universal_address: replaced returned literals by defined constants

* added and adjusted doxy for the new defined return values
* stripped whitespaces for statements in the compare functions

sys/include/universal_address.h

@@ -42,6 +42,17 @@ extern "C" {
 #define UNIVERSAL_ADDRESS_SIZE (IPV6_ADDR_BIT_LEN >> 3)
 #endif
 
+/** @brief return value indicating the compared addresses are equal */
+#define UNIVERSAL_ADDRESS_EQUAL (0)
+
+/** @brief return value indicating the compared addresses match up to a certain prefix */
+#define UNIVERSAL_ADDRESS_MATCHING_PREFIX (1)
+
+/** @brief return value indicating all address bits of the entry are `0`.
+ *         Its considered as default route address that matches any other prefix.
+ */
+#define UNIVERSAL_ADDRESS_IS_ALL_ZERO_ADDRESS (2)
+
 /**
  * @brief The container descriptor used to identify a universal address entry
  */
@@ -69,7 +80,7 @@ void universal_address_reset(void);
  * @param[in] addr_size  the number of bytes required for the address entry
  *
  * @return pointer to the universal_address_container_t containing the address on success
- *         NULL if the address could not be inserted
+ * @return NULL if the address could not be inserted
  */
 universal_address_container_t *universal_address_add(uint8_t *addr, size_t addr_size);
 
@@ -90,7 +101,7 @@ void universal_address_rem(universal_address_container_t *entry);
  *                           this value is overwritten with the actual size required
  *
  * @return addr if the address is copied to the addr destination
- *         NULL if the size is unsufficient for copy
+ * @return NULL if the size is unsufficient for copy
  */
 uint8_t* universal_address_get_address(universal_address_container_t *entry,
                                        uint8_t *addr, size_t *addr_size);
@@ -107,9 +118,12 @@ uint8_t* universal_address_get_address(universal_address_container_t *entry,
  *                                    with the number of matching bits till the
  *                                    first of trailing `0`s
  *
- * @return 0 if the entries are equal
- *         1 if the entry match to a certain prefix (trailing '0's in *entry)
- *         -ENOENT if the given adresses do not match
+ * @return UNIVERSAL_ADDRESS_EQUAL if the entries are equal
+ * @return UNIVERSAL_ADDRESS_MATCHING_PREFIX if the entry matches to a certain prefix
+ *                                           (trailing '0's in @p entry)
+ * @return UNIVERSAL_ADDRESS_IS_ALL_ZERO_ADDRESS if the entry address is all `0`s
+ *                                               and considered as default route
+ * @return -ENOENT if the given adresses do not match
  */
 int universal_address_compare(universal_address_container_t *entry,
                               uint8_t *addr, size_t *addr_size_in_bits);
@@ -128,9 +142,10 @@ int universal_address_compare(universal_address_container_t *entry,
 *                                e.g. for an ipv6_addr_t it would be sizeof(ipv6_addr_t)
 *                                regardless if the stored prefix is < ::/128
 *
-* @return 0 if the entries are equal
-*         1 if the entry match to a certain prefix (trailing '0's in *prefix)
-*         -ENOENT if the given adresses do not match
+* @return UNIVERSAL_ADDRESS_EQUAL if the entries are equal
+* @return UNIVERSAL_ADDRESS_MATCHING_PREFIX if the entry matches to a certain prefix
+*                                           (trailing '0's in @p prefix)
+* @return -ENOENT if the given adresses do not match
 */
 int universal_address_compare_prefix(universal_address_container_t *entry,
                             uint8_t *prefix, size_t prefix_size_in_bits);

sys/universal_address/universal_address.c

@@ -215,13 +215,13 @@ int universal_address_compare(universal_address_container_t *entry,
     if (test_all_zeros) {
         *addr_size_in_bits = 0;
         mutex_unlock(&mtx_access);
-        return 2;
-    } 
+        return UNIVERSAL_ADDRESS_IS_ALL_ZERO_ADDRESS;
+    }
 
     /* if we have no distinct bytes the addresses are equal */
     if (idx == -1) {
         mutex_unlock(&mtx_access);
-        return 0;
+        return UNIVERSAL_ADDRESS_EQUAL;
     }
 
     /* count equal bits */
@@ -235,7 +235,7 @@ int universal_address_compare(universal_address_container_t *entry,
 
     /* get the total number of matching bits */
     *addr_size_in_bits = (idx << 3) + j;
-    ret = 1;
+    ret = UNIVERSAL_ADDRESS_MATCHING_PREFIX;
 
     mutex_unlock(&mtx_access);
     return ret;
@@ -254,31 +254,31 @@ int universal_address_compare_prefix(universal_address_container_t *entry,
 
     /* Get the index of the first trailing `0` */
     int i = 0;
-    for( i = entry->address_size-1; i >= 0; --i) {
-        if( prefix[i] != 0 ) {
+    for (i = entry->address_size-1; i >= 0; --i) {
+        if (prefix[i] != 0) {
             break;
         }
     }
 
-    if( memcmp(entry->address, prefix, i) == 0 ) {
+    if (memcmp(entry->address, prefix, i) == 0) {
         /* if the bytes-1 equals we check the bits of the lowest byte */
         uint8_t bitmask = 0x00;
         /* get a bitmask for the trailing 0b */
-        for( uint8_t j = 0; j < 8; ++j ) {
-            if ( (prefix[i] >> j) & 0x01 ) {
+        for (uint8_t j = 0; j < 8; ++j) {
+            if ((prefix[i] >> j) & 0x01) {
                 bitmask = 0xff << j;
                 break;
             }
         }
 
-        if( (entry->address[i] & bitmask) == (prefix[i] & bitmask) ) {
+        if ((entry->address[i] & bitmask) == (prefix[i] & bitmask)) {
             ret = entry->address[i] != prefix[i];
-            if( ret == 0 ) {
+            if (ret == UNIVERSAL_ADDRESS_EQUAL) {
                 /* check if the remaining bits from entry are significant */
                 i++;
-                for(; i < entry->address_size; ++i) {
-                    if( entry->address[i] != 0 ) {
-                        ret = 1;
+                for ( ; i < entry->address_size; ++i) {
+                    if (entry->address[i] != 0) {
+                        ret = UNIVERSAL_ADDRESS_MATCHING_PREFIX;
                         break;
                     }
                 }