LP-585 Add comments + typo

Author: f5soh

flight/pios/common/pios_rfm22b.c

@@ -339,26 +339,26 @@ static const uint32_t data_rate[] = {
 
 static const uint8_t channel_spacing[] = {
     1, /* 9.6kbps */
-    2, /* 19.2kps */
-    2, /* 32kps */
-    2, /* 57.6kps */
-    2, /* 64kps */
-    3, /* 100kps */
-    4, /* 128kps */
-    4, /* 192kps */
-    4, /* 256kps */
+    2, /* 19.2kbps */
+    2, /* 32kbps */
+    2, /* 57.6kbps */
+    2, /* 64kbps */
+    3, /* 100kbps */
+    4, /* 128kbps */
+    4, /* 192kbps */
+    4, /* 256kbps */
 };
 
 static const uint8_t channel_limits[] = {
     1, /* 9.6kbps */
-    1, /* 19.2kps */
-    1, /* 32kps */
-    1, /* 57.6kps */
-    1, /* 64kps */
-    1, /* 100kps */
-    2, /* 128kps */
-    2, /* 192kps */
-    2, /* 256kps */
+    1, /* 19.2kbps */
+    1, /* 32kbps */
+    1, /* 57.6kbps */
+    1, /* 64kbps */
+    1, /* 100kbps */
+    2, /* 128kbps */
+    2, /* 192kbps */
+    2, /* 256kbps */
 };
 
 static const uint8_t reg_1C[] = { 0x01, 0x05, 0x06, 0x95, 0x95, 0x81, 0x88, 0x8B, 0x8D }; // rfm22_if_filter_bandwidth
@@ -2681,11 +2681,16 @@ static void rfm22_hmac_sha1(const uint8_t *data, size_t len,
 static bool rfm22_gen_channels(uint32_t coordid, enum rfm22b_datarate rate, uint8_t min,
                                uint8_t max, uint8_t channels[MAX_CHANNELS], uint8_t *clen)
 {
-    uint32_t data = 0;
-    uint8_t cpos  = 0;
+    // Define first and last channel to be used within min/max values
+    // according to the frequency deviation, without up/down overflow.
     uint8_t chan_min_limit = min + channel_limits[rate];
     uint8_t chan_max_limit = max - channel_limits[rate];
+
+    // Define how many channels we can use according to the spacing.
     uint8_t chan_count     = ((chan_max_limit - chan_min_limit) / channel_spacing[rate]) + 1;
+
+    uint32_t data = 0;
+    uint8_t cpos  = 0;
     uint8_t key[SHA1_DIGEST_LENGTH] = { 0 };
     uint8_t digest[SHA1_DIGEST_LENGTH];
     uint8_t *all_channels;
@@ -2694,6 +2699,7 @@ static bool rfm22_gen_channels(uint32_t coordid, enum rfm22b_datarate rate, uint
 
     memcpy(key, &coordid, sizeof(coordid));
 
+    // Fill all_channels[] with usable channels
     for (int i = 0; i < chan_count; i++) {
         all_channels[i] = chan_min_limit + (i * channel_spacing[rate]);
     }