Test for PB width < 0, normal PB, or +- limits

Use the absolute value of any negative value that may be passed in via
the width parameter to set_mode.

If RIG_PASSBAND_NORMAL is passed in, call rig_passband_normal() to
determine the normal width for the mode before setting the bandwidth.

The width parameter is tested against wide and narrow filter values and
set to the returned values as upper and lower limits if width falls out
of those bounds.
(cherry picked from commit bb6c6493e1)

kenwood/k3.c

@@ -93,7 +93,7 @@ const struct rig_caps k3_caps = {
 	.rig_model =		RIG_MODEL_K3,
 	.model_name =		"K3/KX3",
 	.mfg_name =		"Elecraft",
-	.version =		"20111122",
+	.version =		"20120615",
 	.copyright =		"LGPL",
 	.status =		RIG_STATUS_BETA,
 	.rig_type =		RIG_TYPE_TRANSCEIVER,
@@ -161,6 +161,7 @@ const struct rig_caps k3_caps = {
 		},
 
 	/* mode/filter list, remember: order matters! */
+	/* Values are arbitrary based on common K3 filter options. */
 	.filters =  {
 		{RIG_MODE_SSB, kHz(2.7)},
 		{RIG_MODE_SSB, kHz(2.8)},
@@ -367,6 +368,21 @@ int k3_set_mode(RIG *rig, vfo_t vfo, rmode_t mode, pbwidth_t width)
 	 * width string value must be padded with leading '0' to equal four
 	 * characters.
 	 */
+
+	/* passband widths vary by mode so gather lower and upper limits */
+	pbwidth_t pb_nar = rig_passband_narrow(rig, mode);
+	pbwidth_t pb_wid = rig_passband_wide(rig, mode);
+
+	if (width < 0)
+		width = labs(width);
+
+	if (width == RIG_PASSBAND_NORMAL)
+		width = rig_passband_normal(rig, mode);
+	else if (width < pb_nar)
+		width = pb_nar;
+	else if (width > pb_wid)
+		width = pb_wid;
+
 	sprintf(cmd_s, "BW%04ld", width / 10);
 	err = kenwood_simple_cmd(rig, cmd_s);
 	if (err != RIG_OK)