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[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [libdecnumber/] [dpd/] [decimal32.c] - Blame information for rev 826

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1 271 jeremybenn
/* Decimal 32-bit format module for the decNumber C Library.
2
   Copyright (C) 2005, 2007, 2009 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 3, or (at your option) any later
10
   version.
11
 
12
   GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13
   WARRANTY; without even the implied warranty of MERCHANTABILITY or
14
   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15
   for more details.
16
 
17
Under Section 7 of GPL version 3, you are granted additional
18
permissions described in the GCC Runtime Library Exception, version
19
3.1, as published by the Free Software Foundation.
20
 
21
You should have received a copy of the GNU General Public License and
22
a copy of the GCC Runtime Library Exception along with this program;
23
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24
<http://www.gnu.org/licenses/>.  */
25
 
26
/* ------------------------------------------------------------------ */
27
/* Decimal 32-bit format module                                       */
28
/* ------------------------------------------------------------------ */
29
/* This module comprises the routines for decimal32 format numbers.   */
30
/* Conversions are supplied to and from decNumber and String.         */
31
/*                                                                    */
32
/* This is used when decNumber provides operations, either for all    */
33
/* operations or as a proxy between decNumber and decSingle.          */
34
/*                                                                    */
35
/* Error handling is the same as decNumber (qv.).                     */
36
/* ------------------------------------------------------------------ */
37
#include <string.h>           /* [for memset/memcpy] */
38
#include <stdio.h>            /* [for printf] */
39
 
40
#include "dconfig.h"          /* GCC definitions */
41
#define  DECNUMDIGITS  7      /* make decNumbers with space for 7 */
42
#include "decNumber.h"        /* base number library */
43
#include "decNumberLocal.h"   /* decNumber local types, etc. */
44
#include "decimal32.h"        /* our primary include */
45
 
46
/* Utility tables and routines [in decimal64.c] */
47
extern const uInt   COMBEXP[32], COMBMSD[32];
48
extern const uShort DPD2BIN[1024];
49
extern const uShort BIN2DPD[1000];
50
extern const uByte  BIN2CHAR[4001];
51
 
52
extern void decDigitsToDPD(const decNumber *, uInt *, Int);
53
extern void decDigitsFromDPD(decNumber *, const uInt *, Int);
54
 
55
#if DECTRACE || DECCHECK
56
void decimal32Show(const decimal32 *);            /* for debug */
57
extern void decNumberShow(const decNumber *);     /* .. */
58
#endif
59
 
60
/* Useful macro */
61
/* Clear a structure (e.g., a decNumber) */
62
#define DEC_clear(d) memset(d, 0, sizeof(*d))
63
 
64
/* ------------------------------------------------------------------ */
65
/* decimal32FromNumber -- convert decNumber to decimal32              */
66
/*                                                                    */
67
/*   ds is the target decimal32                                       */
68
/*   dn is the source number (assumed valid)                          */
69
/*   set is the context, used only for reporting errors               */
70
/*                                                                    */
71
/* The set argument is used only for status reporting and for the     */
72
/* rounding mode (used if the coefficient is more than DECIMAL32_Pmax */
73
/* digits or an overflow is detected).  If the exponent is out of the */
74
/* valid range then Overflow or Underflow will be raised.             */
75
/* After Underflow a subnormal result is possible.                    */
76
/*                                                                    */
77
/* DEC_Clamped is set if the number has to be 'folded down' to fit,   */
78
/* by reducing its exponent and multiplying the coefficient by a      */
79
/* power of ten, or if the exponent on a zero had to be clamped.      */
80
/* ------------------------------------------------------------------ */
81
decimal32 * decimal32FromNumber(decimal32 *d32, const decNumber *dn,
82
                              decContext *set) {
83
  uInt status=0;            /* status accumulator */
84
  Int ae;                          /* adjusted exponent */
85
  decNumber  dw;                   /* work */
86
  decContext dc;                   /* .. */
87
  uInt comb, exp;                  /* .. */
88
  uInt uiwork;                     /* for macros */
89
  uInt targ=0;                      /* target 32-bit */
90
 
91
  /* If the number has too many digits, or the exponent could be */
92
  /* out of range then reduce the number under the appropriate */
93
  /* constraints.  This could push the number to Infinity or zero, */
94
  /* so this check and rounding must be done before generating the */
95
  /* decimal32] */
96
  ae=dn->exponent+dn->digits-1;              /* [0 if special] */
97
  if (dn->digits>DECIMAL32_Pmax              /* too many digits */
98
   || ae>DECIMAL32_Emax                      /* likely overflow */
99
   || ae<DECIMAL32_Emin) {                   /* likely underflow */
100
    decContextDefault(&dc, DEC_INIT_DECIMAL32); /* [no traps] */
101
    dc.round=set->round;                     /* use supplied rounding */
102
    decNumberPlus(&dw, dn, &dc);             /* (round and check) */
103
    /* [this changes -0 to 0, so enforce the sign...] */
104
    dw.bits|=dn->bits&DECNEG;
105
    status=dc.status;                        /* save status */
106
    dn=&dw;                                  /* use the work number */
107
    } /* maybe out of range */
108
 
109
  if (dn->bits&DECSPECIAL) {                      /* a special value */
110
    if (dn->bits&DECINF) targ=DECIMAL_Inf<<24;
111
     else {                                       /* sNaN or qNaN */
112
      if ((*dn->lsu!=0 || dn->digits>1)    /* non-zero coefficient */
113
       && (dn->digits<DECIMAL32_Pmax)) {          /* coefficient fits */
114
        decDigitsToDPD(dn, &targ, 0);
115
        }
116
      if (dn->bits&DECNAN) targ|=DECIMAL_NaN<<24;
117
       else targ|=DECIMAL_sNaN<<24;
118
      } /* a NaN */
119
    } /* special */
120
 
121
   else { /* is finite */
122
    if (decNumberIsZero(dn)) {               /* is a zero */
123
      /* set and clamp exponent */
124
      if (dn->exponent<-DECIMAL32_Bias) {
125
        exp=0;                                /* low clamp */
126
        status|=DEC_Clamped;
127
        }
128
       else {
129
        exp=dn->exponent+DECIMAL32_Bias;     /* bias exponent */
130
        if (exp>DECIMAL32_Ehigh) {           /* top clamp */
131
          exp=DECIMAL32_Ehigh;
132
          status|=DEC_Clamped;
133
          }
134
        }
135
      comb=(exp>>3) & 0x18;             /* msd=0, exp top 2 bits .. */
136
      }
137
     else {                             /* non-zero finite number */
138
      uInt msd;                         /* work */
139
      Int pad=0;                 /* coefficient pad digits */
140
 
141
      /* the dn is known to fit, but it may need to be padded */
142
      exp=(uInt)(dn->exponent+DECIMAL32_Bias);    /* bias exponent */
143
      if (exp>DECIMAL32_Ehigh) {                  /* fold-down case */
144
        pad=exp-DECIMAL32_Ehigh;
145
        exp=DECIMAL32_Ehigh;                      /* [to maximum] */
146
        status|=DEC_Clamped;
147
        }
148
 
149
      /* fastpath common case */
150
      if (DECDPUN==3 && pad==0) {
151
        targ=BIN2DPD[dn->lsu[0]];
152
        if (dn->digits>3) targ|=(uInt)(BIN2DPD[dn->lsu[1]])<<10;
153
        msd=(dn->digits==7 ? dn->lsu[2] : 0);
154
        }
155
       else { /* general case */
156
        decDigitsToDPD(dn, &targ, pad);
157
        /* save and clear the top digit */
158
        msd=targ>>20;
159
        targ&=0x000fffff;
160
        }
161
 
162
      /* create the combination field */
163
      if (msd>=8) comb=0x18 | ((exp>>5) & 0x06) | (msd & 0x01);
164
             else comb=((exp>>3) & 0x18) | msd;
165
      }
166
    targ|=comb<<26;                /* add combination field .. */
167
    targ|=(exp&0x3f)<<20;          /* .. and exponent continuation */
168
    } /* finite */
169
 
170
  if (dn->bits&DECNEG) targ|=0x80000000;  /* add sign bit */
171
 
172
  /* now write to storage; this is endian */
173
  UBFROMUI(d32->bytes, targ);      /* directly store the int */
174
 
175
  if (status!=0) decContextSetStatus(set, status); /* pass on status */
176
  /* decimal32Show(d32); */
177
  return d32;
178
  } /* decimal32FromNumber */
179
 
180
/* ------------------------------------------------------------------ */
181
/* decimal32ToNumber -- convert decimal32 to decNumber                */
182
/*   d32 is the source decimal32                                      */
183
/*   dn is the target number, with appropriate space                  */
184
/* No error is possible.                                              */
185
/* ------------------------------------------------------------------ */
186
decNumber * decimal32ToNumber(const decimal32 *d32, decNumber *dn) {
187
  uInt msd;                        /* coefficient MSD */
188
  uInt exp;                        /* exponent top two bits */
189
  uInt comb;                       /* combination field */
190
  uInt sour;                       /* source 32-bit */
191
  uInt uiwork;                     /* for macros */
192
 
193
  /* load source from storage; this is endian */
194
  sour=UBTOUI(d32->bytes);         /* directly load the int */
195
 
196
  comb=(sour>>26)&0x1f;            /* combination field */
197
 
198
  decNumberZero(dn);               /* clean number */
199
  if (sour&0x80000000) dn->bits=DECNEG; /* set sign if negative */
200
 
201
  msd=COMBMSD[comb];               /* decode the combination field */
202
  exp=COMBEXP[comb];               /* .. */
203
 
204
  if (exp==3) {                    /* is a special */
205
    if (msd==0) {
206
      dn->bits|=DECINF;
207
      return dn;                   /* no coefficient needed */
208
      }
209
    else if (sour&0x02000000) dn->bits|=DECSNAN;
210
    else dn->bits|=DECNAN;
211
    msd=0;                          /* no top digit */
212
    }
213
   else {                          /* is a finite number */
214
    dn->exponent=(exp<<6)+((sour>>20)&0x3f)-DECIMAL32_Bias; /* unbiased */
215
    }
216
 
217
  /* get the coefficient */
218
  sour&=0x000fffff;                /* clean coefficient continuation */
219
  if (msd) {                       /* non-zero msd */
220
    sour|=msd<<20;                 /* prefix to coefficient */
221
    decDigitsFromDPD(dn, &sour, 3); /* process 3 declets */
222
    return dn;
223
    }
224
  /* msd=0 */
225
  if (!sour) return dn;            /* easy: coefficient is 0 */
226
  if (sour&0x000ffc00)             /* need 2 declets? */
227
    decDigitsFromDPD(dn, &sour, 2); /* process 2 declets */
228
   else
229
    decDigitsFromDPD(dn, &sour, 1); /* process 1 declet */
230
  return dn;
231
  } /* decimal32ToNumber */
232
 
233
/* ------------------------------------------------------------------ */
234
/* to-scientific-string -- conversion to numeric string               */
235
/* to-engineering-string -- conversion to numeric string              */
236
/*                                                                    */
237
/*   decimal32ToString(d32, string);                                  */
238
/*   decimal32ToEngString(d32, string);                               */
239
/*                                                                    */
240
/*  d32 is the decimal32 format number to convert                     */
241
/*  string is the string where the result will be laid out            */
242
/*                                                                    */
243
/*  string must be at least 24 characters                             */
244
/*                                                                    */
245
/*  No error is possible, and no status can be set.                   */
246
/* ------------------------------------------------------------------ */
247
char * decimal32ToEngString(const decimal32 *d32, char *string){
248
  decNumber dn;                         /* work */
249
  decimal32ToNumber(d32, &dn);
250
  decNumberToEngString(&dn, string);
251
  return string;
252
  } /* decimal32ToEngString */
253
 
254
char * decimal32ToString(const decimal32 *d32, char *string){
255
  uInt msd;                        /* coefficient MSD */
256
  Int  exp;                        /* exponent top two bits or full */
257
  uInt comb;                       /* combination field */
258
  char *cstart;                    /* coefficient start */
259
  char *c;                         /* output pointer in string */
260
  const uByte *u;                  /* work */
261
  char *s, *t;                     /* .. (source, target) */
262
  Int  dpd;                        /* .. */
263
  Int  pre, e;                     /* .. */
264
  uInt uiwork;                     /* for macros */
265
  uInt sour;                       /* source 32-bit */
266
 
267
  /* load source from storage; this is endian */
268
  sour=UBTOUI(d32->bytes);         /* directly load the int */
269
 
270
  c=string;                        /* where result will go */
271
  if (((Int)sour)<0) *c++='-';      /* handle sign */
272
 
273
  comb=(sour>>26)&0x1f;            /* combination field */
274
  msd=COMBMSD[comb];               /* decode the combination field */
275
  exp=COMBEXP[comb];               /* .. */
276
 
277
  if (exp==3) {
278
    if (msd==0) {                   /* infinity */
279
      strcpy(c,   "Inf");
280
      strcpy(c+3, "inity");
281
      return string;               /* easy */
282
      }
283
    if (sour&0x02000000) *c++='s'; /* sNaN */
284
    strcpy(c, "NaN");              /* complete word */
285
    c+=3;                          /* step past */
286
    if ((sour&0x000fffff)==0) return string; /* zero payload */
287
    /* otherwise drop through to add integer; set correct exp */
288
    exp=0; msd=0;            /* setup for following code */
289
    }
290
   else exp=(exp<<6)+((sour>>20)&0x3f)-DECIMAL32_Bias; /* unbiased */
291
 
292
  /* convert 7 digits of significand to characters */
293
  cstart=c;                        /* save start of coefficient */
294
  if (msd) *c++='0'+(char)msd;     /* non-zero most significant digit */
295
 
296
  /* Now decode the declets.  After extracting each one, it is */
297
  /* decoded to binary and then to a 4-char sequence by table lookup; */
298
  /* the 4-chars are a 1-char length (significant digits, except 000 */
299
  /* has length 0).  This allows us to left-align the first declet */
300
  /* with non-zero content, then remaining ones are full 3-char */
301
  /* length.  We use fixed-length memcpys because variable-length */
302
  /* causes a subroutine call in GCC.  (These are length 4 for speed */
303
  /* and are safe because the array has an extra terminator byte.) */
304
  #define dpd2char u=&BIN2CHAR[DPD2BIN[dpd]*4];                   \
305
                   if (c!=cstart) {memcpy(c, u+1, 4); c+=3;}      \
306
                    else if (*u)  {memcpy(c, u+4-*u, 4); c+=*u;}
307
 
308
  dpd=(sour>>10)&0x3ff;            /* declet 1 */
309
  dpd2char;
310
  dpd=(sour)&0x3ff;                /* declet 2 */
311
  dpd2char;
312
 
313
  if (c==cstart) *c++='0';         /* all zeros -- make 0 */
314
 
315
  if (exp==0) {             /* integer or NaN case -- easy */
316
    *c='\0';                       /* terminate */
317
    return string;
318
    }
319
 
320
  /* non-0 exponent */
321
  e=0;                              /* assume no E */
322
  pre=c-cstart+exp;
323
  /* [here, pre-exp is the digits count (==1 for zero)] */
324
  if (exp>0 || pre<-5) {    /* need exponential form */
325
    e=pre-1;                       /* calculate E value */
326
    pre=1;                         /* assume one digit before '.' */
327
    } /* exponential form */
328
 
329
  /* modify the coefficient, adding 0s, '.', and E+nn as needed */
330
  s=c-1;                           /* source (LSD) */
331
  if (pre>0) {                      /* ddd.ddd (plain), perhaps with E */
332
    char *dotat=cstart+pre;
333
    if (dotat<c) {                 /* if embedded dot needed... */
334
      t=c;                              /* target */
335
      for (; s>=dotat; s--, t--) *t=*s; /* open the gap; leave t at gap */
336
      *t='.';                           /* insert the dot */
337
      c++;                              /* length increased by one */
338
      }
339
 
340
    /* finally add the E-part, if needed; it will never be 0, and has */
341
    /* a maximum length of 3 digits (E-101 case) */
342
    if (e!=0) {
343
      *c++='E';                    /* starts with E */
344
      *c++='+';                    /* assume positive */
345
      if (e<0) {
346
        *(c-1)='-';                /* oops, need '-' */
347
        e=-e;                      /* uInt, please */
348
        }
349
      u=&BIN2CHAR[e*4];            /* -> length byte */
350
      memcpy(c, u+4-*u, 4);        /* copy fixed 4 characters [is safe] */
351
      c+=*u;                       /* bump pointer appropriately */
352
      }
353
    *c='\0';                       /* add terminator */
354
    /*printf("res %s\n", string); */
355
    return string;
356
    } /* pre>0 */
357
 
358
  /* -5<=pre<=0: here for plain 0.ddd or 0.000ddd forms (can never have E) */
359
  t=c+1-pre;
360
  *(t+1)='\0';                          /* can add terminator now */
361
  for (; s>=cstart; s--, t--) *t=*s;    /* shift whole coefficient right */
362
  c=cstart;
363
  *c++='0';                             /* always starts with 0. */
364
  *c++='.';
365
  for (; pre<0; pre++) *c++='0'; /* add any 0's after '.' */
366
  /*printf("res %s\n", string); */
367
  return string;
368
  } /* decimal32ToString */
369
 
370
/* ------------------------------------------------------------------ */
371
/* to-number -- conversion from numeric string                        */
372
/*                                                                    */
373
/*   decimal32FromString(result, string, set);                        */
374
/*                                                                    */
375
/*  result  is the decimal32 format number which gets the result of   */
376
/*          the conversion                                            */
377
/*  *string is the character string which should contain a valid      */
378
/*          number (which may be a special value)                     */
379
/*  set     is the context                                            */
380
/*                                                                    */
381
/* The context is supplied to this routine is used for error handling */
382
/* (setting of status and traps) and for the rounding mode, only.     */
383
/* If an error occurs, the result will be a valid decimal32 NaN.      */
384
/* ------------------------------------------------------------------ */
385
decimal32 * decimal32FromString(decimal32 *result, const char *string,
386
                                decContext *set) {
387
  decContext dc;                             /* work */
388
  decNumber dn;                              /* .. */
389
 
390
  decContextDefault(&dc, DEC_INIT_DECIMAL32); /* no traps, please */
391
  dc.round=set->round;                        /* use supplied rounding */
392
 
393
  decNumberFromString(&dn, string, &dc);     /* will round if needed */
394
  decimal32FromNumber(result, &dn, &dc);
395
  if (dc.status!=0) {                         /* something happened */
396
    decContextSetStatus(set, dc.status);     /* .. pass it on */
397
    }
398
  return result;
399
  } /* decimal32FromString */
400
 
401
/* ------------------------------------------------------------------ */
402
/* decimal32IsCanonical -- test whether encoding is canonical         */
403
/*   d32 is the source decimal32                                      */
404
/*   returns 1 if the encoding of d32 is canonical, 0 otherwise       */
405
/* No error is possible.                                              */
406
/* ------------------------------------------------------------------ */
407
uInt decimal32IsCanonical(const decimal32 *d32) {
408
  decNumber dn;                         /* work */
409
  decimal32 canon;                      /* .. */
410
  decContext dc;                        /* .. */
411
  decContextDefault(&dc, DEC_INIT_DECIMAL32);
412
  decimal32ToNumber(d32, &dn);
413
  decimal32FromNumber(&canon, &dn, &dc);/* canon will now be canonical */
414
  return memcmp(d32, &canon, DECIMAL32_Bytes)==0;
415
  } /* decimal32IsCanonical */
416
 
417
/* ------------------------------------------------------------------ */
418
/* decimal32Canonical -- copy an encoding, ensuring it is canonical   */
419
/*   d32 is the source decimal32                                      */
420
/*   result is the target (may be the same decimal32)                 */
421
/*   returns result                                                   */
422
/* No error is possible.                                              */
423
/* ------------------------------------------------------------------ */
424
decimal32 * decimal32Canonical(decimal32 *result, const decimal32 *d32) {
425
  decNumber dn;                         /* work */
426
  decContext dc;                        /* .. */
427
  decContextDefault(&dc, DEC_INIT_DECIMAL32);
428
  decimal32ToNumber(d32, &dn);
429
  decimal32FromNumber(result, &dn, &dc);/* result will now be canonical */
430
  return result;
431
  } /* decimal32Canonical */
432
 
433
#if DECTRACE || DECCHECK
434
/* Macros for accessing decimal32 fields.  These assume the argument
435
   is a reference (pointer) to the decimal32 structure, and the
436
   decimal32 is in network byte order (big-endian) */
437
/* Get sign */
438
#define decimal32Sign(d)       ((unsigned)(d)->bytes[0]>>7)
439
 
440
/* Get combination field */
441
#define decimal32Comb(d)       (((d)->bytes[0] & 0x7c)>>2)
442
 
443
/* Get exponent continuation [does not remove bias] */
444
#define decimal32ExpCon(d)     ((((d)->bytes[0] & 0x03)<<4)           \
445
                             | ((unsigned)(d)->bytes[1]>>4))
446
 
447
/* Set sign [this assumes sign previously 0] */
448
#define decimal32SetSign(d, b) {                                      \
449
  (d)->bytes[0]|=((unsigned)(b)<<7);}
450
 
451
/* Set exponent continuation [does not apply bias] */
452
/* This assumes range has been checked and exponent previously 0; */
453
/* type of exponent must be unsigned */
454
#define decimal32SetExpCon(d, e) {                                    \
455
  (d)->bytes[0]|=(uByte)((e)>>4);                                      \
456
  (d)->bytes[1]|=(uByte)(((e)&0x0F)<<4);}
457
 
458
/* ------------------------------------------------------------------ */
459
/* decimal32Show -- display a decimal32 in hexadecimal [debug aid]    */
460
/*   d32 -- the number to show                                        */
461
/* ------------------------------------------------------------------ */
462
/* Also shows sign/cob/expconfields extracted - valid bigendian only */
463
void decimal32Show(const decimal32 *d32) {
464
  char buf[DECIMAL32_Bytes*2+1];
465
  Int i, j=0;
466
 
467
  if (DECLITEND) {
468
    for (i=0; i<DECIMAL32_Bytes; i++, j+=2) {
469
      sprintf(&buf[j], "%02x", d32->bytes[3-i]);
470
      }
471
    printf(" D32> %s [S:%d Cb:%02x Ec:%02x] LittleEndian\n", buf,
472
           d32->bytes[3]>>7, (d32->bytes[3]>>2)&0x1f,
473
           ((d32->bytes[3]&0x3)<<4)| (d32->bytes[2]>>4));
474
    }
475
   else {
476
    for (i=0; i<DECIMAL32_Bytes; i++, j+=2) {
477
      sprintf(&buf[j], "%02x", d32->bytes[i]);
478
      }
479
    printf(" D32> %s [S:%d Cb:%02x Ec:%02x] BigEndian\n", buf,
480
           decimal32Sign(d32), decimal32Comb(d32), decimal32ExpCon(d32));
481
    }
482
  } /* decimal32Show */
483
#endif

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