newlib/include/floatformat.h

/* IEEE floating point support declarations, for GDB, the GNU Debugger.
   Copyright 1991, 1994, 1995, 1997, 2000, 2003, 2005
   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 2 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, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */

#if !defined (FLOATFORMAT_H)
#define FLOATFORMAT_H 1

#include "ansidecl.h"

/* A floatformat consists of a sign bit, an exponent and a mantissa.  Once the
   bytes are concatenated according to the byteorder flag, then each of those
   fields is contiguous.  We number the bits with 0 being the most significant
   (i.e. BITS_BIG_ENDIAN type numbering), and specify which bits each field
   contains with the *_start and *_len fields.  */

/* What is the order of the bytes?  */

enum floatformat_byteorders {
  /* Standard little endian byte order.
     EX: 1.2345678e10 => 00 00 80 c5 e0 fe 06 42 */
  floatformat_little,

  /* Standard big endian byte order.
     EX: 1.2345678e10 => 42 06 fe e0 c5 80 00 00 */
  floatformat_big,

  /* Little endian byte order but big endian word order.
     EX: 1.2345678e10 => e0 fe 06 42 00 00 80 c5 */
  floatformat_littlebyte_bigword,

  /* VAX byte order.  Little endian byte order with 16-bit words.  The
     following example is an illustration of the byte order only; VAX
     doesn't have a fully IEEE compliant floating-point format.
     EX: 1.2345678e10 => 80 c5 00 00 06 42 e0 fe */
  floatformat_vax
};

enum floatformat_intbit { floatformat_intbit_yes, floatformat_intbit_no };

struct floatformat
{
  enum floatformat_byteorders byteorder;
  unsigned int totalsize;	/* Total size of number in bits */

  /* Sign bit is always one bit long.  1 means negative, 0 means positive.  */
  unsigned int sign_start;

  unsigned int exp_start;
  unsigned int exp_len;
  /* Bias added to a "true" exponent to form the biased exponent.  It
     is intentionally signed as, otherwize, -exp_bias can turn into a
     very large number (e.g., given the exp_bias of 0x3fff and a 64
     bit long, the equation (long)(1 - exp_bias) evaluates to
     4294950914) instead of -16382).  */
  int exp_bias;
  /* Exponent value which indicates NaN.  This is the actual value stored in
     the float, not adjusted by the exp_bias.  This usually consists of all
     one bits.  */
  unsigned int exp_nan;

  unsigned int man_start;
  unsigned int man_len;

  /* Is the integer bit explicit or implicit?  */
  enum floatformat_intbit intbit;

  /* Internal name for debugging. */
  const char *name;

  /* Validator method.  */
  int (*is_valid) (const struct floatformat *fmt, const void *from);

  /* Is the format actually the sum of two smaller floating point
     formats (IBM long double, as described in
     gcc/config/rs6000/darwin-ldouble-format)?  If so, this is the
     smaller format in question, and the fields sign_start through
     intbit describe the first half.  If not, this is NULL.  */
  const struct floatformat *split_half;
};

/* floatformats for IEEE single and double, big and little endian.  */

extern const struct floatformat floatformat_ieee_half_big;
extern const struct floatformat floatformat_ieee_half_little;
extern const struct floatformat floatformat_ieee_single_big;
extern const struct floatformat floatformat_ieee_single_little;
extern const struct floatformat floatformat_ieee_double_big;
extern const struct floatformat floatformat_ieee_double_little;

/* floatformat for ARM IEEE double, little endian bytes and big endian words */

extern const struct floatformat floatformat_ieee_double_littlebyte_bigword;

/* floatformats for VAX.  */

extern const struct floatformat floatformat_vax_f;
extern const struct floatformat floatformat_vax_d;
extern const struct floatformat floatformat_vax_g;

/* floatformats for various extendeds.  */

extern const struct floatformat floatformat_i387_ext;
extern const struct floatformat floatformat_m68881_ext;
extern const struct floatformat floatformat_i960_ext;
extern const struct floatformat floatformat_m88110_ext;
extern const struct floatformat floatformat_m88110_harris_ext;
extern const struct floatformat floatformat_arm_ext_big;
extern const struct floatformat floatformat_arm_ext_littlebyte_bigword;
/* IA-64 Floating Point register spilt into memory.  */
extern const struct floatformat floatformat_ia64_spill_big;
extern const struct floatformat floatformat_ia64_spill_little;
extern const struct floatformat floatformat_ia64_quad_big;
extern const struct floatformat floatformat_ia64_quad_little;
/* IBM long double (double+double).  */
extern const struct floatformat floatformat_ibm_long_double;

/* Convert from FMT to a double.
   FROM is the address of the extended float.
   Store the double in *TO.  */

extern void
floatformat_to_double (const struct floatformat *, const void *, double *);

/* The converse: convert the double *FROM to FMT
   and store where TO points.  */

extern void
floatformat_from_double (const struct floatformat *, const double *, void *);

/* Return non-zero iff the data at FROM is a valid number in format FMT.  */

extern int
floatformat_is_valid (const struct floatformat *fmt, const void *from);

#endif	/* defined (FLOATFORMAT_H) */