From 1185226bef2131f4216676d298e7c4e724e8a9bd Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Sat, 22 Jun 2024 15:02:49 -0400
Subject: renumbas: add *useless* -b option (just for shiggles).

---
 renumbas.1   | 11 +++++++++--
 renumbas.c   | 19 ++++++++++++++++---
 renumbas.rst |  9 ++++++++-
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/renumbas.1 b/renumbas.1
index 3252fab..495b204 100644
--- a/renumbas.1
+++ b/renumbas.1
@@ -27,12 +27,12 @@ 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 "RENUMBAS" 1 "2024-06-18" "0.2.1" "Urchlay's Atari 8-bit Tools"
+.TH "RENUMBAS" 1 "2024-06-22" "0.2.1" "Urchlay's Atari 8-bit Tools"
 .SH NAME
 renumbas \- Renumber Atari 8-bit BASIC programs
 .SH SYNOPSIS
 .sp
-renumbas [\fB\-v\fP] [\fB\-s\fP \fIstart\-lineno\fP] [\fB\-i\fP \fIincrement\fP] [\fB\-f\fP \fIfirst\-lineno\fP] \fIinput\-file\fP \fIoutput\-file\fP
+renumbas [\fB\-v\fP] [\fB\-s\fP \fIstart\-lineno\fP] [\fB\-i\fP \fIincrement\fP] [\fB\-f\fP \fIfirst\-lineno\fP] [\fB\-b\fP] \fIinput\-file\fP \fIoutput\-file\fP
 .SH DESCRIPTION
 .sp
 \fBrenumbas\fP reads a tokenized Atari 8\-bit BASIC program and writes a
@@ -86,6 +86,13 @@ Line number increment between successive lines. Default: 10.
 .B \fB\-f\fP \fIfirst\-lineno\fP
 Line number in original program where renumbering will start. Lines
 numbered lower that this will not be renumbered. Default: 0.
+.TP
+.B \fB\-b\fP
+Renumber program backwards (line numbers in descending
+order). This option is completely useless, but exists for testing
+purposes. Programs renumbered this way won\(aqt \fIRUN\fP correctly,
+although they will \fILOAD\fP and \fILIST\fP\&. When using this option, set
+\fB\-s\fP to a higher number than the default.
 .UNINDENT
 .SS General Options
 .INDENT 0.0
diff --git a/renumbas.c b/renumbas.c
index 62a4f07..6f4f51e 100644
--- a/renumbas.c
+++ b/renumbas.c
@@ -13,6 +13,7 @@ unsigned short startlineno = 10;
 unsigned short increment   = 10;
 unsigned short limit       = 0;
 unsigned short newno;
+int backwards = 0;
 
 void print_help(void) {
    printf("Usage: %s [-v] [-s start-lineno] [-i increment] [-f first-lineno] <inputfile> <outputfile>\n", self);
@@ -20,6 +21,7 @@ void print_help(void) {
    printf("  -s <num>: Starting line number (default: 10).\n");
    printf("  -i <num>: Increment (default: 10).\n");
    printf("  -f <num>: Don't renumber lines less than <num> (default: 0).\n");
+	printf("        -b: Number backwards (creates invalid program).\n");
 }
 
 unsigned short getlineno(char opt, const char *arg) {
@@ -46,9 +48,10 @@ unsigned short getlineno(char opt, const char *arg) {
 void parse_args(int argc, char **argv) {
 	int opt;
 
-	while( (opt = getopt(argc, argv, "vs:i:f:")) != -1) {
+	while( (opt = getopt(argc, argv, "vbs:i:f:")) != -1) {
 		switch(opt) {
-			case 'v': verbose = 1; break;
+			case 'v': verbose   = 1; break;
+			case 'b': backwards = 1; break;
 			case 's': startlineno = getlineno(opt, optarg); break;
 			case 'i': increment   = getlineno(opt, optarg); break;
 			case 'f': limit       = getlineno(opt, optarg); break;
@@ -86,7 +89,17 @@ CALLBACK(renumber_line) {
 	for(i = 0; i < refcounts[lineno]; i++)
 		memmove(program + linerefs[lineno][i].pos, fpnewno, 6);
 	setword(pos, newno);
-	newno += increment;
+
+	if(backwards) {
+		if(newno < increment) {
+			fprintf(stderr, "%s: Fatal: New line number %d would be <0.\n", self, newno);
+			exit(1);
+		} else {
+			newno -= increment;
+		}
+	} else {
+		newno += increment;
+	}
 }
 
 void check_refs(void) {
diff --git a/renumbas.rst b/renumbas.rst
index f71bf01..a442ccb 100644
--- a/renumbas.rst
+++ b/renumbas.rst
@@ -10,7 +10,7 @@ Renumber Atari 8-bit BASIC programs
 
 SYNOPSIS
 ========
-renumbas [**-v**] [**-s** *start-lineno*] [**-i** *increment*] [**-f** *first-lineno*] *input-file* *output-file*
+renumbas [**-v**] [**-s** *start-lineno*] [**-i** *increment*] [**-f** *first-lineno*] [**-b**] *input-file* *output-file*
 
 DESCRIPTION
 ===========
@@ -68,6 +68,13 @@ Renumber Options
   Line number in original program where renumbering will start. Lines
   numbered lower that this will not be renumbered. Default: 0.
 
+**-b**
+  Renumber program backwards (line numbers in descending
+  order). This option is completely useless, but exists for testing
+  purposes. Programs renumbered this way won't *RUN* correctly,
+  although they will *LOAD* and *LIST*. When using this option, set
+  **-s** to a higher number than the default.
+
 .. include:: genopts.rst
 
 DIAGNOSTICS
-- 
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