1169695Skan/* Decimal 128-bit format module from the decNumber C Library. 2169695Skan Copyright (C) 2005 Free Software Foundation, Inc. 3169695Skan Contributed by IBM Corporation. Author Mike Cowlishaw. 4169695Skan 5169695Skan This file is part of GCC. 6169695Skan 7169695Skan GCC is free software; you can redistribute it and/or modify it under 8169695Skan the terms of the GNU General Public License as published by the Free 9169695Skan Software Foundation; either version 2, or (at your option) any later 10169695Skan version. 11169695Skan 12169695Skan In addition to the permissions in the GNU General Public License, 13169695Skan the Free Software Foundation gives you unlimited permission to link 14169695Skan the compiled version of this file into combinations with other 15169695Skan programs, and to distribute those combinations without any 16169695Skan restriction coming from the use of this file. (The General Public 17169695Skan License restrictions do apply in other respects; for example, they 18169695Skan cover modification of the file, and distribution when not linked 19169695Skan into a combine executable.) 20169695Skan 21169695Skan GCC is distributed in the hope that it will be useful, but WITHOUT ANY 22169695Skan WARRANTY; without even the implied warranty of MERCHANTABILITY or 23169695Skan FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 24169695Skan for more details. 25169695Skan 26169695Skan You should have received a copy of the GNU General Public License 27169695Skan along with GCC; see the file COPYING. If not, write to the Free 28169695Skan Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 29169695Skan 02110-1301, USA. */ 30169695Skan 31169695Skan/* ------------------------------------------------------------------ */ 32169695Skan/* This module comprises the routines for decimal128 format numbers. */ 33169695Skan/* Conversions are supplied to and from decNumber and String. */ 34169695Skan/* */ 35169695Skan/* No arithmetic routines are included; decNumber provides these. */ 36169695Skan/* */ 37169695Skan/* Error handling is the same as decNumber (qv.). */ 38169695Skan/* ------------------------------------------------------------------ */ 39169695Skan#include <string.h> /* [for memset/memcpy] */ 40169695Skan#include <stdio.h> /* [for printf] */ 41169695Skan 42169695Skan#define DECNUMDIGITS 34 /* we need decNumbers with space for 34 */ 43169695Skan#include "config.h" 44169695Skan#include "decNumber.h" /* base number library */ 45169695Skan#include "decNumberLocal.h" /* decNumber local types, etc. */ 46169695Skan#include "decimal128.h" /* our primary include */ 47169695Skan#include "decUtility.h" /* utility routines */ 48169695Skan 49169695Skan#if DECTRACE || DECCHECK 50169695Skanvoid decimal128Show (const decimal128 *); /* for debug */ 51169695Skanvoid decNumberShow (const decNumber *); /* .. */ 52169695Skan#endif 53169695Skan 54169695Skan/* Useful macro */ 55169695Skan/* Clear a structure (e.g., a decNumber) */ 56169695Skan#define DEC_clear(d) memset(d, 0, sizeof(*d)) 57169695Skan 58169695Skan/* ------------------------------------------------------------------ */ 59169695Skan/* decimal128FromNumber -- convert decNumber to decimal128 */ 60169695Skan/* */ 61169695Skan/* ds is the target decimal128 */ 62169695Skan/* dn is the source number (assumed valid) */ 63169695Skan/* set is the context, used only for reporting errors */ 64169695Skan/* */ 65169695Skan/* The set argument is used only for status reporting and for the */ 66169695Skan/* rounding mode (used if the coefficient is more than DECIMAL128_Pmax*/ 67169695Skan/* digits or an overflow is detected). If the exponent is out of the */ 68169695Skan/* valid range then Overflow or Underflow will be raised. */ 69169695Skan/* After Underflow a subnormal result is possible. */ 70169695Skan/* */ 71169695Skan/* DEC_Clamped is set if the number has to be 'folded down' to fit, */ 72169695Skan/* by reducing its exponent and multiplying the coefficient by a */ 73169695Skan/* power of ten, or if the exponent on a zero had to be clamped. */ 74169695Skan/* ------------------------------------------------------------------ */ 75169695Skandecimal128 * 76169695Skandecimal128FromNumber (decimal128 * d128, const decNumber * dn, decContext * set) 77169695Skan{ 78169695Skan uInt status = 0; /* status accumulator */ 79169695Skan Int pad = 0; /* coefficient pad digits */ 80169695Skan decNumber dw; /* work */ 81169695Skan decContext dc; /* .. */ 82169695Skan uByte isneg = dn->bits & DECNEG; /* non-0 if original sign set */ 83169695Skan uInt comb, exp; /* work */ 84169695Skan 85169695Skan /* If the number is finite, and has too many digits, or the exponent */ 86169695Skan /* could be out of range then we reduce the number under the */ 87169695Skan /* appropriate constraints */ 88169695Skan if (!(dn->bits & DECSPECIAL)) 89169695Skan { /* not a special value */ 90169695Skan Int ae = dn->exponent + dn->digits - 1; /* adjusted exponent */ 91169695Skan if (dn->digits > DECIMAL128_Pmax /* too many digits */ 92169695Skan || ae > DECIMAL128_Emax /* likely overflow */ 93169695Skan || ae < DECIMAL128_Emin) 94169695Skan { /* likely underflow */ 95169695Skan decContextDefault (&dc, DEC_INIT_DECIMAL128); /* [no traps] */ 96169695Skan dc.round = set->round; /* use supplied rounding */ 97169695Skan decNumberPlus (&dw, dn, &dc); /* (round and check) */ 98169695Skan /* [this changes -0 to 0, but it will be restored below] */ 99169695Skan status |= dc.status; /* save status */ 100169695Skan dn = &dw; /* use the work number */ 101169695Skan } 102169695Skan /* [this could have pushed number to Infinity or zero, so this */ 103169695Skan /* rounding must be done before we generate the decimal128] */ 104169695Skan } 105169695Skan 106169695Skan DEC_clear (d128); /* clean the target */ 107169695Skan if (dn->bits & DECSPECIAL) 108169695Skan { /* a special value */ 109169695Skan uByte top; /* work */ 110169695Skan if (dn->bits & DECINF) 111169695Skan top = DECIMAL_Inf; 112169695Skan else 113169695Skan { /* sNaN or qNaN */ 114169695Skan if ((*dn->lsu != 0 || dn->digits > 1) /* non-zero coefficient */ 115169695Skan && (dn->digits < DECIMAL128_Pmax)) 116169695Skan { /* coefficient fits */ 117169695Skan decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), 0); 118169695Skan } 119169695Skan if (dn->bits & DECNAN) 120169695Skan top = DECIMAL_NaN; 121169695Skan else 122169695Skan top = DECIMAL_sNaN; 123169695Skan } 124169695Skan d128->bytes[0] = top; 125169695Skan } 126169695Skan else if (decNumberIsZero (dn)) 127169695Skan { /* a zero */ 128169695Skan /* set and clamp exponent */ 129169695Skan if (dn->exponent < -DECIMAL128_Bias) 130169695Skan { 131169695Skan exp = 0; 132169695Skan status |= DEC_Clamped; 133169695Skan } 134169695Skan else 135169695Skan { 136169695Skan exp = dn->exponent + DECIMAL128_Bias; /* bias exponent */ 137169695Skan if (exp > DECIMAL128_Ehigh) 138169695Skan { /* top clamp */ 139169695Skan exp = DECIMAL128_Ehigh; 140169695Skan status |= DEC_Clamped; 141169695Skan } 142169695Skan } 143169695Skan comb = (exp >> 9) & 0x18; /* combination field */ 144169695Skan d128->bytes[0] = (uByte) (comb << 2); 145169695Skan exp &= 0xfff; /* remaining exponent bits */ 146169695Skan decimal128SetExpCon (d128, exp); 147169695Skan } 148169695Skan else 149169695Skan { /* non-zero finite number */ 150169695Skan uInt msd; /* work */ 151169695Skan 152169695Skan /* we have a dn that fits, but it may need to be padded */ 153169695Skan exp = (uInt) (dn->exponent + DECIMAL128_Bias); /* bias exponent */ 154169695Skan 155169695Skan if (exp > DECIMAL128_Ehigh) 156169695Skan { /* fold-down case */ 157169695Skan pad = exp - DECIMAL128_Ehigh; 158169695Skan exp = DECIMAL128_Ehigh; /* [to maximum] */ 159169695Skan status |= DEC_Clamped; 160169695Skan } 161169695Skan 162169695Skan decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), pad); 163169695Skan 164169695Skan /* save and clear the top digit */ 165169695Skan msd = ((unsigned) d128->bytes[1] << 2) & 0x0c; /* top 2 bits */ 166169695Skan msd |= ((unsigned) d128->bytes[2] >> 6); /* low 2 bits */ 167169695Skan d128->bytes[1] &= 0xfc; 168169695Skan d128->bytes[2] &= 0x3f; 169169695Skan 170169695Skan /* create the combination field */ 171169695Skan if (msd >= 8) 172169695Skan comb = 0x18 | (msd & 0x01) | ((exp >> 11) & 0x06); 173169695Skan else 174169695Skan comb = (msd & 0x07) | ((exp >> 9) & 0x18); 175169695Skan d128->bytes[0] = (uByte) (comb << 2); 176169695Skan exp &= 0xfff; /* remaining exponent bits */ 177169695Skan decimal128SetExpCon (d128, exp); 178169695Skan } 179169695Skan 180169695Skan if (isneg) 181169695Skan decimal128SetSign (d128, 1); 182169695Skan if (status != 0) 183169695Skan decContextSetStatus (set, status); /* pass on status */ 184169695Skan 185169695Skan /* decimal128Show(d128); */ 186169695Skan return d128; 187169695Skan} 188169695Skan 189169695Skan/* ------------------------------------------------------------------ */ 190169695Skan/* decimal128ToNumber -- convert decimal128 to decNumber */ 191169695Skan/* d128 is the source decimal128 */ 192169695Skan/* dn is the target number, with appropriate space */ 193169695Skan/* No error is possible. */ 194169695Skan/* ------------------------------------------------------------------ */ 195169695SkandecNumber * 196169695Skandecimal128ToNumber (const decimal128 * d128, decNumber * dn) 197169695Skan{ 198169695Skan uInt msd; /* coefficient MSD */ 199169695Skan decimal128 wk; /* working copy, if needed */ 200169695Skan uInt top = d128->bytes[0] & 0x7f; /* top byte, less sign bit */ 201169695Skan decNumberZero (dn); /* clean target */ 202169695Skan /* set the sign if negative */ 203169695Skan if (decimal128Sign (d128)) 204169695Skan dn->bits = DECNEG; 205169695Skan 206169695Skan if (top >= 0x78) 207169695Skan { /* is a special */ 208169695Skan if ((top & 0x7c) == (DECIMAL_Inf & 0x7c)) 209169695Skan dn->bits |= DECINF; 210169695Skan else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e)) 211169695Skan dn->bits |= DECNAN; 212169695Skan else 213169695Skan dn->bits |= DECSNAN; 214169695Skan msd = 0; /* no top digit */ 215169695Skan } 216169695Skan else 217169695Skan { /* have a finite number */ 218169695Skan uInt comb = top >> 2; /* combination field */ 219169695Skan uInt exp; /* exponent */ 220169695Skan 221169695Skan if (comb >= 0x18) 222169695Skan { 223169695Skan msd = 8 + (comb & 0x01); 224169695Skan exp = (comb & 0x06) << 11; /* MSBs */ 225169695Skan } 226169695Skan else 227169695Skan { 228169695Skan msd = comb & 0x07; 229169695Skan exp = (comb & 0x18) << 9; 230169695Skan } 231169695Skan dn->exponent = exp + decimal128ExpCon (d128) - DECIMAL128_Bias; /* remove bias */ 232169695Skan } 233169695Skan 234169695Skan /* get the coefficient, unless infinite */ 235169695Skan if (!(dn->bits & DECINF)) 236169695Skan { 237169695Skan Int bunches = DECIMAL128_Pmax / 3; /* coefficient full bunches to convert */ 238169695Skan Int odd = 0; /* assume MSD is 0 (no odd bunch) */ 239169695Skan if (msd != 0) 240169695Skan { /* coefficient has leading non-0 digit */ 241169695Skan /* make a copy of the decimal128, with an extra bunch which has */ 242169695Skan /* the top digit ready for conversion */ 243169695Skan wk = *d128; /* take a copy */ 244169695Skan wk.bytes[0] = 0; /* clear all but coecon */ 245169695Skan wk.bytes[1] = 0; /* .. */ 246169695Skan wk.bytes[2] &= 0x3f; /* .. */ 247169695Skan wk.bytes[1] |= (msd >> 2); /* and prefix MSD */ 248169695Skan wk.bytes[2] |= (msd << 6); /* .. */ 249169695Skan odd++; /* indicate the extra */ 250169695Skan d128 = &wk; /* use the work copy */ 251169695Skan } 252169695Skan decDenseUnpackCoeff (d128->bytes, sizeof (d128->bytes), dn, bunches, 253169695Skan odd); 254169695Skan } 255169695Skan 256169695Skan /* decNumberShow(dn); */ 257169695Skan return dn; 258169695Skan} 259169695Skan 260169695Skan/* ------------------------------------------------------------------ */ 261169695Skan/* to-scientific-string -- conversion to numeric string */ 262169695Skan/* to-engineering-string -- conversion to numeric string */ 263169695Skan/* */ 264169695Skan/* decimal128ToString(d128, string); */ 265169695Skan/* decimal128ToEngString(d128, string); */ 266169695Skan/* */ 267169695Skan/* d128 is the decimal128 format number to convert */ 268169695Skan/* string is the string where the result will be laid out */ 269169695Skan/* */ 270169695Skan/* string must be at least 24 characters */ 271169695Skan/* */ 272169695Skan/* No error is possible, and no status can be set. */ 273169695Skan/* ------------------------------------------------------------------ */ 274169695Skanchar * 275169695Skandecimal128ToString (const decimal128 * d128, char *string) 276169695Skan{ 277169695Skan decNumber dn; /* work */ 278169695Skan decimal128ToNumber (d128, &dn); 279169695Skan decNumberToString (&dn, string); 280169695Skan return string; 281169695Skan} 282169695Skan 283169695Skanchar * 284169695Skandecimal128ToEngString (const decimal128 * d128, char *string) 285169695Skan{ 286169695Skan decNumber dn; /* work */ 287169695Skan decimal128ToNumber (d128, &dn); 288169695Skan decNumberToEngString (&dn, string); 289169695Skan return string; 290169695Skan} 291169695Skan 292169695Skan/* ------------------------------------------------------------------ */ 293169695Skan/* to-number -- conversion from numeric string */ 294169695Skan/* */ 295169695Skan/* decimal128FromString(result, string, set); */ 296169695Skan/* */ 297169695Skan/* result is the decimal128 format number which gets the result of */ 298169695Skan/* the conversion */ 299169695Skan/* *string is the character string which should contain a valid */ 300169695Skan/* number (which may be a special value) */ 301169695Skan/* set is the context */ 302169695Skan/* */ 303169695Skan/* The context is supplied to this routine is used for error handling */ 304169695Skan/* (setting of status and traps) and for the rounding mode, only. */ 305169695Skan/* If an error occurs, the result will be a valid decimal128 NaN. */ 306169695Skan/* ------------------------------------------------------------------ */ 307169695Skandecimal128 * 308169695Skandecimal128FromString (decimal128 * result, const char *string, decContext * set) 309169695Skan{ 310169695Skan decContext dc; /* work */ 311169695Skan decNumber dn; /* .. */ 312169695Skan 313169695Skan decContextDefault (&dc, DEC_INIT_DECIMAL128); /* no traps, please */ 314169695Skan dc.round = set->round; /* use supplied rounding */ 315169695Skan 316169695Skan decNumberFromString (&dn, string, &dc); /* will round if needed */ 317169695Skan decimal128FromNumber (result, &dn, &dc); 318169695Skan if (dc.status != 0) 319169695Skan { /* something happened */ 320169695Skan decContextSetStatus (set, dc.status); /* .. pass it on */ 321169695Skan } 322169695Skan return result; 323169695Skan} 324169695Skan 325169695Skan 326169695Skan#if DECTRACE || DECCHECK 327169695Skan/* ------------------------------------------------------------------ */ 328169695Skan/* decimal128Show -- display a single in hexadecimal [debug aid] */ 329169695Skan/* d128 -- the number to show */ 330169695Skan/* ------------------------------------------------------------------ */ 331169695Skan/* Also shows sign/cob/expconfields extracted */ 332169695Skanvoid 333169695Skandecimal128Show (const decimal128 * d128) 334169695Skan{ 335169695Skan char buf[DECIMAL128_Bytes * 2 + 1]; 336169695Skan Int i, j; 337169695Skan j = 0; 338169695Skan for (i = 0; i < DECIMAL128_Bytes; i++) 339169695Skan { 340169695Skan sprintf (&buf[j], "%02x", d128->bytes[i]); 341169695Skan j = j + 2; 342169695Skan } 343169695Skan printf (" D128> %s [S:%d Cb:%02x E:%d]\n", buf, 344169695Skan decimal128Sign (d128), decimal128Comb (d128), 345169695Skan decimal128ExpCon (d128)); 346169695Skan} 347169695Skan#endif 348