libdecnumber/decContext.c

   1 /* Decimal context module for the decNumber C Library.
   2    Copyright (C) 2005 Free Software Foundation, Inc.
   3    Contributed by IBM Corporation.  Author Mike Cowlishaw.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it under
   8    the terms of the GNU General Public License as published by the Free
   9    Software Foundation; either version 2, or (at your option) any later
  10    version.
  11
  12    In addition to the permissions in the GNU General Public License,
  13    the Free Software Foundation gives you unlimited permission to link
  14    the compiled version of this file into combinations with other
  15    programs, and to distribute those combinations without any
  16    restriction coming from the use of this file.  (The General Public
  17    License restrictions do apply in other respects; for example, they
  18    cover modification of the file, and distribution when not linked
  19    into a combine executable.)
  20
  21    GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  22    WARRANTY; without even the implied warranty of MERCHANTABILITY or
  23    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  24    for more details.
  25
  26    You should have received a copy of the GNU General Public License
  27    along with GCC; see the file COPYING.  If not, write to the Free
  28    Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  29    02110-1301, USA.  */
  30
  31 /*  This module compirises the routines for handling the arithmetic
  32     context structures. */
  33
  34 #include <string.h>             /* for strcmp */
  35 #include "config.h"
  36 #include "decContext.h"         /* context and base types */
  37 #include "decNumberLocal.h"     /* decNumber local types, etc. */
  38
  39 /* ------------------------------------------------------------------ */
  40 /* decContextDefault -- initialize a context structure                */
  41 /*                                                                    */
  42 /*  context is the structure to be initialized                        */
  43 /*  kind selects the required set of default values, one of:          */
  44 /*      DEC_INIT_BASE       -- select ANSI X3-274 defaults            */
  45 /*      DEC_INIT_DECIMAL32  -- select IEEE 754r defaults, 32-bit      */
  46 /*      DEC_INIT_DECIMAL64  -- select IEEE 754r defaults, 64-bit      */
  47 /*      DEC_INIT_DECIMAL128 -- select IEEE 754r defaults, 128-bit     */
  48 /*      For any other value a valid context is returned, but with     */
  49 /*      Invalid_operation set in the status field.                    */
  50 /*  returns a context structure with the appropriate initial values.  */
  51 /* ------------------------------------------------------------------ */
  52 decContext *
  53 decContextDefault (decContext * context, Int kind)
  54 {
  55   /* set defaults... */
  56   context->digits = 9;          /* 9 digits */
  57   context->emax = DEC_MAX_EMAX; /* 9-digit exponents */
  58   context->emin = DEC_MIN_EMIN; /* .. balanced */
  59   context->round = DEC_ROUND_HALF_UP;   /* 0.5 rises */
  60   context->traps = DEC_Errors;  /* all but informational */
  61   context->status = 0;          /* cleared */
  62   context->clamp = 0;           /* no clamping */
  63 #if DECSUBSET
  64   context->extended = 0;        /* cleared */
  65 #endif
  66   switch (kind)
  67     {
  68     case DEC_INIT_BASE:
  69       /* [use defaults] */
  70       break;
  71     case DEC_INIT_DECIMAL32:
  72       context->digits = 7;      /* digits */
  73       context->emax = 96;       /* Emax */
  74       context->emin = -95;      /* Emin */
  75       context->round = DEC_ROUND_HALF_EVEN;     /* 0.5 to nearest even */
  76       context->traps = 0;       /* no traps set */
  77       context->clamp = 1;       /* clamp exponents */
  78 #if DECSUBSET
  79       context->extended = 1;    /* set */
  80 #endif
  81       break;
  82     case DEC_INIT_DECIMAL64:
  83       context->digits = 16;     /* digits */
  84       context->emax = 384;      /* Emax */
  85       context->emin = -383;     /* Emin */
  86       context->round = DEC_ROUND_HALF_EVEN;     /* 0.5 to nearest even */
  87       context->traps = 0;       /* no traps set */
  88       context->clamp = 1;       /* clamp exponents */
  89 #if DECSUBSET
  90       context->extended = 1;    /* set */
  91 #endif
  92       break;
  93     case DEC_INIT_DECIMAL128:
  94       context->digits = 34;     /* digits */
  95       context->emax = 6144;     /* Emax */
  96       context->emin = -6143;    /* Emin */
  97       context->round = DEC_ROUND_HALF_EVEN;     /* 0.5 to nearest even */
  98       context->traps = 0;       /* no traps set */
  99       context->clamp = 1;       /* clamp exponents */
 100 #if DECSUBSET
 101       context->extended = 1;    /* set */
 102 #endif
 103       break;
 104
 105     default:                    /* invalid Kind */
 106       /* use defaults, and .. */
 107       decContextSetStatus (context, DEC_Invalid_operation);     /* trap */
 108     }
 109   return context;
 110 }                               /* decContextDefault */
 111
 112 /* ------------------------------------------------------------------ */
 113 /* decContextStatusToString -- convert status flags to a string       */
 114 /*                                                                    */
 115 /*  context is a context with valid status field                      */
 116 /*                                                                    */
 117 /*  returns a constant string describing the condition.  If multiple  */
 118 /*    (or no) flags are set, a generic constant message is returned.  */
 119 /* ------------------------------------------------------------------ */
 120 const char *
 121 decContextStatusToString (const decContext * context)
 122 {
 123   Int status = context->status;
 124   if (status == DEC_Conversion_syntax)
 125     return DEC_Condition_CS;
 126   if (status == DEC_Division_by_zero)
 127     return DEC_Condition_DZ;
 128   if (status == DEC_Division_impossible)
 129     return DEC_Condition_DI;
 130   if (status == DEC_Division_undefined)
 131     return DEC_Condition_DU;
 132   if (status == DEC_Inexact)
 133     return DEC_Condition_IE;
 134   if (status == DEC_Insufficient_storage)
 135     return DEC_Condition_IS;
 136   if (status == DEC_Invalid_context)
 137     return DEC_Condition_IC;
 138   if (status == DEC_Invalid_operation)
 139     return DEC_Condition_IO;
 140 #if DECSUBSET
 141   if (status == DEC_Lost_digits)
 142     return DEC_Condition_LD;
 143 #endif
 144   if (status == DEC_Overflow)
 145     return DEC_Condition_OV;
 146   if (status == DEC_Clamped)
 147     return DEC_Condition_PA;
 148   if (status == DEC_Rounded)
 149     return DEC_Condition_RO;
 150   if (status == DEC_Subnormal)
 151     return DEC_Condition_SU;
 152   if (status == DEC_Underflow)
 153     return DEC_Condition_UN;
 154   if (status == 0)
 155     return DEC_Condition_ZE;
 156   return DEC_Condition_MU;      /* Multiple errors */
 157 }                               /* decContextStatusToString */
 158
 159 /* ------------------------------------------------------------------ */
 160 /* decContextSetStatusFromString -- set status from a string          */
 161 /*                                                                    */
 162 /*  context is the controlling context                                */
 163 /*  string is a string exactly equal to one that might be returned    */
 164 /*            by decContextStatusToString                             */
 165 /*                                                                    */
 166 /*  The status bit corresponding to the string is set, and a trap     */
 167 /*  is raised if appropriate.                                         */
 168 /*                                                                    */
 169 /*  returns the context structure, unless the string is equal to      */
 170 /*    DEC_Condition_MU or is not recognized.  In these cases NULL is  */
 171 /*    returned.                                                       */
 172 /* ------------------------------------------------------------------ */
 173 decContext *
 174 decContextSetStatusFromString (decContext * context, const char *string)
 175 {
 176   if (strcmp (string, DEC_Condition_CS) == 0)
 177     return decContextSetStatus (context, DEC_Conversion_syntax);
 178   if (strcmp (string, DEC_Condition_DZ) == 0)
 179     return decContextSetStatus (context, DEC_Division_by_zero);
 180   if (strcmp (string, DEC_Condition_DI) == 0)
 181     return decContextSetStatus (context, DEC_Division_impossible);
 182   if (strcmp (string, DEC_Condition_DU) == 0)
 183     return decContextSetStatus (context, DEC_Division_undefined);
 184   if (strcmp (string, DEC_Condition_IE) == 0)
 185     return decContextSetStatus (context, DEC_Inexact);
 186   if (strcmp (string, DEC_Condition_IS) == 0)
 187     return decContextSetStatus (context, DEC_Insufficient_storage);
 188   if (strcmp (string, DEC_Condition_IC) == 0)
 189     return decContextSetStatus (context, DEC_Invalid_context);
 190   if (strcmp (string, DEC_Condition_IO) == 0)
 191     return decContextSetStatus (context, DEC_Invalid_operation);
 192 #if DECSUBSET
 193   if (strcmp (string, DEC_Condition_LD) == 0)
 194     return decContextSetStatus (context, DEC_Lost_digits);
 195 #endif
 196   if (strcmp (string, DEC_Condition_OV) == 0)
 197     return decContextSetStatus (context, DEC_Overflow);
 198   if (strcmp (string, DEC_Condition_PA) == 0)
 199     return decContextSetStatus (context, DEC_Clamped);
 200   if (strcmp (string, DEC_Condition_RO) == 0)
 201     return decContextSetStatus (context, DEC_Rounded);
 202   if (strcmp (string, DEC_Condition_SU) == 0)
 203     return decContextSetStatus (context, DEC_Subnormal);
 204   if (strcmp (string, DEC_Condition_UN) == 0)
 205     return decContextSetStatus (context, DEC_Underflow);
 206   if (strcmp (string, DEC_Condition_ZE) == 0)
 207     return context;
 208   return NULL;                  /* Multiple status, or unknown */
 209 }                               /* decContextSetStatusFromString */
 210
 211 /* ------------------------------------------------------------------ */
 212 /* decContextSetStatus -- set status and raise trap if appropriate    */
 213 /*                                                                    */
 214 /*  context is the controlling context                                */
 215 /*  status  is the DEC_ exception code                                */
 216 /*  returns the context structure                                     */
 217 /*                                                                    */
 218 /* Control may never return from this routine, if there is a signal   */
 219 /* handler and it takes a long jump.                                  */
 220 /* ------------------------------------------------------------------ */
 221 decContext *
 222 decContextSetStatus (decContext * context, uInt status)
 223 {
 224   context->status |= status;
 225   if (status & context->traps)
 226     raise (SIGFPE);
 227   return context;
 228 }                               /* decContextSetStatus */