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/*

FUNCTION

        <<memcpy>>---copy memory regions, optimized for the mips processors

ANSI_SYNOPSIS

        #include <string.h>

        void* memcpy(void *<[out]>, const void *<[in]>, size_t <[n]>);

TRAD_SYNOPSIS

        void *memcpy(<[out]>, <[in]>, <[n]>

        void *<[out]>;

        void *<[in]>;

        size_t <[n]>;

DESCRIPTION

        This function copies <[n]> bytes from the memory region

        pointed to by <[in]> to the memory region pointed to by

        <[out]>.

        If the regions overlap, the behavior is undefined.

RETURNS

        <<memcpy>> returns a pointer to the first byte of the <[out]>

        region.

PORTABILITY

<<memcpy>> is ANSI C.

<<memcpy>> requires no supporting OS subroutines.

QUICKREF

        memcpy ansi pure

        */

#include <_ansi.h>

#include <stddef.h>

#include <limits.h>

#ifdef __mips64

#define wordtype long long

#else

#define wordtype long

#endif

/* Nonzero if either X or Y is not aligned on a "long" boundary.  */

#define UNALIGNED(X, Y) \

  (((long)X & (sizeof (wordtype) - 1)) | ((long)Y & (sizeof (wordtype) - 1)))

/* How many bytes are copied each iteration of the 4X unrolled loop.  */

#define BIGBLOCKSIZE    (sizeof (wordtype) << 2)

/* How many bytes are copied each iteration of the word copy loop.  */

#define LITTLEBLOCKSIZE (sizeof (wordtype))

/* Threshhold for punting to the byte copier.  */

#define TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)

_PTR

_DEFUN (memcpy, (dst0, src0, len0),

        _PTR dst0 _AND

        _CONST _PTR src0 _AND

        size_t len0)

{

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

  char *dst = (char *) dst0;

  char *src = (char *) src0;

  _PTR save = dst0;

  while (len0--)

    {

      *dst++ = *src++;

    }

  return save;

#else

  char *dst = dst0;

  _CONST char *src = src0;

  wordtype *aligned_dst;

  _CONST wordtype *aligned_src;

  int   len =  len0;

  size_t iter;

  /* Handle aligned moves here.  */

  if (!UNALIGNED (src, dst))

    {

      iter = len / BIGBLOCKSIZE;

      len = len % BIGBLOCKSIZE;

      aligned_dst = (wordtype *)dst;

      aligned_src = (wordtype *)src;

          /* Copy 4X long or long long words at a time if possible.  */

      while (iter > 0)

        {

          wordtype tmp0 = aligned_src[0];

          wordtype tmp1 = aligned_src[1];

          wordtype tmp2 = aligned_src[2];

          wordtype tmp3 = aligned_src[3];

          aligned_dst[0] = tmp0;

          aligned_dst[1] = tmp1;

          aligned_dst[2] = tmp2;

          aligned_dst[3] = tmp3;

          aligned_src += 4;

          aligned_dst += 4;

          iter--;

        }

      /* Copy one long or long long word at a time if possible.  */

      iter = len / LITTLEBLOCKSIZE;

      len = len % LITTLEBLOCKSIZE;

      while (iter > 0)

        {

          *aligned_dst++ = *aligned_src++;

          iter--;

        }

      /* Pick up any residual with a byte copier.  */

      dst = (char*)aligned_dst;

      src = (char*)aligned_src;

      while (len > 0)

        {

          *dst++ = *src++;

          len--;

        }

      return dst0;

    }

  /* Handle unaligned moves here, using lwr/lwl and swr/swl where possible */

  else

    {

#ifndef NO_UNALIGNED_LOADSTORE

      int tmp;

      int *int_src = (int *)src;

      int *int_dst = (int *)dst;

      iter = len / 4;

      len = len % 4;

      while (iter > 0)

        {

          __asm__ ("ulw %0,%1" : "=r" (tmp) : "m" (*int_src));

          iter--;

          int_src++;

          __asm__ ("usw %1,%0" : "=m" (*int_dst) : "r" (tmp));

          int_dst++;

        }

      /* Pick up any residual with a byte copier.  */

      dst = (char*)int_dst;

      src = (char*)int_src;

#endif

      while (len > 0)

        {

          *dst++ = *src++;

          len--;

        }

      return dst0;

    }

#endif /* not PREFER_SIZE_OVER_SPEED */

}