zmalloc: also add alloc at begin of first fit to test differences in

speed and memory fragmentation. alloc at end is faster during loading.
no data yet on memory fragmentation.

lib/zmalloc.c

@@ -45,7 +45,20 @@ void *zmalloc(size_t size) {
     for (p = base; p && !(p->free && p->size >= size); p = p->next) ; // find
     if (!p) return NULL;
 
-    if (p->size - size > block_info_size) { // split, alloc at end
+    if (p->size - size > block_info_size) {
+#if 0
+        // split, alloc at begin
+        struct block_info *q = (void *) p + block_info_size + size;
+        q->next = p->next;
+        p->next = q;
+        q->prev = p;
+        if (q->next) q->next->prev = q;
+        q->size = p->size - block_info_size - size;
+        p->size = size;
+        q->free = 1;
+#endif
+#if 1
+        // split, alloc at end
         struct block_info *q = (void *) p + p->size - size;
         p->size -= size + block_info_size;
         q->size = size;
@@ -54,6 +67,7 @@ void *zmalloc(size_t size) {
         q->prev = p;
         if (q->next) q->next->prev = q;
         p = q;
+#endif
     }
 
     p->free = 0;