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[/] [openrisc/] [trunk/] [gnu-old/] [gcc-4.2.2/] [libdecnumber/] [decimal64.c] - Blame information for rev 853

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/* Decimal 64-bit format module for the decNumber C Library
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   Copyright (C) 2005 Free Software Foundation, Inc.
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   Contributed by IBM Corporation.  Author Mike Cowlishaw.
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   This file is part of GCC.
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   GCC is free software; you can redistribute it and/or modify it under
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   the terms of the GNU General Public License as published by the Free
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   Software Foundation; either version 2, or (at your option) any later
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   version.
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   In addition to the permissions in the GNU General Public License,
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   the Free Software Foundation gives you unlimited permission to link
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   the compiled version of this file into combinations with other
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   programs, and to distribute those combinations without any
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   restriction coming from the use of this file.  (The General Public
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   License restrictions do apply in other respects; for example, they
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   cover modification of the file, and distribution when not linked
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   into a combine executable.)
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   GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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   WARRANTY; without even the implied warranty of MERCHANTABILITY or
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   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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   for more details.
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   You should have received a copy of the GNU General Public License
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   along with GCC; see the file COPYING.  If not, write to the Free
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   Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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   02110-1301, USA.  */
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31
/* ------------------------------------------------------------------ */
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/* This module comprises the routines for decimal64 format numbers.   */
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/* Conversions are supplied to and from decNumber and String.         */
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/*                                                                    */
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/* No arithmetic routines are included; decNumber provides these.     */
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/*                                                                    */
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/* Error handling is the same as decNumber (qv.).                     */
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/* ------------------------------------------------------------------ */
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#include <string.h>             /* [for memset/memcpy] */
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#include <stdio.h>              /* [for printf] */
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#define  DECNUMDIGITS 16        /* we need decNumbers with space for 16 */
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#include "config.h"
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#include "decNumber.h"          /* base number library */
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#include "decNumberLocal.h"     /* decNumber local types, etc. */
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#include "decimal64.h"          /* our primary include */
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#include "decUtility.h"         /* utility routines */
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#if DECTRACE || DECCHECK
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void decimal64Show (const decimal64 *); /* for debug */
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void decNumberShow (const decNumber *); /* .. */
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#endif
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/* Useful macro */
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/* Clear a structure (e.g., a decNumber) */
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#define DEC_clear(d) memset(d, 0, sizeof(*d))
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58
/* ------------------------------------------------------------------ */
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/* decimal64FromNumber -- convert decNumber to decimal64              */
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/*                                                                    */
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/*   ds is the target decimal64                                       */
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/*   dn is the source number (assumed valid)                          */
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/*   set is the context, used only for reporting errors               */
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/*                                                                    */
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/* The set argument is used only for status reporting and for the     */
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/* rounding mode (used if the coefficient is more than DECIMAL64_Pmax */
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/* digits or an overflow is detected).  If the exponent is out of the */
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/* valid range then Overflow or Underflow will be raised.             */
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/* After Underflow a subnormal result is possible.                    */
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/*                                                                    */
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/* DEC_Clamped is set if the number has to be 'folded down' to fit,   */
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/* by reducing its exponent and multiplying the coefficient by a      */
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/* power of ten, or if the exponent on a zero had to be clamped.      */
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/* ------------------------------------------------------------------ */
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decimal64 *
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decimal64FromNumber (decimal64 * d64, const decNumber * dn, decContext * set)
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{
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  uInt status = 0;               /* status accumulator */
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  Int pad = 0;                   /* coefficient pad digits */
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  decNumber dw;                 /* work */
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  decContext dc;                /* .. */
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  uByte isneg = dn->bits & DECNEG;      /* non-0 if original sign set */
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  uInt comb, exp;               /* work */
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  /* If the number is finite, and has too many digits, or the exponent */
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  /* could be out of range then we reduce the number under the */
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  /* appropriate constraints */
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  if (!(dn->bits & DECSPECIAL))
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    {                           /* not a special value */
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      Int ae = dn->exponent + dn->digits - 1;   /* adjusted exponent */
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      if (dn->digits > DECIMAL64_Pmax   /* too many digits */
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          || ae > DECIMAL64_Emax        /* likely overflow */
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          || ae < DECIMAL64_Emin)
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        {                       /* likely underflow */
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          decContextDefault (&dc, DEC_INIT_DECIMAL64);  /* [no traps] */
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          dc.round = set->round;        /* use supplied rounding */
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          decNumberPlus (&dw, dn, &dc); /* (round and check) */
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          /* [this changes -0 to 0, but it will be restored below] */
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          status |= dc.status;  /* save status */
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          dn = &dw;             /* use the work number */
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        }
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      /* [this could have pushed number to Infinity or zero, so this */
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      /* rounding must be done before we generate the decimal64] */
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    }
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  DEC_clear (d64);              /* clean the target */
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  if (dn->bits & DECSPECIAL)
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    {                           /* a special value */
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      uByte top;                /* work */
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      if (dn->bits & DECINF)
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        top = DECIMAL_Inf;
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      else
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        {                       /* sNaN or qNaN */
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          if ((*dn->lsu != 0 || dn->digits > 1)  /* non-zero coefficient */
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              && (dn->digits < DECIMAL64_Pmax))
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            {                   /* coefficient fits */
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              decDensePackCoeff (dn, d64->bytes, sizeof (d64->bytes), 0);
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            }
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          if (dn->bits & DECNAN)
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            top = DECIMAL_NaN;
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          else
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            top = DECIMAL_sNaN;
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        }
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      d64->bytes[0] = top;
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    }
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  else if (decNumberIsZero (dn))
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    {                           /* a zero */
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      /* set and clamp exponent */
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      if (dn->exponent < -DECIMAL64_Bias)
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        {
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          exp = 0;
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          status |= DEC_Clamped;
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        }
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      else
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        {
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          exp = dn->exponent + DECIMAL64_Bias;  /* bias exponent */
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          if (exp > DECIMAL64_Ehigh)
138
            {                   /* top clamp */
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              exp = DECIMAL64_Ehigh;
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              status |= DEC_Clamped;
141
            }
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        }
143
      comb = (exp >> 5) & 0x18; /* combination field */
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      d64->bytes[0] = (uByte) (comb << 2);
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      exp &= 0xff;              /* remaining exponent bits */
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      decimal64SetExpCon (d64, exp);
147
    }
148
  else
149
    {                           /* non-zero finite number */
150
      uInt msd;                 /* work */
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152
      /* we have a dn that fits, but it may need to be padded */
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      exp = (uInt) (dn->exponent + DECIMAL64_Bias);     /* bias exponent */
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      if (exp > DECIMAL64_Ehigh)
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        {                       /* fold-down case */
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          pad = exp - DECIMAL64_Ehigh;
157
          exp = DECIMAL64_Ehigh;        /* [to maximum] */
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          status |= DEC_Clamped;
159
        }
160
 
161
      decDensePackCoeff (dn, d64->bytes, sizeof (d64->bytes), pad);
162
 
163
      /* save and clear the top digit */
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      msd = ((unsigned) d64->bytes[1] >> 2) & 0x0f;
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      d64->bytes[1] &= 0x03;
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      /* create the combination field */
167
      if (msd >= 8)
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        comb = 0x18 | (msd & 0x01) | ((exp >> 7) & 0x06);
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      else
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        comb = (msd & 0x07) | ((exp >> 5) & 0x18);
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      d64->bytes[0] = (uByte) (comb << 2);
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      exp &= 0xff;              /* remaining exponent bits */
173
      decimal64SetExpCon (d64, exp);
174
    }
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176
  if (isneg)
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    decimal64SetSign (d64, 1);
178
  if (status != 0)
179
    decContextSetStatus (set, status);  /* pass on status */
180
 
181
  /*decimal64Show(d64); */
182
  return d64;
183
}
184
 
185
/* ------------------------------------------------------------------ */
186
/* decimal64ToNumber -- convert decimal64 to decNumber                */
187
/*   d64 is the source decimal64                                      */
188
/*   dn is the target number, with appropriate space                  */
189
/* No error is possible.                                              */
190
/* ------------------------------------------------------------------ */
191
decNumber *
192
decimal64ToNumber (const decimal64 * d64, decNumber * dn)
193
{
194
  uInt msd;                     /* coefficient MSD */
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  decimal64 wk;                 /* working copy, if needed */
196
  uInt top = d64->bytes[0] & 0x7f;       /* top byte, less sign bit */
197
  decNumberZero (dn);           /* clean target */
198
  /* set the sign if negative */
199
  if (decimal64Sign (d64))
200
    dn->bits = DECNEG;
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202
  if (top >= 0x78)
203
    {                           /* is a special */
204
      if ((top & 0x7c) == (DECIMAL_Inf & 0x7c))
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        dn->bits |= DECINF;
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      else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e))
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        dn->bits |= DECNAN;
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      else
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        dn->bits |= DECSNAN;
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      msd = 0;                   /* no top digit */
211
    }
212
  else
213
    {                           /* have a finite number */
214
      uInt comb = top >> 2;     /* combination field */
215
      uInt exp;                 /* exponent */
216
 
217
      if (comb >= 0x18)
218
        {
219
          msd = 8 + (comb & 0x01);
220
          exp = (comb & 0x06) << 7;     /* MSBs */
221
        }
222
      else
223
        {
224
          msd = comb & 0x07;
225
          exp = (comb & 0x18) << 5;
226
        }
227
      dn->exponent = exp + decimal64ExpCon (d64) - DECIMAL64_Bias;      /* remove bias */
228
    }
229
 
230
  /* get the coefficient, unless infinite */
231
  if (!(dn->bits & DECINF))
232
    {
233
      Int bunches = DECIMAL64_Pmax / 3; /* coefficient full bunches to convert */
234
      Int odd = 0;               /* assume MSD is 0 (no odd bunch) */
235
      if (msd != 0)
236
        {                       /* coefficient has leading non-0 digit */
237
          /* make a copy of the decimal64, with an extra bunch which has */
238
          /* the top digit ready for conversion */
239
          wk = *d64;            /* take a copy */
240
          wk.bytes[0] = 0;        /* clear all but coecon */
241
          wk.bytes[1] &= 0x03;  /* .. */
242
          wk.bytes[1] |= (msd << 2);    /* and prefix MSD */
243
          odd++;                /* indicate the extra */
244
          d64 = &wk;            /* use the work copy */
245
        }
246
      decDenseUnpackCoeff (d64->bytes, sizeof (d64->bytes), dn, bunches, odd);
247
    }
248
  return dn;
249
}
250
 
251
/* ------------------------------------------------------------------ */
252
/* to-scientific-string -- conversion to numeric string               */
253
/* to-engineering-string -- conversion to numeric string              */
254
/*                                                                    */
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/*   decimal64ToString(d64, string);                                  */
256
/*   decimal64ToEngString(d64, string);                               */
257
/*                                                                    */
258
/*  d64 is the decimal64 format number to convert                     */
259
/*  string is the string where the result will be laid out            */
260
/*                                                                    */
261
/*  string must be at least 24 characters                             */
262
/*                                                                    */
263
/*  No error is possible, and no status can be set.                   */
264
/* ------------------------------------------------------------------ */
265
char *
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decimal64ToString (const decimal64 * d64, char *string)
267
{
268
  decNumber dn;                 /* work */
269
  decimal64ToNumber (d64, &dn);
270
  decNumberToString (&dn, string);
271
  return string;
272
}
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274
char *
275
decimal64ToEngString (const decimal64 * d64, char *string)
276
{
277
  decNumber dn;                 /* work */
278
  decimal64ToNumber (d64, &dn);
279
  decNumberToEngString (&dn, string);
280
  return string;
281
}
282
 
283
/* ------------------------------------------------------------------ */
284
/* to-number -- conversion from numeric string                        */
285
/*                                                                    */
286
/*   decimal64FromString(result, string, set);                        */
287
/*                                                                    */
288
/*  result  is the decimal64 format number which gets the result of   */
289
/*          the conversion                                            */
290
/*  *string is the character string which should contain a valid      */
291
/*          number (which may be a special value)                     */
292
/*  set     is the context                                            */
293
/*                                                                    */
294
/* The context is supplied to this routine is used for error handling */
295
/* (setting of status and traps) and for the rounding mode, only.     */
296
/* If an error occurs, the result will be a valid decimal64 NaN.      */
297
/* ------------------------------------------------------------------ */
298
decimal64 *
299
decimal64FromString (decimal64 * result, const char *string, decContext * set)
300
{
301
  decContext dc;                /* work */
302
  decNumber dn;                 /* .. */
303
 
304
  decContextDefault (&dc, DEC_INIT_DECIMAL64);  /* no traps, please */
305
  dc.round = set->round;        /* use supplied rounding */
306
 
307
  decNumberFromString (&dn, string, &dc);       /* will round if needed */
308
 
309
  decimal64FromNumber (result, &dn, &dc);
310
  if (dc.status != 0)
311
    {                           /* something happened */
312
      decContextSetStatus (set, dc.status);     /* .. pass it on */
313
    }
314
  return result;
315
}
316
 
317
#if DECTRACE || DECCHECK
318
/* ------------------------------------------------------------------ */
319
/* decimal64Show -- display a single in hexadecimal [debug aid]       */
320
/*   d64 -- the number to show                                        */
321
/* ------------------------------------------------------------------ */
322
/* Also shows sign/cob/expconfields extracted */
323
void
324
decimal64Show (const decimal64 * d64)
325
{
326
  char buf[DECIMAL64_Bytes * 2 + 1];
327
  Int i, j;
328
  j = 0;
329
  for (i = 0; i < DECIMAL64_Bytes; i++)
330
    {
331
      sprintf (&buf[j], "%02x", d64->bytes[i]);
332
      j = j + 2;
333
    }
334
  printf (" D64> %s [S:%d Cb:%02x E:%d]\n", buf,
335
          decimal64Sign (d64), decimal64Comb (d64), decimal64ExpCon (d64));
336
}
337
#endif

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