[SQUASH ME] fixed prefix search

sys/universal_address/universal_address.c

@@ -196,48 +196,47 @@ int universal_address_compare(universal_address_container_t *entry,
         return ret;
     }
 
-    /* Get the index of the first trailing `0` (indicates a prefix) */
-    int i = 0;
-    for( i = entry->address_size-1; i > 0; --i) {
-        if( entry->address[i] != 0 ) {
+    /* compare up to fist distinct byte, pretty clumsy method for now */
+    int idx = -1;
+    bool test_all_zeros = true;
+    for( size_t i = 0; i < entry->address_size; i++) {
+        if ( (idx == -1) && (entry->address[i] != addr[i]) ) {
+            idx = i;
+        }
+        if ( test_all_zeros ) {
+            test_all_zeros = (entry->address[i] == 0);
+        }
+        if ( (idx != -1) && !test_all_zeros ) {
             break;
         }
     }
 
-    /* if the address is all 0 its most probably the default gateway address */
-    if ((i == 0) && (entry->address[i] == 0)) {
+    /* if the address is all 0 its a default route address */
+    if ( test_all_zeros ) {
         *addr_size_in_bits = 0;
         mutex_unlock(&mtx_access);
         return 2;
     } 
 
-    if( memcmp(entry->address, addr, i) == 0 ) {
-        /* if the bytes-1 equals we check the bits of the lowest byte */
-        uint8_t bitmask = 0x00;
-        uint8_t j = 0;
-        /* get a bitmask for the trailing 0b */
-        for( ; j < 8; ++j ) {
-            if ( (entry->address[i] >> j) & 0x01 ) {
-                bitmask = 0xff << j;
-                break;
-            }
-        }
-        if( (entry->address[i] & bitmask) == (addr[i] & bitmask) ) {
-            ret = entry->address[i] != addr[i];
-            *addr_size_in_bits = (i<<3) + (8-j);
-            if( ret == 0 ) {
-                /* check if the remaining bits from addr are significant */
-                i++;
-                for(; i < entry->address_size; ++i) {
-                    if( addr[i] != 0 ) {
-                        ret = 1;
-                        break;
-                    }
-                }
-            }
+    /* if we have no distinct bytes the addresses are equal */
+    if (idx == -1) {
+        mutex_unlock(&mtx_access);
+        return 0;
+    }
+
+    /* count equal bits */
+    uint8_t xor = entry->address[idx]^addr[idx];
+    int8_t j = 7;
+    for( ; j > 0; --j ) {
+        if ( (xor >> j) & 0x01 ) {
+            break;
         }
     }
 
+    /* get the total number of matching bits */
+    *addr_size_in_bits = (idx << 3) + j;
+    ret = 1;
+
     mutex_unlock(&mtx_access);
     return ret;
 }

tests/unittests/tests-fib/tests-fib.c

@@ -664,8 +664,10 @@ static void test_fib_16_prefix_match(void)
     /* test fail */
     addr_dst[14] = (char)0x3c;    /* 0011 1100 */
     addr_lookup[14] = (char)0x34; /* 0011 0100 */
+    addr_lookup[13] += 1; 
     add_buf_size = 16;
     prefix_len = _get_prefix_bits_num(addr_dst, strlen(addr_dst));
+
     fib_add_entry(&test_fib_table, 42, (uint8_t *)addr_dst,
                   add_buf_size - 1, ((prefix_len << FIB_FLAG_NET_PREFIX_SHIFT) | 0x123),
                   (uint8_t *)addr_nxt, add_buf_size -
@@ -681,6 +683,7 @@ static void test_fib_16_prefix_match(void)
 
     /* test success (again) by adjusting the lsb */
     addr_lookup[14] = (char)0x3e; /* 0011 1110 */
+    addr_lookup[13] -= 1; 
     add_buf_size = 16;
 
     memset(addr_nxt, 0, add_buf_size);