Patchwork [v5,17/24] util: add linux bit ordering reversal functions

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Submitter Kuo-Jung Su
Date Feb. 27, 2013, 7:15 a.m.
Message ID <1361949350-22241-18-git-send-email-dantesu@gmail.com>
Download mbox | patch
Permalink /patch/223528/
State New
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Comments

Kuo-Jung Su - Feb. 27, 2013, 7:15 a.m.
From: Kuo-Jung Su <dantesu@faraday-tech.com>

Some ethernet mac relies on the bit ordering reversal functions
to performance the multicast address hash code calculation.
So I've ported the bitrev.[ch] from linux kernel into QEMU.

Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
---
 include/qemu/bitrev.h |   25 +++++++++++++++++++++
 util/Makefile.objs    |    2 +-
 util/bitrev.c         |   59 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 1 deletion(-)
 create mode 100644 include/qemu/bitrev.h
 create mode 100644 util/bitrev.c
Peter Maydell - Feb. 28, 2013, 5:17 p.m.
On 27 February 2013 07:15, Kuo-Jung Su <dantesu@gmail.com> wrote:
> From: Kuo-Jung Su <dantesu@faraday-tech.com>
>
> Some ethernet mac relies on the bit ordering reversal functions
> to performance the multicast address hash code calculation.
> So I've ported the bitrev.[ch] from linux kernel into QEMU.
>
> Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
> ---
>  include/qemu/bitrev.h |   25 +++++++++++++++++++++
>  util/Makefile.objs    |    2 +-
>  util/bitrev.c         |   59 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 85 insertions(+), 1 deletion(-)
>  create mode 100644 include/qemu/bitrev.h
>  create mode 100644 util/bitrev.c
>
> diff --git a/include/qemu/bitrev.h b/include/qemu/bitrev.h
> new file mode 100644
> index 0000000..7d570c2
> --- /dev/null
> +++ b/include/qemu/bitrev.h

There's no need for a new header just for these three functions:
put them in include/qemu/bitops.h.

Similarly, the implementations should go in utils/bitops.c.
There is a minor snag that bitops.[ch] are LGPL2.1+ and this code
is GPL2, but since LGPL lets you "upgrade" the LGPL code to GPL,
we can just mark the whole of bitops.[ch] as GPL by updating the
license statement at the top.

I've cc'd Anthony to advise on the specific mechanics of doing that.

> @@ -0,0 +1,25 @@
> +/*
> + * Bit ordering reversal functions (From linux-kernel/include/linux/bitrev.h)
> + *
> + * Written by Akinobu Mita <akinobu.mita@gmail.com>
> + * Ported to QEMU by Kuo-Jung Su <dantesu@gmail.com>
> + *
> + * This code is licensed under GNU GPL
> + */
> +
> +#ifndef BITREV_H
> +#define BITREV_H
> +
> +#include "qemu-common.h"
> +
> +extern uint8_t const byte_rev_table[256];
> +
> +static inline uint8_t bitrev8(uint8_t byte)
> +{
> +    return byte_rev_table[byte];
> +}
> +
> +extern uint16_t bitrev16(uint16_t in);
> +extern uint32_t bitrev32(uint32_t in);

Please provide documentation comments for all these functions
(in the header file, not in the .c file).

thanks
-- PMM

Patch

diff --git a/include/qemu/bitrev.h b/include/qemu/bitrev.h
new file mode 100644
index 0000000..7d570c2
--- /dev/null
+++ b/include/qemu/bitrev.h
@@ -0,0 +1,25 @@ 
+/*
+ * Bit ordering reversal functions (From linux-kernel/include/linux/bitrev.h)
+ *
+ * Written by Akinobu Mita <akinobu.mita@gmail.com>
+ * Ported to QEMU by Kuo-Jung Su <dantesu@gmail.com>
+ *
+ * This code is licensed under GNU GPL
+ */
+
+#ifndef BITREV_H
+#define BITREV_H
+
+#include "qemu-common.h"
+
+extern uint8_t const byte_rev_table[256];
+
+static inline uint8_t bitrev8(uint8_t byte)
+{
+    return byte_rev_table[byte];
+}
+
+extern uint16_t bitrev16(uint16_t in);
+extern uint32_t bitrev32(uint32_t in);
+
+#endif /* BITREV_H */
diff --git a/util/Makefile.objs b/util/Makefile.objs
index 495a178..3be5427 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -2,7 +2,7 @@  util-obj-y = osdep.o cutils.o qemu-timer-common.o
 util-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o event_notifier-win32.o
 util-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o event_notifier-posix.o
 util-obj-y += envlist.o path.o host-utils.o cache-utils.o module.o
-util-obj-y += bitmap.o bitops.o hbitmap.o
+util-obj-y += bitmap.o bitops.o bitrev.o hbitmap.o
 util-obj-y += acl.o
 util-obj-y += error.o qemu-error.o
 util-obj-$(CONFIG_POSIX) += compatfd.o
diff --git a/util/bitrev.c b/util/bitrev.c
new file mode 100644
index 0000000..c34e79a
--- /dev/null
+++ b/util/bitrev.c
@@ -0,0 +1,59 @@ 
+/*
+ * Bit ordering reversal functions (From linux-kernel/lib/bitrec.c)
+ *
+ * Written by Akinobu Mita <akinobu.mita@gmail.com>
+ * Ported to QEMU by Kuo-Jung Su <dantesu@gmail.com>
+ *
+ * This code is licensed under GNU GPL
+ */
+
+#include "qemu/bitrev.h"
+
+const uint8_t byte_rev_table[256] = {
+    0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
+    0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
+    0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
+    0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
+    0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
+    0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
+    0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
+    0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
+    0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
+    0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
+    0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
+    0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
+    0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
+    0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
+    0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
+    0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
+    0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
+    0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
+    0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
+    0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
+    0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
+    0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
+    0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
+    0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
+    0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
+    0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
+    0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
+    0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
+    0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
+    0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
+    0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
+    0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
+};
+
+uint16_t bitrev16(uint16_t x)
+{
+    return (bitrev8(x & 0xff) << 8) | bitrev8(x >> 8);
+}
+
+/**
+ * bitrev32 - reverse the order of bits in a uint32_t value
+ * @x: value to be bit-reversed
+ */
+uint32_t bitrev32(uint32_t x)
+{
+    return (bitrev16(x & 0xffff) << 16) | bitrev16(x >> 16);
+}