qemu/bitops.h: add bitrev8 implementation

This will be required for an upcoming checksum calculation.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Finn Thain <fthain@linux-m68k.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210625065401.30170-7-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
This commit is contained in:
Mark Cave-Ayland 2021-06-25 07:53:57 +01:00 committed by Philippe Mathieu-Daudé
parent c3250c8e6b
commit db1ffc32dd

View File

@ -618,4 +618,26 @@ static inline uint64_t half_unshuffle64(uint64_t x)
return x;
}
/**
* bitrev8:
* @x: 8-bit value to be reversed
*
* Given an input value with bits::
*
* ABCDEFGH
*
* return the value with its bits reversed from left to right::
*
* HGFEDCBA
*
* Returns: the bit-reversed value.
*/
static inline uint8_t bitrev8(uint8_t x)
{
x = ((x >> 1) & 0x55) | ((x << 1) & 0xaa);
x = ((x >> 2) & 0x33) | ((x << 2) & 0xcc);
x = (x >> 4) | (x << 4) ;
return x;
}
#endif