Add support for shortened mnemonic elements

src/wordlist.c

@@ -6,6 +6,10 @@ static int bstrcmp(const void *l, const void *r)
     return strcmp(l, (*(const char **)r));
 }
 
+static int bstr4cmp(const void *l, const void *r) {
+    return strncmp(l, (*(const char **)r), 4);
+}
+
 /* https://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious */
 static int get_bits(size_t n)
 {
@@ -72,12 +76,12 @@ size_t wordlist_lookup_word(const struct words *w, const char *word)
     const size_t size = sizeof(const char *);
     const char **found = NULL;
 
-    if (w->sorted)
-        found = (const char **)bsearch(word, w->indices, w->len, size, bstrcmp);
-    else {
+    if (w->sorted) {
+        found = (const char **)bsearch(word, w->indices, w->len, size, bstr4cmp);
+    } else {
         size_t i;
         for (i = 0; i < w->len && !found; ++i)
-            if (!strcmp(word, w->indices[i]))
+            if (!strncmp(word, w->indices[i], 4))
                 found = w->indices + i;
     }
     return found ? found - w->indices + 1u : 0u;