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Re: [XEN PATCH][for-4.19 v3 1/8] xen/include: add macro LOWEST_BIT
- To: Julien Grall <julien@xxxxxxx>
- From: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
- Date: Mon, 23 Oct 2023 09:31:05 +0200
- Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, sstabellini@xxxxxxxxxx, michal.orzel@xxxxxxx, xenia.ragiadakou@xxxxxxx, ayan.kumar.halder@xxxxxxx, consulting@xxxxxxxxxxx, jbeulich@xxxxxxxx, andrew.cooper3@xxxxxxxxxx, roger.pau@xxxxxxxxxx, Simone Ballarin <simone.ballarin@xxxxxxxxxxx>, Doug Goldstein <cardoe@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Mon, 23 Oct 2023 07:31:14 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 20/10/2023 19:03, Julien Grall wrote:
Hi Nicola,
On 20/10/2023 16:28, Nicola Vetrini wrote:
diff --git a/xen/include/xen/macros.h b/xen/include/xen/macros.h
index d0caae7db298..49f3ebf848e9 100644
--- a/xen/include/xen/macros.h
+++ b/xen/include/xen/macros.h
@@ -8,8 +8,11 @@
#define DIV_ROUND(n, d) (((n) + (d) / 2) / (d))
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
-#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
-#define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))
+/* Returns the 2^ffs(x) or 0, where ffs(x) is the index of the lowest
set bit */
+#define LOWEST_BIT(x) ((x) & -(x))
+
+#define MASK_EXTR(v, m) (((v) & (m)) / LOWEST_BIT(m))
+#define MASK_INSR(v, m) (((v) * LOWEST_BIT(m)) & (m))
#define count_args_(dot, a1, a2, a3, a4, a5, a6, a7, a8, x, ...) x
#define count_args(args...) \
diff --git a/xen/include/xen/types.h b/xen/include/xen/types.h
index aea259db1ef2..23cad71c8a47 100644
--- a/xen/include/xen/types.h
+++ b/xen/include/xen/types.h
I don't understand how the changes in this file are related to the
commit. Did you intend to create a separate commit?
The rest LGTM.
Oh, I made a mistake. This hunk should have been part of patch 7 as a
cleanup.
I can resubmit with this removed, or it could be ignored altogether.
@@ -31,9 +31,9 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
#define NULL ((void*)0)
#endif
-#define INT8_MIN (-127-1)
-#define INT16_MIN (-32767-1)
-#define INT32_MIN (-2147483647-1)
+#define INT8_MIN (-127 - 1)
+#define INT16_MIN (-32767 - 1)
+#define INT32_MIN (-2147483647 - 1)
#define INT8_MAX (127)
#define INT16_MAX (32767)
@@ -43,10 +43,10 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
#define UINT16_MAX (65535)
#define UINT32_MAX (4294967295U)
-#define INT_MAX ((int)(~0U>>1))
+#define INT_MAX ((int)(~0U >> 1))
#define INT_MIN (-INT_MAX - 1)
#define UINT_MAX (~0U)
-#define LONG_MAX ((long)(~0UL>>1))
+#define LONG_MAX ((long)(~0UL >> 1))
#define LONG_MIN (-LONG_MAX - 1)
#define ULONG_MAX (~0UL)
Cheers,
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)
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