Пример #1
1
void ode_evaluate(
	CppAD::vector<Float> &x  , 
	size_t m                 , 
	CppAD::vector<Float> &fm )
{
	typedef CppAD::vector<Float> Vector;

	size_t n = x.size();
	size_t ell;
	CPPAD_ASSERT_KNOWN( m == 0 || m == 1,
		"ode_evaluate: m is not zero or one"
	);
	CPPAD_ASSERT_KNOWN( 
		((m==0) & (fm.size()==n)) || ((m==1) & (fm.size()==n*n)),
		"ode_evaluate: the size of fm is not correct"
	);
	if( m == 0 )
		ell = n;
	else	ell = n + n * n;

	// set up the case we are integrating
	Float  ti   = 0.;
	Float  tf   = 1.;
	Float  smin = 1e-5;
	Float smax  = 1.;
	Float scur  = 1.;
	Float erel  = 0.;
	vector<Float> yi(ell), eabs(ell);
	size_t i, j;
	for(i = 0; i < ell; i++)
	{	eabs[i] = 1e-10;
		if( i < n )
			yi[i] = 1.;
		else	yi[i]  = 0.;
	}

	// return values
	Vector yf(ell), ef(ell), maxabs(ell);
	size_t nstep;

	// construct ode method for taking one step
	ode_evaluate_method<Float> method(m, x);

	// solve differential equation
	yf = OdeErrControl(method, 
		ti, tf, yi, smin, smax, scur, eabs, erel, ef, maxabs, nstep);

	if( m == 0 )
	{	for(i = 0; i < n; i++)
			fm[i] = yf[i];
	}
	else
	{	for(i = 0; i < n; i++)
			for(j = 0; j < n; j++)
				fm[i * n + j] = yf[n + i * n + j];
	}
	return;
}
Пример #2
0
bool OdeErrMaxabs(void)
{   bool ok = true;     // initial return value

    CppAD::vector<double> w(2);
    w[0] = 10.;
    w[1] = 1.;
    Method method(w);

    CppAD::vector<double> xi(2);
    xi[0] = 1.;
    xi[1] = 0.;

    CppAD::vector<double> eabs(2);
    eabs[0] = 0.;
    eabs[1] = 0.;

    CppAD::vector<double> ef(2);
    CppAD::vector<double> xf(2);
    CppAD::vector<double> maxabs(2);

    double ti   = 0.;
    double tf   = 1.;
    double smin = .5;
    double smax = 1.;
    double scur = .5;
    double erel = 1e-4;

    bool accurate = false;
    while( ! accurate )
    {   xf = OdeErrControl(method,
                           ti, tf, xi, smin, smax, scur, eabs, erel, ef, maxabs);
        accurate = true;
        size_t i;
        for(i = 0; i < 2; i++)
            accurate &= ef[i] <= erel * maxabs[i];
        if( ! accurate )
            smin = smin / 2;
    }

    double x0 = exp(-w[0]*tf);
    ok &= CppAD::NearEqual(x0, xf[0], erel, 0.);
    ok &= CppAD::NearEqual(0., ef[0], erel, erel);

    double x1 = w[0] * (exp(-w[0]*tf) - exp(-w[1]*tf))/(w[1] - w[0]);
    ok &= CppAD::NearEqual(x1, xf[1], erel, 0.);
    ok &= CppAD::NearEqual(0., ef[1], erel, erel);

    return ok;
}
Пример #3
0
bool OdeErrControl_three(void)
{	bool ok = true;     // initial return value

	double alpha = 10.;
	Method_three method(alpha);

	CppAD::vector<double> xi(2);
	xi[0] = 1.;
	xi[1] = 0.;

	CppAD::vector<double> eabs(2);
	eabs[0] = 1e-4;
	eabs[1] = 1e-4;

	// inputs
	double ti   = 0.;
	double tf   = 1.;
	double smin = 1e-4;
	double smax = 1.;
	double scur = 1.;
	double erel = 0.;

	// outputs
	CppAD::vector<double> ef(2);
	CppAD::vector<double> xf(2);
	CppAD::vector<double> maxabs(2);
	size_t nstep;


	xf = OdeErrControl(method,
		ti, tf, xi, smin, smax, scur, eabs, erel, ef, maxabs, nstep);


	double x0       = exp( alpha * tf * tf );
	ok &= CppAD::NearEqual(x0, xf[0], 1e-4, 1e-4);
	ok &= CppAD::NearEqual(0., ef[0], 1e-4, 1e-4);

	double root_pi    = sqrt( 4. * atan(1.));
	double root_alpha = sqrt( alpha );
	double x1 = CppAD::erf(alpha * tf) * root_pi / (2 * root_alpha);
	ok &= CppAD::NearEqual(x1, xf[1], 1e-4, 1e-4);
	ok &= CppAD::NearEqual(0., ef[1], 1e-4, 1e-4);

	ok &= method.F.was_negative();

	return ok;
}
Пример #4
0
bool OdeGearControl(void)
{	bool ok = true;     // initial return value

	CPPAD_TEST_VECTOR<double> w(2);
	w[0] = 10.;
	w[1] = 1.;
	Fun F(w);

	CPPAD_TEST_VECTOR<double> xi(2);
	xi[0] = 1.;
	xi[1] = 0.;

	CPPAD_TEST_VECTOR<double> eabs(2);
	eabs[0] = 1e-4;
	eabs[1] = 1e-4;

	// return values
	CPPAD_TEST_VECTOR<double> ef(2);
	CPPAD_TEST_VECTOR<double> maxabs(2);
	CPPAD_TEST_VECTOR<double> xf(2);
	size_t                nstep;

	// input values
	size_t  M   = 5;
	double ti   = 0.;
	double tf   = 1.;
	double smin = 1e-8;
	double smax = 1.;
	double sini = 1e-10;
	double erel = 0.;
	
	xf = CppAD::OdeGearControl(F, M,
		ti, tf, xi, smin, smax, sini, eabs, erel, ef, maxabs, nstep);

	double x0 = exp(-w[0]*tf);
	ok &= CppAD::NearEqual(x0, xf[0], 1e-4, 1e-4);
	ok &= CppAD::NearEqual(0., ef[0], 1e-4, 1e-4);

	double x1 = w[0] * (exp(-w[0]*tf) - exp(-w[1]*tf))/(w[1] - w[0]);
	ok &= CppAD::NearEqual(x1, xf[1], 1e-4, 1e-4);
	ok &= CppAD::NearEqual(0., ef[1], 1e-4, 1e-4);

	return ok;
}
Пример #5
0
bool OdeErrControl_two(void)
{	bool ok = true;     // initial return value

	CppAD::vector<double> w(2);
	w[0] = 10.;
	w[1] = 1.;
	Method_two method(w);

	CppAD::vector<double> xi(2);
	xi[0] = 1.;
	xi[1] = 0.;

	CppAD::vector<double> eabs(2);
	eabs[0] = 1e-4;
	eabs[1] = 1e-4;

	// inputs
	double ti   = 0.;
	double tf   = 1.;
	double smin = 1e-4;
	double smax = 1.;
	double scur = .5;
	double erel = 0.;

	// outputs
	CppAD::vector<double> ef(2);
	CppAD::vector<double> xf(2);
	CppAD::vector<double> maxabs(2);
	size_t nstep;


	xf = OdeErrControl(method,
		ti, tf, xi, smin, smax, scur, eabs, erel, ef, maxabs, nstep);

	double x0 = exp(-w[0]*tf);
	ok &= CppAD::NearEqual(x0, xf[0], 1e-4, 1e-4);
	ok &= CppAD::NearEqual(0., ef[0], 1e-4, 1e-4);

	double x1 = w[0] * (exp(-w[0]*tf) - exp(-w[1]*tf))/(w[1] - w[0]);
	ok &= CppAD::NearEqual(x1, xf[1], 1e-4, 1e-4);
	ok &= CppAD::NearEqual(0., ef[1], 1e-4, 1e-4);

	return ok;
}
Пример #6
0
bool OdeErrControl_one(void)
{	bool   ok = true;     // initial return value

	// Runge45 should yield exact results for x_i (t) = t^(i+1), i < 4
	size_t  n = 6;

	// construct method for n component solution
	Method_one method(n);

	// inputs to OdeErrControl

	double ti   = 0.;
	double tf   = .9;
	double smin = 1e-2;
	double smax = 1.;
	double scur = .5;
	double erel = 1e-7;

	CppAD::vector<double> xi(n);
	CppAD::vector<double> eabs(n);
	size_t i;
	for(i = 0; i < n; i++)
	{	xi[i]   = 0.;
		eabs[i] = 0.;
	}

	// outputs from OdeErrControl

	CppAD::vector<double> ef(n);
	CppAD::vector<double> xf(n);

	xf = OdeErrControl(method,
		ti, tf, xi, smin, smax, scur, eabs, erel, ef);

	double check = 1.;
	for(i = 0; i < n; i++)
	{	check *= tf;
		ok &= CppAD::NearEqual(check, xf[i], erel, 0.);
	}

	return ok;
}
Пример #7
0
bool OdeErrControl_four(void)
{	bool   ok = true;     // initial return value

	// construct method for n component solution
	size_t  n = 6;
	Method_four method(n);

	// inputs to OdeErrControl

	// special case where scur is converted to ti - tf
	// (so it is not equal to smin)
	double ti   = 0.;
	double tf   = .9;
	double smin = .8;
	double smax = 1.;
	double scur = smin;
	double erel = 1e-7;

	CppAD::vector<double> xi(n);
	CppAD::vector<double> eabs(n);
	size_t i;
	for(i = 0; i < n; i++)
	{	xi[i]   = 0.;
		eabs[i] = 0.;
	}

	// outputs from OdeErrControl
	CppAD::vector<double> ef(n);
	CppAD::vector<double> xf(n);

	xf = OdeErrControl(method,
		ti, tf, xi, smin, smax, scur, eabs, erel, ef);

	// check that Fun_four always returning nan results in nan
	for(i = 0; i < n; i++)
	{	ok &= CppAD::isnan(xf[i]);
		ok &= CppAD::isnan(ef[i]);
	}

	return ok;
}
Пример #8
0
void
compute_fringe_widths (struct frame *f, bool redraw_p)
{
  int o_left = FRAME_LEFT_FRINGE_WIDTH (f);
  int o_right = FRAME_RIGHT_FRINGE_WIDTH (f);
  int o_cols = FRAME_FRINGE_COLS (f);

  Lisp_Object left_fringe = Fassq (Qleft_fringe, f->param_alist);
  Lisp_Object right_fringe = Fassq (Qright_fringe, f->param_alist);
  int left_fringe_width, right_fringe_width;

  if (!NILP (left_fringe))
    left_fringe = Fcdr (left_fringe);
  if (!NILP (right_fringe))
    right_fringe = Fcdr (right_fringe);

  left_fringe_width = ((NILP (left_fringe) || !INTEGERP (left_fringe)) ? 8 :
		       XINT (left_fringe));
  right_fringe_width = ((NILP (right_fringe) || !INTEGERP (right_fringe)) ? 8 :
			XINT (right_fringe));

  if (left_fringe_width || right_fringe_width)
    {
      int left_wid = eabs (left_fringe_width);
      int right_wid = eabs (right_fringe_width);
      int conf_wid = left_wid + right_wid;
      int font_wid = FRAME_COLUMN_WIDTH (f);
      int cols = (left_wid + right_wid + font_wid-1) / font_wid;
      int real_wid = cols * font_wid;
      if (left_wid && right_wid)
	{
	  if (left_fringe_width < 0)
	    {
	      /* Left fringe width is fixed, adjust right fringe if necessary */
	      FRAME_LEFT_FRINGE_WIDTH (f) = left_wid;
	      FRAME_RIGHT_FRINGE_WIDTH (f) = real_wid - left_wid;
	    }
	  else if (right_fringe_width < 0)
	    {
	      /* Right fringe width is fixed, adjust left fringe if necessary */
	      FRAME_LEFT_FRINGE_WIDTH (f) = real_wid - right_wid;
	      FRAME_RIGHT_FRINGE_WIDTH (f) = right_wid;
	    }
	  else
	    {
	      /* Adjust both fringes with an equal amount.
		 Note that we are doing integer arithmetic here, so don't
		 lose a pixel if the total width is an odd number.  */
	      int fill = real_wid - conf_wid;
	      FRAME_LEFT_FRINGE_WIDTH (f) = left_wid + fill/2;
	      FRAME_RIGHT_FRINGE_WIDTH (f) = right_wid + fill - fill/2;
	    }
	}
      else if (left_fringe_width)
	{
	  FRAME_LEFT_FRINGE_WIDTH (f) = real_wid;
	  FRAME_RIGHT_FRINGE_WIDTH (f) = 0;
	}
      else
	{
	  FRAME_LEFT_FRINGE_WIDTH (f) = 0;
	  FRAME_RIGHT_FRINGE_WIDTH (f) = real_wid;
	}
      FRAME_FRINGE_COLS (f) = cols;
    }
  else
    {
      FRAME_LEFT_FRINGE_WIDTH (f) = 0;
      FRAME_RIGHT_FRINGE_WIDTH (f) = 0;
      FRAME_FRINGE_COLS (f) = 0;
    }

  if (redraw_p && FRAME_VISIBLE_P (f))
    if (o_left != FRAME_LEFT_FRINGE_WIDTH (f) ||
	o_right != FRAME_RIGHT_FRINGE_WIDTH (f) ||
	o_cols != FRAME_FRINGE_COLS (f))
      redraw_frame (f);
}
Пример #9
0
Lisp_Object
get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
{
  char *from, *to, *name, *p, *p1;
  int fd;
  int offset;
  EMACS_INT position;
  Lisp_Object file, tem, pos;
  ptrdiff_t count;
  USE_SAFE_ALLOCA;

  if (INTEGERP (filepos))
    {
      file = Vdoc_file_name;
      pos = filepos;
    }
  else if (CONSP (filepos))
    {
      file = XCAR (filepos);
      pos = XCDR (filepos);
    }
  else
    return Qnil;

  position = eabs (XINT (pos));

  if (!STRINGP (Vdoc_directory))
    return Qnil;

  if (!STRINGP (file))
    return Qnil;

  /* Put the file name in NAME as a C string.
     If it is relative, combine it with Vdoc_directory.  */

  tem = Ffile_name_absolute_p (file);
  file = ENCODE_FILE (file);
  Lisp_Object docdir
    = NILP (tem) ? ENCODE_FILE (Vdoc_directory) : empty_unibyte_string;
  ptrdiff_t docdir_sizemax = SBYTES (docdir) + 1;
#ifndef CANNOT_DUMP
  docdir_sizemax = max (docdir_sizemax, sizeof sibling_etc);
#endif
  name = SAFE_ALLOCA (docdir_sizemax + SBYTES (file));
  lispstpcpy (lispstpcpy (name, docdir), file);

  fd = emacs_open (name, O_RDONLY, 0);
  if (fd < 0)
    {
#ifndef CANNOT_DUMP
      if (!NILP (Vpurify_flag))
	{
	  /* Preparing to dump; DOC file is probably not installed.
	     So check in ../etc.  */
	  lispstpcpy (stpcpy (name, sibling_etc), file);

	  fd = emacs_open (name, O_RDONLY, 0);
	}
#endif
      if (fd < 0)
	{
	  if (errno == EMFILE || errno == ENFILE)
	    report_file_error ("Read error on documentation file", file);

	  SAFE_FREE ();
	  AUTO_STRING (cannot_open, "Cannot open doc string file \"");
	  AUTO_STRING (quote_nl, "\"\n");
	  return concat3 (cannot_open, file, quote_nl);
	}
    }
  count = SPECPDL_INDEX ();
  record_unwind_protect_int (close_file_unwind, fd);

  /* Seek only to beginning of disk block.  */
  /* Make sure we read at least 1024 bytes before `position'
     so we can check the leading text for consistency.  */
  offset = min (position, max (1024, position % (8 * 1024)));
  if (TYPE_MAXIMUM (off_t) < position
      || lseek (fd, position - offset, 0) < 0)
    error ("Position %"pI"d out of range in doc string file \"%s\"",
	   position, name);

  /* Read the doc string into get_doc_string_buffer.
     P points beyond the data just read.  */

  p = get_doc_string_buffer;
  while (1)
    {
      ptrdiff_t space_left = (get_doc_string_buffer_size - 1
			      - (p - get_doc_string_buffer));
      int nread;

      /* Allocate or grow the buffer if we need to.  */
      if (space_left <= 0)
	{
	  ptrdiff_t in_buffer = p - get_doc_string_buffer;
	  get_doc_string_buffer
	    = xpalloc (get_doc_string_buffer, &get_doc_string_buffer_size,
		       16 * 1024, -1, 1);
	  p = get_doc_string_buffer + in_buffer;
	  space_left = (get_doc_string_buffer_size - 1
			- (p - get_doc_string_buffer));
	}

      /* Read a disk block at a time.
         If we read the same block last time, maybe skip this?  */
      if (space_left > 1024 * 8)
	space_left = 1024 * 8;
      nread = emacs_read (fd, p, space_left);
      if (nread < 0)
	report_file_error ("Read error on documentation file", file);
      p[nread] = 0;
      if (!nread)
	break;
      if (p == get_doc_string_buffer)
	p1 = strchr (p + offset, '\037');
      else
	p1 = strchr (p, '\037');
      if (p1)
	{
	  *p1 = 0;
	  p = p1;
	  break;
	}
      p += nread;
    }
  unbind_to (count, Qnil);
  SAFE_FREE ();

  /* Sanity checking.  */
  if (CONSP (filepos))
    {
      int test = 1;
      /* A dynamic docstring should be either at the very beginning of a "#@
	 comment" or right after a dynamic docstring delimiter (in case we
	 pack several such docstrings within the same comment).  */
      if (get_doc_string_buffer[offset - test] != '\037')
	{
	  if (get_doc_string_buffer[offset - test++] != ' ')
	    return Qnil;
	  while (get_doc_string_buffer[offset - test] >= '0'
		 && get_doc_string_buffer[offset - test] <= '9')
	    test++;
	  if (get_doc_string_buffer[offset - test++] != '@'
	      || get_doc_string_buffer[offset - test] != '#')
	    return Qnil;
	}
    }
  else
    {
      int test = 1;
      if (get_doc_string_buffer[offset - test++] != '\n')
	return Qnil;
      while (get_doc_string_buffer[offset - test] > ' ')
	test++;
      if (get_doc_string_buffer[offset - test] != '\037')
	return Qnil;
    }

  /* Scan the text and perform quoting with ^A (char code 1).
     ^A^A becomes ^A, ^A0 becomes a null char, and ^A_ becomes a ^_.  */
  from = get_doc_string_buffer + offset;
  to = get_doc_string_buffer + offset;
  while (from != p)
    {
      if (*from == 1)
	{
	  int c;

	  from++;
	  c = *from++;
	  if (c == 1)
	    *to++ = c;
	  else if (c == '0')
	    *to++ = 0;
	  else if (c == '_')
	    *to++ = 037;
	  else
	    {
	      unsigned char uc = c;
	      error ("\
Invalid data in documentation file -- %c followed by code %03o",
		     1, uc);
	    }
	}
      else
	*to++ = *from++;
    }

  /* If DEFINITION, read from this buffer
     the same way we would read bytes from a file.  */
  if (definition)
    {
      read_bytecode_pointer = (unsigned char *) get_doc_string_buffer + offset;
      return Fread (Qlambda);
    }

  if (unibyte)
    return make_unibyte_string (get_doc_string_buffer + offset,
				to - (get_doc_string_buffer + offset));
  else
    {
      /* The data determines whether the string is multibyte.  */
      ptrdiff_t nchars
	= multibyte_chars_in_text (((unsigned char *) get_doc_string_buffer
				    + offset),
				   to - (get_doc_string_buffer + offset));
      return make_string_from_bytes (get_doc_string_buffer + offset,
				     nchars,
				     to - (get_doc_string_buffer + offset));
    }
}
Пример #10
0
Lisp_Object
get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
{
  char *from, *to, *name, *p, *p1;
  int fd;
  ptrdiff_t minsize;
  int offset;
  EMACS_INT position;
  Lisp_Object file, tem, pos;
  USE_SAFE_ALLOCA;

  if (INTEGERP (filepos))
    {
      file = Vdoc_file_name;
      pos = filepos;
    }
  else if (CONSP (filepos))
    {
      file = XCAR (filepos);
      pos = XCDR (filepos);
    }
  else
    return Qnil;

  position = eabs (XINT (pos));

  if (!STRINGP (Vdoc_directory))
    return Qnil;

  if (!STRINGP (file))
    return Qnil;

  /* Put the file name in NAME as a C string.
     If it is relative, combine it with Vdoc_directory.  */

  tem = Ffile_name_absolute_p (file);
  file = ENCODE_FILE (file);
  if (NILP (tem))
    {
      Lisp_Object docdir = ENCODE_FILE (Vdoc_directory);
      minsize = SCHARS (docdir);
      /* sizeof ("../etc/") == 8 */
      if (minsize < 8)
	minsize = 8;
      name = SAFE_ALLOCA (minsize + SCHARS (file) + 8);
      strcpy (name, SSDATA (docdir));
      strcat (name, SSDATA (file));
    }
  else
    {
      name = SSDATA (file);
    }

  fd = emacs_open (name, O_RDONLY, 0);
  if (fd < 0)
    {
#ifndef CANNOT_DUMP
      if (!NILP (Vpurify_flag))
	{
	  /* Preparing to dump; DOC file is probably not installed.
	     So check in ../etc.  */
	  strcpy (name, "../etc/");
	  strcat (name, SSDATA (file));

	  fd = emacs_open (name, O_RDONLY, 0);
	}
#endif
      if (fd < 0)
	return concat3 (build_string ("Cannot open doc string file \""),
			file, build_string ("\"\n"));
    }

  /* Seek only to beginning of disk block.  */
  /* Make sure we read at least 1024 bytes before `position'
     so we can check the leading text for consistency.  */
  offset = min (position, max (1024, position % (8 * 1024)));
  if (TYPE_MAXIMUM (off_t) < position
      || lseek (fd, position - offset, 0) < 0)
    {
      emacs_close (fd);
      error ("Position %"pI"d out of range in doc string file \"%s\"",
	     position, name);
    }

  SAFE_FREE ();

  /* Read the doc string into get_doc_string_buffer.
     P points beyond the data just read.  */

  p = get_doc_string_buffer;
  while (1)
    {
      ptrdiff_t space_left = (get_doc_string_buffer_size - 1
			      - (p - get_doc_string_buffer));
      int nread;

      /* Allocate or grow the buffer if we need to.  */
      if (space_left <= 0)
	{
	  ptrdiff_t in_buffer = p - get_doc_string_buffer;
	  get_doc_string_buffer =
	    xpalloc (get_doc_string_buffer, &get_doc_string_buffer_size,
		     16 * 1024, -1, 1);
	  p = get_doc_string_buffer + in_buffer;
	  space_left = (get_doc_string_buffer_size - 1
			- (p - get_doc_string_buffer));
	}

      /* Read a disk block at a time.
         If we read the same block last time, maybe skip this?  */
      if (space_left > 1024 * 8)
	space_left = 1024 * 8;
      nread = emacs_read (fd, p, space_left);
      if (nread < 0)
	{
	  emacs_close (fd);
	  error ("Read error on documentation file");
	}
      p[nread] = 0;
      if (!nread)
	break;
      if (p == get_doc_string_buffer)
	p1 = strchr (p + offset, '\037');
      else
	p1 = strchr (p, '\037');
      if (p1)
	{
	  *p1 = 0;
	  p = p1;
	  break;
	}
      p += nread;
    }
  emacs_close (fd);

  /* Sanity checking.  */
  if (CONSP (filepos))
    {
      int test = 1;
      if (get_doc_string_buffer[offset - test++] != ' ')
	return Qnil;
      while (get_doc_string_buffer[offset - test] >= '0'
	     && get_doc_string_buffer[offset - test] <= '9')
	test++;
      if (get_doc_string_buffer[offset - test++] != '@'
	  || get_doc_string_buffer[offset - test] != '#')
	return Qnil;
    }
  else
    {
      int test = 1;
      if (get_doc_string_buffer[offset - test++] != '\n')
	return Qnil;
      while (get_doc_string_buffer[offset - test] > ' ')
	test++;
      if (get_doc_string_buffer[offset - test] != '\037')
	return Qnil;
    }

  /* Scan the text and perform quoting with ^A (char code 1).
     ^A^A becomes ^A, ^A0 becomes a null char, and ^A_ becomes a ^_.  */
  from = get_doc_string_buffer + offset;
  to = get_doc_string_buffer + offset;
  while (from != p)
    {
      if (*from == 1)
	{
	  int c;

	  from++;
	  c = *from++;
	  if (c == 1)
	    *to++ = c;
	  else if (c == '0')
	    *to++ = 0;
	  else if (c == '_')
	    *to++ = 037;
	  else
	    {
	      unsigned char uc = c;
	      error ("\
Invalid data in documentation file -- %c followed by code %03o",
		     1, uc);
	    }
	}
      else
	*to++ = *from++;
    }

  /* If DEFINITION, read from this buffer
     the same way we would read bytes from a file.  */
  if (definition)
    {
      read_bytecode_pointer = (unsigned char *) get_doc_string_buffer + offset;
      return Fread (Qlambda);
    }

  if (unibyte)
    return make_unibyte_string (get_doc_string_buffer + offset,
				to - (get_doc_string_buffer + offset));
  else
    {
      /* The data determines whether the string is multibyte.  */
      ptrdiff_t nchars =
	multibyte_chars_in_text (((unsigned char *) get_doc_string_buffer
				  + offset),
				 to - (get_doc_string_buffer + offset));
      return make_string_from_bytes (get_doc_string_buffer + offset,
				     nchars,
				     to - (get_doc_string_buffer + offset));
    }
}