limitations to the quote mode, but in any case the effects of the limits were detectable only with strings longer than the screen line width limit of 72.
• added to tbas the capability to work with different EOL formats (that basically prevented the correct execution of algebra and of LIST (indentation).
• solved a bug in INPUT$ that didn't echo the typed characters, so I enabled the typing according to the OPTION ECHO/NO ECHO, which is enabled by default.
• changed the destination directory for tbas man page to /usr/local/man rather than /usr/share/man which was non-standard. Before installation, type as root 'make uninstall' in the previous installation directory to remove all previous instances of tbas.1 if you want a clean state
• Fixed a bug in ON..GOSUB that didn't calculate exactly the OTHERWISE clause address
• Fixed a bug in MAT INV that sometimes conflicted with OPTION BASE 1 because of a wrong indexing in the last code lines
• added to EXIT SUB the ability to exit from the sub writing the name of the SUB rather than using the keyword SUB; the two following are equivalent: EXIT SUB and EXIT myfunc
• designed a more cute exiting message from the interactive environment
• fixed a bug in the recognition of the user string, that in Windows caused a SIGSEGV error, due to a void string generation (signaled by Bruce)
• solved a bug in MAT INV ... ELSE (the ELSE part) that was not working as expected
• increased in tbas.h some constants for the execution of the recursion, to avoid (possibly) the segmentation error
• solved the nth bug discovered by Ian (they must be one thousand now!): at times when a tick comment was used, the program got confused by the possible spaces between the last character of the statement and the tick comment. Now the execution removes both the tick comment and the spaces before it.
• removed the ability for LEFT$ and RIGHT$ to work without arguments but the first. Now the second argument is due. Also, removed the ability for MID$ and SEG$ to work without the second argument, but maintained the third optional (as Tom suggested, comparing the QBASIC output)
• enabled error condition for LEFT$ and RIGHT$ when the second argument is negative
• enabled error condition for MID$ and SEG$ when the second optional argument is negative or null
• enabled error condition for MID$ and SEG$ when the third optional argument is negative.
• solved another bug discovered by Ian (no, really?): the CASE .. TO .. was 'strangely' messed up
• solved a bug in the color system: at the end of execution, default colors weren't correctly restored
• renamed EVAL to EXEC
• renamed VAL to EVAL
• added EVAL to execute more string arguments, separated by comma or semicolon
• solved a bug signaled by Bruce, that caused the algebraic parser to read the current declaring variable, fact that prevented the correct assignment of variables with SUB or DEF having arguments with the same name of variables passed as arguments
• enabled CALL to be used to call user SUBs (requested by Bruce), independently of their being functions or procedures. Calling a procedure is available but mainly useless (because the procedure is directly callable); calling a function can be used to obtain the side-effects that the function may produce, without the need to assign some result value to dummy variables
• now the line number of a Library SUB/DEF in the error string is not referring to the total source but is local to the SUB
• solved a bug signaled by Bruce, for errors in string/numeric error functions ESM, ESL, ERR$ etc; actually, an error in the number parser was generated in case those functions were used with an empty argument, and that caused an infinite loop
• solved a bug in INKEY$ that didn't reset the inner string if overtime (signaled by Bruce)
• solved a bug in OPEN (a bug revealed by Ian) that in case of multiple (really big) file open/close processes, could generate an error (in practice the highly frequent processes of open/close caused at some point that the file couldn't be really opened). This was a bug I couldn't spot in a million years if Ian didn't force me to look at the code!
• solved a bug in ERASE that didn't retain the variable order
• many other minor changes were applied. The manual is updated, so check it for further notices.

Infinite thanks to Bruce Axtens, who, for this version, discovered many bugs (oh my!) and push me to add new features!. He also put tbas code to the Rosetta code site. Well done!

Bruce, Ian and I are the tbas team!

You can download tbas Alpha 3 sources here.
You can download tbas Alpha 3 executable for Windows, compiled by Bruce Axtens, here.

changelog for version Alpha 3

• solved a bug in SUB and multi-lines DEF that prevented the recursion (this bug was signaled by Bruce).
• solved a bug in DEFFN which didn't work in case the DEFFN had no variables like in DEFFNA=... Probably this bug is due to later patches to the code, not restored before uploading....(signaled by BA). This required the removing of error 200.
• added to DEF FN functions the possibility to accept strings and string variables as arguments; this, though, doesn't change the numerical nature of DEFFN, so that the FNX is always a number, but in all, if strings are necessary in the body, they can now be used (suggested by Bruce).
• solved a bug in LIBRARY that reset the DATA indices during library loading (signaled by Bruce).
• added the COMMAND$ system string to return the console arguments after file name (suggested by Bruce).
• added the statements COLOR (to change the output text color and or invert), LOCATE (to position the cursor anywhere in the screen) and CLS (to clear the screen using monitor codes); the last is a synonym of CLEAR, but CLEAR uses shell commands to reset the screen and does not reset the colors, while CLS uses monitor codes and resets the colors to default.
• added to MAT READ and MAT INPUT the ability to redimension matrices (suggested by BA)
• increased the memory space for variables and SUBs nesting.
• modified some error messages
• Updated the make manual and the make pdfmanual processes in the makefile, and updated the man page. Also corrected some formatting errors in the manual.
• modified makefile to make tbas compilable under different systems.

Version 1.0.alpha (September 22, 2017)

Infinite thanks to Ian Jones , a friend and a great tester, who compiled and ran tbas an incredibly high number of times, finding all sort of errors in the listings. Ian and I are the tbas team!

You can download tbas Alpha sources here.



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I wait for your impressions and bugs. Send me your suggestions, your considerations, your corrections; even send me your working BASIC programs for tbas, all commented and completed with your own name and data: they will be part of the next package, of course.

It's GPL! Enjoy!