[deliverable/binutils-gdb.git] / gas / config / atof-tahoe.c

/* atof_tahoe.c - turn a string into a Tahoe floating point number
   Copyright 1987, 1993, 2000 Free Software Foundation, Inc.

/* This is really a simplified version of atof_vax.c. I glommed it wholesale
   and then shaved it down. I don't even know how it works. (Don't you find
   my honesty refreshing?  Devon E Bowen <bowen@cs.buffalo.edu>

   I don't allow uppercase letters in the precision descrpitors.
   i.e. 'f' and 'd' are allowed but 'F' and 'D' aren't.  */

#include "as.h"

/* Precision in LittleNums.  */
#define MAX_PRECISION (4)
#define D_PRECISION (4)
#define F_PRECISION (2)

/* Precision in chars.  */
#define D_PRECISION_CHARS (8)
#define F_PRECISION_CHARS (4)

/* Length in LittleNums of guard bits.  */
#define GUARD (2)

static const long int mask[] =
{
  0x00000000,
  0x00000001,
  0x00000003,
  0x00000007,
  0x0000000f,
  0x0000001f,
  0x0000003f,
  0x0000007f,
  0x000000ff,
  0x000001ff,
  0x000003ff,
  0x000007ff,
  0x00000fff,
  0x00001fff,
  0x00003fff,
  0x00007fff,
  0x0000ffff,
  0x0001ffff,
  0x0003ffff,
  0x0007ffff,
  0x000fffff,
  0x001fffff,
  0x003fffff,
  0x007fffff,
  0x00ffffff,
  0x01ffffff,
  0x03ffffff,
  0x07ffffff,
  0x0fffffff,
  0x1fffffff,
  0x3fffffff,
  0x7fffffff,
  0xffffffff
};
\f
/* Shared between flonum_gen2tahoe and next_bits.  */
static int bits_left_in_littlenum;
static LITTLENUM_TYPE *littlenum_pointer;
static LITTLENUM_TYPE *littlenum_end;

#if __STDC__ == 1

int flonum_gen2tahoe (int format_letter, FLONUM_TYPE * f,
		      LITTLENUM_TYPE * words);

#else /* not __STDC__  */

int flonum_gen2tahoe ();

#endif /* not __STDC__  */

static int
next_bits (number_of_bits)
     int number_of_bits;
{
  int return_value;

  if (littlenum_pointer < littlenum_end)
    return 0;
  if (number_of_bits >= bits_left_in_littlenum)
    {
      return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
      number_of_bits -= bits_left_in_littlenum;
      return_value <<= number_of_bits;
      bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
      littlenum_pointer--;
      if (littlenum_pointer >= littlenum_end)
	return_value |= ((*littlenum_pointer) >> (bits_left_in_littlenum)) &
	  mask[number_of_bits];
    }
  else
    {
      bits_left_in_littlenum -= number_of_bits;
      return_value = mask[number_of_bits] &
	((*littlenum_pointer) >> bits_left_in_littlenum);
    }
  return return_value;
}

static void
make_invalid_floating_point_number (words)
     LITTLENUM_TYPE *words;
{
  /* Floating Reserved Operand Code.  */
  *words = 0x8000;
}
\f
static int			/* 0 means letter is OK.  */
what_kind_of_float (letter, precisionP, exponent_bitsP)
     /* In: lowercase please. What kind of float?  */
     char letter;

     /* Number of 16-bit words in the float.  */
     int *precisionP;

     /* Number of exponent bits.  */
     long int *exponent_bitsP;
{
  int retval;			/* 0: OK.  */

  retval = 0;
  switch (letter)
    {
    case 'f':
      *precisionP = F_PRECISION;
      *exponent_bitsP = 8;
      break;

    case 'd':
      *precisionP = D_PRECISION;
      *exponent_bitsP = 8;
      break;

    default:
      retval = 69;
      break;
    }
  return (retval);
}
\f
/* Warning: This returns 16-bit LITTLENUMs, because that is what the
   VAX thinks in.  It is up to the caller to figure out any alignment
   problems and to conspire for the bytes/word to be emitted in the
   right order. Bigendians beware!  */

char *				/* Return pointer past text consumed.  */
atof_tahoe (str, what_kind, words)
     char *str;			/* Text to convert to binary.  */
     char what_kind;		/* 'd', 'f', 'g', 'h' */
     LITTLENUM_TYPE *words;	/* Build the binary here.  */
{
  FLONUM_TYPE f;
  LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
  /* Extra bits for zeroed low-order bits.  */
  /* The 1st MAX_PRECISION are zeroed, the last contain flonum bits.  */
  char *return_value;
  int precision;		/* Number of 16-bit words in the format.  */
  long int exponent_bits;

  return_value = str;
  f.low = bits + MAX_PRECISION;
  f.high = NULL;
  f.leader = NULL;
  f.exponent = NULL;
  f.sign = '\0';

  if (what_kind_of_float (what_kind, &precision, &exponent_bits))
    {
      /* We lost.  */
      return_value = NULL;
      make_invalid_floating_point_number (words);
    }
  if (return_value)
    {
      memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);

      /* Use more LittleNums than seems necessary:
	 the highest flonum may have 15 leading 0 bits, so could be
	 useless.  */
      f.high = f.low + precision - 1 + GUARD;

      if (atof_generic (&return_value, ".", "eE", &f))
	{
	  make_invalid_floating_point_number (words);
	  /* We lost.  */
	  return_value = NULL;
	}
      else
	{
	  if (flonum_gen2tahoe (what_kind, &f, words))
	    return_value = NULL;
	}
    }
  return return_value;
}
\f
/* In: a flonum, a Tahoe floating point format.
   Out: a Tahoe floating-point bit pattern.  */

int				/* 0: OK.  */
flonum_gen2tahoe (format_letter, f, words)
     char format_letter;	/* One of 'd' 'f'.  */
     FLONUM_TYPE *f;
     LITTLENUM_TYPE *words;	/* Deliver answer here.  */
{
  LITTLENUM_TYPE *lp;
  int precision;
  long int exponent_bits;
  int return_value;		/* 0 == OK.  */

  return_value =
    what_kind_of_float (format_letter, &precision, &exponent_bits);
  if (return_value != 0)
    {
      make_invalid_floating_point_number (words);
    }
  else
    {
      if (f->low > f->leader)
	{
	  /* 0.0e0 seen.  */
	  memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision);
	}
      else
	{
	  long int exponent_1;
	  long int exponent_2;
	  long int exponent_3;
	  long int exponent_4;
	  int exponent_skippage;
	  LITTLENUM_TYPE word1;

	  /* JF: Deal with new Nan, +Inf and -Inf codes.  */
	  if (f->sign != '-' && f->sign != '+')
	    {
	      make_invalid_floating_point_number (words);
	      return return_value;
	    }
	  /* All tahoe floating_point formats have:
	     Bit 15 is sign bit.
	     Bits 14:n are excess-whatever exponent.
	     Bits n-1:0 (if any) are most significant bits of fraction.
	     Bits 15:0 of the next word are the next most significant bits.
	     And so on for each other word.

	     So we need: number of bits of exponent, number of bits of
	     mantissa.  */

	  bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
	  littlenum_pointer = f->leader;
	  littlenum_end = f->low;

	  /* Seek (and forget) 1st significant bit.  */
	  for (exponent_skippage = 0;
	       !next_bits (1);
	       exponent_skippage++)
	    ;

	  exponent_1 = f->exponent + f->leader + 1 - f->low;

	  /* Radix LITTLENUM_RADIX, point just higher than f -> leader.  */
	  exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;

	  /* Radix 2.  */
	  exponent_3 = exponent_2 - exponent_skippage;

	  /* Forget leading zeros, forget 1st bit.  */
	  exponent_4 = exponent_3 + (1 << (exponent_bits - 1));

	  /* Offset exponent.  */

	  if (exponent_4 & ~mask[exponent_bits])
	    {
	      /* Exponent overflow. Lose immediately.  */

	      make_invalid_floating_point_number (words);

	      /* We leave return_value alone: admit we read the
	        number, but return a floating exception because we
	        can't encode the number.  */
	    }
	  else
	    {
	      lp = words;

	      /* Word 1.  Sign, exponent and perhaps high bits.  */
	      /* Assume 2's complement integers.  */
	      word1 = ((exponent_4 & mask[exponent_bits])
		       << (15 - exponent_bits))
		| ((f->sign == '+') ? 0 : 0x8000)
		| next_bits (15 - exponent_bits);
	      *lp++ = word1;

	      /* The rest of the words are just mantissa bits.  */
	      for (; lp < words + precision; lp++)
		*lp = next_bits (LITTLENUM_NUMBER_OF_BITS);

	      if (next_bits (1))
		{
		  /* Since the NEXT bit is a 1, round UP the mantissa.
		     The cunning design of these hidden-1 floats permits
		     us to let the mantissa overflow into the exponent, and
		     it 'does the right thing'. However, we lose if the
		     highest-order bit of the lowest-order word flips.
		     Is that clear?  */

		  unsigned long int carry;

		  /* #if (sizeof(carry)) < ((sizeof(bits[0]) *
		     BITS_PER_CHAR) + 2) Please allow at least 1 more
		     bit in carry than is in a LITTLENUM.  We need
		     that extra bit to hold a carry during a LITTLENUM
		     carry propagation. Another extra bit (kept 0)
		     will assure us that we don't get a sticky sign
		     bit after shifting right, and that permits us to
		     propagate the carry without any masking of bits.
		     #endif  */
		  for (carry = 1, lp--;
		       carry && (lp >= words);
		       lp--)
		    {
		      carry = *lp + carry;
		      *lp = carry;
		      carry >>= LITTLENUM_NUMBER_OF_BITS;
		    }

		  if ((word1 ^ *words)
		      & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
		    {
		      make_invalid_floating_point_number (words);
		      /* We leave return_value alone: admit we read
			 the number, but return a floating exception
			 because we can't encode the number.  */
		    }
		}		/* if (we needed to round up)  */
	    }			/* if (exponent overflow)  */
	}			/* if (0.0e0)  */
    }				/* if (float_type was OK)  */
  return return_value;
}
\f
/* In:	input_line_pointer -> the 1st character of a floating-point
 *		number.
 *	1 letter denoting the type of statement that wants a
 *		binary floating point number returned.
 *	Address of where to build floating point literal.
 *		Assumed to be 'big enough'.
 *	Address of where to return size of literal (in chars).
 *
 * Out:	Input_line_pointer -> of next char after floating number.
 *	Error message, or 0.
 *	Floating point literal.
 *	Number of chars we used for the literal.  */

char *
md_atof (what_statement_type, literalP, sizeP)
     char what_statement_type;
     char *literalP;
     int *sizeP;
{
  LITTLENUM_TYPE words[MAX_PRECISION];
  register char kind_of_float;
  register int number_of_chars;
  register LITTLENUM_TYPE *littlenum_pointer;

  switch (what_statement_type)
    {
    case 'f':			/* .ffloat  */
    case 'd':			/* .dfloat  */
      kind_of_float = what_statement_type;
      break;

    default:
      kind_of_float = 0;
      break;
    }

  if (kind_of_float)
    {
      register LITTLENUM_TYPE *limit;

      input_line_pointer = atof_tahoe (input_line_pointer,
				       kind_of_float,
				       words);
      /* The atof_tahoe() builds up 16-bit numbers.
	 Since the assembler may not be running on
	 a different-endian machine, be very careful about
	 converting words to chars.  */
      number_of_chars = (kind_of_float == 'f' ? F_PRECISION_CHARS :
			 (kind_of_float == 'd' ? D_PRECISION_CHARS : 0));
      know (number_of_chars <= MAX_PRECISION * sizeof (LITTLENUM_TYPE));
      limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE));
      for (littlenum_pointer = words;
	   littlenum_pointer < limit;
	   littlenum_pointer++)
	{
	  md_number_to_chars (literalP, *littlenum_pointer,
			      sizeof (LITTLENUM_TYPE));
	  literalP += sizeof (LITTLENUM_TYPE);
	}
    }
  else
    {
      number_of_chars = 0;
    }

  *sizeP = number_of_chars;
  return kind_of_float ? 0 : _("Bad call to md_atof()");
}
Commit	Line	Data
252b5132	1	/* atof_tahoe.c - turn a string into a Tahoe floating point number
f7e42eb4	2	Copyright 1987, 1993, 2000 Free Software Foundation, Inc.
252b5132 RH	3
	4	/* This is really a simplified version of atof_vax.c. I glommed it wholesale
	5	and then shaved it down. I don't even know how it works. (Don't you find
2d484c7f	6	my honesty refreshing? Devon E Bowen <bowen@cs.buffalo.edu>
252b5132	7
2d484c7f KH	8	I don't allow uppercase letters in the precision descrpitors.
2d484c7f KH	9	i.e. 'f' and 'd' are allowed but 'F' and 'D' aren't. */
252b5132 RH	10
	11	#include "as.h"
	12
2d484c7f	13	/* Precision in LittleNums. */
252b5132 RH	14	#define MAX_PRECISION (4)
	15	#define D_PRECISION (4)
	16	#define F_PRECISION (2)
	17
2d484c7f	18	/* Precision in chars. */
252b5132 RH	19	#define D_PRECISION_CHARS (8)
	20	#define F_PRECISION_CHARS (4)
	21
2d484c7f	22	/* Length in LittleNums of guard bits. */
252b5132 RH	23	#define GUARD (2)
	24
	25	static const long int mask[] =
	26	{
	27	0x00000000,
	28	0x00000001,
	29	0x00000003,
	30	0x00000007,
	31	0x0000000f,
	32	0x0000001f,
	33	0x0000003f,
	34	0x0000007f,
	35	0x000000ff,
	36	0x000001ff,
	37	0x000003ff,
	38	0x000007ff,
	39	0x00000fff,
	40	0x00001fff,
	41	0x00003fff,
	42	0x00007fff,
	43	0x0000ffff,
	44	0x0001ffff,
	45	0x0003ffff,
	46	0x0007ffff,
	47	0x000fffff,
	48	0x001fffff,
	49	0x003fffff,
	50	0x007fffff,
	51	0x00ffffff,
	52	0x01ffffff,
	53	0x03ffffff,
	54	0x07ffffff,
	55	0x0fffffff,
	56	0x1fffffff,
	57	0x3fffffff,
	58	0x7fffffff,
	59	0xffffffff
	60	};
	61	\f
2d484c7f	62	/* Shared between flonum_gen2tahoe and next_bits. */
252b5132 RH	63	static int bits_left_in_littlenum;
	64	static LITTLENUM_TYPE *littlenum_pointer;
	65	static LITTLENUM_TYPE *littlenum_end;
	66
	67	#if __STDC__ == 1
	68
2d484c7f KH	69	int flonum_gen2tahoe (int format_letter, FLONUM_TYPE * f,
2d484c7f KH	70	LITTLENUM_TYPE * words);
252b5132	71
2d484c7f	72	#else /* not __STDC__ */
252b5132 RH	73
	74	int flonum_gen2tahoe ();
	75
2d484c7f	76	#endif /* not __STDC__ */
252b5132 RH	77
	78	static int
	79	next_bits (number_of_bits)
	80	int number_of_bits;
	81	{
	82	int return_value;
	83
	84	if (littlenum_pointer < littlenum_end)
	85	return 0;
	86	if (number_of_bits >= bits_left_in_littlenum)
	87	{
	88	return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
	89	number_of_bits -= bits_left_in_littlenum;
	90	return_value <<= number_of_bits;
	91	bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
	92	littlenum_pointer--;
	93	if (littlenum_pointer >= littlenum_end)
	94	return_value \|= ((*littlenum_pointer) >> (bits_left_in_littlenum)) &
	95	mask[number_of_bits];
	96	}
	97	else
	98	{
	99	bits_left_in_littlenum -= number_of_bits;
	100	return_value = mask[number_of_bits] &
	101	((*littlenum_pointer) >> bits_left_in_littlenum);
	102	}
2d484c7f	103	return return_value;
252b5132 RH	104	}
	105
	106	static void
	107	make_invalid_floating_point_number (words)
	108	LITTLENUM_TYPE *words;
	109	{
2d484c7f KH	110	/* Floating Reserved Operand Code. */
2d484c7f KH	111	*words = 0x8000;
252b5132 RH	112	}
252b5132 RH	113	\f
2d484c7f	114	static int /* 0 means letter is OK. */
252b5132	115	what_kind_of_float (letter, precisionP, exponent_bitsP)
2d484c7f KH	116	/* In: lowercase please. What kind of float? */
	117	char letter;
	118
	119	/* Number of 16-bit words in the float. */
	120	int *precisionP;
	121
	122	/* Number of exponent bits. */
	123	long int *exponent_bitsP;
252b5132	124	{
2d484c7f	125	int retval; /* 0: OK. */
252b5132 RH	126
	127	retval = 0;
	128	switch (letter)
	129	{
	130	case 'f':
	131	*precisionP = F_PRECISION;
	132	*exponent_bitsP = 8;
	133	break;
	134
	135	case 'd':
	136	*precisionP = D_PRECISION;
	137	*exponent_bitsP = 8;
	138	break;
	139
	140	default:
	141	retval = 69;
	142	break;
	143	}
	144	return (retval);
	145	}
	146	\f
2d484c7f KH	147	/* Warning: This returns 16-bit LITTLENUMs, because that is what the
	148	VAX thinks in. It is up to the caller to figure out any alignment
	149	problems and to conspire for the bytes/word to be emitted in the
	150	right order. Bigendians beware! */
	151
	152	char * /* Return pointer past text consumed. */
252b5132	153	atof_tahoe (str, what_kind, words)
2d484c7f	154	char str; / Text to convert to binary. */
252b5132	155	char what_kind; /* 'd', 'f', 'g', 'h' */
2d484c7f	156	LITTLENUM_TYPE words; / Build the binary here. */
252b5132 RH	157	{
	158	FLONUM_TYPE f;
	159	LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
2d484c7f KH	160	/* Extra bits for zeroed low-order bits. */
2d484c7f KH	161	/* The 1st MAX_PRECISION are zeroed, the last contain flonum bits. */
252b5132	162	char *return_value;
2d484c7f	163	int precision; /* Number of 16-bit words in the format. */
252b5132 RH	164	long int exponent_bits;
	165
	166	return_value = str;
	167	f.low = bits + MAX_PRECISION;
	168	f.high = NULL;
	169	f.leader = NULL;
	170	f.exponent = NULL;
	171	f.sign = '\0';
	172
	173	if (what_kind_of_float (what_kind, &precision, &exponent_bits))
	174	{
2d484c7f KH	175	/* We lost. */
2d484c7f KH	176	return_value = NULL;
252b5132 RH	177	make_invalid_floating_point_number (words);
	178	}
	179	if (return_value)
	180	{
	181	memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);
	182
2d484c7f KH	183	/* Use more LittleNums than seems necessary:
	184	the highest flonum may have 15 leading 0 bits, so could be
	185	useless. */
252b5132 RH	186	f.high = f.low + precision - 1 + GUARD;
	187
	188	if (atof_generic (&return_value, ".", "eE", &f))
	189	{
	190	make_invalid_floating_point_number (words);
2d484c7f KH	191	/* We lost. */
2d484c7f KH	192	return_value = NULL;
252b5132 RH	193	}
	194	else
	195	{
	196	if (flonum_gen2tahoe (what_kind, &f, words))
2d484c7f	197	return_value = NULL;
252b5132 RH	198	}
252b5132 RH	199	}
2d484c7f	200	return return_value;
252b5132 RH	201	}
252b5132 RH	202	\f
2d484c7f KH	203	/* In: a flonum, a Tahoe floating point format.
2d484c7f KH	204	Out: a Tahoe floating-point bit pattern. */
252b5132	205
2d484c7f	206	int /* 0: OK. */
252b5132	207	flonum_gen2tahoe (format_letter, f, words)
2d484c7f	208	char format_letter; /* One of 'd' 'f'. */
252b5132	209	FLONUM_TYPE *f;
2d484c7f	210	LITTLENUM_TYPE words; / Deliver answer here. */
252b5132 RH	211	{
	212	LITTLENUM_TYPE *lp;
	213	int precision;
	214	long int exponent_bits;
2d484c7f	215	int return_value; /* 0 == OK. */
252b5132	216
2d484c7f KH	217	return_value =
2d484c7f KH	218	what_kind_of_float (format_letter, &precision, &exponent_bits);
252b5132 RH	219	if (return_value != 0)
	220	{
	221	make_invalid_floating_point_number (words);
	222	}
	223	else
	224	{
	225	if (f->low > f->leader)
	226	{
2d484c7f	227	/* 0.0e0 seen. */
252b5132 RH	228	memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision);
	229	}
	230	else
	231	{
	232	long int exponent_1;
	233	long int exponent_2;
	234	long int exponent_3;
	235	long int exponent_4;
	236	int exponent_skippage;
	237	LITTLENUM_TYPE word1;
	238
2d484c7f	239	/* JF: Deal with new Nan, +Inf and -Inf codes. */
252b5132 RH	240	if (f->sign != '-' && f->sign != '+')
	241	{
	242	make_invalid_floating_point_number (words);
	243	return return_value;
	244	}
2d484c7f KH	245	/* All tahoe floating_point formats have:
	246	Bit 15 is sign bit.
	247	Bits 14:n are excess-whatever exponent.
	248	Bits n-1:0 (if any) are most significant bits of fraction.
	249	Bits 15:0 of the next word are the next most significant bits.
	250	And so on for each other word.
	251
	252	So we need: number of bits of exponent, number of bits of
	253	mantissa. */
252b5132 RH	254
	255	bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
	256	littlenum_pointer = f->leader;
	257	littlenum_end = f->low;
2d484c7f KH	258
2d484c7f KH	259	/* Seek (and forget) 1st significant bit. */
252b5132 RH	260	for (exponent_skippage = 0;
	261	!next_bits (1);
	262	exponent_skippage++)
2d484c7f KH	263	;
2d484c7f KH	264
252b5132	265	exponent_1 = f->exponent + f->leader + 1 - f->low;
2d484c7f KH	266
2d484c7f KH	267	/* Radix LITTLENUM_RADIX, point just higher than f -> leader. */
252b5132	268	exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
2d484c7f KH	269
2d484c7f KH	270	/* Radix 2. */
252b5132	271	exponent_3 = exponent_2 - exponent_skippage;
2d484c7f KH	272
2d484c7f KH	273	/* Forget leading zeros, forget 1st bit. */
252b5132	274	exponent_4 = exponent_3 + (1 << (exponent_bits - 1));
2d484c7f KH	275
2d484c7f KH	276	/* Offset exponent. */
252b5132 RH	277
	278	if (exponent_4 & ~mask[exponent_bits])
	279	{
2d484c7f	280	/* Exponent overflow. Lose immediately. */
252b5132 RH	281
	282	make_invalid_floating_point_number (words);
	283
2d484c7f KH	284	/* We leave return_value alone: admit we read the
	285	number, but return a floating exception because we
	286	can't encode the number. */
252b5132 RH	287	}
	288	else
	289	{
	290	lp = words;
	291
2d484c7f KH	292	/* Word 1. Sign, exponent and perhaps high bits. */
	293	/* Assume 2's complement integers. */
	294	word1 = ((exponent_4 & mask[exponent_bits])
	295	<< (15 - exponent_bits))
252b5132 RH	296	\| ((f->sign == '+') ? 0 : 0x8000)
	297	\| next_bits (15 - exponent_bits);
	298	*lp++ = word1;
	299
2d484c7f	300	/* The rest of the words are just mantissa bits. */
252b5132	301	for (; lp < words + precision; lp++)
2d484c7f	302	*lp = next_bits (LITTLENUM_NUMBER_OF_BITS);
252b5132 RH	303
	304	if (next_bits (1))
	305	{
2d484c7f KH	306	/* Since the NEXT bit is a 1, round UP the mantissa.
	307	The cunning design of these hidden-1 floats permits
	308	us to let the mantissa overflow into the exponent, and
	309	it 'does the right thing'. However, we lose if the
	310	highest-order bit of the lowest-order word flips.
	311	Is that clear? */
252b5132 RH	312
	313	unsigned long int carry;
	314
2d484c7f KH	315	/* #if (sizeof(carry)) < ((sizeof(bits[0]) *
	316	BITS_PER_CHAR) + 2) Please allow at least 1 more
	317	bit in carry than is in a LITTLENUM. We need
	318	that extra bit to hold a carry during a LITTLENUM
	319	carry propagation. Another extra bit (kept 0)
	320	will assure us that we don't get a sticky sign
	321	bit after shifting right, and that permits us to
	322	propagate the carry without any masking of bits.
	323	#endif */
252b5132 RH	324	for (carry = 1, lp--;
	325	carry && (lp >= words);
	326	lp--)
	327	{
	328	carry = *lp + carry;
	329	*lp = carry;
	330	carry >>= LITTLENUM_NUMBER_OF_BITS;
	331	}
	332
2d484c7f KH	333	if ((word1 ^ *words)
2d484c7f KH	334	& (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
252b5132 RH	335	{
252b5132 RH	336	make_invalid_floating_point_number (words);
2d484c7f KH	337	/* We leave return_value alone: admit we read
	338	the number, but return a floating exception
	339	because we can't encode the number. */
252b5132	340	}
2d484c7f KH	341	} /* if (we needed to round up) */
	342	} /* if (exponent overflow) */
	343	} /* if (0.0e0) */
	344	} /* if (float_type was OK) */
	345	return return_value;
252b5132 RH	346	}
252b5132 RH	347	\f
2d484c7f	348	/* In: input_line_pointer -> the 1st character of a floating-point
252b5132 RH	349	* number.
	350	* 1 letter denoting the type of statement that wants a
	351	* binary floating point number returned.
	352	* Address of where to build floating point literal.
	353	* Assumed to be 'big enough'.
	354	* Address of where to return size of literal (in chars).
	355	*
	356	* Out: Input_line_pointer -> of next char after floating number.
	357	* Error message, or 0.
	358	* Floating point literal.
2d484c7f	359	* Number of chars we used for the literal. */
252b5132 RH	360
	361	char *
	362	md_atof (what_statement_type, literalP, sizeP)
	363	char what_statement_type;
	364	char *literalP;
	365	int *sizeP;
	366	{
	367	LITTLENUM_TYPE words[MAX_PRECISION];
	368	register char kind_of_float;
	369	register int number_of_chars;
	370	register LITTLENUM_TYPE *littlenum_pointer;
	371
	372	switch (what_statement_type)
	373	{
2d484c7f KH	374	case 'f': /* .ffloat */
2d484c7f KH	375	case 'd': /* .dfloat */
252b5132 RH	376	kind_of_float = what_statement_type;
	377	break;
	378
	379	default:
	380	kind_of_float = 0;
	381	break;
2d484c7f	382	}
252b5132 RH	383
	384	if (kind_of_float)
	385	{
	386	register LITTLENUM_TYPE *limit;
	387
	388	input_line_pointer = atof_tahoe (input_line_pointer,
	389	kind_of_float,
	390	words);
2d484c7f KH	391	/* The atof_tahoe() builds up 16-bit numbers.
	392	Since the assembler may not be running on
	393	a different-endian machine, be very careful about
	394	converting words to chars. */
252b5132 RH	395	number_of_chars = (kind_of_float == 'f' ? F_PRECISION_CHARS :
	396	(kind_of_float == 'd' ? D_PRECISION_CHARS : 0));
	397	know (number_of_chars <= MAX_PRECISION * sizeof (LITTLENUM_TYPE));
	398	limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE));
	399	for (littlenum_pointer = words;
	400	littlenum_pointer < limit;
	401	littlenum_pointer++)
	402	{
	403	md_number_to_chars (literalP, *littlenum_pointer,
	404	sizeof (LITTLENUM_TYPE));
	405	literalP += sizeof (LITTLENUM_TYPE);
2d484c7f	406	}
252b5132 RH	407	}
	408	else
	409	{
	410	number_of_chars = 0;
2d484c7f	411	}
252b5132 RH	412
	413	*sizeP = number_of_chars;
	414	return kind_of_float ? 0 : _("Bad call to md_atof()");
	415	}