uclibc-ng/libc/string/generic/_memcpy_fwd.c

/* _wordcopy_fwd_aligned -- Copy block beginning at SRCP to
   block beginning at DSTP with LEN `op_t' words (not LEN bytes!).
   Both SRCP and DSTP should be aligned for memory operations on `op_t's.  */

static void _wordcopy_fwd_aligned (long int dstp, long int srcp, size_t len)
{
  op_t a0, a1;

  switch (len % 8)
    {
    case 2:
      a0 = ((op_t *) srcp)[0];
      srcp -= 6 * OPSIZ;
      dstp -= 7 * OPSIZ;
      len += 6;
      goto do1;
    case 3:
      a1 = ((op_t *) srcp)[0];
      srcp -= 5 * OPSIZ;
      dstp -= 6 * OPSIZ;
      len += 5;
      goto do2;
    case 4:
      a0 = ((op_t *) srcp)[0];
      srcp -= 4 * OPSIZ;
      dstp -= 5 * OPSIZ;
      len += 4;
      goto do3;
    case 5:
      a1 = ((op_t *) srcp)[0];
      srcp -= 3 * OPSIZ;
      dstp -= 4 * OPSIZ;
      len += 3;
      goto do4;
    case 6:
      a0 = ((op_t *) srcp)[0];
      srcp -= 2 * OPSIZ;
      dstp -= 3 * OPSIZ;
      len += 2;
      goto do5;
    case 7:
      a1 = ((op_t *) srcp)[0];
      srcp -= 1 * OPSIZ;
      dstp -= 2 * OPSIZ;
      len += 1;
      goto do6;

    case 0:
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	return;
      a0 = ((op_t *) srcp)[0];
      srcp -= 0 * OPSIZ;
      dstp -= 1 * OPSIZ;
      goto do7;
    case 1:
      a1 = ((op_t *) srcp)[0];
      srcp -=-1 * OPSIZ;
      dstp -= 0 * OPSIZ;
      len -= 1;
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	goto do0;
      goto do8;			/* No-op.  */
    }

  do
    {
    do8:
      a0 = ((op_t *) srcp)[0];
      ((op_t *) dstp)[0] = a1;
    do7:
      a1 = ((op_t *) srcp)[1];
      ((op_t *) dstp)[1] = a0;
    do6:
      a0 = ((op_t *) srcp)[2];
      ((op_t *) dstp)[2] = a1;
    do5:
      a1 = ((op_t *) srcp)[3];
      ((op_t *) dstp)[3] = a0;
    do4:
      a0 = ((op_t *) srcp)[4];
      ((op_t *) dstp)[4] = a1;
    do3:
      a1 = ((op_t *) srcp)[5];
      ((op_t *) dstp)[5] = a0;
    do2:
      a0 = ((op_t *) srcp)[6];
      ((op_t *) dstp)[6] = a1;
    do1:
      a1 = ((op_t *) srcp)[7];
      ((op_t *) dstp)[7] = a0;

      srcp += 8 * OPSIZ;
      dstp += 8 * OPSIZ;
      len -= 8;
    }
  while (len != 0);

  /* This is the right position for do0.  Please don't move
     it into the loop.  */
 do0:
  ((op_t *) dstp)[0] = a1;
}

/* _wordcopy_fwd_dest_aligned -- Copy block beginning at SRCP to
   block beginning at DSTP with LEN `op_t' words (not LEN bytes!).
   DSTP should be aligned for memory operations on `op_t's, but SRCP must
   *not* be aligned.  */

static void _wordcopy_fwd_dest_aligned (long int dstp, long int srcp, size_t len)
{
  op_t a0, a1, a2, a3;
  int sh_1, sh_2;

  /* Calculate how to shift a word read at the memory operation
     aligned srcp to make it aligned for copy.  */

  sh_1 = 8 * (srcp % OPSIZ);
  sh_2 = 8 * OPSIZ - sh_1;

  /* Make SRCP aligned by rounding it down to the beginning of the `op_t'
     it points in the middle of.  */
  srcp &= -OPSIZ;

  switch (len % 4)
    {
    case 2:
      a1 = ((op_t *) srcp)[0];
      a2 = ((op_t *) srcp)[1];
      srcp -= 1 * OPSIZ;
      dstp -= 3 * OPSIZ;
      len += 2;
      goto do1;
    case 3:
      a0 = ((op_t *) srcp)[0];
      a1 = ((op_t *) srcp)[1];
      srcp -= 0 * OPSIZ;
      dstp -= 2 * OPSIZ;
      len += 1;
      goto do2;
    case 0:
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	return;
      a3 = ((op_t *) srcp)[0];
      a0 = ((op_t *) srcp)[1];
      srcp -=-1 * OPSIZ;
      dstp -= 1 * OPSIZ;
      len += 0;
      goto do3;
    case 1:
      a2 = ((op_t *) srcp)[0];
      a3 = ((op_t *) srcp)[1];
      srcp -=-2 * OPSIZ;
      dstp -= 0 * OPSIZ;
      len -= 1;
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	goto do0;
      goto do4;			/* No-op.  */
    }

  do
    {
    do4:
      a0 = ((op_t *) srcp)[0];
      ((op_t *) dstp)[0] = MERGE (a2, sh_1, a3, sh_2);
    do3:
      a1 = ((op_t *) srcp)[1];
      ((op_t *) dstp)[1] = MERGE (a3, sh_1, a0, sh_2);
    do2:
      a2 = ((op_t *) srcp)[2];
      ((op_t *) dstp)[2] = MERGE (a0, sh_1, a1, sh_2);
    do1:
      a3 = ((op_t *) srcp)[3];
      ((op_t *) dstp)[3] = MERGE (a1, sh_1, a2, sh_2);

      srcp += 4 * OPSIZ;
      dstp += 4 * OPSIZ;
      len -= 4;
    }
  while (len != 0);

  /* This is the right position for do0.  Please don't move
     it into the loop.  */
 do0:
  ((op_t *) dstp)[0] = MERGE (a2, sh_1, a3, sh_2);
}