Fix Icom IC-756 filter handling.

The IC-756 only has two filters per mode unlike the later IC-756
variants that have three. The code was sending invalid commands
due to trying to select the third filter for certain bandwidths.

Also the default filter bandwidths were incorrect for this model.

Signed-off-by: Nate Bargmann <n0nb@n0nb.us>

icom/ic756.c

@@ -81,13 +81,40 @@
 		 { 247 ,60 } \
 	} }
 
+/*
+ *  This function deals with the older type radios with only 2 filter widths
+ *  (0 - normal, 1 - narrow)
+ */
+static int r2i_mode(RIG *rig, rmode_t mode, pbwidth_t width,
+		    unsigned char *md, signed char *pd)
+{
+  int err;
+
+  err = rig2icom_mode(rig, mode, width, md, pd);
+
+  if (err != RIG_OK)
+    return err;
+
+  if (PD_WIDE_3 == *pd)
+    {
+      *pd = PD_MEDIUM_2;
+    }
+  else if (*pd > PD_WIDE_3)
+    {
+      (*pd)--;
+    }
+
+  return RIG_OK;
+}
+
 /*
  * ic756 rig capabilities.
  */
 static const struct icom_priv_caps ic756_priv_caps = {
 		0x50,	/* default address */
 		0,		/* 731 mode */
-		ic756_ts_sc_list
+		ic756_ts_sc_list,
+		.r2i_mode = r2i_mode
 };
 
 const struct rig_caps ic756_caps = {
@@ -170,11 +197,12 @@ const struct rig_caps ic756_caps = {
 	/* mode/filter list, remember: order matters! */
 .filters = 	{
 		{RIG_MODE_SSB|RIG_MODE_RTTY, kHz(2.4)},
+		{RIG_MODE_CW, kHz(2.4)},
 		{RIG_MODE_CW, Hz(500)},
-		{RIG_MODE_AM, kHz(8)},
+		{RIG_MODE_AM, kHz(9)},
 		{RIG_MODE_AM, kHz(2.4)},
 		{RIG_MODE_FM, kHz(15)},
-		{RIG_MODE_FM, kHz(8)},
+		{RIG_MODE_FM, kHz(9)},
 		RIG_FLT_END,
 	},
 .str_cal = IC756PRO_STR_CAL,