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memcpy.c

/*
 * Copyright (C) 2002 Mark Debbage (Mark.Debbage@superh.com)
 *
 * May be copied or modified under the terms of the GNU General Public
 * License.  See linux/COPYING for more information.
 *
 */

#include <linux/types.h>
#include <asm/string.h>

// This is a simplistic optimization of memcpy to increase the
// granularity of access beyond one byte using aligned
// loads and stores. This is not an optimal implementation
// for SH-5 (especially with regard to prefetching and the cache),
// and a better version should be provided later ...

void *memcpy(void *dest, const void *src, size_t count)
{
      char *d = (char *) dest, *s = (char *) src;

      if (count >= 32) {
            int i = 8 - (((unsigned long) d) & 0x7);

            if (i != 8)
                  while (i-- && count--) {
                        *d++ = *s++;
                  }

            if (((((unsigned long) d) & 0x7) == 0) &&
                ((((unsigned long) s) & 0x7) == 0)) {
                  while (count >= 32) {
                        unsigned long long t1, t2, t3, t4;
                        t1 = *(unsigned long long *) (s);
                        t2 = *(unsigned long long *) (s + 8);
                        t3 = *(unsigned long long *) (s + 16);
                        t4 = *(unsigned long long *) (s + 24);
                        *(unsigned long long *) (d) = t1;
                        *(unsigned long long *) (d + 8) = t2;
                        *(unsigned long long *) (d + 16) = t3;
                        *(unsigned long long *) (d + 24) = t4;
                        d += 32;
                        s += 32;
                        count -= 32;
                  }
                  while (count >= 8) {
                        *(unsigned long long *) d =
                            *(unsigned long long *) s;
                        d += 8;
                        s += 8;
                        count -= 8;
                  }
            }

            if (((((unsigned long) d) & 0x3) == 0) &&
                ((((unsigned long) s) & 0x3) == 0)) {
                  while (count >= 4) {
                        *(unsigned long *) d = *(unsigned long *) s;
                        d += 4;
                        s += 4;
                        count -= 4;
                  }
            }

            if (((((unsigned long) d) & 0x1) == 0) &&
                ((((unsigned long) s) & 0x1) == 0)) {
                  while (count >= 2) {
                        *(unsigned short *) d = *(unsigned short *) s;
                        d += 2;
                        s += 2;
                        count -= 2;
                  }
            }
      }

      while (count--) {
            *d++ = *s++;
      }

      return d;
}

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