decimal32.c revision 169695
1169695Skan/* Decimal 32-bit format module for 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 decimal32 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 7 /* we need decNumbers with space for 7 */ 43169695Skan#include "config.h" 44169695Skan#include "decNumber.h" /* base number library */ 45169695Skan#include "decNumberLocal.h" /* decNumber local types, etc. */ 46169695Skan#include "decimal32.h" /* our primary include */ 47169695Skan#include "decUtility.h" /* utility routines */ 48169695Skan 49169695Skan#if DECTRACE || DECCHECK 50169695Skanvoid decimal32Show (const decimal32 *); /* 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/* decimal32FromNumber -- convert decNumber to decimal32 */ 60169695Skan/* */ 61169695Skan/* ds is the target decimal32 */ 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 DECIMAL32_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/* ------------------------------------------------------------------ */ 75169695Skandecimal32 * 76169695Skandecimal32FromNumber (decimal32 * d32, 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 > DECIMAL32_Pmax /* too many digits */ 92169695Skan || ae > DECIMAL32_Emax /* likely overflow */ 93169695Skan || ae < DECIMAL32_Emin) 94169695Skan { /* likely underflow */ 95169695Skan decContextDefault (&dc, DEC_INIT_DECIMAL32); /* [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 decimal32] */ 104169695Skan } 105169695Skan 106169695Skan DEC_clear (d32); /* 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 < DECIMAL32_Pmax)) 116169695Skan { /* coefficient fits */ 117169695Skan decDensePackCoeff (dn, d32->bytes, sizeof (d32->bytes), 0); 118169695Skan } 119169695Skan if (dn->bits & DECNAN) 120169695Skan top = DECIMAL_NaN; 121169695Skan else 122169695Skan top = DECIMAL_sNaN; 123169695Skan } 124169695Skan d32->bytes[0] = top; 125169695Skan } 126169695Skan else if (decNumberIsZero (dn)) 127169695Skan { /* a zero */ 128169695Skan /* set and clamp exponent */ 129169695Skan if (dn->exponent < -DECIMAL32_Bias) 130169695Skan { 131169695Skan exp = 0; 132169695Skan status |= DEC_Clamped; 133169695Skan } 134169695Skan else 135169695Skan { 136169695Skan exp = dn->exponent + DECIMAL32_Bias; /* bias exponent */ 137169695Skan if (exp > DECIMAL32_Ehigh) 138169695Skan { /* top clamp */ 139169695Skan exp = DECIMAL32_Ehigh; 140169695Skan status |= DEC_Clamped; 141169695Skan } 142169695Skan } 143169695Skan comb = (exp >> 3) & 0x18; /* combination field */ 144169695Skan d32->bytes[0] = (uByte) (comb << 2); 145169695Skan exp &= 0x3f; /* remaining exponent bits */ 146169695Skan decimal32SetExpCon (d32, 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 + DECIMAL32_Bias); /* bias exponent */ 154169695Skan 155169695Skan if (exp > DECIMAL32_Ehigh) 156169695Skan { /* fold-down case */ 157169695Skan pad = exp - DECIMAL32_Ehigh; 158169695Skan exp = DECIMAL32_Ehigh; /* [to maximum] */ 159169695Skan status |= DEC_Clamped; 160169695Skan } 161169695Skan 162169695Skan decDensePackCoeff (dn, d32->bytes, sizeof (d32->bytes), pad); 163169695Skan 164169695Skan /* save and clear the top digit */ 165169695Skan msd = ((unsigned) d32->bytes[1] >> 4); 166169695Skan d32->bytes[1] &= 0x0f; 167169695Skan /* create the combination field */ 168169695Skan if (msd >= 8) 169169695Skan comb = 0x18 | (msd & 0x01) | ((exp >> 5) & 0x06); 170169695Skan else 171169695Skan comb = (msd & 0x07) | ((exp >> 3) & 0x18); 172169695Skan d32->bytes[0] = (uByte) (comb << 2); 173169695Skan exp &= 0x3f; /* remaining exponent bits */ 174169695Skan decimal32SetExpCon (d32, exp); 175169695Skan } 176169695Skan 177169695Skan if (isneg) 178169695Skan decimal32SetSign (d32, 1); 179169695Skan if (status != 0) 180169695Skan decContextSetStatus (set, status); /* pass on status */ 181169695Skan 182169695Skan /*decimal32Show(d32); */ 183169695Skan return d32; 184169695Skan} 185169695Skan 186169695Skan/* ------------------------------------------------------------------ */ 187169695Skan/* decimal32ToNumber -- convert decimal32 to decNumber */ 188169695Skan/* d32 is the source decimal32 */ 189169695Skan/* dn is the target number, with appropriate space */ 190169695Skan/* No error is possible. */ 191169695Skan/* ------------------------------------------------------------------ */ 192169695SkandecNumber * 193169695Skandecimal32ToNumber (const decimal32 * d32, decNumber * dn) 194169695Skan{ 195169695Skan uInt msd; /* coefficient MSD */ 196169695Skan decimal32 wk; /* working copy, if needed */ 197169695Skan uInt top = d32->bytes[0] & 0x7f; /* top byte, less sign bit */ 198169695Skan decNumberZero (dn); /* clean target */ 199169695Skan /* set the sign if negative */ 200169695Skan if (decimal32Sign (d32)) 201169695Skan dn->bits = DECNEG; 202169695Skan 203169695Skan if (top >= 0x78) 204169695Skan { /* is a special */ 205169695Skan if ((top & 0x7c) == (DECIMAL_Inf & 0x7c)) 206169695Skan dn->bits |= DECINF; 207169695Skan else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e)) 208169695Skan dn->bits |= DECNAN; 209169695Skan else 210169695Skan dn->bits |= DECSNAN; 211169695Skan msd = 0; /* no top digit */ 212169695Skan } 213169695Skan else 214169695Skan { /* have a finite number */ 215169695Skan uInt comb = top >> 2; /* combination field */ 216169695Skan uInt exp; /* working exponent */ 217169695Skan 218169695Skan if (comb >= 0x18) 219169695Skan { 220169695Skan msd = 8 + (comb & 0x01); 221169695Skan exp = (comb & 0x06) << 5; /* MSBs */ 222169695Skan } 223169695Skan else 224169695Skan { 225169695Skan msd = comb & 0x07; 226169695Skan exp = (comb & 0x18) << 3; 227169695Skan } 228169695Skan dn->exponent = exp + decimal32ExpCon (d32) - DECIMAL32_Bias; /* remove bias */ 229169695Skan } 230169695Skan 231169695Skan /* get the coefficient, unless infinite */ 232169695Skan if (!(dn->bits & DECINF)) 233169695Skan { 234169695Skan Int bunches = DECIMAL32_Pmax / 3; /* coefficient full bunches to convert */ 235169695Skan Int odd = 0; /* assume MSD is 0 (no odd bunch) */ 236169695Skan if (msd != 0) 237169695Skan { /* coefficient has leading non-0 digit */ 238169695Skan /* make a copy of the decimal32, with an extra bunch which has */ 239169695Skan /* the top digit ready for conversion */ 240169695Skan wk = *d32; /* take a copy */ 241169695Skan wk.bytes[0] = 0; /* clear all but coecon */ 242169695Skan wk.bytes[1] &= 0x0f; /* .. */ 243169695Skan wk.bytes[1] |= (msd << 4); /* and prefix MSD */ 244169695Skan odd++; /* indicate the extra */ 245169695Skan d32 = &wk; /* use the work copy */ 246169695Skan } 247169695Skan decDenseUnpackCoeff (d32->bytes, sizeof (d32->bytes), dn, bunches, odd); 248169695Skan } 249169695Skan return dn; 250169695Skan} 251169695Skan 252169695Skan/* ------------------------------------------------------------------ */ 253169695Skan/* to-scientific-string -- conversion to numeric string */ 254169695Skan/* to-engineering-string -- conversion to numeric string */ 255169695Skan/* */ 256169695Skan/* decimal32ToString(d32, string); */ 257169695Skan/* decimal32ToEngString(d32, string); */ 258169695Skan/* */ 259169695Skan/* d32 is the decimal32 format number to convert */ 260169695Skan/* string is the string where the result will be laid out */ 261169695Skan/* */ 262169695Skan/* string must be at least 24 characters */ 263169695Skan/* */ 264169695Skan/* No error is possible, and no status can be set. */ 265169695Skan/* ------------------------------------------------------------------ */ 266169695Skanchar * 267169695Skandecimal32ToString (const decimal32 * d32, char *string) 268169695Skan{ 269169695Skan decNumber dn; /* work */ 270169695Skan decimal32ToNumber (d32, &dn); 271169695Skan decNumberToString (&dn, string); 272169695Skan return string; 273169695Skan} 274169695Skan 275169695Skanchar * 276169695Skandecimal32ToEngString (const decimal32 * d32, char *string) 277169695Skan{ 278169695Skan decNumber dn; /* work */ 279169695Skan decimal32ToNumber (d32, &dn); 280169695Skan decNumberToEngString (&dn, string); 281169695Skan return string; 282169695Skan} 283169695Skan 284169695Skan/* ------------------------------------------------------------------ */ 285169695Skan/* to-number -- conversion from numeric string */ 286169695Skan/* */ 287169695Skan/* decimal32FromString(result, string, set); */ 288169695Skan/* */ 289169695Skan/* result is the decimal32 format number which gets the result of */ 290169695Skan/* the conversion */ 291169695Skan/* *string is the character string which should contain a valid */ 292169695Skan/* number (which may be a special value) */ 293169695Skan/* set is the context */ 294169695Skan/* */ 295169695Skan/* The context is supplied to this routine is used for error handling */ 296169695Skan/* (setting of status and traps) and for the rounding mode, only. */ 297169695Skan/* If an error occurs, the result will be a valid decimal32 NaN. */ 298169695Skan/* ------------------------------------------------------------------ */ 299169695Skandecimal32 * 300169695Skandecimal32FromString (decimal32 * result, const char *string, decContext * set) 301169695Skan{ 302169695Skan decContext dc; /* work */ 303169695Skan decNumber dn; /* .. */ 304169695Skan 305169695Skan decContextDefault (&dc, DEC_INIT_DECIMAL32); /* no traps, please */ 306169695Skan dc.round = set->round; /* use supplied rounding */ 307169695Skan 308169695Skan decNumberFromString (&dn, string, &dc); /* will round if needed */ 309169695Skan decimal32FromNumber (result, &dn, &dc); 310169695Skan if (dc.status != 0) 311169695Skan { /* something happened */ 312169695Skan decContextSetStatus (set, dc.status); /* .. pass it on */ 313169695Skan } 314169695Skan return result; 315169695Skan} 316169695Skan 317169695Skan#if DECTRACE || DECCHECK 318169695Skan/* ------------------------------------------------------------------ */ 319169695Skan/* decimal32Show -- display a single in hexadecimal [debug aid] */ 320169695Skan/* d32 -- the number to show */ 321169695Skan/* ------------------------------------------------------------------ */ 322169695Skan/* Also shows sign/cob/expconfields extracted */ 323169695Skanvoid 324169695Skandecimal32Show (const decimal32 * d32) 325169695Skan{ 326169695Skan char buf[DECIMAL32_Bytes * 2 + 1]; 327169695Skan Int i, j; 328169695Skan j = 0; 329169695Skan for (i = 0; i < DECIMAL32_Bytes; i++) 330169695Skan { 331169695Skan sprintf (&buf[j], "%02x", d32->bytes[i]); 332169695Skan j = j + 2; 333169695Skan } 334169695Skan printf (" D32> %s [S:%d Cb:%02x E:%d]\n", buf, 335169695Skan decimal32Sign (d32), decimal32Comb (d32), decimal32ExpCon (d32)); 336169695Skan} 337169695Skan#endif 338