include/floatformat.h

   1 /* IEEE floating point support declarations, for GDB, the GNU Debugger.
   2    Copyright 1991, 1994, 1995, 1997, 2000, 2003, 2005, 2010
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GDB.
   6
   7 This program 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 of the License, or
  10 (at your option) any later version.
  11
  12 This program 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 this program; if not, write to the Free Software
  19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  20
  21 #if !defined (FLOATFORMAT_H)
  22 #define FLOATFORMAT_H 1
  23
  24 #include "ansidecl.h"
  25
  26 /* A floatformat consists of a sign bit, an exponent and a mantissa.  Once the
  27    bytes are concatenated according to the byteorder flag, then each of those
  28    fields is contiguous.  We number the bits with 0 being the most significant
  29    (i.e. BITS_BIG_ENDIAN type numbering), and specify which bits each field
  30    contains with the *_start and *_len fields.  */
  31
  32 /* What is the order of the bytes?  */
  33
  34 enum floatformat_byteorders {
  35   /* Standard little endian byte order.
  36      EX: 1.2345678e10 => 00 00 80 c5 e0 fe 06 42 */
  37   floatformat_little,
  38
  39   /* Standard big endian byte order.
  40      EX: 1.2345678e10 => 42 06 fe e0 c5 80 00 00 */
  41   floatformat_big,
  42
  43   /* Little endian byte order but big endian word order.
  44      EX: 1.2345678e10 => e0 fe 06 42 00 00 80 c5 */
  45   floatformat_littlebyte_bigword,
  46
  47   /* VAX byte order.  Little endian byte order with 16-bit words.  The
  48      following example is an illustration of the byte order only; VAX
  49      doesn't have a fully IEEE compliant floating-point format.
  50      EX: 1.2345678e10 => 80 c5 00 00 06 42 e0 fe */
  51   floatformat_vax
  52 };
  53
  54 enum floatformat_intbit { floatformat_intbit_yes, floatformat_intbit_no };
  55
  56 struct floatformat
  57 {
  58   enum floatformat_byteorders byteorder;
  59   unsigned int totalsize;       /* Total size of number in bits */
  60
  61   /* Sign bit is always one bit long.  1 means negative, 0 means positive.  */
  62   unsigned int sign_start;
  63
  64   unsigned int exp_start;
  65   unsigned int exp_len;
  66   /* Bias added to a "true" exponent to form the biased exponent.  It
  67      is intentionally signed as, otherwize, -exp_bias can turn into a
  68      very large number (e.g., given the exp_bias of 0x3fff and a 64
  69      bit long, the equation (long)(1 - exp_bias) evaluates to
  70      4294950914) instead of -16382).  */
  71   int exp_bias;
  72   /* Exponent value which indicates NaN.  This is the actual value stored in
  73      the float, not adjusted by the exp_bias.  This usually consists of all
  74      one bits.  */
  75   unsigned int exp_nan;
  76
  77   unsigned int man_start;
  78   unsigned int man_len;
  79
  80   /* Is the integer bit explicit or implicit?  */
  81   enum floatformat_intbit intbit;
  82
  83   /* Internal name for debugging. */
  84   const char *name;
  85
  86   /* Validator method.  */
  87   int (*is_valid) (const struct floatformat *fmt, const void *from);
  88
  89   /* Is the format actually the sum of two smaller floating point
  90      formats (IBM long double, as described in
  91      gcc/config/rs6000/darwin-ldouble-format)?  If so, this is the
  92      smaller format in question, and the fields sign_start through
  93      intbit describe the first half.  If not, this is NULL.  */
  94   const struct floatformat *split_half;
  95 };
  96
  97 /* floatformats for IEEE single and double, big and little endian.  */
  98
  99 extern const struct floatformat floatformat_ieee_half_big;
 100 extern const struct floatformat floatformat_ieee_half_little;
 101 extern const struct floatformat floatformat_ieee_single_big;
 102 extern const struct floatformat floatformat_ieee_single_little;
 103 extern const struct floatformat floatformat_ieee_double_big;
 104 extern const struct floatformat floatformat_ieee_double_little;
 105
 106 /* floatformat for ARM IEEE double, little endian bytes and big endian words */
 107
 108 extern const struct floatformat floatformat_ieee_double_littlebyte_bigword;
 109
 110 /* floatformats for VAX.  */
 111
 112 extern const struct floatformat floatformat_vax_f;
 113 extern const struct floatformat floatformat_vax_d;
 114 extern const struct floatformat floatformat_vax_g;
 115
 116 /* floatformats for various extendeds.  */
 117
 118 extern const struct floatformat floatformat_i387_ext;
 119 extern const struct floatformat floatformat_m68881_ext;
 120 extern const struct floatformat floatformat_i960_ext;
 121 extern const struct floatformat floatformat_m88110_ext;
 122 extern const struct floatformat floatformat_m88110_harris_ext;
 123 extern const struct floatformat floatformat_arm_ext_big;
 124 extern const struct floatformat floatformat_arm_ext_littlebyte_bigword;
 125 /* IA-64 Floating Point register spilt into memory.  */
 126 extern const struct floatformat floatformat_ia64_spill_big;
 127 extern const struct floatformat floatformat_ia64_spill_little;
 128 extern const struct floatformat floatformat_ia64_quad_big;
 129 extern const struct floatformat floatformat_ia64_quad_little;
 130 /* IBM long double (double+double).  */
 131 extern const struct floatformat floatformat_ibm_long_double_big;
 132 extern const struct floatformat floatformat_ibm_long_double_little;
 133
 134 /* Convert from FMT to a double.
 135    FROM is the address of the extended float.
 136    Store the double in *TO.  */
 137
 138 extern void
 139 floatformat_to_double (const struct floatformat *, const void *, double *);
 140
 141 /* The converse: convert the double *FROM to FMT
 142    and store where TO points.  */
 143
 144 extern void
 145 floatformat_from_double (const struct floatformat *, const double *, void *);
 146
 147 /* Return non-zero iff the data at FROM is a valid number in format FMT.  */
 148
 149 extern int
 150 floatformat_is_valid (const struct floatformat *fmt, const void *from);
 151
 152 #endif  /* defined (FLOATFORMAT_H) */