lib: packing: replace bit_reverse() with bitrev8()

Remove bit_reverse() function.  Instead use bitrev8() from linux/bitrev.h +
bitshift.  Reduces code-repetition.

Signed-off-by: Uladzislau Koshchanka <koshchanka@gmail.com>
Link: https://lore.kernel.org/r/20221210004423.32332-1-koshchanka@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/lib/Kconfig b/lib/Kconfig
index 9bbf8a4..cc969ef 100644 (file)
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -24,6 +24,7 @@ config LINEAR_RANGES
 
 config PACKING
        bool "Generic bitfield packing and unpacking"
+       select BITREVERSE
        default n
        help
          This option provides the packing() helper function, which permits

diff --git a/lib/packing.c b/lib/packing.c
index 9a72f4b..a961692 100644 (file)
--- a/lib/packing.c
+++ b/lib/packing.c
@@ -7,6 +7,7 @@
 #include <linux/bitops.h>
 #include <linux/errno.h>
 #include <linux/types.h>
+#include <linux/bitrev.h>
 
 static int get_le_offset(int offset)
 {
@@ -29,19 +30,6 @@ static int get_reverse_lsw32_offset(int offset, size_t len)
        return word_index * 4 + offset;
 }
 
-static u64 bit_reverse(u64 val, unsigned int width)
-{
-       u64 new_val = 0;
-       unsigned int bit;
-       unsigned int i;
-
-       for (i = 0; i < width; i++) {
-               bit = (val & (1 << i)) != 0;
-               new_val |= (bit << (width - i - 1));
-       }
-       return new_val;
-}
-
 static void adjust_for_msb_right_quirk(u64 *to_write, int *box_start_bit,
                                       int *box_end_bit, u8 *box_mask)
 {
@@ -49,7 +37,7 @@ static void adjust_for_msb_right_quirk(u64 *to_write, int *box_start_bit,
        int new_box_start_bit, new_box_end_bit;
 
        *to_write >>= *box_end_bit;
-       *to_write = bit_reverse(*to_write, box_bit_width);
+       *to_write = bitrev8(*to_write) >> (8 - box_bit_width);
        *to_write <<= *box_end_bit;
 
        new_box_end_bit   = box_bit_width - *box_start_bit - 1;