lrwn: Add get_new_channel_req_dr_range fn.

This function given the data-rates supported by the device, returns the
min_dr / max_dr values to be used with the NewChannelReq mac-command.
Note that in some cases (e.g. in EU868) the min_dr / max_dr have a
special meaning (in which case the max_dr is 0, and the min_dr > 0).

Author: brocaar

lrwn/src/region/as923.rs

@@ -1,4 +1,3 @@
-use std::collections::HashMap;
 use std::time::Duration;
 
 use anyhow::Result;
@@ -996,6 +995,31 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        let dr_min = *data_rates
+            .first()
+            .ok_or_else(|| anyhow!("Can not get first data-rate"))?;
+        let dr_max = *data_rates
+            .last()
+            .ok_or_else(|| anyhow!("Can not get last data-rate"))?;
+
+        if dr_max - dr_min == (data_rates.len() - 1) as u8 {
+            // In case data_rates is a consecutive range.
+            Ok((dr_min, dr_max))
+        } else {
+            // Use special encoding as specified by RP002.
+            match data_rates {
+                [0, 1, 2, 3, 4, 5, 12, 13] => Ok((1, 0)),
+                [1, 2, 3, 4, 5, 12, 13] => Ok((2, 0)),
+                [2, 3, 4, 5, 12, 13] => Ok((3, 0)),
+                [3, 4, 5, 12, 13] => Ok((4, 0)),
+                [4, 5, 12, 13] => Ok((5, 0)),
+                [5, 12, 13] => Ok((6, 0)),
+                _ => Err(anyhow!("Unsupported data-rate range: {:?}", data_rates)),
+            }
+        }
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/au915.rs

@@ -706,6 +706,10 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        self.base.get_new_channel_req_dr_range(data_rates)
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/cn470.rs

@@ -508,6 +508,10 @@ impl Region for Configuration {
         self.base.add_channel(frequency, min_dr, max_dr)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        self.base.get_new_channel_req_dr_range(data_rates)
+    }
+
     fn get_uplink_channel(&self, channel: usize) -> Result<Channel> {
         self.base.get_uplink_channel(channel)
     }

lrwn/src/region/cn779.rs

@@ -464,6 +464,10 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        self.base.get_new_channel_req_dr_range(data_rates)
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/eu433.rs

@@ -702,6 +702,31 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        let dr_min = *data_rates
+            .first()
+            .ok_or_else(|| anyhow!("Can not get first data-rate"))?;
+        let dr_max = *data_rates
+            .last()
+            .ok_or_else(|| anyhow!("Can not get last data-rate"))?;
+
+        if dr_max - dr_min == (data_rates.len() - 1) as u8 {
+            // In case data_rates is a consecutive range.
+            Ok((dr_min, dr_max))
+        } else {
+            // Use special encoding as specified by RP002.
+            match data_rates {
+                [0, 1, 2, 3, 4, 5, 12, 13] => Ok((1, 0)),
+                [1, 2, 3, 4, 5, 12, 13] => Ok((2, 0)),
+                [2, 3, 4, 5, 12, 13] => Ok((3, 0)),
+                [3, 4, 5, 12, 13] => Ok((4, 0)),
+                [4, 5, 12, 13] => Ok((5, 0)),
+                [5, 12, 13] => Ok((6, 0)),
+                _ => Err(anyhow!("Unsupported data-rate range: {:?}", data_rates)),
+            }
+        }
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/eu868.rs

@@ -781,6 +781,31 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        let dr_min = *data_rates
+            .first()
+            .ok_or_else(|| anyhow!("Can not get first data-rate"))?;
+        let dr_max = *data_rates
+            .last()
+            .ok_or_else(|| anyhow!("Can not get last data-rate"))?;
+
+        if dr_max - dr_min == (data_rates.len() - 1) as u8 {
+            // In case data_rates is a consecutive range.
+            Ok((dr_min, dr_max))
+        } else {
+            // Use special encoding as specified by RP002.
+            match data_rates {
+                [0, 1, 2, 3, 4, 5, 12, 13] => Ok((1, 0)),
+                [1, 2, 3, 4, 5, 12, 13] => Ok((2, 0)),
+                [2, 3, 4, 5, 12, 13] => Ok((3, 0)),
+                [3, 4, 5, 12, 13] => Ok((4, 0)),
+                [4, 5, 12, 13] => Ok((5, 0)),
+                [5, 12, 13] => Ok((6, 0)),
+                _ => Err(anyhow!("Unsupported data-rate range: {:?}", data_rates)),
+            }
+        }
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,
@@ -988,6 +1013,20 @@ mod tests {
         }
     }
 
+    #[test]
+    fn get_new_channel_req_dr_range() {
+        let c = Configuration::new(false);
+        let tests: Vec<(Vec<u8>, (u8, u8))> = vec![
+            (vec![0, 1, 2, 3, 4, 5], (0, 5)),
+            (vec![0, 1, 2, 3, 4, 5, 12, 13], (1, 0)),
+            (vec![5, 12, 13], (6, 0)),
+        ];
+
+        for t in &tests {
+            assert_eq!(t.1, c.get_new_channel_req_dr_range(&t.0).unwrap());
+        }
+    }
+
     #[test]
     fn get_user_defined_uplink_channel_indices() {
         assert_eq!(

lrwn/src/region/in865.rs

@@ -610,6 +610,31 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        let dr_min = *data_rates
+            .first()
+            .ok_or_else(|| anyhow!("Can not get first data-rate"))?;
+        let dr_max = *data_rates
+            .last()
+            .ok_or_else(|| anyhow!("Can not get last data-rate"))?;
+
+        if dr_max - dr_min == (data_rates.len() - 1) as u8 {
+            // In case data_rates is a consecutive range.
+            Ok((dr_min, dr_max))
+        } else {
+            // Use special encoding as specified by RP002.
+            match data_rates {
+                [0, 1, 2, 3, 4, 5, 12, 13] => Ok((1, 0)),
+                [1, 2, 3, 4, 5, 12, 13] => Ok((2, 0)),
+                [2, 3, 4, 5, 12, 13] => Ok((3, 0)),
+                [3, 4, 5, 12, 13] => Ok((4, 0)),
+                [4, 5, 12, 13] => Ok((5, 0)),
+                [5, 12, 13] => Ok((6, 0)),
+                _ => Err(anyhow!("Unsupported data-rate range: {:?}", data_rates)),
+            }
+        }
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/ism2400.rs

@@ -290,6 +290,10 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        self.base.get_new_channel_req_dr_range(data_rates)
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/kr920.rs

@@ -558,6 +558,31 @@ impl Region for Configuration {
         self.base.get_data_rate(uplink, dr_index)
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        let dr_min = *data_rates
+            .first()
+            .ok_or_else(|| anyhow!("Can not get first data-rate"))?;
+        let dr_max = *data_rates
+            .last()
+            .ok_or_else(|| anyhow!("Can not get last data-rate"))?;
+
+        if dr_max - dr_min == (data_rates.len() - 1) as u8 {
+            // In case data_rates is a consecutive range.
+            Ok((dr_min, dr_max))
+        } else {
+            // Use special encoding as specified by RP002.
+            match data_rates {
+                [0, 1, 2, 3, 4, 5, 12, 13] => Ok((1, 0)),
+                [1, 2, 3, 4, 5, 12, 13] => Ok((2, 0)),
+                [2, 3, 4, 5, 12, 13] => Ok((3, 0)),
+                [3, 4, 5, 12, 13] => Ok((4, 0)),
+                [4, 5, 12, 13] => Ok((5, 0)),
+                [5, 12, 13] => Ok((6, 0)),
+                _ => Err(anyhow!("Unsupported data-rate range: {:?}", data_rates)),
+            }
+        }
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,

lrwn/src/region/mod.rs

@@ -414,6 +414,14 @@ pub trait Region {
     /// Returns the modulation parameters given the data-rate.
     fn get_data_rate(&self, uplink: bool, dr_index: u8) -> Result<DataRateModulation>;
 
+    /// Returns the NewChannelReq data-rate range for the given data-rates.
+    /// Notes:
+    /// * It is expected that the provided range is sorted.
+    /// * By default this returns the first item as min_dr and the last item
+    ///   as max_dr. For some regions, there can be gaps in the range and a
+    ///   special encoding is used (e.g. in case of EU868).
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)>;
+
     /// Returns the max downlink payload-size for the given data-rate index, protocol version
     /// and regional-parameters revision.
     /// When the version or revision is unknown, it will return the most recent
@@ -566,6 +574,14 @@ impl RegionBaseConfig {
         ))
     }
 
+    fn get_new_channel_req_dr_range(&self, data_rates: &[u8]) -> Result<(u8, u8)> {
+        if data_rates.is_empty() {
+            return Err(anyhow!("data_rates can not be empty"));
+        }
+
+        Ok((data_rates[0], data_rates[data_rates.len() - 1]))
+    }
+
     fn get_max_dl_payload_size(
         &self,
         mac_version: MacVersion,