include/floatformat.h

   1 /* IEEE floating point support declarations, for GDB, the GNU Debugger.
   2    Copyright (C) 1991-2023 Free Software Foundation, Inc.
   3
   4 This file is part of GDB.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 #if !defined (FLOATFORMAT_H)
  21 #define FLOATFORMAT_H 1
  22
  23 #include "ansidecl.h"
  24
  25 #ifdef __cplusplus
  26 extern "C" {
  27 #endif
  28
  29 /* A floatformat consists of a sign bit, an exponent and a mantissa.  Once the
  30    bytes are concatenated according to the byteorder flag, then each of those
  31    fields is contiguous.  We number the bits with 0 being the most significant
  32    (i.e. BITS_BIG_ENDIAN type numbering), and specify which bits each field
  33    contains with the *_start and *_len fields.  */
  34
  35 /* What is the order of the bytes?  */
  36
  37 enum floatformat_byteorders {
  38   /* Standard little endian byte order.
  39      EX: 1.2345678e10 => 00 00 80 c5 e0 fe 06 42 */
  40   floatformat_little,
  41
  42   /* Standard big endian byte order.
  43      EX: 1.2345678e10 => 42 06 fe e0 c5 80 00 00 */
  44   floatformat_big,
  45
  46   /* Little endian byte order but big endian word order.
  47      EX: 1.2345678e10 => e0 fe 06 42 00 00 80 c5 */
  48   floatformat_littlebyte_bigword,
  49
  50   /* VAX byte order.  Little endian byte order with 16-bit words.  The
  51      following example is an illustration of the byte order only; VAX
  52      doesn't have a fully IEEE compliant floating-point format.
  53      EX: 1.2345678e10 => 80 c5 00 00 06 42 e0 fe */
  54   floatformat_vax
  55 };
  56
  57 enum floatformat_intbit { floatformat_intbit_yes, floatformat_intbit_no };
  58
  59 struct floatformat
  60 {
  61   enum floatformat_byteorders byteorder;
  62   unsigned int totalsize;       /* Total size of number in bits */
  63
  64   /* Sign bit is always one bit long.  1 means negative, 0 means positive.  */
  65   unsigned int sign_start;
  66
  67   unsigned int exp_start;
  68   unsigned int exp_len;
  69   /* Bias added to a "true" exponent to form the biased exponent.  It
  70      is intentionally signed as, otherwize, -exp_bias can turn into a
  71      very large number (e.g., given the exp_bias of 0x3fff and a 64
  72      bit long, the equation (long)(1 - exp_bias) evaluates to
  73      4294950914) instead of -16382).  */
  74   int exp_bias;
  75   /* Exponent value which indicates NaN.  This is the actual value stored in
  76      the float, not adjusted by the exp_bias.  This usually consists of all
  77      one bits.  */
  78   unsigned int exp_nan;
  79
  80   unsigned int man_start;
  81   unsigned int man_len;
  82
  83   /* Is the integer bit explicit or implicit?  */
  84   enum floatformat_intbit intbit;
  85
  86   /* Internal name for debugging. */
  87   const char *name;
  88
  89   /* Validator method.  */
  90   int (*is_valid) (const struct floatformat *fmt, const void *from);
  91
  92   /* Is the format actually the sum of two smaller floating point
  93      formats (IBM long double, as described in
  94      libgcc/config/rs6000/ibm-ldouble-format)?  If so, this is the
  95      smaller format in question, and the fields sign_start through
  96      intbit describe the first half.  If not, this is NULL.  */
  97   const struct floatformat *split_half;
  98 };
  99
 100 /* floatformats for IEEE half, single, double and quad, big and little endian.  */
 101
 102 extern const struct floatformat floatformat_ieee_half_big;
 103 extern const struct floatformat floatformat_ieee_half_little;
 104 extern const struct floatformat floatformat_ieee_single_big;
 105 extern const struct floatformat floatformat_ieee_single_little;
 106 extern const struct floatformat floatformat_ieee_double_big;
 107 extern const struct floatformat floatformat_ieee_double_little;
 108 extern const struct floatformat floatformat_ieee_quad_big;
 109 extern const struct floatformat floatformat_ieee_quad_little;
 110
 111 /* floatformat for ARM IEEE double, little endian bytes and big endian words */
 112
 113 extern const struct floatformat floatformat_ieee_double_littlebyte_bigword;
 114
 115 /* floatformats for VAX.  */
 116
 117 extern const struct floatformat floatformat_vax_f;
 118 extern const struct floatformat floatformat_vax_d;
 119 extern const struct floatformat floatformat_vax_g;
 120
 121 /* floatformats for various extendeds.  */
 122
 123 extern const struct floatformat floatformat_i387_ext;
 124 extern const struct floatformat floatformat_m68881_ext;
 125 extern const struct floatformat floatformat_i960_ext;
 126 extern const struct floatformat floatformat_m88110_ext;
 127 extern const struct floatformat floatformat_m88110_harris_ext;
 128 extern const struct floatformat floatformat_arm_ext_big;
 129 extern const struct floatformat floatformat_arm_ext_littlebyte_bigword;
 130 /* IA-64 Floating Point register spilt into memory.  */
 131 extern const struct floatformat floatformat_ia64_spill_big;
 132 extern const struct floatformat floatformat_ia64_spill_little;
 133 /* IBM long double (double+double).  */
 134 extern const struct floatformat floatformat_ibm_long_double_big;
 135 extern const struct floatformat floatformat_ibm_long_double_little;
 136 /* bfloat16.  */
 137 extern const struct floatformat floatformat_bfloat16_big;
 138 extern const struct floatformat floatformat_bfloat16_little;
 139
 140 /* Convert from FMT to a double.
 141    FROM is the address of the extended float.
 142    Store the double in *TO.  */
 143
 144 extern void
 145 floatformat_to_double (const struct floatformat *, const void *, double *);
 146
 147 /* The converse: convert the double *FROM to FMT
 148    and store where TO points.  */
 149
 150 extern void
 151 floatformat_from_double (const struct floatformat *, const double *, void *);
 152
 153 /* Return non-zero iff the data at FROM is a valid number in format FMT.  */
 154
 155 extern int
 156 floatformat_is_valid (const struct floatformat *fmt, const void *from);
 157
 158 #ifdef __cplusplus
 159 }
 160 #endif
 161
 162 #endif  /* defined (FLOATFORMAT_H) */