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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.2.2/] [libdecnumber/] [decimal128.c] - Blame information for rev 280

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/* Decimal 128-bit format module from 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 decimal128 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 34        /* we need decNumbers with space for 34 */
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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 "decimal128.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 decimal128Show (const decimal128 *);       /* 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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/* decimal128FromNumber -- convert decNumber to decimal128            */
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/*                                                                    */
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/*   ds is the target decimal128                                      */
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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 DECIMAL128_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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decimal128 *
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decimal128FromNumber (decimal128 * d128, 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 > DECIMAL128_Pmax  /* too many digits */
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          || ae > DECIMAL128_Emax       /* likely overflow */
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          || ae < DECIMAL128_Emin)
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        {                       /* likely underflow */
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          decContextDefault (&dc, DEC_INIT_DECIMAL128); /* [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 decimal128] */
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    }
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  DEC_clear (d128);             /* 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 < DECIMAL128_Pmax))
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            {                   /* coefficient fits */
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              decDensePackCoeff (dn, d128->bytes, sizeof (d128->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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      d128->bytes[0] = top;
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    }
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  else if (decNumberIsZero (dn))
127
    {                           /* a zero */
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      /* set and clamp exponent */
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      if (dn->exponent < -DECIMAL128_Bias)
130
        {
131
          exp = 0;
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          status |= DEC_Clamped;
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        }
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      else
135
        {
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          exp = dn->exponent + DECIMAL128_Bias; /* bias exponent */
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          if (exp > DECIMAL128_Ehigh)
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            {                   /* top clamp */
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              exp = DECIMAL128_Ehigh;
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              status |= DEC_Clamped;
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            }
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        }
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      comb = (exp >> 9) & 0x18; /* combination field */
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      d128->bytes[0] = (uByte) (comb << 2);
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      exp &= 0xfff;             /* remaining exponent bits */
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      decimal128SetExpCon (d128, exp);
147
    }
148
  else
149
    {                           /* non-zero finite number */
150
      uInt msd;                 /* work */
151
 
152
      /* we have a dn that fits, but it may need to be padded */
153
      exp = (uInt) (dn->exponent + DECIMAL128_Bias);    /* bias exponent */
154
 
155
      if (exp > DECIMAL128_Ehigh)
156
        {                       /* fold-down case */
157
          pad = exp - DECIMAL128_Ehigh;
158
          exp = DECIMAL128_Ehigh;       /* [to maximum] */
159
          status |= DEC_Clamped;
160
        }
161
 
162
      decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), pad);
163
 
164
      /* save and clear the top digit */
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      msd = ((unsigned) d128->bytes[1] << 2) & 0x0c;    /* top 2 bits */
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      msd |= ((unsigned) d128->bytes[2] >> 6);  /* low 2 bits */
167
      d128->bytes[1] &= 0xfc;
168
      d128->bytes[2] &= 0x3f;
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170
      /* create the combination field */
171
      if (msd >= 8)
172
        comb = 0x18 | (msd & 0x01) | ((exp >> 11) & 0x06);
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      else
174
        comb = (msd & 0x07) | ((exp >> 9) & 0x18);
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      d128->bytes[0] = (uByte) (comb << 2);
176
      exp &= 0xfff;             /* remaining exponent bits */
177
      decimal128SetExpCon (d128, exp);
178
    }
179
 
180
  if (isneg)
181
    decimal128SetSign (d128, 1);
182
  if (status != 0)
183
    decContextSetStatus (set, status);  /* pass on status */
184
 
185
  /* decimal128Show(d128); */
186
  return d128;
187
}
188
 
189
/* ------------------------------------------------------------------ */
190
/* decimal128ToNumber -- convert decimal128 to decNumber              */
191
/*   d128 is the source decimal128                                    */
192
/*   dn is the target number, with appropriate space                  */
193
/* No error is possible.                                              */
194
/* ------------------------------------------------------------------ */
195
decNumber *
196
decimal128ToNumber (const decimal128 * d128, decNumber * dn)
197
{
198
  uInt msd;                     /* coefficient MSD */
199
  decimal128 wk;                /* working copy, if needed */
200
  uInt top = d128->bytes[0] & 0x7f;      /* top byte, less sign bit */
201
  decNumberZero (dn);           /* clean target */
202
  /* set the sign if negative */
203
  if (decimal128Sign (d128))
204
    dn->bits = DECNEG;
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206
  if (top >= 0x78)
207
    {                           /* is a special */
208
      if ((top & 0x7c) == (DECIMAL_Inf & 0x7c))
209
        dn->bits |= DECINF;
210
      else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e))
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        dn->bits |= DECNAN;
212
      else
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        dn->bits |= DECSNAN;
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      msd = 0;                   /* no top digit */
215
    }
216
  else
217
    {                           /* have a finite number */
218
      uInt comb = top >> 2;     /* combination field */
219
      uInt exp;                 /* exponent */
220
 
221
      if (comb >= 0x18)
222
        {
223
          msd = 8 + (comb & 0x01);
224
          exp = (comb & 0x06) << 11;    /* MSBs */
225
        }
226
      else
227
        {
228
          msd = comb & 0x07;
229
          exp = (comb & 0x18) << 9;
230
        }
231
      dn->exponent = exp + decimal128ExpCon (d128) - DECIMAL128_Bias;   /* remove bias */
232
    }
233
 
234
  /* get the coefficient, unless infinite */
235
  if (!(dn->bits & DECINF))
236
    {
237
      Int bunches = DECIMAL128_Pmax / 3;        /* coefficient full bunches to convert */
238
      Int odd = 0;               /* assume MSD is 0 (no odd bunch) */
239
      if (msd != 0)
240
        {                       /* coefficient has leading non-0 digit */
241
          /* make a copy of the decimal128, with an extra bunch which has */
242
          /* the top digit ready for conversion */
243
          wk = *d128;           /* take a copy */
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          wk.bytes[0] = 0;        /* clear all but coecon */
245
          wk.bytes[1] = 0;       /* .. */
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          wk.bytes[2] &= 0x3f;  /* .. */
247
          wk.bytes[1] |= (msd >> 2);    /* and prefix MSD */
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          wk.bytes[2] |= (msd << 6);    /* .. */
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          odd++;                /* indicate the extra */
250
          d128 = &wk;           /* use the work copy */
251
        }
252
      decDenseUnpackCoeff (d128->bytes, sizeof (d128->bytes), dn, bunches,
253
                           odd);
254
    }
255
 
256
  /* decNumberShow(dn); */
257
  return dn;
258
}
259
 
260
/* ------------------------------------------------------------------ */
261
/* to-scientific-string -- conversion to numeric string               */
262
/* to-engineering-string -- conversion to numeric string              */
263
/*                                                                    */
264
/*   decimal128ToString(d128, string);                                */
265
/*   decimal128ToEngString(d128, string);                             */
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/*                                                                    */
267
/*  d128 is the decimal128 format number to convert                   */
268
/*  string is the string where the result will be laid out            */
269
/*                                                                    */
270
/*  string must be at least 24 characters                             */
271
/*                                                                    */
272
/*  No error is possible, and no status can be set.                   */
273
/* ------------------------------------------------------------------ */
274
char *
275
decimal128ToString (const decimal128 * d128, char *string)
276
{
277
  decNumber dn;                 /* work */
278
  decimal128ToNumber (d128, &dn);
279
  decNumberToString (&dn, string);
280
  return string;
281
}
282
 
283
char *
284
decimal128ToEngString (const decimal128 * d128, char *string)
285
{
286
  decNumber dn;                 /* work */
287
  decimal128ToNumber (d128, &dn);
288
  decNumberToEngString (&dn, string);
289
  return string;
290
}
291
 
292
/* ------------------------------------------------------------------ */
293
/* to-number -- conversion from numeric string                        */
294
/*                                                                    */
295
/*   decimal128FromString(result, string, set);                       */
296
/*                                                                    */
297
/*  result  is the decimal128 format number which gets the result of  */
298
/*          the conversion                                            */
299
/*  *string is the character string which should contain a valid      */
300
/*          number (which may be a special value)                     */
301
/*  set     is the context                                            */
302
/*                                                                    */
303
/* The context is supplied to this routine is used for error handling */
304
/* (setting of status and traps) and for the rounding mode, only.     */
305
/* If an error occurs, the result will be a valid decimal128 NaN.     */
306
/* ------------------------------------------------------------------ */
307
decimal128 *
308
decimal128FromString (decimal128 * result, const char *string, decContext * set)
309
{
310
  decContext dc;                /* work */
311
  decNumber dn;                 /* .. */
312
 
313
  decContextDefault (&dc, DEC_INIT_DECIMAL128); /* no traps, please */
314
  dc.round = set->round;        /* use supplied rounding */
315
 
316
  decNumberFromString (&dn, string, &dc);       /* will round if needed */
317
  decimal128FromNumber (result, &dn, &dc);
318
  if (dc.status != 0)
319
    {                           /* something happened */
320
      decContextSetStatus (set, dc.status);     /* .. pass it on */
321
    }
322
  return result;
323
}
324
 
325
 
326
#if DECTRACE || DECCHECK
327
/* ------------------------------------------------------------------ */
328
/* decimal128Show -- display a single in hexadecimal [debug aid]      */
329
/*   d128 -- the number to show                                       */
330
/* ------------------------------------------------------------------ */
331
/* Also shows sign/cob/expconfields extracted */
332
void
333
decimal128Show (const decimal128 * d128)
334
{
335
  char buf[DECIMAL128_Bytes * 2 + 1];
336
  Int i, j;
337
  j = 0;
338
  for (i = 0; i < DECIMAL128_Bytes; i++)
339
    {
340
      sprintf (&buf[j], "%02x", d128->bytes[i]);
341
      j = j + 2;
342
    }
343
  printf (" D128> %s [S:%d Cb:%02x E:%d]\n", buf,
344
          decimal128Sign (d128), decimal128Comb (d128),
345
          decimal128ExpCon (d128));
346
}
347
#endif

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