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Diffstat (limited to 'unprotbas.rst')
| -rw-r--r-- | unprotbas.rst | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/unprotbas.rst b/unprotbas.rst index daf391f..dfd3f5a 100644 --- a/unprotbas.rst +++ b/unprotbas.rst @@ -16,12 +16,12 @@ unprotbas [**-v**] [**-f**] [**-n**] [**-g**] **input-file** **output-file** DESCRIPTION =========== -**unprotbas** modifies LIST-protected Atari 8-bit BASIC programs, +**unprotbas** modifies a LIST-protected Atari 8-bit BASIC program, creating a new non-protected copy. See **DETAILS**, below, to understand how the protection and unprotection works. -**input-file** must be a tokenized Atari BASIC program. Use *-* to -read from standard input. +**input-file** must be a tokenized (SAVEd) Atari BASIC program. Use +*-* to read from standard input. **output-file** will be the unprotected tokenized BASIC program. If it already exists, it will be overwritten. Use *-* to write to standard @@ -37,14 +37,15 @@ To use filenames beginning with *-*, write them as *./-file*, or they will be treated as options. **-v** - Verbose operation. TODO: it's always verbose right now... + Verbose operation. **-f** Force the variable name table to be rebuilt, even if it looks OK. + This option cannot be combined with **-n**. **-n** Don't rebuild the variable table (only fix the line pointers, if - needed). + needed). This option cannot be combined with **-f**. **-g** Remove any "garbage" data from the end of the file. By default, @@ -124,11 +125,6 @@ Variable name table scrambling table might be smaller. Bad next-line pointer - Generally, this is done with line number 32768. Yes, this line - number is outside the range BASIC accepts... but BASIC uses it - internally for immediate-mode commands. And when SAVE or CSAVE are - executed, this line gets saved, too. - Every line of tokenized BASIC contains a line length byte, which BASIC uses as a pointer to the next line of code. Before printing the READY prompt, BASIC iterates over every line of code in the @@ -145,10 +141,9 @@ Bad next-line pointer (due to END, STOP, an error, or the Break key), BASIC will get stuck again. - This doesn't *have* to be done with line 32768. Any line of code - that doesn't have to be traversed at runtime would work (in other - words, a regular line whose line number is higher than any code that - ever gets executed, usually the last line in the file). + This doesn't *have* to be done with the last line in the + program. The "poisoned" line could be followed by more lines of + code, though they could never actually execute. Line 32100 in the example above does this job, taking advantage of the STMCUR pointer used by BASIC, which holds the address of the |