initial commit

lib/initrd.c

@@ -0,0 +1,88 @@
+#include <stddef.h>
+#include <initrd.h>
+#include <kmalloc.h>
+#include <random.h>
+#include <string.h>
+
+#define nullnode ((file_node_t *)0)
+
+void _init_node(file_node_t *node) {
+  node->l = nullnode;
+  node->r = nullnode;
+  node->rand = random();
+  node->node_size = 1;
+}
+
+void _pull_from(file_node_t *to, file_node_t *from)
+{
+  if (!from)
+    return;
+
+  to->node_size += from->node_size;
+}
+
+void _pull(file_node_t *node)
+{
+  node->node_size = 1;
+  _pull_from(node, node->l);
+  _pull_from(node, node->r);
+}
+
+file_node_t *_merge(file_node_t *a, file_node_t *b)
+{
+  if (!a || !b)
+    return a ?: b;
+
+  if (a->rand < b->rand) {
+    a->r = _merge(a->r, b);
+    _pull(a);
+    return a;
+  }
+  b->l = _merge(a, b->l);
+  _pull(b);
+  return b;
+}
+
+void _split(file_node_t *rt, const char *s, file_node_t **a, file_node_t **b)
+{
+  if (!rt) {
+    *a = *b = nullnode;
+    return;
+  }
+
+  if (strcmp(s, rt->filename) < 0) {
+    *a = rt;
+    _split((*a)->r, s, &(*a)->r, b);
+    _pull(*a);
+  } else {
+    *b = rt;
+    _split((*b)->l, s, a, &(*b)->l);
+    _pull(*b);
+  }
+}
+
+
+file_node_t *initrd_init(void)
+{
+  // TODO
+  
+  return nullnode;
+}
+
+file_node_t *_node_bs(file_node_t *cur, const char *s)
+{
+  if (!cur) 
+    return nullnode;
+
+  int cmp = strcmp(s, cur->filename);
+  if (cmp < 0)
+    return _node_bs(cur->r, s);
+  if (cmp > 0)
+    return _node_bs(cur->l, s);
+  return cur; // cmp == 0
+}
+
+file_node_t *initrd_get(file_node_t *root, const char *filename)
+{
+  return _node_bs(root, filename);
+}