gcc/libdecnumber/decContext.c

/* Decimal context module for the decNumber C Library.
   Copyright (C) 2005 Free Software Foundation, Inc.
   Contributed by IBM Corporation.  Author Mike Cowlishaw.

   This file is part of GCC.

   GCC 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, or (at your option) any later
   version.

   In addition to the permissions in the GNU General Public License,
   the Free Software Foundation gives you unlimited permission to link
   the compiled version of this file into combinations with other
   programs, and to distribute those combinations without any
   restriction coming from the use of this file.  (The General Public
   License restrictions do apply in other respects; for example, they
   cover modification of the file, and distribution when not linked
   into a combine executable.)

   GCC 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 GCC; see the file COPYING.  If not, write to the Free
   Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.  */

/*  This module compirises the routines for handling the arithmetic
    context structures. */

#include <string.h>		/* for strcmp */
#include "config.h"
#include "decContext.h"		/* context and base types */
#include "decNumberLocal.h"	/* decNumber local types, etc. */

/* ------------------------------------------------------------------ */
/* decContextDefault -- initialize a context structure                */
/*                                                                    */
/*  context is the structure to be initialized                        */
/*  kind selects the required set of default values, one of:          */
/*      DEC_INIT_BASE       -- select ANSI X3-274 defaults            */
/*      DEC_INIT_DECIMAL32  -- select IEEE 754r defaults, 32-bit      */
/*      DEC_INIT_DECIMAL64  -- select IEEE 754r defaults, 64-bit      */
/*      DEC_INIT_DECIMAL128 -- select IEEE 754r defaults, 128-bit     */
/*      For any other value a valid context is returned, but with     */
/*      Invalid_operation set in the status field.                    */
/*  returns a context structure with the appropriate initial values.  */
/* ------------------------------------------------------------------ */
decContext *
decContextDefault (decContext * context, Int kind)
{
  /* set defaults... */
  context->digits = 9;		/* 9 digits */
  context->emax = DEC_MAX_EMAX;	/* 9-digit exponents */
  context->emin = DEC_MIN_EMIN;	/* .. balanced */
  context->round = DEC_ROUND_HALF_UP;	/* 0.5 rises */
  context->traps = DEC_Errors;	/* all but informational */
  context->status = 0;		/* cleared */
  context->clamp = 0;		/* no clamping */
#if DECSUBSET
  context->extended = 0;	/* cleared */
#endif
  switch (kind)
    {
    case DEC_INIT_BASE:
      /* [use defaults] */
      break;
    case DEC_INIT_DECIMAL32:
      context->digits = 7;	/* digits */
      context->emax = 96;	/* Emax */
      context->emin = -95;	/* Emin */
      context->round = DEC_ROUND_HALF_EVEN;	/* 0.5 to nearest even */
      context->traps = 0;	/* no traps set */
      context->clamp = 1;	/* clamp exponents */
#if DECSUBSET
      context->extended = 1;	/* set */
#endif
      break;
    case DEC_INIT_DECIMAL64:
      context->digits = 16;	/* digits */
      context->emax = 384;	/* Emax */
      context->emin = -383;	/* Emin */
      context->round = DEC_ROUND_HALF_EVEN;	/* 0.5 to nearest even */
      context->traps = 0;	/* no traps set */
      context->clamp = 1;	/* clamp exponents */
#if DECSUBSET
      context->extended = 1;	/* set */
#endif
      break;
    case DEC_INIT_DECIMAL128:
      context->digits = 34;	/* digits */
      context->emax = 6144;	/* Emax */
      context->emin = -6143;	/* Emin */
      context->round = DEC_ROUND_HALF_EVEN;	/* 0.5 to nearest even */
      context->traps = 0;	/* no traps set */
      context->clamp = 1;	/* clamp exponents */
#if DECSUBSET
      context->extended = 1;	/* set */
#endif
      break;

    default:			/* invalid Kind */
      /* use defaults, and .. */
      decContextSetStatus (context, DEC_Invalid_operation);	/* trap */
    }
  return context;
}				/* decContextDefault */

/* ------------------------------------------------------------------ */
/* decContextStatusToString -- convert status flags to a string       */
/*                                                                    */
/*  context is a context with valid status field                      */
/*                                                                    */
/*  returns a constant string describing the condition.  If multiple  */
/*    (or no) flags are set, a generic constant message is returned.  */
/* ------------------------------------------------------------------ */
const char *
decContextStatusToString (const decContext * context)
{
  Int status = context->status;
  if (status == DEC_Conversion_syntax)
    return DEC_Condition_CS;
  if (status == DEC_Division_by_zero)
    return DEC_Condition_DZ;
  if (status == DEC_Division_impossible)
    return DEC_Condition_DI;
  if (status == DEC_Division_undefined)
    return DEC_Condition_DU;
  if (status == DEC_Inexact)
    return DEC_Condition_IE;
  if (status == DEC_Insufficient_storage)
    return DEC_Condition_IS;
  if (status == DEC_Invalid_context)
    return DEC_Condition_IC;
  if (status == DEC_Invalid_operation)
    return DEC_Condition_IO;
#if DECSUBSET
  if (status == DEC_Lost_digits)
    return DEC_Condition_LD;
#endif
  if (status == DEC_Overflow)
    return DEC_Condition_OV;
  if (status == DEC_Clamped)
    return DEC_Condition_PA;
  if (status == DEC_Rounded)
    return DEC_Condition_RO;
  if (status == DEC_Subnormal)
    return DEC_Condition_SU;
  if (status == DEC_Underflow)
    return DEC_Condition_UN;
  if (status == 0)
    return DEC_Condition_ZE;
  return DEC_Condition_MU;	/* Multiple errors */
}				/* decContextStatusToString */

/* ------------------------------------------------------------------ */
/* decContextSetStatusFromString -- set status from a string          */
/*                                                                    */
/*  context is the controlling context                                */
/*  string is a string exactly equal to one that might be returned    */
/*            by decContextStatusToString                             */
/*                                                                    */
/*  The status bit corresponding to the string is set, and a trap     */
/*  is raised if appropriate.                                         */
/*                                                                    */
/*  returns the context structure, unless the string is equal to      */
/*    DEC_Condition_MU or is not recognized.  In these cases NULL is  */
/*    returned.                                                       */
/* ------------------------------------------------------------------ */
decContext *
decContextSetStatusFromString (decContext * context, const char *string)
{
  if (strcmp (string, DEC_Condition_CS) == 0)
    return decContextSetStatus (context, DEC_Conversion_syntax);
  if (strcmp (string, DEC_Condition_DZ) == 0)
    return decContextSetStatus (context, DEC_Division_by_zero);
  if (strcmp (string, DEC_Condition_DI) == 0)
    return decContextSetStatus (context, DEC_Division_impossible);
  if (strcmp (string, DEC_Condition_DU) == 0)
    return decContextSetStatus (context, DEC_Division_undefined);
  if (strcmp (string, DEC_Condition_IE) == 0)
    return decContextSetStatus (context, DEC_Inexact);
  if (strcmp (string, DEC_Condition_IS) == 0)
    return decContextSetStatus (context, DEC_Insufficient_storage);
  if (strcmp (string, DEC_Condition_IC) == 0)
    return decContextSetStatus (context, DEC_Invalid_context);
  if (strcmp (string, DEC_Condition_IO) == 0)
    return decContextSetStatus (context, DEC_Invalid_operation);
#if DECSUBSET
  if (strcmp (string, DEC_Condition_LD) == 0)
    return decContextSetStatus (context, DEC_Lost_digits);
#endif
  if (strcmp (string, DEC_Condition_OV) == 0)
    return decContextSetStatus (context, DEC_Overflow);
  if (strcmp (string, DEC_Condition_PA) == 0)
    return decContextSetStatus (context, DEC_Clamped);
  if (strcmp (string, DEC_Condition_RO) == 0)
    return decContextSetStatus (context, DEC_Rounded);
  if (strcmp (string, DEC_Condition_SU) == 0)
    return decContextSetStatus (context, DEC_Subnormal);
  if (strcmp (string, DEC_Condition_UN) == 0)
    return decContextSetStatus (context, DEC_Underflow);
  if (strcmp (string, DEC_Condition_ZE) == 0)
    return context;
  return NULL;			/* Multiple status, or unknown */
}				/* decContextSetStatusFromString */

/* ------------------------------------------------------------------ */
/* decContextSetStatus -- set status and raise trap if appropriate    */
/*                                                                    */
/*  context is the controlling context                                */
/*  status  is the DEC_ exception code                                */
/*  returns the context structure                                     */
/*                                                                    */
/* Control may never return from this routine, if there is a signal   */
/* handler and it takes a long jump.                                  */
/* ------------------------------------------------------------------ */
decContext *
decContextSetStatus (decContext * context, uInt status)
{
  context->status |= status;
  if (status & context->traps)
    raise (SIGFPE);
  return context;
}				/* decContextSetStatus */