[thirdparty/binutils-gdb.git] / gas / config / atof-vax.c

/* atof_vax.c - turn a Flonum into a VAX floating point number
   Copyright 1987, 1992, 1993, 1995, 1997, 1999, 2000, 2005
   Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GAS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GAS; see the file COPYING.  If not, write to the Free
   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
   02111-1307, USA.  */

#include "as.h"

/* Precision in LittleNums.  */
#define MAX_PRECISION	8
#define H_PRECISION	8
#define G_PRECISION	4
#define D_PRECISION	4
#define F_PRECISION	2

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

int flonum_gen2vax (int, FLONUM_TYPE *, LITTLENUM_TYPE *);

/* Number of chars in flonum type 'letter'.  */

static int
atof_vax_sizeof (int letter)
{
  int return_value;

  /* Permitting uppercase letters is probably a bad idea.
     Please use only lower-cased letters in case the upper-cased
     ones become unsupported!  */
  switch (letter)
    {
    case 'f':
    case 'F':
      return_value = 4;
      break;

    case 'd':
    case 'D':
    case 'g':
    case 'G':
      return_value = 8;
      break;

    case 'h':
    case 'H':
      return_value = 16;
      break;

    default:
      return_value = 0;
      break;
    }

  return return_value;
}

static const long 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_gen2vax and next_bits.  */
static int bits_left_in_littlenum;
static LITTLENUM_TYPE *littlenum_pointer;
static LITTLENUM_TYPE *littlenum_end;

static int
next_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 (LITTLENUM_TYPE *words)
{
  *words = 0x8000;		/* Floating Reserved Operand Code.  */
}

\f
static int			/* 0 means letter is OK.  */
what_kind_of_float (int letter,			/* In: lowercase please. What kind of float?  */
		    int *precisionP,		/* Number of 16-bit words in the float.  */
		    long *exponent_bitsP)	/* Number of exponent bits.  */
{
  int retval;

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

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

    case 'g':
      *precisionP = G_PRECISION;
      *exponent_bitsP = 11;
      break;

    case 'h':
      *precisionP = H_PRECISION;
      *exponent_bitsP = 15;
      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!  */

static char *
atof_vax (char *str,			/* Text to convert to binary.  */
	  int 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 exponent_bits;

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

  if (what_kind_of_float (what_kind, &precision, &exponent_bits))
    {
      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);
	  return_value = NULL;
	}
      else if (flonum_gen2vax (what_kind, &f, words))
	return_value = NULL;
    }

  return return_value;
}
\f
/* In: a flonum, a vax floating point format.
   Out: a vax floating-point bit pattern.  */

int
flonum_gen2vax (int format_letter,	/* One of 'd' 'f' 'g' 'h'.  */
		FLONUM_TYPE *f,
		LITTLENUM_TYPE *words)	/* Deliver answer here.  */
{
  LITTLENUM_TYPE *lp;
  int precision;
  long 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 exponent_1;
	  long exponent_2;
	  long exponent_3;
	  long 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 vaxen floating_point formats (so far) 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.

	     All this to be compatible with a KF11?? (Which is still faster
	     than lots of vaxen I can think of, but it also has higher
	     maintenance costs ... sigh).

	     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 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.  */
		    }
		}
	    }
	}
    }
  return return_value;
}

/* JF this used to be in vax.c but this looks like a better place for it.  */

/* 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.  */

#define MAXIMUM_NUMBER_OF_LITTLENUMS  8 	/* For .hfloats.  */

char *
md_atof (int what_statement_type,
	 char *literalP,
	 int *sizeP)
{
  LITTLENUM_TYPE words[MAXIMUM_NUMBER_OF_LITTLENUMS];
  char kind_of_float;
  int number_of_chars;
  LITTLENUM_TYPE *littlenumP;

  switch (what_statement_type)
    {
    case 'F':
    case 'f':
      kind_of_float = 'f';
      break;

    case 'D':
    case 'd':
      kind_of_float = 'd';
      break;

    case 'g':
      kind_of_float = 'g';
      break;

    case 'h':
      kind_of_float = 'h';
      break;

    default:
      kind_of_float = 0;
      break;
    };

  if (kind_of_float)
    {
      LITTLENUM_TYPE *limit;

      input_line_pointer = atof_vax (input_line_pointer,
				     kind_of_float,
				     words);
      /* The atof_vax() builds up 16-bit numbers.
         Since the assembler may not be running on
         a little-endian machine, be very careful about
         converting words to chars.  */
      number_of_chars = atof_vax_sizeof (kind_of_float);
      know (number_of_chars <= MAXIMUM_NUMBER_OF_LITTLENUMS * sizeof (LITTLENUM_TYPE));
      limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE));
      for (littlenumP = words; littlenumP < limit; littlenumP++)
	{
	  md_number_to_chars (literalP, *littlenumP, sizeof (LITTLENUM_TYPE));
	  literalP += sizeof (LITTLENUM_TYPE);
	};
    }
  else
    number_of_chars = 0;

  *sizeP = number_of_chars;
  return kind_of_float ? NULL : _("Bad call to md_atof()");
}
Commit	Line	Data
252b5132	1	/* atof_vax.c - turn a Flonum into a VAX floating point number
4d5f9b2a	2	Copyright 1987, 1992, 1993, 1995, 1997, 1999, 2000, 2005
12951dca	3	Free Software Foundation, Inc.
252b5132 RH	4
	5	This file is part of GAS, the GNU Assembler.
	6
	7	GAS is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2, or (at your option)
	10	any later version.
	11
	12	GAS is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with GAS; see the file COPYING. If not, write to the Free
	19	Software Foundation, 59 Temple Place - Suite 330, Boston, MA
	20	02111-1307, USA. */
	21
	22	#include "as.h"
	23
4a1805b1	24	/* Precision in LittleNums. */
4d5f9b2a NC	25	#define MAX_PRECISION 8
	26	#define H_PRECISION 8
	27	#define G_PRECISION 4
	28	#define D_PRECISION 4
	29	#define F_PRECISION 2
252b5132	30
4a1805b1	31	/* Length in LittleNums of guard bits. */
4d5f9b2a	32	#define GUARD 2
252b5132	33
4d5f9b2a	34	int flonum_gen2vax (int, FLONUM_TYPE , LITTLENUM_TYPE );
252b5132	35
4a1805b1	36	/* Number of chars in flonum type 'letter'. */
4d5f9b2a	37
252b5132	38	static int
4d5f9b2a	39	atof_vax_sizeof (int letter)
252b5132 RH	40	{
	41	int return_value;
	42
4d5f9b2a NC	43	/* Permitting uppercase letters is probably a bad idea.
	44	Please use only lower-cased letters in case the upper-cased
	45	ones become unsupported! */
252b5132 RH	46	switch (letter)
	47	{
	48	case 'f':
	49	case 'F':
	50	return_value = 4;
	51	break;
	52
	53	case 'd':
	54	case 'D':
	55	case 'g':
	56	case 'G':
	57	return_value = 8;
	58	break;
	59
	60	case 'h':
	61	case 'H':
	62	return_value = 16;
	63	break;
	64
	65	default:
	66	return_value = 0;
	67	break;
	68	}
4d5f9b2a NC	69
	70	return return_value;
	71	}
252b5132 RH	72
	73	static const long mask[] =
	74	{
	75	0x00000000,
	76	0x00000001,
	77	0x00000003,
	78	0x00000007,
	79	0x0000000f,
	80	0x0000001f,
	81	0x0000003f,
	82	0x0000007f,
	83	0x000000ff,
	84	0x000001ff,
	85	0x000003ff,
	86	0x000007ff,
	87	0x00000fff,
	88	0x00001fff,
	89	0x00003fff,
	90	0x00007fff,
	91	0x0000ffff,
	92	0x0001ffff,
	93	0x0003ffff,
	94	0x0007ffff,
	95	0x000fffff,
	96	0x001fffff,
	97	0x003fffff,
	98	0x007fffff,
	99	0x00ffffff,
	100	0x01ffffff,
	101	0x03ffffff,
	102	0x07ffffff,
	103	0x0fffffff,
	104	0x1fffffff,
	105	0x3fffffff,
	106	0x7fffffff,
	107	0xffffffff
	108	};
	109	\f
	110
4d5f9b2a	111	/* Shared between flonum_gen2vax and next_bits. */
252b5132 RH	112	static int bits_left_in_littlenum;
	113	static LITTLENUM_TYPE *littlenum_pointer;
	114	static LITTLENUM_TYPE *littlenum_end;
	115
	116	static int
4d5f9b2a	117	next_bits (int number_of_bits)
252b5132 RH	118	{
	119	int return_value;
	120
	121	if (littlenum_pointer < littlenum_end)
	122	return 0;
	123	if (number_of_bits >= bits_left_in_littlenum)
	124	{
	125	return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
	126	number_of_bits -= bits_left_in_littlenum;
	127	return_value <<= number_of_bits;
	128	bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
	129	littlenum_pointer--;
	130	if (littlenum_pointer >= littlenum_end)
	131	return_value \|= ((*littlenum_pointer) >> (bits_left_in_littlenum)) & mask[number_of_bits];
	132	}
	133	else
	134	{
	135	bits_left_in_littlenum -= number_of_bits;
	136	return_value = mask[number_of_bits] & ((*littlenum_pointer) >> bits_left_in_littlenum);
	137	}
4d5f9b2a	138	return return_value;
252b5132 RH	139	}
	140
	141	static void
4d5f9b2a	142	make_invalid_floating_point_number (LITTLENUM_TYPE *words)
252b5132	143	{
4d5f9b2a	144	words = 0x8000; / Floating Reserved Operand Code. */
252b5132	145	}
4d5f9b2a	146
252b5132	147	\f
4a1805b1	148	static int /* 0 means letter is OK. */
4d5f9b2a NC	149	what_kind_of_float (int letter, /* In: lowercase please. What kind of float? */
	150	int precisionP, / Number of 16-bit words in the float. */
	151	long exponent_bitsP) / Number of exponent bits. */
252b5132	152	{
4d5f9b2a	153	int retval;
252b5132 RH	154
	155	retval = 0;
	156	switch (letter)
	157	{
	158	case 'f':
	159	*precisionP = F_PRECISION;
	160	*exponent_bitsP = 8;
	161	break;
	162
	163	case 'd':
	164	*precisionP = D_PRECISION;
	165	*exponent_bitsP = 8;
	166	break;
	167
	168	case 'g':
	169	*precisionP = G_PRECISION;
	170	*exponent_bitsP = 11;
	171	break;
	172
	173	case 'h':
	174	*precisionP = H_PRECISION;
	175	*exponent_bitsP = 15;
	176	break;
	177
	178	default:
	179	retval = 69;
	180	break;
	181	}
4d5f9b2a	182	return retval;
252b5132 RH	183	}
252b5132 RH	184	\f
4d5f9b2a NC	185	/* Warning: this returns 16-bit LITTLENUMs, because that is
	186	what the VAX thinks in. It is up to the caller to figure
	187	out any alignment problems and to conspire for the bytes/word
	188	to be emitted in the right order. Bigendians beware! */
	189
	190	static char *
	191	atof_vax (char str, / Text to convert to binary. */
	192	int what_kind, /* 'd', 'f', 'g', 'h' */
	193	LITTLENUM_TYPE words) / Build the binary here. */
252b5132 RH	194	{
	195	FLONUM_TYPE f;
	196	LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
4d5f9b2a NC	197	/* Extra bits for zeroed low-order bits.
	198	The 1st MAX_PRECISION are zeroed,
	199	the last contain flonum bits. */
252b5132	200	char *return_value;
4a1805b1	201	int precision; /* Number of 16-bit words in the format. */
252b5132 RH	202	long exponent_bits;
	203
	204	return_value = str;
	205	f.low = bits + MAX_PRECISION;
	206	f.high = NULL;
	207	f.leader = NULL;
	208	f.exponent = 0;
	209	f.sign = '\0';
	210
	211	if (what_kind_of_float (what_kind, &precision, &exponent_bits))
	212	{
4d5f9b2a	213	return_value = NULL;
252b5132 RH	214	make_invalid_floating_point_number (words);
	215	}
	216
	217	if (return_value)
	218	{
	219	memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION);
	220
4d5f9b2a NC	221	/* Use more LittleNums than seems
	222	necessary: the highest flonum may have
	223	15 leading 0 bits, so could be useless. */
252b5132 RH	224	f.high = f.low + precision - 1 + GUARD;
	225
	226	if (atof_generic (&return_value, ".", "eE", &f))
	227	{
	228	make_invalid_floating_point_number (words);
4d5f9b2a	229	return_value = NULL;
252b5132	230	}
4d5f9b2a NC	231	else if (flonum_gen2vax (what_kind, &f, words))
4d5f9b2a NC	232	return_value = NULL;
252b5132	233	}
4d5f9b2a NC	234
	235	return return_value;
	236	}
252b5132	237	\f
4d5f9b2a NC	238	/* In: a flonum, a vax floating point format.
	239	Out: a vax floating-point bit pattern. */
	240
	241	int
	242	flonum_gen2vax (int format_letter, /* One of 'd' 'f' 'g' 'h'. */
	243	FLONUM_TYPE *f,
	244	LITTLENUM_TYPE words) / Deliver answer here. */
252b5132 RH	245	{
	246	LITTLENUM_TYPE *lp;
	247	int precision;
	248	long exponent_bits;
4a1805b1	249	int return_value; /* 0 == OK. */
252b5132 RH	250
	251	return_value = what_kind_of_float (format_letter, &precision, &exponent_bits);
	252
	253	if (return_value != 0)
4d5f9b2a NC	254	make_invalid_floating_point_number (words);
4d5f9b2a NC	255
252b5132 RH	256	else
	257	{
	258	if (f->low > f->leader)
4d5f9b2a NC	259	/* 0.0e0 seen. */
	260	memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision);
	261
252b5132 RH	262	else
	263	{
	264	long exponent_1;
	265	long exponent_2;
	266	long exponent_3;
	267	long exponent_4;
	268	int exponent_skippage;
	269	LITTLENUM_TYPE word1;
	270
4d5f9b2a	271	/* JF: Deal with new Nan, +Inf and -Inf codes. */
252b5132 RH	272	if (f->sign != '-' && f->sign != '+')
	273	{
	274	make_invalid_floating_point_number (words);
	275	return return_value;
	276	}
4d5f9b2a NC	277
	278	/* All vaxen floating_point formats (so far) have:
	279	Bit 15 is sign bit.
	280	Bits 14:n are excess-whatever exponent.
	281	Bits n-1:0 (if any) are most significant bits of fraction.
	282	Bits 15:0 of the next word are the next most significant bits.
	283	And so on for each other word.
	284
	285	All this to be compatible with a KF11?? (Which is still faster
	286	than lots of vaxen I can think of, but it also has higher
	287	maintenance costs ... sigh).
	288
	289	So we need: number of bits of exponent, number of bits of
	290	mantissa. */
252b5132 RH	291
	292	bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
	293	littlenum_pointer = f->leader;
	294	littlenum_end = f->low;
4d5f9b2a	295	/* Seek (and forget) 1st significant bit. */
252b5132 RH	296	for (exponent_skippage = 0;
	297	!next_bits (1);
	298	exponent_skippage++);;
	299
	300	exponent_1 = f->exponent + f->leader + 1 - f->low;
4a1805b1	301	/* Radix LITTLENUM_RADIX, point just higher than f->leader. */
252b5132	302	exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
4a1805b1	303	/* Radix 2. */
252b5132	304	exponent_3 = exponent_2 - exponent_skippage;
4a1805b1	305	/* Forget leading zeros, forget 1st bit. */
252b5132	306	exponent_4 = exponent_3 + (1 << (exponent_bits - 1));
4a1805b1	307	/* Offset exponent. */
252b5132 RH	308
	309	if (exponent_4 & ~mask[exponent_bits])
	310	{
4d5f9b2a	311	/* Exponent overflow. Lose immediately. */
252b5132 RH	312	make_invalid_floating_point_number (words);
252b5132 RH	313
4d5f9b2a NC	314	/* We leave return_value alone: admit we read the
	315	number, but return a floating exception
	316	because we can't encode the number. */
252b5132 RH	317	}
	318	else
	319	{
	320	lp = words;
	321
4d5f9b2a NC	322	/* Word 1. Sign, exponent and perhaps high bits.
4d5f9b2a NC	323	Assume 2's complement integers. */
252b5132 RH	324	word1 = (((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits))
	325	\| ((f->sign == '+') ? 0 : 0x8000)
	326	\| next_bits (15 - exponent_bits));
	327	*lp++ = word1;
	328
4a1805b1	329	/* The rest of the words are just mantissa bits. */
252b5132	330	for (; lp < words + precision; lp++)
4d5f9b2a	331	*lp = next_bits (LITTLENUM_NUMBER_OF_BITS);
252b5132 RH	332
	333	if (next_bits (1))
	334	{
4d5f9b2a NC	335	/* Since the NEXT bit is a 1, round UP the mantissa.
	336	The cunning design of these hidden-1 floats permits
	337	us to let the mantissa overflow into the exponent, and
	338	it 'does the right thing'. However, we lose if the
	339	highest-order bit of the lowest-order word flips.
	340	Is that clear? */
252b5132 RH	341	unsigned long carry;
	342
	343	/*
4d5f9b2a NC	344	#if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
	345	Please allow at least 1 more bit in carry than is in a LITTLENUM.
	346	We need that extra bit to hold a carry during a LITTLENUM carry
	347	propagation. Another extra bit (kept 0) will assure us that we
	348	don't get a sticky sign bit after shifting right, and that
	349	permits us to propagate the carry without any masking of bits.
	350	#endif */
252b5132 RH	351	for (carry = 1, lp--;
	352	carry && (lp >= words);
	353	lp--)
	354	{
	355	carry = *lp + carry;
	356	*lp = carry;
	357	carry >>= LITTLENUM_NUMBER_OF_BITS;
	358	}
	359
	360	if ((word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)))
	361	{
	362	make_invalid_floating_point_number (words);
4d5f9b2a NC	363	/* We leave return_value alone: admit we read the
	364	number, but return a floating exception
	365	because we can't encode the number. */
252b5132	366	}
4d5f9b2a NC	367	}
	368	}
	369	}
	370	}
	371	return return_value;
	372	}
	373
	374	/* JF this used to be in vax.c but this looks like a better place for it. */
	375
	376	/* In: input_line_pointer->the 1st character of a floating-point
	377	number.
	378	1 letter denoting the type of statement that wants a
	379	binary floating point number returned.
	380	Address of where to build floating point literal.
	381	Assumed to be 'big enough'.
	382	Address of where to return size of literal (in chars).
	383
	384	Out: Input_line_pointer->of next char after floating number.
	385	Error message, or 0.
	386	Floating point literal.
	387	Number of chars we used for the literal. */
	388
	389	#define MAXIMUM_NUMBER_OF_LITTLENUMS 8 /* For .hfloats. */
252b5132 RH	390
252b5132 RH	391	char *
4d5f9b2a NC	392	md_atof (int what_statement_type,
	393	char *literalP,
	394	int *sizeP)
252b5132 RH	395	{
252b5132 RH	396	LITTLENUM_TYPE words[MAXIMUM_NUMBER_OF_LITTLENUMS];
4d5f9b2a NC	397	char kind_of_float;
	398	int number_of_chars;
	399	LITTLENUM_TYPE *littlenumP;
252b5132 RH	400
	401	switch (what_statement_type)
	402	{
4d5f9b2a NC	403	case 'F':
4d5f9b2a NC	404	case 'f':
252b5132 RH	405	kind_of_float = 'f';
	406	break;
	407
4d5f9b2a NC	408	case 'D':
4d5f9b2a NC	409	case 'd':
252b5132 RH	410	kind_of_float = 'd';
	411	break;
	412
4d5f9b2a	413	case 'g':
252b5132 RH	414	kind_of_float = 'g';
	415	break;
	416
4d5f9b2a	417	case 'h':
252b5132 RH	418	kind_of_float = 'h';
	419	break;
	420
	421	default:
	422	kind_of_float = 0;
	423	break;
	424	};
	425
	426	if (kind_of_float)
	427	{
4d5f9b2a	428	LITTLENUM_TYPE *limit;
252b5132 RH	429
	430	input_line_pointer = atof_vax (input_line_pointer,
	431	kind_of_float,
	432	words);
4d5f9b2a NC	433	/* The atof_vax() builds up 16-bit numbers.
	434	Since the assembler may not be running on
	435	a little-endian machine, be very careful about
	436	converting words to chars. */
252b5132 RH	437	number_of_chars = atof_vax_sizeof (kind_of_float);
	438	know (number_of_chars <= MAXIMUM_NUMBER_OF_LITTLENUMS * sizeof (LITTLENUM_TYPE));
	439	limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE));
	440	for (littlenumP = words; littlenumP < limit; littlenumP++)
	441	{
	442	md_number_to_chars (literalP, *littlenumP, sizeof (LITTLENUM_TYPE));
	443	literalP += sizeof (LITTLENUM_TYPE);
	444	};
	445	}
	446	else
4d5f9b2a	447	number_of_chars = 0;
252b5132 RH	448
252b5132 RH	449	*sizeP = number_of_chars;
2ab9b79e	450	return kind_of_float ? NULL : _("Bad call to md_atof()");
252b5132	451	}