# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1651006113 -7200
# Node ID ca77703917089203d4bcd5cf0c8e5f1299745d4b
# Parent  2f085a61c06bec8adabcf62c255ccf25e29b934d
Made page_order able to handle arbitrary sizes, also employing l4util_log2.

diff -r 2f085a61c06b -r ca7770391708 libmem/lib/src/memory_utils.cc
--- a/libmem/lib/src/memory_utils.cc	Tue Apr 26 16:36:17 2022 +0200
+++ b/libmem/lib/src/memory_utils.cc	Tue Apr 26 22:48:33 2022 +0200
@@ -1,7 +1,7 @@
 /*
  * Memory quantity calculation utilities.
  *
- * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk>
+ * Copyright (C) 2021, 2022 Paul Boddie <paul@boddie.org.uk>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -19,6 +19,8 @@
  * Boston, MA  02110-1301, USA
  */
 
+#include <l4/util/bitops.h> /* l4util_log2 */
+
 #include "memory_utils.h"
 
 
@@ -30,15 +32,17 @@
     return PAGE_SIZE * n;
 }
 
-/* Return the order of 'size', where 2 ** order yields the size. */
+/* Return the order of 'size', where 2 ** order yields the size. For sizes not
+   corresponding to 2 ** order precisely, a larger order is returned. */
 
 unsigned int page_order(offset_t size)
 {
-    /* Count zeros from the left, stopping at the first set bit, using the width
-       of the size value (in bits, starting with the width in bytes) to
-       calculate the position of this bit and thus the order of the value. */
+    unsigned int exp = l4util_log2(size);
 
-    return sizeof(unsigned long) * 8 - 1 - __builtin_clzl(size);
+    if ((1UL << exp) < size)
+        return exp + 1;
+    else
+        return exp;
 }
 
 /* Return 'value' rounded up to the nearest 'increment'. */