source: rtems/c/src/lib/libcpu/m68k/shared/misc/memcpy.c @ 3f5480c

/*
 *  C library memcpy routine
 *
 *  This routine has code to optimize performance on the CPU32+
 *  and another version for other 68k machines.
 *
 *  It could be optimized more for machines with MOVE16 instructions.
 *
 *  The routine is placed in this source directory to ensure that it
 *  is picked up by all applications.
 *
 *  W. Eric Norum
 *  Saskatchewan Accelerator Laboratory
 *  University of Saskatchewan
 *  Saskatoon, Saskatchewan, CANADA
 *  eric@skatter.usask.ca
 */

#include <string.h>
#include <rtems/score/m68k.h>

#if defined(__mcpu32__)
#define COPYSETUP(n)    n--
#define COPY(to,from,n,size) \
        asm volatile ("1:\n" \
             "\tmove." size " (%0)+,(%1)+\n" \
             "\tdbf %2,1b\n"  \
             "\tsub.l #0x10000,%2\n" \
             "\tbpl.b 1b\n" : \
                "=a" (from), "=a" (to), "=d" (n) :\
                 "0" (from),  "1" (to), "2" (n) : \
                 "cc", "memory")
#else
#define COPYSETUP(n)
#define COPY(to,from,n,size) \
        asm volatile ("1:\n" \
             "\tmove." size " (%0)+,(%1)+\n" \
             "\tsubq.l #1,%2\n\tbne.b 1b\n" : \
                "=a" (from), "=a" (to), "=d" (n) :\
                 "0" (from),  "1" (to), "2" (n) : \
                 "cc", "memory")
#endif

/* gcc doesn't know that cpu32+ is better than cpu32 :( */
#if defined(__mcpu32p__)
#undef M68k_HAS_MISALIGNED
#define M68k_HAS_MISALIGNED 1
#endif

void *
memcpy(void *s1, const void *s2, size_t n)
{
        char *p1 = s1;
        const char *p2 = s2;

        if (n) {
                if (n < 16) {
                        COPYSETUP (n);
                        COPY (p1, p2, n, "b");
                }
                else {
                        int nbyte;
                        int nl;
                        nbyte = (int)p1 & 0x3;
                        if (nbyte) {
                                nbyte = 4 - nbyte;
                                n -= nbyte;
                                COPYSETUP (nbyte);
                                COPY (p1, p2, nbyte, "b");
                        }
#if (M68K_HAS_MISALIGNED == 0)
                        /*
                         * Take care of machines that can't
                         * handle misaligned references.
                         */
                        if ((int)p2 & 0x1) {
                                COPYSETUP (n);
                                COPY (p1, p2, n, "b");
                                return s1;
                        }
#endif
                        nl = (unsigned int)n >> 2;
                        COPYSETUP (nl);
                        COPY (p1, p2, nl, "l");
                        nbyte = (int)n & 0x3;
                        if (nbyte) {
                                COPYSETUP (nbyte);
                                COPY (p1, p2, nbyte, "b");
                        }
                }
        }
        return s1;
}