2004-10-27 Marcus Brinkmann <marcus@gnu.org>

	* l4/gnu/space.h (l4_fpage_xspan): New function.

2 files changed, 66 insertions, 0 deletions

diff --git a/libl4/ChangeLog b/libl4/ChangeLog
index c466bf4..ac7e267 100644
--- a/libl4/ChangeLog
+++ b/libl4/ChangeLog
@@ -1,3 +1,7 @@
+2004-10-27  Marcus Brinkmann  <marcus@gnu.org>
+
+	* l4/gnu/space.h (l4_fpage_xspan): New function.
+
 2004-10-23  Marcus Brinkmann  <marcus@gnu.org>
 
 	* l4/gnu/ipc.h (l4_ipc, l4_lipc): New functions.
diff --git a/libl4/l4/gnu/space.h b/libl4/l4/gnu/space.h
index 9ae560e..a09b1ba 100644
--- a/libl4/l4/gnu/space.h
+++ b/libl4/l4/gnu/space.h
@@ -288,3 +288,65 @@ l4_fpage_span (l4_word_t start, l4_word_t end, l4_fpage_t *fpages)
 
   return nr_fpages;
 }
+
+
+/* Determine the fpages covering the (page aligned) virtual address
+   space from START to END (inclusive) under the conditions that it is
+   going to be mapped (or granted) to the virtual address DEST.  START
+   and DEST must be page aligned, while END must be the address of the
+   last byte in the area.  MAX_FPAGES is the count of available fpages
+   that can be stored at FPAGES.  The actual number required can be
+   very large (thousands and tens of thousands) due to bad alignment.
+   The function returns the number of fpages returned in FPAGES.  The
+   generated fpages are fully accessible.  */
+static inline unsigned int
+l4_fpage_xspan (l4_word_t start, l4_word_t end, l4_word_t dest,
+		l4_fpage_t *fpages, l4_word_t max_fpages)
+{
+  l4_word_t min_page_size = l4_min_page_size ();
+  unsigned int nr_fpages = 0;
+
+  if (start > end)
+    return 0;
+
+  /* Round START and DEST down to a multiple of the minimum page size.  */
+  start &= ~(min_page_size - 1);
+  dest &= ~(min_page_size - 1);
+
+  /* Round END up to one less than a multiple of the minimum page size.  */
+  end = (end & ~(min_page_size - 1)) + min_page_size - 1;
+
+  end = ((end + min_page_size) & ~(min_page_size - 1)) - 1;
+
+  /* END is now at least MIN_PAGE_SIZE - 1 larger than START.  */
+  do
+    {
+      unsigned int addr_align;
+      unsigned int dest_align;
+      unsigned int size_align;
+
+      /* Each fpage must be self-aligned.  */
+      addr_align = start ? l4_lsb (start) - 1 : (_L4_MAX_PAGE_SIZE_LOG2 - 1);
+      dest_align = dest ? l4_lsb (dest) - 1 : (_L4_MAX_PAGE_SIZE_LOG2 - 1);
+      size_align = (end + 1 - start) ? l4_msb (end + 1 - start) - 1
+	: (_L4_MAX_PAGE_SIZE_LOG2 - 1);
+
+      if (addr_align < size_align)
+	size_align = addr_align;
+      if (dest_align < size_align)
+	size_align = dest_align;
+
+      fpages[nr_fpages]
+	= l4_fpage_add_rights (l4_fpage_log2 (start, size_align),
+			       L4_FPAGE_FULLY_ACCESSIBLE);
+
+      /* This may overflow and result in zero.  In that case, the
+	 while loop will terminate.  */
+      start += l4_size (fpages[nr_fpages]);
+      dest += l4_size (fpages[nr_fpages]);
+      nr_fpages++;
+    }
+  while (start && start < end && nr_fpages < max_fpages);
+
+  return nr_fpages;
+}