contrib/gcc-4.4/libdecnumber/dpd/decimal32.c

   1 /* 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 *pu;                        /* .. */
  88   uInt comb, exp;                  /* .. */
  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   pu=(uInt *)d32->bytes;           /* overlay */
 174   *pu=targ;                        /* directly store the int */
 175
 176   if (status!=0) decContextSetStatus(set, status); /* pass on status */
 177   /* decimal32Show(d32); */
 178   return d32;
 179   } /* decimal32FromNumber */
 180
 181 /* ------------------------------------------------------------------ */
 182 /* decimal32ToNumber -- convert decimal32 to decNumber                */
 183 /*   d32 is the source decimal32                                      */
 184 /*   dn is the target number, with appropriate space                  */
 185 /* No error is possible.                                              */
 186 /* ------------------------------------------------------------------ */
 187 decNumber * decimal32ToNumber(const decimal32 *d32, decNumber *dn) {
 188   uInt msd;                        /* coefficient MSD */
 189   uInt exp;                        /* exponent top two bits */
 190   uInt comb;                       /* combination field */
 191   uInt sour;                       /* source 32-bit */
 192   const uInt *pu;                  /* work */
 193
 194   /* load source from storage; this is endian */
 195   pu=(const uInt *)d32->bytes;     /* overlay */
 196   sour=*pu;                        /* directly load the int */
 197
 198   comb=(sour>>26)&0x1f;            /* combination field */
 199
 200   decNumberZero(dn);               /* clean number */
 201   if (sour&0x80000000) dn->bits=DECNEG; /* set sign if negative */
 202
 203   msd=COMBMSD[comb];               /* decode the combination field */
 204   exp=COMBEXP[comb];               /* .. */
 205
 206   if (exp==3) {                    /* is a special */
 207     if (msd==0) {
 208       dn->bits|=DECINF;
 209       return dn;                   /* no coefficient needed */
 210       }
 211     else if (sour&0x02000000) dn->bits|=DECSNAN;
 212     else dn->bits|=DECNAN;
 213     msd=0;                         /* no top digit */
 214     }
 215    else {                          /* is a finite number */
 216     dn->exponent=(exp<<6)+((sour>>20)&0x3f)-DECIMAL32_Bias; /* unbiased */
 217     }
 218
 219   /* get the coefficient */
 220   sour&=0x000fffff;                /* clean coefficient continuation */
 221   if (msd) {                       /* non-zero msd */
 222     sour|=msd<<20;                 /* prefix to coefficient */
 223     decDigitsFromDPD(dn, &sour, 3); /* process 3 declets */
 224     return dn;
 225     }
 226   /* msd=0 */
 227   if (!sour) return dn;            /* easy: coefficient is 0 */
 228   if (sour&0x000ffc00)             /* need 2 declets? */
 229     decDigitsFromDPD(dn, &sour, 2); /* process 2 declets */
 230    else
 231     decDigitsFromDPD(dn, &sour, 1); /* process 1 declet */
 232   return dn;
 233   } /* decimal32ToNumber */
 234
 235 /* ------------------------------------------------------------------ */
 236 /* to-scientific-string -- conversion to numeric string               */
 237 /* to-engineering-string -- conversion to numeric string              */
 238 /*                                                                    */
 239 /*   decimal32ToString(d32, string);                                  */
 240 /*   decimal32ToEngString(d32, string);                               */
 241 /*                                                                    */
 242 /*  d32 is the decimal32 format number to convert                     */
 243 /*  string is the string where the result will be laid out            */
 244 /*                                                                    */
 245 /*  string must be at least 24 characters                             */
 246 /*                                                                    */
 247 /*  No error is possible, and no status can be set.                   */
 248 /* ------------------------------------------------------------------ */
 249 char * decimal32ToEngString(const decimal32 *d32, char *string){
 250   decNumber dn;                         /* work */
 251   decimal32ToNumber(d32, &dn);
 252   decNumberToEngString(&dn, string);
 253   return string;
 254   } /* decimal32ToEngString */
 255
 256 char * decimal32ToString(const decimal32 *d32, char *string){
 257   uInt msd;                        /* coefficient MSD */
 258   Int  exp;                        /* exponent top two bits or full */
 259   uInt comb;                       /* combination field */
 260   char *cstart;                    /* coefficient start */
 261   char *c;                         /* output pointer in string */
 262   const uInt *pu;                  /* work */
 263   const uByte *u;                  /* .. */
 264   char *s, *t;                     /* .. (source, target) */
 265   Int  dpd;                        /* .. */
 266   Int  pre, e;                     /* .. */
 267   uInt sour;                       /* source 32-bit */
 268
 269   /* load source from storage; this is endian */
 270   pu=(const uInt *)d32->bytes;     /* overlay */
 271   sour=*pu;                        /* directly load the int */
 272
 273   c=string;                        /* where result will go */
 274   if (((Int)sour)<0) *c++='-';     /* handle sign */
 275
 276   comb=(sour>>26)&0x1f;            /* combination field */
 277   msd=COMBMSD[comb];               /* decode the combination field */
 278   exp=COMBEXP[comb];               /* .. */
 279
 280   if (exp==3) {
 281     if (msd==0) {                  /* infinity */
 282       strcpy(c,   "Inf");
 283       strcpy(c+3, "inity");
 284       return string;               /* easy */
 285       }
 286     if (sour&0x02000000) *c++='s'; /* sNaN */
 287     strcpy(c, "NaN");              /* complete word */
 288     c+=3;                          /* step past */
 289     if ((sour&0x000fffff)==0) return string; /* zero payload */
 290     /* otherwise drop through to add integer; set correct exp */
 291     exp=0; msd=0;                  /* setup for following code */
 292     }
 293    else exp=(exp<<6)+((sour>>20)&0x3f)-DECIMAL32_Bias; /* unbiased */
 294
 295   /* convert 7 digits of significand to characters */
 296   cstart=c;                        /* save start of coefficient */
 297   if (msd) *c++='0'+(char)msd;     /* non-zero most significant digit */
 298
 299   /* Now decode the declets.  After extracting each one, it is */
 300   /* decoded to binary and then to a 4-char sequence by table lookup; */
 301   /* the 4-chars are a 1-char length (significant digits, except 000 */
 302   /* has length 0).  This allows us to left-align the first declet */
 303   /* with non-zero content, then remaining ones are full 3-char */
 304   /* length.  We use fixed-length memcpys because variable-length */
 305   /* causes a subroutine call in GCC.  (These are length 4 for speed */
 306   /* and are safe because the array has an extra terminator byte.) */
 307   #define dpd2char u=&BIN2CHAR[DPD2BIN[dpd]*4];                   \
 308                    if (c!=cstart) {memcpy(c, u+1, 4); c+=3;}      \
 309                     else if (*u)  {memcpy(c, u+4-*u, 4); c+=*u;}
 310
 311   dpd=(sour>>10)&0x3ff;            /* declet 1 */
 312   dpd2char;
 313   dpd=(sour)&0x3ff;                /* declet 2 */
 314   dpd2char;
 315
 316   if (c==cstart) *c++='0';         /* all zeros -- make 0 */
 317
 318   if (exp==0) {                    /* integer or NaN case -- easy */
 319     *c='\0';                       /* terminate */
 320     return string;
 321     }
 322
 323   /* non-0 exponent */
 324   e=0;                             /* assume no E */
 325   pre=c-cstart+exp;
 326   /* [here, pre-exp is the digits count (==1 for zero)] */
 327   if (exp>0 || pre<-5) {           /* need exponential form */
 328     e=pre-1;                       /* calculate E value */
 329     pre=1;                         /* assume one digit before '.' */
 330     } /* exponential form */
 331
 332   /* modify the coefficient, adding 0s, '.', and E+nn as needed */
 333   s=c-1;                           /* source (LSD) */
 334   if (pre>0) {                     /* ddd.ddd (plain), perhaps with E */
 335     char *dotat=cstart+pre;
 336     if (dotat<c) {                 /* if embedded dot needed... */
 337       t=c;                              /* target */
 338       for (; s>=dotat; s--, t--) *t=*s; /* open the gap; leave t at gap */
 339       *t='.';                           /* insert the dot */
 340       c++;                              /* length increased by one */
 341       }
 342
 343     /* finally add the E-part, if needed; it will never be 0, and has */
 344     /* a maximum length of 3 digits (E-101 case) */
 345     if (e!=0) {
 346       *c++='E';                    /* starts with E */
 347       *c++='+';                    /* assume positive */
 348       if (e<0) {
 349         *(c-1)='-';                /* oops, need '-' */
 350         e=-e;                      /* uInt, please */
 351         }
 352       u=&BIN2CHAR[e*4];            /* -> length byte */
 353       memcpy(c, u+4-*u, 4);        /* copy fixed 4 characters [is safe] */
 354       c+=*u;                       /* bump pointer appropriately */
 355       }
 356     *c='\0';                       /* add terminator */
 357     /*printf("res %s\n", string); */
 358     return string;
 359     } /* pre>0 */
 360
 361   /* -5<=pre<=0: here for plain 0.ddd or 0.000ddd forms (can never have E) */
 362   t=c+1-pre;
 363   *(t+1)='\0';                          /* can add terminator now */
 364   for (; s>=cstart; s--, t--) *t=*s;    /* shift whole coefficient right */
 365   c=cstart;
 366   *c++='0';                             /* always starts with 0. */
 367   *c++='.';
 368   for (; pre<0; pre++) *c++='0';        /* add any 0's after '.' */
 369   /*printf("res %s\n", string); */
 370   return string;
 371   } /* decimal32ToString */
 372
 373 /* ------------------------------------------------------------------ */
 374 /* to-number -- conversion from numeric string                        */
 375 /*                                                                    */
 376 /*   decimal32FromString(result, string, set);                        */
 377 /*                                                                    */
 378 /*  result  is the decimal32 format number which gets the result of   */
 379 /*          the conversion                                            */
 380 /*  *string is the character string which should contain a valid      */
 381 /*          number (which may be a special value)                     */
 382 /*  set     is the context                                            */
 383 /*                                                                    */
 384 /* The context is supplied to this routine is used for error handling */
 385 /* (setting of status and traps) and for the rounding mode, only.     */
 386 /* If an error occurs, the result will be a valid decimal32 NaN.      */
 387 /* ------------------------------------------------------------------ */
 388 decimal32 * decimal32FromString(decimal32 *result, const char *string,
 389                                 decContext *set) {
 390   decContext dc;                             /* work */
 391   decNumber dn;                              /* .. */
 392
 393   decContextDefault(&dc, DEC_INIT_DECIMAL32); /* no traps, please */
 394   dc.round=set->round;                        /* use supplied rounding */
 395
 396   decNumberFromString(&dn, string, &dc);     /* will round if needed */
 397   decimal32FromNumber(result, &dn, &dc);
 398   if (dc.status!=0) {                        /* something happened */
 399     decContextSetStatus(set, dc.status);     /* .. pass it on */
 400     }
 401   return result;
 402   } /* decimal32FromString */
 403
 404 /* ------------------------------------------------------------------ */
 405 /* decimal32IsCanonical -- test whether encoding is canonical         */
 406 /*   d32 is the source decimal32                                      */
 407 /*   returns 1 if the encoding of d32 is canonical, 0 otherwise       */
 408 /* No error is possible.                                              */
 409 /* ------------------------------------------------------------------ */
 410 uint32_t decimal32IsCanonical(const decimal32 *d32) {
 411   decNumber dn;                         /* work */
 412   decimal32 canon;                      /* .. */
 413   decContext dc;                        /* .. */
 414   decContextDefault(&dc, DEC_INIT_DECIMAL32);
 415   decimal32ToNumber(d32, &dn);
 416   decimal32FromNumber(&canon, &dn, &dc);/* canon will now be canonical */
 417   return memcmp(d32, &canon, DECIMAL32_Bytes)==0;
 418   } /* decimal32IsCanonical */
 419
 420 /* ------------------------------------------------------------------ */
 421 /* decimal32Canonical -- copy an encoding, ensuring it is canonical   */
 422 /*   d32 is the source decimal32                                      */
 423 /*   result is the target (may be the same decimal32)                 */
 424 /*   returns result                                                   */
 425 /* No error is possible.                                              */
 426 /* ------------------------------------------------------------------ */
 427 decimal32 * decimal32Canonical(decimal32 *result, const decimal32 *d32) {
 428   decNumber dn;                         /* work */
 429   decContext dc;                        /* .. */
 430   decContextDefault(&dc, DEC_INIT_DECIMAL32);
 431   decimal32ToNumber(d32, &dn);
 432   decimal32FromNumber(result, &dn, &dc);/* result will now be canonical */
 433   return result;
 434   } /* decimal32Canonical */
 435
 436 #if DECTRACE || DECCHECK
 437 /* Macros for accessing decimal32 fields.  These assume the argument
 438    is a reference (pointer) to the decimal32 structure, and the
 439    decimal32 is in network byte order (big-endian) */
 440 /* Get sign */
 441 #define decimal32Sign(d)       ((unsigned)(d)->bytes[0]>>7)
 442
 443 /* Get combination field */
 444 #define decimal32Comb(d)       (((d)->bytes[0] & 0x7c)>>2)
 445
 446 /* Get exponent continuation [does not remove bias] */
 447 #define decimal32ExpCon(d)     ((((d)->bytes[0] & 0x03)<<4)           \
 448                              | ((unsigned)(d)->bytes[1]>>4))
 449
 450 /* Set sign [this assumes sign previously 0] */
 451 #define decimal32SetSign(d, b) {                                      \
 452   (d)->bytes[0]|=((unsigned)(b)<<7);}
 453
 454 /* Set exponent continuation [does not apply bias] */
 455 /* This assumes range has been checked and exponent previously 0; */
 456 /* type of exponent must be unsigned */
 457 #define decimal32SetExpCon(d, e) {                                    \
 458   (d)->bytes[0]|=(uint8_t)((e)>>4);                                   \
 459   (d)->bytes[1]|=(uint8_t)(((e)&0x0F)<<4);}
 460
 461 /* ------------------------------------------------------------------ */
 462 /* decimal32Show -- display a decimal32 in hexadecimal [debug aid]    */
 463 /*   d32 -- the number to show                                        */
 464 /* ------------------------------------------------------------------ */
 465 /* Also shows sign/cob/expconfields extracted - valid bigendian only */
 466 void decimal32Show(const decimal32 *d32) {
 467   char buf[DECIMAL32_Bytes*2+1];
 468   Int i, j=0;
 469
 470   if (DECLITEND) {
 471     for (i=0; i<DECIMAL32_Bytes; i++, j+=2) {
 472       sprintf(&buf[j], "%02x", d32->bytes[3-i]);
 473       }
 474     printf(" D32> %s [S:%d Cb:%02x Ec:%02x] LittleEndian\n", buf,
 475            d32->bytes[3]>>7, (d32->bytes[3]>>2)&0x1f,
 476            ((d32->bytes[3]&0x3)<<4)| (d32->bytes[2]>>4));
 477     }
 478    else {
 479     for (i=0; i<DECIMAL32_Bytes; i++, j+=2) {
 480       sprintf(&buf[j], "%02x", d32->bytes[i]);
 481       }
 482     printf(" D32> %s [S:%d Cb:%02x Ec:%02x] BigEndian\n", buf,
 483            decimal32Sign(d32), decimal32Comb(d32), decimal32ExpCon(d32));
 484     }
 485   } /* decimal32Show */
 486 #endif