Commit 652a4b7e authored by Richard Henderson's avatar Richard Henderson
Browse files

host-utils: Add revbit functions 



Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
parent 89b8c750

include/qemu/host-utils.h

+77 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#define HOST_UTILS_H 1



#include "qemu/compiler.h"   /* QEMU_GNUC_PREREQ */

#include "qemu/bswap.h"

#include <limits.h>

#include <stdbool.h>
@@ -391,6 +392,80 @@ static inline int ctpop64(uint64_t val) 
#endif

}



/**

 * revbit8 - reverse the bits in an 8-bit value.

 * @x: The value to modify.

 */

static inline uint8_t revbit8(uint8_t x)

{

    /* Assign the correct nibble position.  */

    x = ((x & 0xf0) >> 4)

      | ((x & 0x0f) << 4);

    /* Assign the correct bit position.  */

    x = ((x & 0x88) >> 3)

      | ((x & 0x44) >> 1)

      | ((x & 0x22) << 1)

      | ((x & 0x11) << 3);

    return x;

}



/**

 * revbit16 - reverse the bits in a 16-bit value.

 * @x: The value to modify.

 */

static inline uint16_t revbit16(uint16_t x)

{

    /* Assign the correct byte position.  */

    x = bswap16(x);

    /* Assign the correct nibble position.  */

    x = ((x & 0xf0f0) >> 4)

      | ((x & 0x0f0f) << 4);

    /* Assign the correct bit position.  */

    x = ((x & 0x8888) >> 3)

      | ((x & 0x4444) >> 1)

      | ((x & 0x2222) << 1)

      | ((x & 0x1111) << 3);

    return x;

}



/**

 * revbit32 - reverse the bits in a 32-bit value.

 * @x: The value to modify.

 */

static inline uint32_t revbit32(uint32_t x)

{

    /* Assign the correct byte position.  */

    x = bswap32(x);

    /* Assign the correct nibble position.  */

    x = ((x & 0xf0f0f0f0u) >> 4)

      | ((x & 0x0f0f0f0fu) << 4);

    /* Assign the correct bit position.  */

    x = ((x & 0x88888888u) >> 3)

      | ((x & 0x44444444u) >> 1)

      | ((x & 0x22222222u) << 1)

      | ((x & 0x11111111u) << 3);

    return x;

}



/**

 * revbit64 - reverse the bits in a 64-bit value.

 * @x: The value to modify.

 */

static inline uint64_t revbit64(uint64_t x)

{

    /* Assign the correct byte position.  */

    x = bswap64(x);

    /* Assign the correct nibble position.  */

    x = ((x & 0xf0f0f0f0f0f0f0f0ull) >> 4)

      | ((x & 0x0f0f0f0f0f0f0f0full) << 4);

    /* Assign the correct bit position.  */

    x = ((x & 0x8888888888888888ull) >> 3)

      | ((x & 0x4444444444444444ull) >> 1)

      | ((x & 0x2222222222222222ull) << 1)

      | ((x & 0x1111111111111111ull) << 3);

    return x;

}



/* Host type specific sizes of these routines.  */



#if ULONG_MAX == UINT32_MAX
@@ -399,12 +474,14 @@ static inline int ctpop64(uint64_t val) 
# define clol   clo32

# define ctol   cto32

# define ctpopl ctpop32

# define revbitl revbit32

#elif ULONG_MAX == UINT64_MAX

# define clzl   clz64

# define ctzl   ctz64

# define clol   clo64

# define ctol   cto64

# define ctpopl ctpop64

# define revbitl revbit64

#else

# error Unknown sizeof long

#endif