binutils-gdb/gdb/target-float.c

/* Floating point routines for GDB, the GNU debugger.

   Copyright (C) 2017 Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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 3 of the License, or
   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "gdbtypes.h"
#include "floatformat.h"
#include "target-float.h"


/* Helper routines operating on binary floating-point data.  */

#include <math.h>

#if (defined HAVE_LONG_DOUBLE && defined PRINTF_HAS_LONG_DOUBLE \
     && defined SCANF_HAS_LONG_DOUBLE)
typedef long double DOUBLEST;
#else
typedef double DOUBLEST;
/* If we can't scan or print long double, we don't want to use it
   anywhere.  */
# undef HAVE_LONG_DOUBLE
# undef PRINTF_HAS_LONG_DOUBLE
# undef SCANF_HAS_LONG_DOUBLE
#endif

/* Different kinds of floatformat numbers recognized by
   floatformat_classify.  To avoid portability issues, we use local
   values instead of the C99 macros (FP_NAN et cetera).  */
enum float_kind {
  float_nan,
  float_infinite,
  float_zero,
  float_normal,
  float_subnormal
};

/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
   going to bother with trying to muck around with whether it is defined in
   a system header, what we do if not, etc.  */
#define FLOATFORMAT_CHAR_BIT 8

/* The number of bytes that the largest floating-point type that we
   can convert to doublest will need.  */
#define FLOATFORMAT_LARGEST_BYTES 16

/* Return the floatformat's total size in host bytes.  */
static size_t
floatformat_totalsize_bytes (const struct floatformat *fmt)
{
  return ((fmt->totalsize + FLOATFORMAT_CHAR_BIT - 1)
	  / FLOATFORMAT_CHAR_BIT);
}

/* Return the precision of the floating point format FMT.  */
static int
floatformat_precision (const struct floatformat *fmt)
{
  /* Assume the precision of and IBM long double is twice the precision
     of the underlying double.  This matches what GCC does.  */
  if (fmt->split_half)
    return 2 * floatformat_precision (fmt->split_half);

  /* Otherwise, the precision is the size of mantissa in bits,
     including the implicit bit if present.  */
  int prec = fmt->man_len;
  if (fmt->intbit == floatformat_intbit_no)
    prec++;

  return prec;
}

/* Normalize the byte order of FROM into TO.  If no normalization is
   needed then FMT->byteorder is returned and TO is not changed;
   otherwise the format of the normalized form in TO is returned.  */
static enum floatformat_byteorders
floatformat_normalize_byteorder (const struct floatformat *fmt,
				 const void *from, void *to)
{
  const unsigned char *swapin;
  unsigned char *swapout;
  int words;

  if (fmt->byteorder == floatformat_little
      || fmt->byteorder == floatformat_big)
    return fmt->byteorder;

  words = fmt->totalsize / FLOATFORMAT_CHAR_BIT;
  words >>= 2;

  swapout = (unsigned char *)to;
  swapin = (const unsigned char *)from;

  if (fmt->byteorder == floatformat_vax)
    {
      while (words-- > 0)
	{
	  *swapout++ = swapin[1];
	  *swapout++ = swapin[0];
	  *swapout++ = swapin[3];
	  *swapout++ = swapin[2];
	  swapin += 4;
	}
      /* This may look weird, since VAX is little-endian, but it is
	 easier to translate to big-endian than to little-endian.  */
      return floatformat_big;
    }
  else
    {
      gdb_assert (fmt->byteorder == floatformat_littlebyte_bigword);

      while (words-- > 0)
	{
	  *swapout++ = swapin[3];
	  *swapout++ = swapin[2];
	  *swapout++ = swapin[1];
	  *swapout++ = swapin[0];
	  swapin += 4;
	}
      return floatformat_big;
    }
}

/* Extract a field which starts at START and is LEN bytes long.  DATA and
   TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER.  */
static unsigned long
get_field (const bfd_byte *data, enum floatformat_byteorders order,
	   unsigned int total_len, unsigned int start, unsigned int len)
{
  unsigned long result;
  unsigned int cur_byte;
  int cur_bitshift;

  /* Caller must byte-swap words before calling this routine.  */
  gdb_assert (order == floatformat_little || order == floatformat_big);

  /* Start at the least significant part of the field.  */
  if (order == floatformat_little)
    {
      /* We start counting from the other end (i.e, from the high bytes
	 rather than the low bytes).  As such, we need to be concerned
	 with what happens if bit 0 doesn't start on a byte boundary.
	 I.e, we need to properly handle the case where total_len is
	 not evenly divisible by 8.  So we compute ``excess'' which
	 represents the number of bits from the end of our starting
	 byte needed to get to bit 0.  */
      int excess = FLOATFORMAT_CHAR_BIT - (total_len % FLOATFORMAT_CHAR_BIT);

      cur_byte = (total_len / FLOATFORMAT_CHAR_BIT)
                 - ((start + len + excess) / FLOATFORMAT_CHAR_BIT);
      cur_bitshift = ((start + len + excess) % FLOATFORMAT_CHAR_BIT)
                     - FLOATFORMAT_CHAR_BIT;
    }
  else
    {
      cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT;
      cur_bitshift =
	((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT;
    }
  if (cur_bitshift > -FLOATFORMAT_CHAR_BIT)
    result = *(data + cur_byte) >> (-cur_bitshift);
  else
    result = 0;
  cur_bitshift += FLOATFORMAT_CHAR_BIT;
  if (order == floatformat_little)
    ++cur_byte;
  else
    --cur_byte;

  /* Move towards the most significant part of the field.  */
  while (cur_bitshift < len)
    {
      result |= (unsigned long)*(data + cur_byte) << cur_bitshift;
      cur_bitshift += FLOATFORMAT_CHAR_BIT;
      switch (order)
	{
	case floatformat_little:
	  ++cur_byte;
	  break;
	case floatformat_big:
	  --cur_byte;
	  break;
	}
    }
  if (len < sizeof(result) * FLOATFORMAT_CHAR_BIT)
    /* Mask out bits which are not part of the field.  */
    result &= ((1UL << len) - 1);
  return result;
}

/* Set a field which starts at START and is LEN bytes long.  DATA and
   TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER.  */
static void
put_field (unsigned char *data, enum floatformat_byteorders order,
	   unsigned int total_len, unsigned int start, unsigned int len,
	   unsigned long stuff_to_put)
{
  unsigned int cur_byte;
  int cur_bitshift;

  /* Caller must byte-swap words before calling this routine.  */
  gdb_assert (order == floatformat_little || order == floatformat_big);

  /* Start at the least significant part of the field.  */
  if (order == floatformat_little)
    {
      int excess = FLOATFORMAT_CHAR_BIT - (total_len % FLOATFORMAT_CHAR_BIT);

      cur_byte = (total_len / FLOATFORMAT_CHAR_BIT)
                 - ((start + len + excess) / FLOATFORMAT_CHAR_BIT);
      cur_bitshift = ((start + len + excess) % FLOATFORMAT_CHAR_BIT)
                     - FLOATFORMAT_CHAR_BIT;
    }
  else
    {
      cur_byte = (start + len) / FLOATFORMAT_CHAR_BIT;
      cur_bitshift =
	((start + len) % FLOATFORMAT_CHAR_BIT) - FLOATFORMAT_CHAR_BIT;
    }
  if (cur_bitshift > -FLOATFORMAT_CHAR_BIT)
    {
      *(data + cur_byte) &=
	~(((1 << ((start + len) % FLOATFORMAT_CHAR_BIT)) - 1)
	  << (-cur_bitshift));
      *(data + cur_byte) |=
	(stuff_to_put & ((1 << FLOATFORMAT_CHAR_BIT) - 1)) << (-cur_bitshift);
    }
  cur_bitshift += FLOATFORMAT_CHAR_BIT;
  if (order == floatformat_little)
    ++cur_byte;
  else
    --cur_byte;

  /* Move towards the most significant part of the field.  */
  while (cur_bitshift < len)
    {
      if (len - cur_bitshift < FLOATFORMAT_CHAR_BIT)
	{
	  /* This is the last byte.  */
	  *(data + cur_byte) &=
	    ~((1 << (len - cur_bitshift)) - 1);
	  *(data + cur_byte) |= (stuff_to_put >> cur_bitshift);
	}
      else
	*(data + cur_byte) = ((stuff_to_put >> cur_bitshift)
			      & ((1 << FLOATFORMAT_CHAR_BIT) - 1));
      cur_bitshift += FLOATFORMAT_CHAR_BIT;
      if (order == floatformat_little)
	++cur_byte;
      else
	--cur_byte;
    }
}

/* Check if VAL (which is assumed to be a floating point number whose
   format is described by FMT) is negative.  */
static int
floatformat_is_negative (const struct floatformat *fmt,
			 const bfd_byte *uval)
{
  enum floatformat_byteorders order;
  unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];

  gdb_assert (fmt != NULL);
  gdb_assert (fmt->totalsize
	      <= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);

  /* An IBM long double (a two element array of double) always takes the
     sign of the first double.  */
  if (fmt->split_half)
    fmt = fmt->split_half;

  order = floatformat_normalize_byteorder (fmt, uval, newfrom);

  if (order != fmt->byteorder)
    uval = newfrom;

  return get_field (uval, order, fmt->totalsize, fmt->sign_start, 1);
}

/* Check if VAL is "not a number" (NaN) for FMT.  */
static enum float_kind
floatformat_classify (const struct floatformat *fmt,
		      const bfd_byte *uval)
{
  long exponent;
  unsigned long mant;
  unsigned int mant_bits, mant_off;
  int mant_bits_left;
  enum floatformat_byteorders order;
  unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];
  int mant_zero;

  gdb_assert (fmt != NULL);
  gdb_assert (fmt->totalsize
	      <= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);

  /* An IBM long double (a two element array of double) can be classified
     by looking at the first double.  inf and nan are specified as
     ignoring the second double.  zero and subnormal will always have
     the second double 0.0 if the long double is correctly rounded.  */
  if (fmt->split_half)
    fmt = fmt->split_half;

  order = floatformat_normalize_byteorder (fmt, uval, newfrom);

  if (order != fmt->byteorder)
    uval = newfrom;

  exponent = get_field (uval, order, fmt->totalsize, fmt->exp_start,
			fmt->exp_len);

  mant_bits_left = fmt->man_len;
  mant_off = fmt->man_start;

  mant_zero = 1;
  while (mant_bits_left > 0)
    {
      mant_bits = std::min (mant_bits_left, 32);

      mant = get_field (uval, order, fmt->totalsize, mant_off, mant_bits);

      /* If there is an explicit integer bit, mask it off.  */
      if (mant_off == fmt->man_start
	  && fmt->intbit == floatformat_intbit_yes)
	mant &= ~(1 << (mant_bits - 1));

      if (mant)
	{
	  mant_zero = 0;
	  break;
	}

      mant_off += mant_bits;
      mant_bits_left -= mant_bits;
    }

  /* If exp_nan is not set, assume that inf, NaN, and subnormals are not
     supported.  */
  if (! fmt->exp_nan)
    {
      if (mant_zero)
	return float_zero;
      else
	return float_normal;
    }

  if (exponent == 0)
    {
      if (mant_zero)
	return float_zero;
      else
	return float_subnormal;
    }

  if (exponent == fmt->exp_nan)
    {
      if (mant_zero)
	return float_infinite;
      else
	return float_nan;
    }

  return float_normal;
}

/* Convert the mantissa of VAL (which is assumed to be a floating
   point number whose format is described by FMT) into a hexadecimal
   and store it in a static string.  Return a pointer to that string.  */
static const char *
floatformat_mantissa (const struct floatformat *fmt,
		      const bfd_byte *val)
{
  unsigned char *uval = (unsigned char *) val;
  unsigned long mant;
  unsigned int mant_bits, mant_off;
  int mant_bits_left;
  static char res[50];
  char buf[9];
  int len;
  enum floatformat_byteorders order;
  unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];

  gdb_assert (fmt != NULL);
  gdb_assert (fmt->totalsize
	      <= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);

  /* For IBM long double (a two element array of double), return the
     mantissa of the first double.  The problem with returning the
     actual mantissa from both doubles is that there can be an
     arbitrary number of implied 0's or 1's between the mantissas
     of the first and second double.  In any case, this function
     is only used for dumping out nans, and a nan is specified to
     ignore the value in the second double.  */
  if (fmt->split_half)
    fmt = fmt->split_half;

  order = floatformat_normalize_byteorder (fmt, uval, newfrom);

  if (order != fmt->byteorder)
    uval = newfrom;

  if (! fmt->exp_nan)
    return 0;

  /* Make sure we have enough room to store the mantissa.  */
  gdb_assert (sizeof res > ((fmt->man_len + 7) / 8) * 2);

  mant_off = fmt->man_start;
  mant_bits_left = fmt->man_len;
  mant_bits = (mant_bits_left % 32) > 0 ? mant_bits_left % 32 : 32;

  mant = get_field (uval, order, fmt->totalsize, mant_off, mant_bits);

  len = xsnprintf (res, sizeof res, "%lx", mant);

  mant_off += mant_bits;
  mant_bits_left -= mant_bits;

  while (mant_bits_left > 0)
    {
      mant = get_field (uval, order, fmt->totalsize, mant_off, 32);

      xsnprintf (buf, sizeof buf, "%08lx", mant);
      gdb_assert (len + strlen (buf) <= sizeof res);
      strcat (res, buf);

      mant_off += 32;
      mant_bits_left -= 32;
    }

  return res;
}

/* Convert TO/FROM target to the hosts DOUBLEST floating-point format.

   If the host and target formats agree, we just copy the raw data
   into the appropriate type of variable and return, letting the host
   increase precision as necessary.  Otherwise, we call the conversion
   routine and let it do the dirty work.  Note that even if the target
   and host floating-point formats match, the length of the types
   might still be different, so the conversion routines must make sure
   to not overrun any buffers.  For example, on x86, long double is
   the 80-bit extended precision type on both 32-bit and 64-bit ABIs,
   but by default it is stored as 12 bytes on 32-bit, and 16 bytes on
   64-bit, for alignment reasons.  See comment in store_typed_floating
   for a discussion about zeroing out remaining bytes in the target
   buffer.  */

static const struct floatformat *host_float_format = GDB_HOST_FLOAT_FORMAT;
static const struct floatformat *host_double_format = GDB_HOST_DOUBLE_FORMAT;
static const struct floatformat *host_long_double_format
  = GDB_HOST_LONG_DOUBLE_FORMAT;

/* Convert from FMT to a DOUBLEST.  FROM is the address of the extended float.
   Store the DOUBLEST in *TO.  */
static void
floatformat_to_doublest (const struct floatformat *fmt,
			 const void *from, DOUBLEST *to)
{
  gdb_assert (fmt != NULL);

  if (fmt == host_float_format)
    {
      float val = 0;

      memcpy (&val, from, floatformat_totalsize_bytes (fmt));
      *to = val;
      return;
    }
  else if (fmt == host_double_format)
    {
      double val = 0;

      memcpy (&val, from, floatformat_totalsize_bytes (fmt));
      *to = val;
      return;
    }
  else if (fmt == host_long_double_format)
    {
      long double val = 0;

      memcpy (&val, from, floatformat_totalsize_bytes (fmt));
      *to = val;
      return;
    }

  unsigned char *ufrom = (unsigned char *) from;
  DOUBLEST dto;
  long exponent;
  unsigned long mant;
  unsigned int mant_bits, mant_off;
  int mant_bits_left;
  int special_exponent;		/* It's a NaN, denorm or zero.  */
  enum floatformat_byteorders order;
  unsigned char newfrom[FLOATFORMAT_LARGEST_BYTES];
  enum float_kind kind;

  gdb_assert (fmt->totalsize
	      <= FLOATFORMAT_LARGEST_BYTES * FLOATFORMAT_CHAR_BIT);

  /* For non-numbers, reuse libiberty's logic to find the correct
     format.  We do not lose any precision in this case by passing
     through a double.  */
  kind = floatformat_classify (fmt, (const bfd_byte *) from);
  if (kind == float_infinite || kind == float_nan)
    {
      double dto;

      floatformat_to_double (fmt->split_half ? fmt->split_half : fmt,
			     from, &dto);
      *to = (DOUBLEST) dto;
      return;
    }

  order = floatformat_normalize_byteorder (fmt, ufrom, newfrom);

  if (order != fmt->byteorder)
    ufrom = newfrom;

  if (fmt->split_half)
    {
      DOUBLEST dtop, dbot;

      floatformat_to_doublest (fmt->split_half, ufrom, &dtop);
      /* Preserve the sign of 0, which is the sign of the top
	 half.  */
      if (dtop == 0.0)
	{
	  *to = dtop;
	  return;
	}
      floatformat_to_doublest (fmt->split_half,
			     ufrom + fmt->totalsize / FLOATFORMAT_CHAR_BIT / 2,
			     &dbot);
      *to = dtop + dbot;
      return;
    }

  exponent = get_field (ufrom, order, fmt->totalsize, fmt->exp_start,
			fmt->exp_len);
  /* Note that if exponent indicates a NaN, we can't really do anything useful
     (not knowing if the host has NaN's, or how to build one).  So it will
     end up as an infinity or something close; that is OK.  */

  mant_bits_left = fmt->man_len;
  mant_off = fmt->man_start;
  dto = 0.0;

  special_exponent = exponent == 0 || exponent == fmt->exp_nan;

  /* Don't bias NaNs.  Use minimum exponent for denorms.  For
     simplicity, we don't check for zero as the exponent doesn't matter.
     Note the cast to int; exp_bias is unsigned, so it's important to
     make sure the operation is done in signed arithmetic.  */
  if (!special_exponent)
    exponent -= fmt->exp_bias;
  else if (exponent == 0)
    exponent = 1 - fmt->exp_bias;

  /* Build the result algebraically.  Might go infinite, underflow, etc;
     who cares.  */

  /* If this format uses a hidden bit, explicitly add it in now.  Otherwise,
     increment the exponent by one to account for the integer bit.  */

  if (!special_exponent)
    {
      if (fmt->intbit == floatformat_intbit_no)
	dto = ldexp (1.0, exponent);
      else
	exponent++;
    }

  while (mant_bits_left > 0)
    {
      mant_bits = std::min (mant_bits_left, 32);

      mant = get_field (ufrom, order, fmt->totalsize, mant_off, mant_bits);

      dto += ldexp ((double) mant, exponent - mant_bits);
      exponent -= mant_bits;
      mant_off += mant_bits;
      mant_bits_left -= mant_bits;
    }

  /* Negate it if negative.  */
  if (get_field (ufrom, order, fmt->totalsize, fmt->sign_start, 1))
    dto = -dto;
  *to = dto;
}

/* Convert the DOUBLEST *FROM to an extended float in format FMT and
   store where TO points.  */
static void
floatformat_from_doublest (const struct floatformat *fmt,
			   const DOUBLEST *from, void *to)
{
  gdb_assert (fmt != NULL);

  if (fmt == host_float_format)
    {
      float val = *from;

      memcpy (to, &val, floatformat_totalsize_bytes (fmt));
      return;
    }
  else if (fmt == host_double_format)
    {
      double val = *from;

      memcpy (to, &val, floatformat_totalsize_bytes (fmt));
      return;
    }
  else if (fmt == host_long_double_format)
    {
      long double val = *from;

      memcpy (to, &val, floatformat_totalsize_bytes (fmt));
      return;
    }

  DOUBLEST dfrom;
  int exponent;
  DOUBLEST mant;
  unsigned int mant_bits, mant_off;
  int mant_bits_left;
  unsigned char *uto = (unsigned char *) to;
  enum floatformat_byteorders order = fmt->byteorder;
  unsigned char newto[FLOATFORMAT_LARGEST_BYTES];

  if (order != floatformat_little)
    order = floatformat_big;

  if (order != fmt->byteorder)
    uto = newto;

  memcpy (&dfrom, from, sizeof (dfrom));
  memset (uto, 0, floatformat_totalsize_bytes (fmt));

  if (fmt->split_half)
    {
      /* Use static volatile to ensure that any excess precision is
	 removed via storing in memory, and so the top half really is
	 the result of converting to double.  */
      static volatile double dtop, dbot;
      DOUBLEST dtopnv, dbotnv;

      dtop = (double) dfrom;
      /* If the rounded top half is Inf, the bottom must be 0 not NaN
	 or Inf.  */
      if (dtop + dtop == dtop && dtop != 0.0)
	dbot = 0.0;
      else
	dbot = (double) (dfrom - (DOUBLEST) dtop);
      dtopnv = dtop;
      dbotnv = dbot;
      floatformat_from_doublest (fmt->split_half, &dtopnv, uto);
      floatformat_from_doublest (fmt->split_half, &dbotnv,
			       (uto
				+ fmt->totalsize / FLOATFORMAT_CHAR_BIT / 2));
      return;
    }

  if (dfrom == 0)
    goto finalize_byteorder;	/* Result is zero */
  if (dfrom != dfrom)		/* Result is NaN */
    {
      /* From is NaN */
      put_field (uto, order, fmt->totalsize, fmt->exp_start,
		 fmt->exp_len, fmt->exp_nan);
      /* Be sure it's not infinity, but NaN value is irrel.  */
      put_field (uto, order, fmt->totalsize, fmt->man_start,
		 fmt->man_len, 1);
      goto finalize_byteorder;
    }

  /* If negative, set the sign bit.  */
  if (dfrom < 0)
    {
      put_field (uto, order, fmt->totalsize, fmt->sign_start, 1, 1);
      dfrom = -dfrom;
    }

  if (dfrom + dfrom == dfrom && dfrom != 0.0)	/* Result is Infinity.  */
    {
      /* Infinity exponent is same as NaN's.  */
      put_field (uto, order, fmt->totalsize, fmt->exp_start,
		 fmt->exp_len, fmt->exp_nan);
      /* Infinity mantissa is all zeroes.  */
      put_field (uto, order, fmt->totalsize, fmt->man_start,
		 fmt->man_len, 0);
      goto finalize_byteorder;
    }

#ifdef HAVE_LONG_DOUBLE
  mant = frexpl (dfrom, &exponent);
#else
  mant = frexp (dfrom, &exponent);
#endif

  if (exponent + fmt->exp_bias <= 0)
    {
      /* The value is too small to be expressed in the destination
	 type (not enough bits in the exponent.  Treat as 0.  */
      put_field (uto, order, fmt->totalsize, fmt->exp_start,
		 fmt->exp_len, 0);
      put_field (uto, order, fmt->totalsize, fmt->man_start,
		 fmt->man_len, 0);
      goto finalize_byteorder;
    }

  if (exponent + fmt->exp_bias >= (1 << fmt->exp_len))
    {
      /* The value is too large to fit into the destination.
	 Treat as infinity.  */
      put_field (uto, order, fmt->totalsize, fmt->exp_start,
		 fmt->exp_len, fmt->exp_nan);
      put_field (uto, order, fmt->totalsize, fmt->man_start,
		 fmt->man_len, 0);
      goto finalize_byteorder;
    }

  put_field (uto, order, fmt->totalsize, fmt->exp_start, fmt->exp_len,
	     exponent + fmt->exp_bias - 1);

  mant_bits_left = fmt->man_len;
  mant_off = fmt->man_start;
  while (mant_bits_left > 0)
    {
      unsigned long mant_long;

      mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;

      mant *= 4294967296.0;
      mant_long = ((unsigned long) mant) & 0xffffffffL;
      mant -= mant_long;

      /* If the integer bit is implicit, then we need to discard it.
         If we are discarding a zero, we should be (but are not) creating
         a denormalized number which means adjusting the exponent
         (I think).  */
      if (mant_bits_left == fmt->man_len
	  && fmt->intbit == floatformat_intbit_no)
	{
	  mant_long <<= 1;
	  mant_long &= 0xffffffffL;
          /* If we are processing the top 32 mantissa bits of a doublest
             so as to convert to a float value with implied integer bit,
             we will only be putting 31 of those 32 bits into the
             final value due to the discarding of the top bit.  In the
             case of a small float value where the number of mantissa
             bits is less than 32, discarding the top bit does not alter
             the number of bits we will be adding to the result.  */
          if (mant_bits == 32)
            mant_bits -= 1;
	}

      if (mant_bits < 32)
	{
	  /* The bits we want are in the most significant MANT_BITS bits of
	     mant_long.  Move them to the least significant.  */
	  mant_long >>= 32 - mant_bits;
	}

      put_field (uto, order, fmt->totalsize,
		 mant_off, mant_bits, mant_long);
      mant_off += mant_bits;
      mant_bits_left -= mant_bits;
    }

 finalize_byteorder:
  /* Do we need to byte-swap the words in the result?  */
  if (order != fmt->byteorder)
    floatformat_normalize_byteorder (fmt, newto, to);
}

/* Convert the byte-stream ADDR, interpreted as floating-point format FMT,
   to a string, optionally using the print format FORMAT.  */
static std::string
floatformat_to_string (const struct floatformat *fmt,
		       const gdb_byte *in, const char *format)
{
  /* Unless we need to adhere to a specific format, provide special
     output for certain cases.  */
  if (format == nullptr)
    {
      /* Detect invalid representations.  */
      if (!floatformat_is_valid (fmt, in))
	return "<invalid float value>";

      /* Handle NaN and Inf.  */
      enum float_kind kind = floatformat_classify (fmt, in);
      if (kind == float_nan)
	{
	  const char *sign = floatformat_is_negative (fmt, in)? "-" : "";
	  const char *mantissa = floatformat_mantissa (fmt, in);
	  return string_printf ("%snan(0x%s)", sign, mantissa);
	}
      else if (kind == float_infinite)
	{
	  const char *sign = floatformat_is_negative (fmt, in)? "-" : "";
	  return string_printf ("%sinf", sign);
	}
    }

  /* Determine the format string to use on the host side.  */
  std::string host_format;
  char conversion;

  if (format == nullptr)
    {
      /* If no format was specified, print the number using a format string
	 where the precision is set to the DECIMAL_DIG value for the given
	 floating-point format.  This value is computed as

		ceil(1 + p * log10(b)),

	 where p is the precision of the floating-point format in bits, and
	 b is the base (which is always 2 for the formats we support).  */
      const double log10_2 = .30102999566398119521;
      double d_decimal_dig = 1 + floatformat_precision (fmt) * log10_2;
      int decimal_dig = d_decimal_dig;
      if (decimal_dig < d_decimal_dig)
	decimal_dig++;

      host_format = string_printf ("%%.%d", decimal_dig);
      conversion = 'g';
    }
  else
    {
      /* Use the specified format, stripping out the conversion character
         and length modifier, if present.  */
      size_t len = strlen (format);
      gdb_assert (len > 1);
      conversion = format[--len];
      gdb_assert (conversion == 'e' || conversion == 'f' || conversion == 'g'
		  || conversion == 'E' || conversion == 'G');
      if (format[len - 1] == 'L')
	len--;

      host_format = std::string (format, len);
    }

  /* Add the length modifier and conversion character appropriate for
     handling the host DOUBLEST type.  */
#ifdef HAVE_LONG_DOUBLE
  host_format += 'L';
#endif
  host_format += conversion;

  DOUBLEST doub;
  floatformat_to_doublest (fmt, in, &doub);
  return string_printf (host_format.c_str (), doub);
}

/* Parse string STRING into a target floating-number of format FMT and
   store it as byte-stream ADDR.  Return whether parsing succeeded.  */
static bool
floatformat_from_string (const struct floatformat *fmt, gdb_byte *out,
			 const std::string &in)
{
  DOUBLEST doub;
  int n, num;
#ifdef HAVE_LONG_DOUBLE
  const char *scan_format = "%Lg%n";
#else
  const char *scan_format = "%lg%n";
#endif
  num = sscanf (in.c_str (), scan_format, &doub, &n);

  /* The sscanf man page suggests not making any assumptions on the effect
     of %n on the result, so we don't.
     That is why we simply test num == 0.  */
  if (num == 0)
    return false;

  /* We only accept the whole string.  */
  if (in[n])
    return false;

  floatformat_from_doublest (fmt, &doub, out);
  return true;
}

/* Convert the byte-stream ADDR, interpreted as floating-point format FMT,
   to an integer value (rounding towards zero).  */
static LONGEST
floatformat_to_longest (const struct floatformat *fmt, const gdb_byte *addr)
{
  DOUBLEST d;
  floatformat_to_doublest (fmt, addr, &d);
  return (LONGEST) d;
}

/* Convert signed integer VAL to a target floating-number of format FMT
   and store it as byte-stream ADDR.  */
static void
floatformat_from_longest (const struct floatformat *fmt, gdb_byte *addr,
			  LONGEST val)
{
  DOUBLEST d = (DOUBLEST) val;
  floatformat_from_doublest (fmt, &d, addr);
}

/* Convert unsigned integer VAL to a target floating-number of format FMT
   and store it as byte-stream ADDR.  */
static void
floatformat_from_ulongest (const struct floatformat *fmt, gdb_byte *addr,
			   ULONGEST val)
{
  DOUBLEST d = (DOUBLEST) val;
  floatformat_from_doublest (fmt, &d, addr);
}

/* Convert the byte-stream ADDR, interpreted as floating-point format FMT,
   to a floating-point value in the host "double" format.  */
static double
floatformat_to_host_double (const struct floatformat *fmt,
			    const gdb_byte *addr)
{
  DOUBLEST d;
  floatformat_to_doublest (fmt, addr, &d);
  return (double) d;
}

/* Convert floating-point value VAL in the host "double" format to a target
   floating-number of format FMT and store it as byte-stream ADDR.  */
static void
floatformat_from_host_double (const struct floatformat *fmt, gdb_byte *addr,
			      double val)
{
  DOUBLEST d = (DOUBLEST) val;
  floatformat_from_doublest (fmt, &d, addr);
}

/* Convert a floating-point number of format FROM_FMT from the target
   byte-stream FROM to a floating-point number of format TO_FMT, and
   store it to the target byte-stream TO.  */
static void
floatformat_convert (const gdb_byte *from, const struct floatformat *from_fmt,
		     gdb_byte *to, const struct floatformat *to_fmt)
{
  if (from_fmt == to_fmt)
    {
      /* The floating-point formats match, so we simply copy the data.  */
      memcpy (to, from, floatformat_totalsize_bytes (to_fmt));
    }
  else
    {
      /* The floating-point formats don't match.  The best we can do
	 (apart from simulating the target FPU) is converting to the
	 widest floating-point type supported by the host, and then
	 again to the desired type.  */
      DOUBLEST d;

      floatformat_to_doublest (from_fmt, from, &d);
      floatformat_from_doublest (to_fmt, &d, to);
    }
}

/* Perform the binary operation indicated by OPCODE, using as operands the
   target byte streams X and Y, interpreted as floating-point numbers of
   formats FMT_X and FMT_Y, respectively.  Convert the result to format
   FMT_RES and store it into the byte-stream RES.  */
static void
floatformat_binop (enum exp_opcode op,
		   const struct floatformat *fmt_x, const gdb_byte *x,
		   const struct floatformat *fmt_y, const gdb_byte *y,
		   const struct floatformat *fmt_result, gdb_byte *result)
{
  DOUBLEST v1, v2, v = 0;

  floatformat_to_doublest (fmt_x, x, &v1);
  floatformat_to_doublest (fmt_y, y, &v2);

  switch (op)
    {
      case BINOP_ADD:
	v = v1 + v2;
	break;

      case BINOP_SUB:
	v = v1 - v2;
	break;

      case BINOP_MUL:
	v = v1 * v2;
	break;

      case BINOP_DIV:
	v = v1 / v2;
	break;

      case BINOP_EXP:
	errno = 0;
	v = pow (v1, v2);
	if (errno)
	  error (_("Cannot perform exponentiation: %s"),
		 safe_strerror (errno));
	break;

      case BINOP_MIN:
	v = v1 < v2 ? v1 : v2;
	break;

      case BINOP_MAX:
	v = v1 > v2 ? v1 : v2;
	break;

      default:
	error (_("Integer-only operation on floating point number."));
	break;
    }

  floatformat_from_doublest (fmt_result, &v, result);
}

/* Compare the two target byte streams X and Y, interpreted as floating-point
   numbers of formats FMT_X and FMT_Y, respectively.  Return zero if X and Y
   are equal, -1 if X is less than Y, and 1 otherwise.  */
static int
floatformat_compare (const struct floatformat *fmt_x, const gdb_byte *x,
		     const struct floatformat *fmt_y, const gdb_byte *y)
{
  DOUBLEST v1, v2;

  floatformat_to_doublest (fmt_x, x, &v1);
  floatformat_to_doublest (fmt_y, y, &v2);

  if (v1 == v2)
    return 0;
  if (v1 < v2)
    return -1;
  return 1;
}


/* Helper routines operating on decimal floating-point data.  */

/* Decimal floating point is one of the extension to IEEE 754, which is
   described in http://grouper.ieee.org/groups/754/revision.html and
   http://www2.hursley.ibm.com/decimal/.  It completes binary floating
   point by representing floating point more exactly.  */

/* The order of the following headers is important for making sure
   decNumber structure is large enough to hold decimal128 digits.  */

#include "dpd/decimal128.h"
#include "dpd/decimal64.h"
#include "dpd/decimal32.h"

/* When using decimal128, this is the maximum string length + 1
   (value comes from libdecnumber's DECIMAL128_String constant).  */
#define MAX_DECIMAL_STRING  43

/* In GDB, we are using an array of gdb_byte to represent decimal values.
   They are stored in host byte order.  This routine does the conversion if
   the target byte order is different.  */
static void
match_endianness (const gdb_byte *from, int len, enum bfd_endian byte_order,
		  gdb_byte *to)
{
  int i;

#if WORDS_BIGENDIAN
#define OPPOSITE_BYTE_ORDER BFD_ENDIAN_LITTLE
#else
#define OPPOSITE_BYTE_ORDER BFD_ENDIAN_BIG
#endif

  if (byte_order == OPPOSITE_BYTE_ORDER)
    for (i = 0; i < len; i++)
      to[i] = from[len - i - 1];
  else
    for (i = 0; i < len; i++)
      to[i] = from[i];

  return;
}

/* Helper function to get the appropriate libdecnumber context for each size
   of decimal float.  */
static void
set_decnumber_context (decContext *ctx, int len)
{
  switch (len)
    {
      case 4:
	decContextDefault (ctx, DEC_INIT_DECIMAL32);
	break;
      case 8:
	decContextDefault (ctx, DEC_INIT_DECIMAL64);
	break;
      case 16:
	decContextDefault (ctx, DEC_INIT_DECIMAL128);
	break;
    }

  ctx->traps = 0;
}

/* Check for errors signaled in the decimal context structure.  */
static void
decimal_check_errors (decContext *ctx)
{
  /* An error here could be a division by zero, an overflow, an underflow or
     an invalid operation (from the DEC_Errors constant in decContext.h).
     Since GDB doesn't complain about division by zero, overflow or underflow
     errors for binary floating, we won't complain about them for decimal
     floating either.  */
  if (ctx->status & DEC_IEEE_854_Invalid_operation)
    {
      /* Leave only the error bits in the status flags.  */
      ctx->status &= DEC_IEEE_854_Invalid_operation;
      error (_("Cannot perform operation: %s"),
	     decContextStatusToString (ctx));
    }
}

/* Helper function to convert from libdecnumber's appropriate representation
   for computation to each size of decimal float.  */
static void
decimal_from_number (const decNumber *from, gdb_byte *to, int len)
{
  decContext set;

  set_decnumber_context (&set, len);

  switch (len)
    {
      case 4:
	decimal32FromNumber ((decimal32 *) to, from, &set);
	break;
      case 8:
	decimal64FromNumber ((decimal64 *) to, from, &set);
	break;
      case 16:
	decimal128FromNumber ((decimal128 *) to, from, &set);
	break;
    }
}

/* Helper function to convert each size of decimal float to libdecnumber's
   appropriate representation for computation.  */
static void
decimal_to_number (const gdb_byte *from, int len, decNumber *to)
{
  switch (len)
    {
      case 4:
	decimal32ToNumber ((decimal32 *) from, to);
	break;
      case 8:
	decimal64ToNumber ((decimal64 *) from, to);
	break;
      case 16:
	decimal128ToNumber ((decimal128 *) from, to);
	break;
      default:
	error (_("Unknown decimal floating point type."));
	break;
    }
}

/* Convert decimal type to its string representation.  LEN is the length
   of the decimal type, 4 bytes for decimal32, 8 bytes for decimal64 and
   16 bytes for decimal128.  */
static std::string
decimal_to_string (const gdb_byte *decbytes, int len,
		   enum bfd_endian byte_order, const char *format = nullptr)
{
  gdb_byte dec[16];

  match_endianness (decbytes, len, byte_order, dec);

  if (format != nullptr)
    {
      /* We don't handle format strings (yet).  If the host printf supports
	 decimal floating point types, just use this.  Otherwise, fall back
	 to printing the number while ignoring the format string.  */
#if defined (PRINTF_HAS_DECFLOAT)
      /* FIXME: This makes unwarranted assumptions about the host ABI!  */
      return string_printf (format, dec);
#endif
    }

  std::string result;
  result.resize (MAX_DECIMAL_STRING);

  switch (len)
    {
      case 4:
	decimal32ToString ((decimal32 *) dec, &result[0]);
	break;
      case 8:
	decimal64ToString ((decimal64 *) dec, &result[0]);
	break;
      case 16:
	decimal128ToString ((decimal128 *) dec, &result[0]);
	break;
      default:
	error (_("Unknown decimal floating point type."));
	break;
    }

  return result;
}

/* Convert the string form of a decimal value to its decimal representation.
   LEN is the length of the decimal type, 4 bytes for decimal32, 8 bytes for
   decimal64 and 16 bytes for decimal128.  */
static bool
decimal_from_string (gdb_byte *decbytes, int len, enum bfd_endian byte_order,
		     const std::string &string)
{
  decContext set;
  gdb_byte dec[16];

  set_decnumber_context (&set, len);

  switch (len)
    {
      case 4:
	decimal32FromString ((decimal32 *) dec, string.c_str (), &set);
	break;
      case 8:
	decimal64FromString ((decimal64 *) dec, string.c_str (), &set);
	break;
      case 16:
	decimal128FromString ((decimal128 *) dec, string.c_str (), &set);
	break;
      default:
	error (_("Unknown decimal floating point type."));
	break;
    }

  match_endianness (dec, len, byte_order, decbytes);

  /* Check for errors in the DFP operation.  */
  decimal_check_errors (&set);

  return true;
}

/* Converts a LONGEST to a decimal float of specified LEN bytes.  */
static void
decimal_from_longest (LONGEST from,
		      gdb_byte *to, int len, enum bfd_endian byte_order)
{
  gdb_byte dec[16];
  decNumber number;
  if ((int32_t) from != from)
    /* libdecnumber can convert only 32-bit integers.  */
    error (_("Conversion of large integer to a "
	     "decimal floating type is not supported."));

  decNumberFromInt32 (&number, (int32_t) from);

  decimal_from_number (&number, dec, len);
  match_endianness (dec, len, byte_order, to);
}

/* Converts a ULONGEST to a decimal float of specified LEN bytes.  */
static void
decimal_from_ulongest (ULONGEST from,
		       gdb_byte *to, int len, enum bfd_endian byte_order)
{
  gdb_byte dec[16];
  decNumber number;

  if ((uint32_t) from != from)
    /* libdecnumber can convert only 32-bit integers.  */
    error (_("Conversion of large integer to a "
	     "decimal floating type is not supported."));

  decNumberFromUInt32 (&number, (uint32_t) from);

  decimal_from_number (&number, dec, len);
  match_endianness (dec, len, byte_order, to);
}

/* Converts a decimal float of LEN bytes to a LONGEST.  */
static LONGEST
decimal_to_longest (const gdb_byte *from, int len, enum bfd_endian byte_order)
{
  /* libdecnumber has a function to convert from decimal to integer, but
     it doesn't work when the decimal number has a fractional part.  */
  std::string str = decimal_to_string (from, len, byte_order);
  return strtoll (str.c_str (), NULL, 10);
}

/* Perform operation OP with operands X and Y with sizes LEN_X and LEN_Y
   and byte orders BYTE_ORDER_X and BYTE_ORDER_Y, and store value in
   RESULT with size LEN_RESULT and byte order BYTE_ORDER_RESULT.  */
static void
decimal_binop (enum exp_opcode op,
	       const gdb_byte *x, int len_x, enum bfd_endian byte_order_x,
	       const gdb_byte *y, int len_y, enum bfd_endian byte_order_y,
	       gdb_byte *result, int len_result,
	       enum bfd_endian byte_order_result)
{
  decContext set;
  decNumber number1, number2, number3;
  gdb_byte dec1[16], dec2[16], dec3[16];

  match_endianness (x, len_x, byte_order_x, dec1);
  match_endianness (y, len_y, byte_order_y, dec2);

  decimal_to_number (dec1, len_x, &number1);
  decimal_to_number (dec2, len_y, &number2);

  set_decnumber_context (&set, len_result);

  switch (op)
    {
      case BINOP_ADD:
	decNumberAdd (&number3, &number1, &number2, &set);
	break;
      case BINOP_SUB:
	decNumberSubtract (&number3, &number1, &number2, &set);
	break;
      case BINOP_MUL:
	decNumberMultiply (&number3, &number1, &number2, &set);
	break;
      case BINOP_DIV:
	decNumberDivide (&number3, &number1, &number2, &set);
	break;
      case BINOP_EXP:
	decNumberPower (&number3, &number1, &number2, &set);
	break;
     default:
	error (_("Operation not valid for decimal floating point number."));
	break;
    }

  /* Check for errors in the DFP operation.  */
  decimal_check_errors (&set);

  decimal_from_number (&number3, dec3, len_result);

  match_endianness (dec3, len_result, byte_order_result, result);
}

/* Returns true if X (which is LEN bytes wide) is the number zero.  */
static int
decimal_is_zero (const gdb_byte *x, int len, enum bfd_endian byte_order)
{
  decNumber number;
  gdb_byte dec[16];

  match_endianness (x, len, byte_order, dec);
  decimal_to_number (dec, len, &number);

  return decNumberIsZero (&number);
}

/* Compares two numbers numerically.  If X is less than Y then the return value
   will be -1.  If they are equal, then the return value will be 0.  If X is
   greater than the Y then the return value will be 1.  */
static int
decimal_compare (const gdb_byte *x, int len_x, enum bfd_endian byte_order_x,
		 const gdb_byte *y, int len_y, enum bfd_endian byte_order_y)
{
  decNumber number1, number2, result;
  decContext set;
  gdb_byte dec1[16], dec2[16];
  int len_result;

  match_endianness (x, len_x, byte_order_x, dec1);
  match_endianness (y, len_y, byte_order_y, dec2);

  decimal_to_number (dec1, len_x, &number1);
  decimal_to_number (dec2, len_y, &number2);

  /* Perform the comparison in the larger of the two sizes.  */
  len_result = len_x > len_y ? len_x : len_y;
  set_decnumber_context (&set, len_result);

  decNumberCompare (&result, &number1, &number2, &set);

  /* Check for errors in the DFP operation.  */
  decimal_check_errors (&set);

  if (decNumberIsNaN (&result))
    error (_("Comparison with an invalid number (NaN)."));
  else if (decNumberIsZero (&result))
    return 0;
  else if (decNumberIsNegative (&result))
    return -1;
  else
    return 1;
}

/* Convert a decimal value from a decimal type with LEN_FROM bytes to a
   decimal type with LEN_TO bytes.  */
static void
decimal_convert (const gdb_byte *from, int len_from,
		 enum bfd_endian byte_order_from, gdb_byte *to, int len_to,
		 enum bfd_endian byte_order_to)
{
  decNumber number;
  gdb_byte dec[16];

  match_endianness (from, len_from, byte_order_from, dec);

  decimal_to_number (dec, len_from, &number);
  decimal_from_number (&number, dec, len_to);

  match_endianness (dec, len_to, byte_order_to, to);
}


/* Typed floating-point routines.  These routines operate on floating-point
   values in target format, represented by a byte buffer interpreted as a
   "struct type", which may be either a binary or decimal floating-point
   type (TYPE_CODE_FLT or TYPE_CODE_DECFLOAT).  */

/* Return whether the byte-stream ADDR holds a valid value of
   floating-point type TYPE.  */
bool
target_float_is_valid (const gdb_byte *addr, const struct type *type)
{
  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    return floatformat_is_valid (floatformat_from_type (type), addr);

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    return true;

  gdb_assert_not_reached ("unexpected type code");
}

/* Return whether the byte-stream ADDR, interpreted as floating-point
   type TYPE, is numerically equal to zero (of either sign).  */
bool
target_float_is_zero (const gdb_byte *addr, const struct type *type)
{
  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    return (floatformat_classify (floatformat_from_type (type), addr)
	    == float_zero);

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    return decimal_is_zero (addr, TYPE_LENGTH (type),
			    gdbarch_byte_order (get_type_arch (type)));

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert the byte-stream ADDR, interpreted as floating-point type TYPE,
   to a string, optionally using the print format FORMAT.  */
std::string
target_float_to_string (const gdb_byte *addr, const struct type *type,
			const char *format)
{
  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    return floatformat_to_string (floatformat_from_type (type), addr, format);

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    return decimal_to_string (addr, TYPE_LENGTH (type),
			      gdbarch_byte_order (get_type_arch (type)),
			      format);

  gdb_assert_not_reached ("unexpected type code");
}

/* Parse string STRING into a target floating-number of type TYPE and
   store it as byte-stream ADDR.  Return whether parsing succeeded.  */
bool
target_float_from_string (gdb_byte *addr, const struct type *type,
			  const std::string &string)
{
  /* Ensure possible padding bytes in the target buffer are zeroed out.  */
  memset (addr, 0, TYPE_LENGTH (type));

  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    return floatformat_from_string (floatformat_from_type (type), addr,
				    string);

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    return decimal_from_string (addr, TYPE_LENGTH (type),
				gdbarch_byte_order (get_type_arch (type)),
				string);

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert the byte-stream ADDR, interpreted as floating-point type TYPE,
   to an integer value (rounding towards zero).  */
LONGEST
target_float_to_longest (const gdb_byte *addr, const struct type *type)
{
  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    return floatformat_to_longest (floatformat_from_type (type), addr);

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    return decimal_to_longest (addr, TYPE_LENGTH (type),
			       gdbarch_byte_order (get_type_arch (type)));

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert signed integer VAL to a target floating-number of type TYPE
   and store it as byte-stream ADDR.  */
void
target_float_from_longest (gdb_byte *addr, const struct type *type,
			   LONGEST val)
{
  /* Ensure possible padding bytes in the target buffer are zeroed out.  */
  memset (addr, 0, TYPE_LENGTH (type));

  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    {
      floatformat_from_longest (floatformat_from_type (type), addr, val);
      return;
    }

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    {
      decimal_from_longest (val, addr, TYPE_LENGTH (type),
			    gdbarch_byte_order (get_type_arch (type)));
      return;
    }

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert unsigned integer VAL to a target floating-number of type TYPE
   and store it as byte-stream ADDR.  */
void
target_float_from_ulongest (gdb_byte *addr, const struct type *type,
			    ULONGEST val)
{
  /* Ensure possible padding bytes in the target buffer are zeroed out.  */
  memset (addr, 0, TYPE_LENGTH (type));

  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    {
      floatformat_from_ulongest (floatformat_from_type (type), addr, val);
      return;
    }

  if (TYPE_CODE (type) == TYPE_CODE_DECFLOAT)
    {
      decimal_from_ulongest (val, addr, TYPE_LENGTH (type),
			     gdbarch_byte_order (get_type_arch (type)));
      return;
    }

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert the byte-stream ADDR, interpreted as floating-point type TYPE,
   to a floating-point value in the host "double" format.  */
double
target_float_to_host_double (const gdb_byte *addr,
			     const struct type *type)
{
  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    return floatformat_to_host_double (floatformat_from_type (type), addr);

  /* We don't support conversions between target decimal floating-point
     types and the host double type here.  */

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert floating-point value VAL in the host "double" format to a target
   floating-number of type TYPE and store it as byte-stream ADDR.  */
void
target_float_from_host_double (gdb_byte *addr, const struct type *type,
			       double val)
{
  /* Ensure possible padding bytes in the target buffer are zeroed out.  */
  memset (addr, 0, TYPE_LENGTH (type));

  if (TYPE_CODE (type) == TYPE_CODE_FLT)
    {
      floatformat_from_host_double (floatformat_from_type (type), addr, val);
      return;
    }

  /* We don't support conversions between target decimal floating-point
     types and the host double type here.  */

  gdb_assert_not_reached ("unexpected type code");
}

/* Convert a floating-point number of type FROM_TYPE from the target
   byte-stream FROM to a floating-point number of type TO_TYPE, and
   store it to the target byte-stream TO.  */
void
target_float_convert (const gdb_byte *from, const struct type *from_type,
		      gdb_byte *to, const struct type *to_type)
{
  /* Ensure possible padding bytes in the target buffer are zeroed out.  */
  memset (to, 0, TYPE_LENGTH (to_type));

  /* Use direct conversion routines if we have them.  */

  if (TYPE_CODE (from_type) == TYPE_CODE_FLT
      && TYPE_CODE (to_type) == TYPE_CODE_FLT)
    {
      floatformat_convert (from, floatformat_from_type (from_type),
			   to, floatformat_from_type (to_type));
      return;
    }

  if (TYPE_CODE (from_type) == TYPE_CODE_DECFLOAT
      && TYPE_CODE (to_type) == TYPE_CODE_DECFLOAT)
    {
      decimal_convert (from, TYPE_LENGTH (from_type),
		       gdbarch_byte_order (get_type_arch (from_type)),
		       to, TYPE_LENGTH (to_type),
		       gdbarch_byte_order (get_type_arch (to_type)));
      return;
    }

  /* We cannot directly convert between binary and decimal floating-point
     types, so go via an intermediary string.  */

  if ((TYPE_CODE (from_type) == TYPE_CODE_FLT
       && TYPE_CODE (to_type) == TYPE_CODE_DECFLOAT)
      || (TYPE_CODE (from_type) == TYPE_CODE_DECFLOAT
	  && TYPE_CODE (to_type) == TYPE_CODE_FLT))
    {
      std::string str = target_float_to_string (from, from_type);
      target_float_from_string (to, to_type, str);
      return;
    }

  gdb_assert_not_reached ("unexpected type code");
}

/* Perform the binary operation indicated by OPCODE, using as operands the
   target byte streams X and Y, interpreted as floating-point numbers of
   types TYPE_X and TYPE_Y, respectively.  Convert the result to type
   TYPE_RES and store it into the byte-stream RES.

   The three types must either be all binary floating-point types, or else
   all decimal floating-point types.  Binary and decimal floating-point
   types cannot be mixed within a single operation.  */
void
target_float_binop (enum exp_opcode opcode,
		    const gdb_byte *x, const struct type *type_x,
		    const gdb_byte *y, const struct type *type_y,
		    gdb_byte *res, const struct type *type_res)
{
  /* Ensure possible padding bytes in the target buffer are zeroed out.  */
  memset (res, 0, TYPE_LENGTH (type_res));

  if (TYPE_CODE (type_res) == TYPE_CODE_FLT)
    {
      gdb_assert (TYPE_CODE (type_x) == TYPE_CODE_FLT);
      gdb_assert (TYPE_CODE (type_y) == TYPE_CODE_FLT);
      return floatformat_binop (opcode,
				floatformat_from_type (type_x), x,
				floatformat_from_type (type_y), y,
				floatformat_from_type (type_res), res);
    }

  if (TYPE_CODE (type_res) == TYPE_CODE_DECFLOAT)
    {
      gdb_assert (TYPE_CODE (type_x) == TYPE_CODE_DECFLOAT);
      gdb_assert (TYPE_CODE (type_y) == TYPE_CODE_DECFLOAT);
      return decimal_binop (opcode,
			    x, TYPE_LENGTH (type_x),
			    gdbarch_byte_order (get_type_arch (type_x)),
			    y, TYPE_LENGTH (type_y),
			    gdbarch_byte_order (get_type_arch (type_y)),
			    res, TYPE_LENGTH (type_res),
			    gdbarch_byte_order (get_type_arch (type_res)));
    }

  gdb_assert_not_reached ("unexpected type code");
}

/* Compare the two target byte streams X and Y, interpreted as floating-point
   numbers of types TYPE_X and TYPE_Y, respectively.  Return zero if X and Y
   are equal, -1 if X is less than Y, and 1 otherwise.

   The two types must either both be binary floating-point types, or else
   both be decimal floating-point types.  Binary and decimal floating-point
   types cannot compared directly against each other.  */
int
target_float_compare (const gdb_byte *x, const struct type *type_x,
		      const gdb_byte *y, const struct type *type_y)
{
  if (TYPE_CODE (type_x) == TYPE_CODE_FLT)
    {
      gdb_assert (TYPE_CODE (type_y) == TYPE_CODE_FLT);
      return floatformat_compare (floatformat_from_type (type_x), x,
				  floatformat_from_type (type_y), y);
    }

  if (TYPE_CODE (type_x) == TYPE_CODE_DECFLOAT)
    {
      gdb_assert (TYPE_CODE (type_y) == TYPE_CODE_DECFLOAT);
      return decimal_compare (x, TYPE_LENGTH (type_x),
			      gdbarch_byte_order (get_type_arch (type_x)),
			      y, TYPE_LENGTH (type_y),
			      gdbarch_byte_order (get_type_arch (type_y)));
    }

  gdb_assert_not_reached ("unexpected type code");
}