diff options
| -rw-r--r-- | unprotbas.1 | 22 | ||||
| -rw-r--r-- | unprotbas.c | 24 | ||||
| -rw-r--r-- | unprotbas.rst | 18 |
3 files changed, 45 insertions, 19 deletions
diff --git a/unprotbas.1 b/unprotbas.1 index b8123f1..98e17c4 100644 --- a/unprotbas.1 +++ b/unprotbas.1 @@ -27,7 +27,7 @@ level margin: \\n[rst2man-indent\\n[rst2man-indent-level]] .\" new: \\n[rst2man-indent\\n[rst2man-indent-level]] .in \\n[rst2man-indent\\n[rst2man-indent-level]]u .. -.TH "UNPROTBAS" 1 "2024-05-28" "0.2.1" "Urchlay's Atari 8-bit Tools" +.TH "UNPROTBAS" 1 "2024-05-29" "0.2.1" "Urchlay's Atari 8-bit Tools" .SH NAME unprotbas \- Unprotect or create LIST-protected Atari 8-bit BASIC programs .SH SYNOPSIS @@ -235,11 +235,21 @@ This will fail if there\(aqs already a line 32767. .sp One more thing \fBunprotbas\fP can do is remove extra data from the end of the file. It\(aqs possible for BASIC files to contain extra data that -occurs after the end of the program. Some programs use this as a way -to load arbitrary binary data into memory along with the program; for -other programs, the extra data is truly garbage (e.g. an EOF character -if the file came from a CP/M system, or padding to a block size if a -dumb implementation of XMODEM was used to transfer the file). +occurs after the end of the program. Such data might be: +.INDENT 0.0 +.IP \(bu 2 +Arbitrary binary data used by the program at runtime, such as +machine language routines, or fonts. +.IP \(bu 2 +Zero bytes, caused by SAVEing the program with revision B BASIC. Every +time a program is LOADed, edited (or not) and then SAVEd again, 16 +bytes of extra (garbage) data gets added to the program. To avoid +this, don\(aqt use revision B (use rev C if possible, A otherwise). +.IP \(bu 2 +Garbage added by some system previously used to store or transmit +the file. CP/M systems might add an EOF (^Z) character. Dumb +file transfer software might pad the file up to its block size. +.UNINDENT .sp Normally, such "garbage" doesn\(aqt hurt anything. BASIC ignores it. Or it normally does... if you suspect it\(aqs causing a problem, you can diff --git a/unprotbas.c b/unprotbas.c index 6edb38f..37013cf 100644 --- a/unprotbas.c +++ b/unprotbas.c @@ -37,6 +37,11 @@ /* tokenized colon (statement separator) */ #define TOK_COLON 0x14 +/* variable types, bits 6-7 of byte 0 of each vvtable entry. */ +#define TYPE_SCALAR 0 +#define TYPE_ARRAY 1 +#define TYPE_STRING 2 + /* entire file gets read into memory (for now) */ unsigned char data[BUFSIZE]; @@ -98,7 +103,7 @@ void die(const char *msg) { /* read entire file into memory */ int readfile(void) { - int got = fread(data, 1, 65535, input_file); + int got = fread(data, 1, BUFSIZE - 1, input_file); if(verbose) fprintf(stderr, "read %d bytes\n", got); fclose(input_file); if(got < MIN_PROG_SIZE) @@ -282,7 +287,7 @@ void breakcode(void) { void move_code(int offset) { unsigned char *dest = data + vvstart + offset; - if(dest < data || (filelen + offset) > 65535) { + if(dest < data || ((filelen + offset) > (BUFSIZE - 1))) { die("attempt to move memory out of range; corrupt header bytes?\n"); } @@ -394,9 +399,12 @@ int rebuild_vntable(int write) { } switch(type) { - case 1: varname = arrays++; sigil = 0xa8; break; - case 2: varname = strings++; sigil = 0xa4; break; - default: varname = scalars++; break; + case TYPE_SCALAR: varname = scalars++; break; + case TYPE_ARRAY: varname = arrays++; sigil = 0xa8; break; + case TYPE_STRING: varname = strings++; sigil = 0xa4; break; + default: + fprintf(stderr, "Warning: variable value #%d has unknown type.\n", varnum); + break; } if(varname < 26) { @@ -520,15 +528,15 @@ void check_varname(const unsigned char *name, int line) { /* c now has the last char of the name, make sure it matches the variable type */ type = data[vvstart + 8 * (line - 1)] >> 6; /* type: scalar = 0, array = 1, string = 2 */ - if(type == 0) { + if(type == TYPE_SCALAR) { if(c == '$') die_mapfile("type mismatch: numeric variable may not end with $", line); else if(c == '(') die_mapfile("type mismatch: numeric variable may not end with (", line); - } else if(type == 1) { + } else if(type == TYPE_ARRAY) { if(c != '(') die_mapfile("type mismatch: array variable must end with (", line); - } else if(type == 2) { + } else if(type == TYPE_STRING) { if(c != '$') die_mapfile("type mismatch: string variable must end with $", line); } else { diff --git a/unprotbas.rst b/unprotbas.rst index 1df865f..4228d91 100644 --- a/unprotbas.rst +++ b/unprotbas.rst @@ -208,11 +208,19 @@ Bad next-line pointer One more thing **unprotbas** can do is remove extra data from the end of the file. It's possible for BASIC files to contain extra data that -occurs after the end of the program. Some programs use this as a way -to load arbitrary binary data into memory along with the program; for -other programs, the extra data is truly garbage (e.g. an EOF character -if the file came from a CP/M system, or padding to a block size if a -dumb implementation of XMODEM was used to transfer the file). +occurs after the end of the program. Such data might be: + +- Arbitrary binary data used by the program at runtime, such as + machine language routines, or fonts. + +- Zero bytes, caused by SAVEing the program with revision B BASIC. Every + time a program is LOADed, edited (or not) and then SAVEd again, 16 + bytes of extra (garbage) data gets added to the program. To avoid + this, don't use revision B (use rev C if possible, A otherwise). + +- Garbage added by some system previously used to store or transmit + the file. CP/M systems might add an EOF (^Z) character. Dumb + file transfer software might pad the file up to its block size. Normally, such "garbage" doesn't hurt anything. BASIC ignores it. Or it normally does... if you suspect it's causing a problem, you can |