1 files changed, 473 insertions, 0 deletions

diff --git a/src/vppinfra/fheap.c b/src/vppinfra/fheap.c
new file mode 100644
index 00000000..13692456
--- /dev/null
+++ b/src/vppinfra/fheap.c
@@ -0,0 +1,473 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <vppinfra/fheap.h>
+
+/* Fibonacci heaps. */
+always_inline fheap_node_t *
+fheap_get_node (fheap_t * f, u32 i)
+{
+  return i != ~0 ? vec_elt_at_index (f->nodes, i) : 0;
+}
+
+always_inline fheap_node_t *
+fheap_get_root (fheap_t * f)
+{
+  return fheap_get_node (f, f->min_root);
+}
+
+static void
+fheap_validate (fheap_t * f)
+{
+  fheap_node_t *n, *m;
+  uword ni, si;
+
+  if (!CLIB_DEBUG || !f->enable_validate)
+    return;
+
+  vec_foreach_index (ni, f->nodes)
+  {
+    n = vec_elt_at_index (f->nodes, ni);
+
+    if (!n->is_valid)
+      continue;
+
+    /* Min root must have minimal key. */
+    m = vec_elt_at_index (f->nodes, f->min_root);
+    ASSERT (n->key >= m->key);
+
+    /* Min root must have no parent. */
+    if (ni == f->min_root)
+      ASSERT (n->parent == ~0);
+
+    /* Check sibling linkages. */
+    if (n->next_sibling == ~0)
+      ASSERT (n->prev_sibling == ~0);
+    else if (n->prev_sibling == ~0)
+      ASSERT (n->next_sibling == ~0);
+    else
+      {
+	fheap_node_t *prev, *next;
+	u32 si = n->next_sibling, si_start = si;
+	do
+	  {
+	    m = vec_elt_at_index (f->nodes, si);
+	    prev = vec_elt_at_index (f->nodes, m->prev_sibling);
+	    next = vec_elt_at_index (f->nodes, m->next_sibling);
+	    ASSERT (prev->next_sibling == si);
+	    ASSERT (next->prev_sibling == si);
+	    si = m->next_sibling;
+	  }
+	while (si != si_start);
+      }
+
+    /* Loop through all siblings. */
+    {
+      u32 n_siblings = 0;
+
+      foreach_fheap_node_sibling (f, si, n->next_sibling, (
+							    {
+							    m =
+							    vec_elt_at_index
+							    (f->nodes, si);
+							    /* All siblings must have same parent. */
+							    ASSERT (m->parent
+								    ==
+								    n->
+								    parent);
+							    n_siblings += 1;}
+				  ));
+
+      /* Either parent is non-empty or there are siblings present. */
+      if (n->parent == ~0 && ni != f->min_root)
+	ASSERT (n_siblings > 0);
+    }
+
+    /* Loop through all children. */
+    {
+      u32 found_first_child = n->first_child == ~0;
+      u32 n_children = 0;
+
+      foreach_fheap_node_sibling (f, si, n->first_child, (
+							   {
+							   m =
+							   vec_elt_at_index
+							   (f->nodes, si);
+							   /* Children must have larger keys than their parent. */
+							   ASSERT (m->key >=
+								   n->key);
+							   if
+							   (!found_first_child)
+							   found_first_child =
+							   si ==
+							   n->first_child;
+							   n_children += 1;}
+				  ));
+
+      /* Check that first child is present on list. */
+      ASSERT (found_first_child);
+
+      /* Make sure rank is correct. */
+      ASSERT (n->rank == n_children);
+    }
+  }
+
+  /* Increment serial number for each successful validate.
+     Failure can be used as condition for gdb breakpoints. */
+  f->validate_serial++;
+}
+
+always_inline void
+fheap_node_add_sibling (fheap_t * f, u32 ni, u32 ni_to_add)
+{
+  fheap_node_t *n = vec_elt_at_index (f->nodes, ni);
+  fheap_node_t *n_to_add = vec_elt_at_index (f->nodes, ni_to_add);
+  fheap_node_t *n_next = fheap_get_node (f, n->next_sibling);
+  fheap_node_t *parent;
+
+  /* Empty list? */
+  if (n->next_sibling == ~0)
+    {
+      ASSERT (n->prev_sibling == ~0);
+      n->next_sibling = n->prev_sibling = ni_to_add;
+      n_to_add->next_sibling = n_to_add->prev_sibling = ni;
+    }
+  else
+    {
+      /* Add node after existing node. */
+      n_to_add->prev_sibling = ni;
+      n_to_add->next_sibling = n->next_sibling;
+
+      n->next_sibling = ni_to_add;
+      n_next->prev_sibling = ni_to_add;
+    }
+
+  n_to_add->parent = n->parent;
+  parent = fheap_get_node (f, n->parent);
+  if (parent)
+    parent->rank += 1;
+}
+
+void
+fheap_add (fheap_t * f, u32 ni, u32 key)
+{
+  fheap_node_t *r, *n;
+  u32 ri;
+
+  n = vec_elt_at_index (f->nodes, ni);
+
+  memset (n, 0, sizeof (n[0]));
+  n->parent = n->first_child = n->next_sibling = n->prev_sibling = ~0;
+  n->key = key;
+
+  r = fheap_get_root (f);
+  ri = f->min_root;
+  if (!r)
+    {
+      /* No root?  Add node as new root. */
+      f->min_root = ni;
+    }
+  else
+    {
+      /* Add node as sibling of current root. */
+      fheap_node_add_sibling (f, ri, ni);
+
+      /* New node may become new root. */
+      if (r->key > n->key)
+	f->min_root = ni;
+    }
+
+  fheap_validate (f);
+}
+
+always_inline u32
+fheap_node_remove_internal (fheap_t * f, u32 ni, u32 invalidate)
+{
+  fheap_node_t *n = vec_elt_at_index (f->nodes, ni);
+  u32 prev_ni = n->prev_sibling;
+  u32 next_ni = n->next_sibling;
+  u32 list_has_single_element = prev_ni == ni;
+  fheap_node_t *prev = fheap_get_node (f, prev_ni);
+  fheap_node_t *next = fheap_get_node (f, next_ni);
+  fheap_node_t *p = fheap_get_node (f, n->parent);
+
+  if (p)
+    {
+      ASSERT (p->rank > 0);
+      p->rank -= 1;
+      p->first_child = list_has_single_element ? ~0 : next_ni;
+    }
+
+  if (prev)
+    {
+      ASSERT (prev->next_sibling == ni);
+      prev->next_sibling = next_ni;
+    }
+  if (next)
+    {
+      ASSERT (next->prev_sibling == ni);
+      next->prev_sibling = prev_ni;
+    }
+
+  n->prev_sibling = n->next_sibling = ni;
+  n->parent = ~0;
+  n->is_valid = invalidate == 0;
+
+  return list_has_single_element ? ~0 : next_ni;
+}
+
+always_inline u32
+fheap_node_remove (fheap_t * f, u32 ni)
+{
+  return fheap_node_remove_internal (f, ni, /* invalidate */ 0);
+}
+
+always_inline u32
+fheap_node_remove_and_invalidate (fheap_t * f, u32 ni)
+{
+  return fheap_node_remove_internal (f, ni, /* invalidate */ 1);
+}
+
+static void
+fheap_link_root (fheap_t * f, u32 ni)
+{
+  fheap_node_t *n = vec_elt_at_index (f->nodes, ni);
+  fheap_node_t *r, *lo, *hi;
+  u32 ri, lo_i, hi_i, k;
+
+  while (1)
+    {
+      k = n->rank;
+      vec_validate_init_empty (f->root_list_by_rank, k, ~0);
+      ri = f->root_list_by_rank[k];
+      r = fheap_get_node (f, ri);
+      if (!r)
+	{
+	  f->root_list_by_rank[k] = ni;
+	  return;
+	}
+
+      f->root_list_by_rank[k] = ~0;
+
+      /* Sort n/r into lo/hi by their keys. */
+      lo = r, lo_i = ri;
+      hi = n, hi_i = ni;
+      if (hi->key < lo->key)
+	{
+	  u32 ti;
+	  fheap_node_t *tn;
+	  ti = lo_i, tn = lo;
+	  lo = hi, lo_i = hi_i;
+	  hi = tn, hi_i = ti;
+	}
+
+      /* Remove larger key. */
+      fheap_node_remove (f, hi_i);
+
+      /* Add larger key as child of smaller one. */
+      if (lo->first_child == ~0)
+	{
+	  hi->parent = lo_i;
+	  lo->first_child = hi_i;
+	  lo->rank = 1;
+	}
+      else
+	fheap_node_add_sibling (f, lo->first_child, hi_i);
+
+      /* Following Fredman & Trajan: "When making a root node X a child of another node in a linking step,
+         we unmark X". */
+      hi->is_marked = 0;
+
+      ni = lo_i;
+      n = lo;
+    }
+}
+
+u32
+fheap_del_min (fheap_t * f, u32 * min_key)
+{
+  fheap_node_t *r = fheap_get_root (f);
+  u32 to_delete_min_ri = f->min_root;
+  u32 ri, ni;
+
+  /* Empty heap? */
+  if (!r)
+    return ~0;
+
+  /* Root's children become siblings.  Call this step a; see below. */
+  if (r->first_child != ~0)
+    {
+      u32 ci, cni, rni;
+      fheap_node_t *c, *cn, *rn;
+
+      /* Splice child & root circular lists together. */
+      ci = r->first_child;
+      c = vec_elt_at_index (f->nodes, ci);
+
+      cni = c->next_sibling;
+      rni = r->next_sibling;
+      cn = vec_elt_at_index (f->nodes, cni);
+      rn = vec_elt_at_index (f->nodes, rni);
+
+      r->next_sibling = cni;
+      c->next_sibling = rni;
+      cn->prev_sibling = to_delete_min_ri;
+      rn->prev_sibling = ci;
+    }
+
+  /* Remove min root. */
+  ri = fheap_node_remove_and_invalidate (f, to_delete_min_ri);
+
+  /* Find new min root from among siblings including the ones we've just added. */
+  f->min_root = ~0;
+  if (ri != ~0)
+    {
+      u32 ri_last, ri_next, i, min_ds;
+
+      r = fheap_get_node (f, ri);
+      ri_last = r->prev_sibling;
+      while (1)
+	{
+	  /* Step a above can put children (with r->parent != ~0) on root list. */
+	  r->parent = ~0;
+
+	  ri_next = r->next_sibling;
+	  fheap_link_root (f, ri);
+	  if (ri == ri_last)
+	    break;
+	  ri = ri_next;
+	  r = fheap_get_node (f, ri);
+	}
+
+      min_ds = ~0;
+      vec_foreach_index (i, f->root_list_by_rank)
+      {
+	ni = f->root_list_by_rank[i];
+	if (ni == ~0)
+	  continue;
+	f->root_list_by_rank[i] = ~0;
+	r = fheap_get_node (f, ni);
+	if (r->key < min_ds)
+	  {
+	    f->min_root = ni;
+	    min_ds = r->key;
+	    ASSERT (r->parent == ~0);
+	  }
+      }
+    }
+
+  /* Return deleted min root. */
+  r = vec_elt_at_index (f->nodes, to_delete_min_ri);
+  if (min_key)
+    *min_key = r->key;
+
+  fheap_validate (f);
+
+  return to_delete_min_ri;
+}
+
+static void
+fheap_mark_parent (fheap_t * f, u32 pi)
+{
+  fheap_node_t *p = vec_elt_at_index (f->nodes, pi);
+
+  /* Parent is a root: do nothing. */
+  if (p->parent == ~0)
+    return;
+
+  /* If not marked, mark it. */
+  if (!p->is_marked)
+    {
+      p->is_marked = 1;
+      return;
+    }
+
+  /* Its a previously marked, non-root parent.
+     Cut edge to its parent and add to root list. */
+  fheap_node_remove (f, pi);
+  fheap_node_add_sibling (f, f->min_root, pi);
+
+  /* Unmark it since its now a root node. */
+  p->is_marked = 0;
+
+  /* "Cascading cuts": check parent. */
+  if (p->parent != ~0)
+    fheap_mark_parent (f, p->parent);
+}
+
+/* Set key to new smaller value. */
+void
+fheap_decrease_key (fheap_t * f, u32 ni, u32 new_key)
+{
+  fheap_node_t *n = vec_elt_at_index (f->nodes, ni);
+  fheap_node_t *r = fheap_get_root (f);
+
+  n->key = new_key;
+
+  if (n->parent != ~0)
+    {
+      fheap_mark_parent (f, n->parent);
+
+      /* Remove node and add to root list. */
+      fheap_node_remove (f, ni);
+      fheap_node_add_sibling (f, f->min_root, ni);
+    }
+
+  if (n->key < r->key)
+    f->min_root = ni;
+
+  fheap_validate (f);
+}
+
+void
+fheap_del (fheap_t * f, u32 ni)
+{
+  fheap_node_t *n;
+
+  n = vec_elt_at_index (f->nodes, ni);
+
+  if (n->parent == ~0)
+    {
+      ASSERT (ni == f->min_root);
+      fheap_del_min (f, 0);
+    }
+  else
+    {
+      u32 ci;
+
+      fheap_mark_parent (f, n->parent);
+
+      /* Add children to root list. */
+      foreach_fheap_node_sibling (f, ci, n->first_child, (
+							   {
+							   fheap_node_remove
+							   (f, ci);
+							   fheap_node_add_sibling
+							   (f, f->min_root,
+							    ci);}
+				  ));
+
+      fheap_node_remove_and_invalidate (f, ni);
+    }
+
+  fheap_validate (f);
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */