old-cross-binutils/gas/config/atof-ns32k.c

/* atof_ns32k.c - turn a Flonum into a ns32k floating point number
   Copyright (C) 1987 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 1, 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, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* this is atof-m68k.c hacked for ns32k */

#include "as.h"

extern FLONUM_TYPE generic_floating_point_number;	/* Flonums returned here. */

extern const char EXP_CHARS[];
/* Precision in LittleNums. */
#define MAX_PRECISION (4)
#define F_PRECISION (2)
#define D_PRECISION (4)

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

int				/* Number of chars in flonum type 'letter'. */
atof_sizeof (letter)
     char 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':
      return_value = F_PRECISION;
      break;

    case 'd':
      return_value = D_PRECISION;
      break;

    default:
      return_value = 0;
      break;
    }
  return (return_value);
}

static unsigned 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
};

static int bits_left_in_littlenum;
static int littlenums_left;
static LITTLENUM_TYPE *littlenum_pointer;

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

  if (!littlenums_left)
    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;
      if (littlenums_left)
	{
	  bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
	  littlenum_pointer--;
	  --littlenums_left;
	  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;
{
  words[0] = ((unsigned) -1) >> 1;	/* Zero the leftmost bit */
  words[1] = -1;
  words[2] = -1;
  words[3] = -1;
}

/***********************************************************************\
*									*
*	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_ns32k (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;

  long int exponent_1;
  long int exponent_2;
  long int exponent_3;
  long int exponent_4;
  int exponent_skippage;
  LITTLENUM_TYPE word1;
  LITTLENUM_TYPE *lp;

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

  /* Use more LittleNums than seems */
  /* necessary: the highest flonum may have */
  /* 15 leading 0 bits, so could be useless. */

  bzero (bits, sizeof (LITTLENUM_TYPE) * MAX_PRECISION);

  switch (what_kind)
    {
    case 'f':
      precision = F_PRECISION;
      exponent_bits = 8;
      break;

    case 'd':
      precision = D_PRECISION;
      exponent_bits = 11;
      break;

    default:
      make_invalid_floating_point_number (words);
      return NULL;
    }

  f.high = f.low + precision - 1 + GUARD;

  if (atof_generic (&return_value, ".", EXP_CHARS, &f))
    {
      as_warn ("Error converting floating point number (Exponent overflow?)");
      make_invalid_floating_point_number (words);
      return NULL;
    }

  if (f.low > f.leader)
    {
      /* 0.0e0 seen. */
      bzero (words, sizeof (LITTLENUM_TYPE) * precision);
      return return_value;
    }

  if (f.sign != '+' && f.sign != '-')
    {
      make_invalid_floating_point_number (words);
      return NULL;
    }


  /*
		 * 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.
		 *
		 * 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;
  littlenums_left = 1 + f.leader - 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)) - 2);
  /* Offset exponent. */

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

      /*
			 * We leave return_value alone: admit we read the
			 * number, but return a floating exception
			 * because we can't encode the number.
			 */

      as_warn ("Exponent overflow in floating-point number");
      make_invalid_floating_point_number (words);
      return return_value;
    }
  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))
    {
      unsigned long int carry;
      /*
			 * 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?
			 */


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

/* This is really identical to atof_ns32k except for some details */

gen_to_words (words, precision, exponent_bits)
     LITTLENUM_TYPE *words;
     long int exponent_bits;
{
  int return_value = 0;

  long int exponent_1;
  long int exponent_2;
  long int exponent_3;
  long int exponent_4;
  int exponent_skippage;
  LITTLENUM_TYPE word1;
  LITTLENUM_TYPE *lp;

  if (generic_floating_point_number.low > generic_floating_point_number.leader)
    {
      /* 0.0e0 seen. */
      bzero (words, sizeof (LITTLENUM_TYPE) * precision);
      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.
		 *
		 * So we need: number of bits of exponent, number of bits of
		 * mantissa.
		 */
  bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
  littlenum_pointer = generic_floating_point_number.leader;
  littlenums_left = 1 + generic_floating_point_number.leader - generic_floating_point_number.low;
  /* Seek (and forget) 1st significant bit */
  for (exponent_skippage = 0; !next_bits (1); exponent_skippage++)
    ;
  exponent_1 = generic_floating_point_number.exponent + generic_floating_point_number.leader + 1 -
    generic_floating_point_number.low;
  /* Radix LITTLENUM_RADIX, point just higher than generic_floating_point_number.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)) - 2);
  /* Offset exponent. */

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

      /*
			 * We leave return_value alone: admit we read the
			 * number, but return a floating exception
			 * because we can't encode the number.
			 */

      make_invalid_floating_point_number (words);
      return return_value;
    }
  lp = words;

  /* Word 1. Sign, exponent and perhaps high bits. */
  /* Assume 2's complement integers. */
  word1 = ((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits)) |
    ((generic_floating_point_number.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))
    {
      unsigned long int carry;
      /*
			 * 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?
			 */


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

/* This routine is a real kludge.  Someone really should do it better, but
   I'm too lazy, and I don't understand this stuff all too well anyway
   (JF)
 */
void
int_to_gen (x)
     long x;
{
  char buf[20];
  char *bufp;

  sprintf (buf, "%ld", x);
  bufp = &buf[0];
  if (atof_generic (&bufp, ".", EXP_CHARS, &generic_floating_point_number))
    as_warn ("Error converting number to floating point (Exponent overflow?)");
}