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 #ifdef __cplusplus
  27 extern "C" {
  28 #endif
  29
  30 /* A floatformat consists of a sign bit, an exponent and a mantissa.  Once the
  31    bytes are concatenated according to the byteorder flag, then each of those
  32    fields is contiguous.  We number the bits with 0 being the most significant
  33    (i.e. BITS_BIG_ENDIAN type numbering), and specify which bits each field
  34    contains with the *_start and *_len fields.  */
  35
  36 /* What is the order of the bytes?  */
  37
  38 enum floatformat_byteorders {
  39   /* Standard little endian byte order.
  40      EX: 1.2345678e10 => 00 00 80 c5 e0 fe 06 42 */
  41   floatformat_little,
  42
  43   /* Standard big endian byte order.
  44      EX: 1.2345678e10 => 42 06 fe e0 c5 80 00 00 */
  45   floatformat_big,
  46
  47   /* Little endian byte order but big endian word order.
  48      EX: 1.2345678e10 => e0 fe 06 42 00 00 80 c5 */
  49   floatformat_littlebyte_bigword,
  50
  51   /* VAX byte order.  Little endian byte order with 16-bit words.  The
  52      following example is an illustration of the byte order only; VAX
  53      doesn't have a fully IEEE compliant floating-point format.
  54      EX: 1.2345678e10 => 80 c5 00 00 06 42 e0 fe */
  55   floatformat_vax
  56 };
  57
  58 enum floatformat_intbit { floatformat_intbit_yes, floatformat_intbit_no };
  59
  60 struct floatformat
  61 {
  62   enum floatformat_byteorders byteorder;
  63   unsigned int totalsize;       /* Total size of number in bits */
  64
  65   /* Sign bit is always one bit long.  1 means negative, 0 means positive.  */
  66   unsigned int sign_start;
  67
  68   unsigned int exp_start;
  69   unsigned int exp_len;
  70   /* Bias added to a "true" exponent to form the biased exponent.  It
  71      is intentionally signed as, otherwize, -exp_bias can turn into a
  72      very large number (e.g., given the exp_bias of 0x3fff and a 64
  73      bit long, the equation (long)(1 - exp_bias) evaluates to
  74      4294950914) instead of -16382).  */
  75   int exp_bias;
  76   /* Exponent value which indicates NaN.  This is the actual value stored in
  77      the float, not adjusted by the exp_bias.  This usually consists of all
  78      one bits.  */
  79   unsigned int exp_nan;
  80
  81   unsigned int man_start;
  82   unsigned int man_len;
  83
  84   /* Is the integer bit explicit or implicit?  */
  85   enum floatformat_intbit intbit;
  86
  87   /* Internal name for debugging. */
  88   const char *name;
  89
  90   /* Validator method.  */
  91   int (*is_valid) (const struct floatformat *fmt, const void *from);
  92
  93   /* Is the format actually the sum of two smaller floating point
  94      formats (IBM long double, as described in
  95      gcc/config/rs6000/darwin-ldouble-format)?  If so, this is the
  96      smaller format in question, and the fields sign_start through
  97      intbit describe the first half.  If not, this is NULL.  */
  98   const struct floatformat *split_half;
  99 };
 100
 101 /* floatformats for IEEE single and double, big and little endian.  */
 102
 103 extern const struct floatformat floatformat_ieee_half_big;
 104 extern const struct floatformat floatformat_ieee_half_little;
 105 extern const struct floatformat floatformat_ieee_single_big;
 106 extern const struct floatformat floatformat_ieee_single_little;
 107 extern const struct floatformat floatformat_ieee_double_big;
 108 extern const struct floatformat floatformat_ieee_double_little;
 109
 110 /* floatformat for ARM IEEE double, little endian bytes and big endian words */
 111
 112 extern const struct floatformat floatformat_ieee_double_littlebyte_bigword;
 113
 114 /* floatformats for VAX.  */
 115
 116 extern const struct floatformat floatformat_vax_f;
 117 extern const struct floatformat floatformat_vax_d;
 118 extern const struct floatformat floatformat_vax_g;
 119
 120 /* floatformats for various extendeds.  */
 121
 122 extern const struct floatformat floatformat_i387_ext;
 123 extern const struct floatformat floatformat_m68881_ext;
 124 extern const struct floatformat floatformat_i960_ext;
 125 extern const struct floatformat floatformat_m88110_ext;
 126 extern const struct floatformat floatformat_m88110_harris_ext;
 127 extern const struct floatformat floatformat_arm_ext_big;
 128 extern const struct floatformat floatformat_arm_ext_littlebyte_bigword;
 129 /* IA-64 Floating Point register spilt into memory.  */
 130 extern const struct floatformat floatformat_ia64_spill_big;
 131 extern const struct floatformat floatformat_ia64_spill_little;
 132 extern const struct floatformat floatformat_ia64_quad_big;
 133 extern const struct floatformat floatformat_ia64_quad_little;
 134 /* IBM long double (double+double).  */
 135 extern const struct floatformat floatformat_ibm_long_double_big;
 136 extern const struct floatformat floatformat_ibm_long_double_little;
 137
 138 /* Convert from FMT to a double.
 139    FROM is the address of the extended float.
 140    Store the double in *TO.  */
 141
 142 extern void
 143 floatformat_to_double (const struct floatformat *, const void *, double *);
 144
 145 /* The converse: convert the double *FROM to FMT
 146    and store where TO points.  */
 147
 148 extern void
 149 floatformat_from_double (const struct floatformat *, const double *, void *);
 150
 151 /* Return non-zero iff the data at FROM is a valid number in format FMT.  */
 152
 153 extern int
 154 floatformat_is_valid (const struct floatformat *fmt, const void *from);
 155
 156 #ifdef __cplusplus
 157 }
 158 #endif
 159
 160 #endif  /* defined (FLOATFORMAT_H) */