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src/subversion/subversion/libsvn_delta/text_delta.c  view on Meta::CPAN

static APR_INLINE char *
patterning_copy(char *target, const char *source, apr_size_t len)
{
  const char *end = source + len;

  /* On many machines, we can do "chunky" copies. */

#if SVN_UNALIGNED_ACCESS_IS_OK

  if (end + sizeof(apr_uint32_t) <= target)
    {
      /* Source and target are at least 4 bytes apart, so we can copy in
       * 4-byte chunks.  */
      for (; source + sizeof(apr_uint32_t) <= end;
           source += sizeof(apr_uint32_t),
           target += sizeof(apr_uint32_t))
      *(apr_uint32_t *)(target) = *(apr_uint32_t *)(source);
    }

#endif

  /* fall through to byte-wise copy (either for the below-chunk-size tail
   * or the whole copy) */
  for (; source != end; source++)
    *(target++) = *source;

  return target;
}

void
svn_txdelta_apply_instructions(svn_txdelta_window_t *window,
                               const char *sbuf, char *tbuf,
                               apr_size_t *tlen)
{
  const svn_txdelta_op_t *op;
  apr_size_t tpos = 0;

  for (op = window->ops; op < window->ops + window->num_ops; op++)
    {
      const apr_size_t buf_len = (op->length < *tlen - tpos
                                  ? op->length : *tlen - tpos);

      /* Check some invariants common to all instructions.  */
      assert(tpos + op->length <= window->tview_len);

      switch (op->action_code)
        {
        case svn_txdelta_source:
          /* Copy from source area.  */
          assert(sbuf);
          assert(op->offset + op->length <= window->sview_len);
          fast_memcpy(tbuf + tpos, sbuf + op->offset, buf_len);
          break;

        case svn_txdelta_target:
          /* Copy from target area.  We can't use memcpy() or the like
           * since we need a specific semantics for overlapping copies:
           * they must result in repeating patterns.
           * Note that most copies won't have overlapping source and
           * target ranges (they are just a result of self-compressed
           * data) but a small percentage will.  */
          assert(op->offset < tpos);
          patterning_copy(tbuf + tpos, tbuf + op->offset, buf_len);
          break;

        case svn_txdelta_new:
          /* Copy from window new area.  */
          assert(op->offset + op->length <= window->new_data->len);
          fast_memcpy(tbuf + tpos,
                      window->new_data->data + op->offset,
                      buf_len);
          break;

        default:
          assert(!"Invalid delta instruction code");
        }

      tpos += op->length;
      if (tpos >= *tlen)
        return;                 /* The buffer is full. */
    }

  /* Check that we produced the right amount of data.  */
  assert(tpos == window->tview_len);
  *tlen = tpos;
}

/* This is a private interlibrary compatibility wrapper. */
void
svn_txdelta__apply_instructions(svn_txdelta_window_t *window,
                                const char *sbuf, char *tbuf,
                                apr_size_t *tlen);
void
svn_txdelta__apply_instructions(svn_txdelta_window_t *window,
                                const char *sbuf, char *tbuf,
                                apr_size_t *tlen)
{
  svn_txdelta_apply_instructions(window, sbuf, tbuf, tlen);
}


/* Apply WINDOW to the streams given by APPL.  */
static svn_error_t *
apply_window(svn_txdelta_window_t *window, void *baton)
{
  struct apply_baton *ab = (struct apply_baton *) baton;
  apr_size_t len;
  svn_error_t *err;

  if (window == NULL)
    {
      /* We're done; just clean up.  */
      if (ab->result_digest)
        apr_md5_final(ab->result_digest, &(ab->md5_context));

      err = svn_stream_close(ab->target);
      svn_pool_destroy(ab->pool);

      return err;
    }