Subversion Repositories openrisc_2011-10-31

/*

FUNCTION

        <<memset>>---set an area of memory, optimized for the MIPS processors

INDEX

        memset

ANSI_SYNOPSIS

        #include <string.h>

        void *memset(const void *<[dst]>, int <[c]>, size_t <[length]>);

TRAD_SYNOPSIS

        #include <string.h>

        void *memset(<[dst]>, <[c]>, <[length]>)

        void *<[dst]>;

        int <[c]>;

        size_t <[length]>;

DESCRIPTION

        This function converts the argument <[c]> into an unsigned

        char and fills the first <[length]> characters of the array

        pointed to by <[dst]> to the value.

RETURNS

        <<memset>> returns the value of <[m]>.

PORTABILITY

<<memset>> is ANSI C.

    <<memset>> requires no supporting OS subroutines.

QUICKREF

        memset ansi pure

*/

#include <string.h>

#ifdef __mips64

#define wordtype long long

#else

#define wordtype long

#endif

#define LBLOCKSIZE     (sizeof(wordtype))

#define UNALIGNED(X)   ((long)(X) & (LBLOCKSIZE - 1))

#define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE * 4)

_PTR

_DEFUN (memset, (m, c, n),

        _PTR m _AND

        int c _AND

        size_t n)

{

#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) || defined(__mips16)

  char *s = (char *) m;

  while (n-- != 0)

    {

      *s++ = (char) c;

    }

  return m;

#else

  char *s = (char *) m;

  int i;

  unsigned wordtype buffer;

  unsigned wordtype *aligned_addr;

  unsigned short *short_addr;

  size_t iter;

  if (!TOO_SMALL (n))

    {

      int unaligned = UNALIGNED (s);

      /* We know that N is >= LBLOCKSIZE so we can just word

         align the S without having to check the length. */

      if (unaligned)

        {

          while (unaligned++ < LBLOCKSIZE)

            *s++ = (char)c, n--;

        }

      /* S is now word-aligned so we can process the remainder

         in word sized chunks except for a few (< LBLOCKSIZE)

         bytes which might be left over at the end. */

      aligned_addr = (unsigned wordtype *)s;

      /* Store C into each char sized location in BUFFER so that

         we can set large blocks quickly.  */

      c &= 0xff;

      buffer = c;

      if (buffer != 0)

        {

          if (LBLOCKSIZE == 4)

            {

               buffer |= (buffer << 8);

               buffer |= (buffer << 16);

            }

          else if (LBLOCKSIZE == 8)

            {

              buffer |= (buffer << 8);

              buffer |= (buffer << 16);

              buffer |= ((buffer << 31) << 1);

            }

          else

            {

              for (i = 1; i < LBLOCKSIZE; i++)

                buffer = (buffer << 8) | c;

            }

        }

      iter = n / (2*LBLOCKSIZE);

      n = n % (2*LBLOCKSIZE);

      while (iter > 0)

        {

          aligned_addr[0] = buffer;

          aligned_addr[1] = buffer;

          aligned_addr += 2;

          iter--;

        }

      if (n >= LBLOCKSIZE)

        {

          *aligned_addr++ = buffer;

          n -= LBLOCKSIZE;

        }

      /* Pick up the remainder with a bytewise loop.  */

      s = (char*)aligned_addr;

    }

  while (n > 0)

    {

      *s++ = (char)c;

      n--;

    }

  return m;

#endif /* not PREFER_SIZE_OVER_SPEED */

}