1 files changed, 84 insertions, 0 deletions
diff --git a/libstore/derive.c b/libstore/derive.c
new file mode 100644
index 00000000..8c0b2790
--- /dev/null
+++ b/libstore/derive.c
@@ -0,0 +1,84 @@
+/* Calculation of various derived store fields
+
+   Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   The GNU Hurd is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
+
+#include <assert.h>
+
+#include "store.h"
+
+/* Fills in the values of the various fields in STORE that are derivable from
+   the set of runs & the block size.  */
+void
+_store_derive (struct store *store)
+{
+  unsigned i;
+  struct store_run *runs = store->runs;
+  unsigned num_runs = store->num_runs;
+  size_t bsize = store->block_size;
+
+  /* BLOCK & SIZE */
+  store->blocks = 0;
+
+  for (i = 0; i < num_runs; i++)
+    {
+      store->wrap_src += runs[i].length;
+      if (runs[i].start >= 0)	/* Not a hole */
+	store->blocks += runs[i].length;
+    }
+
+  if (store->end == 0)
+    /* END not set; set it using the info from RUNS.  */
+    store->end = store->wrap_src;
+  else if (store->wrap_src < store->end)
+    /* A wrapped disk!  RUNS is repeated N times to reach END.  Adjust BLOCKS
+       to include all iterations.  */
+    {
+      size_t num_iters = store->end / store->wrap_src;
+      off_t last_part_base = num_iters * store->wrap_src;
+
+      store->blocks *= num_iters;
+
+      for (i = 0; i < num_runs; i++)
+	if (last_part_base + runs[i].length < store->end)
+	  {
+	    store->blocks += store->end - (last_part_base + runs[i].length);
+	    break;
+	  }
+	else if (runs[i].start >= 0)
+	  store->blocks += runs[i].length;
+
+      /* WRAP_DST must be set by the caller.  */
+    }
+
+  store->size = store->end * bsize;
+
+  store->log2_block_size = 0;
+  store->log2_blocks_per_page = 0;
+
+  if (bsize != 0)
+    {
+      while ((1 << store->log2_block_size) < bsize)
+	store->log2_block_size++;
+      assert ((1 << store->log2_block_size) == bsize);
+
+      while ((bsize << store->log2_blocks_per_page) < vm_page_size)
+	store->log2_blocks_per_page++;
+      assert ((bsize << store->log2_blocks_per_page) == vm_page_size);
+    }
+}