improve -c parsing and doc

4 files changed, 37 insertions, 35 deletions

diff --git a/usage.c b/usage.c
index c3c4b89..e547068 100644
--- a/usage.c
+++ b/usage.c
@@ -2,7 +2,7 @@ char *usage_opts[] = {
 	"  --: no more options.",
 	"  -1: don't alternate colors.",
 	"  -b: bold color output.",
-	"  -c nnnnn: colors (2 to 5 digits, 0 to 7).",
+	"  -c nnnnn: colors (1 to 5 digits, 0 to 7).",
 	"  -d data: dump this data instead of a file.",
 	"  -h, --help: print this help message.",
 	"  -i: print number of bytes/chars/ascii/multibyte/bad sequences.",
diff --git a/uxd.1 b/uxd.1
index 049d649..d891194 100644
--- a/uxd.1
+++ b/uxd.1
@@ -93,7 +93,7 @@ terminal and its color settings. Ignored if \fB\-m\fP given.
 .INDENT 0.0
 .TP
 .BI \-c \ nnnnn
-Set the colors to use. Must be 2 to 5 digits, from 0 to 7. These are
+Set the colors to use. Must be 1 to 5 digits, from 0 to 7. These are
 standard ANSI colors:
 .INDENT 7.0
 .TP
@@ -125,15 +125,19 @@ white
 The first 2 digits are the alternating colors for
 normal characters, the 3rd and 4th (optional) are the alternating colors for non\-printable
 and space characters, and the 5th (optional) is for invalid UTF\-8
-sequences. Default: \fB23561\fP\&. This option also disables a prior \fB\-m\fP
-option.
+sequences.
+.sp
+Default colors are \fB23561\fP\&. If fewer than 5 colors are supplied,
+the remaining colors keep their default values.
 .sp
 Note that the default color set doesn\(aqt include white or black:
 usually one of these is the terminal\(aqs background
 color. Also, it avoids blue, because blue text is hard to read on
 many terminals.
+.sp
+This option also disables a prior \fB\-m\fP option.
 .UNINDENT
-.\" colors (2 to 5 digits, 0 to 7).
+.\" colors (1 to 5 digits, 0 to 7).
 .
 .INDENT 0.0
 .TP
diff --git a/uxd.c b/uxd.c
index a91520c..109cbf8 100644
--- a/uxd.c
+++ b/uxd.c
@@ -204,36 +204,30 @@ void color_error(void) {
 	exit(1);
 }
 
-void check_color(char c) {
+int num_to_color(char c) {
 	if(c < '0' || c > '7') color_error();
+	return c - '0';
 }
 
 void parse_colors(char *arg) {
-	if(!arg[0]) return; /* should never happen anyway */
-
-	/* first 2 are required */
-	check_color(arg[0]);
-	check_color(arg[1]);
-
-	normal_colors[0] = arg[0] - '0';
-	normal_colors[1] = arg[1] - '0';
-
-	/* optional 3rd color */
-	if(!arg[2]) return;
-	check_color(arg[2]);
-	special_colors[0] = arg[2] - '0';
-
-	/* optional 4th color */
-	if(!arg[3]) return;
-	check_color(arg[3]);
-	special_colors[1] = arg[3] - '0';
-
-	/* optional 5th color */
-	if(!arg[4]) return;
-	check_color(arg[4]);
-	bad_color = arg[4] - '0';
-
-	if(arg[5]) color_error();
+	static int *colors[] = {
+		&normal_colors[0],
+		&normal_colors[1],
+		&special_colors[0],
+		&special_colors[1],
+		&bad_color
+	};
+	int i, c;
+
+	i = strlen(arg);
+	if(i < 1 || i > 5)
+		color_error();
+
+	for(i = 0; i < 5; i++) {
+		c = arg[i];
+		if(!c) break;
+		*colors[i] = num_to_color(c);
+	}
 }
 
 void number_err(int opt) {
diff --git a/uxd.rst b/uxd.rst
index eddbd4f..5ef598b 100644
--- a/uxd.rst
+++ b/uxd.rst
@@ -76,7 +76,7 @@ as *K*, *M*, and *G* for power-of-10 based (e.g. *1K* is 1000 bytes).
 .. bold color output.
 
 -c nnnnn
-  Set the colors to use. Must be 2 to 5 digits, from 0 to 7. These are
+  Set the colors to use. Must be 1 to 5 digits, from 0 to 7. These are
   standard ANSI colors:
 
   0
@@ -106,15 +106,19 @@ as *K*, *M*, and *G* for power-of-10 based (e.g. *1K* is 1000 bytes).
   The first 2 digits are the alternating colors for
   normal characters, the 3rd and 4th (optional) are the alternating colors for non-printable
   and space characters, and the 5th (optional) is for invalid UTF-8
-  sequences. Default: **23561**. This option also disables a prior **-m**
-  option.
+  sequences.
+
+  Default colors are **23561**. If fewer than 5 colors are supplied,
+  the remaining colors keep their default values.
 
   Note that the default color set doesn't include white or black:
   usually one of these is the terminal's background
   color. Also, it avoids blue, because blue text is hard to read on
   many terminals.
 
-.. colors (2 to 5 digits, 0 to 7).
+  This option also disables a prior **-m** option.
+
+.. colors (1 to 5 digits, 0 to 7).
 
 -d data
   Dump this data, instead of reading from a file or stdin. If *data*