1 /* Decimal 64-bit format module for the decNumber C Library 2 Copyright (C) 2005 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 2, or (at your option) any later 10 version. 11 12 In addition to the permissions in the GNU General Public License, 13 the Free Software Foundation gives you unlimited permission to link 14 the compiled version of this file into combinations with other 15 programs, and to distribute those combinations without any 16 restriction coming from the use of this file. (The General Public 17 License restrictions do apply in other respects; for example, they 18 cover modification of the file, and distribution when not linked 19 into a combine executable.) 20 21 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 22 WARRANTY; without even the implied warranty of MERCHANTABILITY or 23 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 24 for more details. 25 26 You should have received a copy of the GNU General Public License 27 along with GCC; see the file COPYING. If not, write to the Free 28 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 29 02110-1301, USA. */ 30 31 /* ------------------------------------------------------------------ */ 32 /* This module comprises the routines for decimal64 format numbers. */ 33 /* Conversions are supplied to and from decNumber and String. */ 34 /* */ 35 /* No arithmetic routines are included; decNumber provides these. */ 36 /* */ 37 /* Error handling is the same as decNumber (qv.). */ 38 /* ------------------------------------------------------------------ */ 39 #include <string.h> /* [for memset/memcpy] */ 40 #include <stdio.h> /* [for printf] */ 41 42 #define DECNUMDIGITS 16 /* we need decNumbers with space for 16 */ 43 #include "config.h" 44 #include "decNumber.h" /* base number library */ 45 #include "decNumberLocal.h" /* decNumber local types, etc. */ 46 #include "decimal64.h" /* our primary include */ 47 #include "decUtility.h" /* utility routines */ 48 49 #if DECTRACE || DECCHECK 50 void decimal64Show (const decimal64 *); /* for debug */ 51 void decNumberShow (const decNumber *); /* .. */ 52 #endif 53 54 /* Useful macro */ 55 /* Clear a structure (e.g., a decNumber) */ 56 #define DEC_clear(d) memset(d, 0, sizeof(*d)) 57 58 /* ------------------------------------------------------------------ */ 59 /* decimal64FromNumber -- convert decNumber to decimal64 */ 60 /* */ 61 /* ds is the target decimal64 */ 62 /* dn is the source number (assumed valid) */ 63 /* set is the context, used only for reporting errors */ 64 /* */ 65 /* The set argument is used only for status reporting and for the */ 66 /* rounding mode (used if the coefficient is more than DECIMAL64_Pmax */ 67 /* digits or an overflow is detected). If the exponent is out of the */ 68 /* valid range then Overflow or Underflow will be raised. */ 69 /* After Underflow a subnormal result is possible. */ 70 /* */ 71 /* DEC_Clamped is set if the number has to be 'folded down' to fit, */ 72 /* by reducing its exponent and multiplying the coefficient by a */ 73 /* power of ten, or if the exponent on a zero had to be clamped. */ 74 /* ------------------------------------------------------------------ */ 75 decimal64 * 76 decimal64FromNumber (decimal64 * d64, const decNumber * dn, decContext * set) 77 { 78 uInt status = 0; /* status accumulator */ 79 Int pad = 0; /* coefficient pad digits */ 80 decNumber dw; /* work */ 81 decContext dc; /* .. */ 82 uByte isneg = dn->bits & DECNEG; /* non-0 if original sign set */ 83 uInt comb, exp; /* work */ 84 85 /* If the number is finite, and has too many digits, or the exponent */ 86 /* could be out of range then we reduce the number under the */ 87 /* appropriate constraints */ 88 if (!(dn->bits & DECSPECIAL)) 89 { /* not a special value */ 90 Int ae = dn->exponent + dn->digits - 1; /* adjusted exponent */ 91 if (dn->digits > DECIMAL64_Pmax /* too many digits */ 92 || ae > DECIMAL64_Emax /* likely overflow */ 93 || ae < DECIMAL64_Emin) 94 { /* likely underflow */ 95 decContextDefault (&dc, DEC_INIT_DECIMAL64); /* [no traps] */ 96 dc.round = set->round; /* use supplied rounding */ 97 decNumberPlus (&dw, dn, &dc); /* (round and check) */ 98 /* [this changes -0 to 0, but it will be restored below] */ 99 status |= dc.status; /* save status */ 100 dn = &dw; /* use the work number */ 101 } 102 /* [this could have pushed number to Infinity or zero, so this */ 103 /* rounding must be done before we generate the decimal64] */ 104 } 105 106 DEC_clear (d64); /* clean the target */ 107 if (dn->bits & DECSPECIAL) 108 { /* a special value */ 109 uByte top; /* work */ 110 if (dn->bits & DECINF) 111 top = DECIMAL_Inf; 112 else 113 { /* sNaN or qNaN */ 114 if ((*dn->lsu != 0 || dn->digits > 1) /* non-zero coefficient */ 115 && (dn->digits < DECIMAL64_Pmax)) 116 { /* coefficient fits */ 117 decDensePackCoeff (dn, d64->bytes, sizeof (d64->bytes), 0); 118 } 119 if (dn->bits & DECNAN) 120 top = DECIMAL_NaN; 121 else 122 top = DECIMAL_sNaN; 123 } 124 d64->bytes[0] = top; 125 } 126 else if (decNumberIsZero (dn)) 127 { /* a zero */ 128 /* set and clamp exponent */ 129 if (dn->exponent < -DECIMAL64_Bias) 130 { 131 exp = 0; 132 status |= DEC_Clamped; 133 } 134 else 135 { 136 exp = dn->exponent + DECIMAL64_Bias; /* bias exponent */ 137 if (exp > DECIMAL64_Ehigh) 138 { /* top clamp */ 139 exp = DECIMAL64_Ehigh; 140 status |= DEC_Clamped; 141 } 142 } 143 comb = (exp >> 5) & 0x18; /* combination field */ 144 d64->bytes[0] = (uByte) (comb << 2); 145 exp &= 0xff; /* remaining exponent bits */ 146 decimal64SetExpCon (d64, 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 + DECIMAL64_Bias); /* bias exponent */ 154 if (exp > DECIMAL64_Ehigh) 155 { /* fold-down case */ 156 pad = exp - DECIMAL64_Ehigh; 157 exp = DECIMAL64_Ehigh; /* [to maximum] */ 158 status |= DEC_Clamped; 159 } 160 161 decDensePackCoeff (dn, d64->bytes, sizeof (d64->bytes), pad); 162 163 /* save and clear the top digit */ 164 msd = ((unsigned) d64->bytes[1] >> 2) & 0x0f; 165 d64->bytes[1] &= 0x03; 166 /* create the combination field */ 167 if (msd >= 8) 168 comb = 0x18 | (msd & 0x01) | ((exp >> 7) & 0x06); 169 else 170 comb = (msd & 0x07) | ((exp >> 5) & 0x18); 171 d64->bytes[0] = (uByte) (comb << 2); 172 exp &= 0xff; /* remaining exponent bits */ 173 decimal64SetExpCon (d64, exp); 174 } 175 176 if (isneg) 177 decimal64SetSign (d64, 1); 178 if (status != 0) 179 decContextSetStatus (set, status); /* pass on status */ 180 181 /*decimal64Show(d64); */ 182 return d64; 183 } 184 185 /* ------------------------------------------------------------------ */ 186 /* decimal64ToNumber -- convert decimal64 to decNumber */ 187 /* d64 is the source decimal64 */ 188 /* dn is the target number, with appropriate space */ 189 /* No error is possible. */ 190 /* ------------------------------------------------------------------ */ 191 decNumber * 192 decimal64ToNumber (const decimal64 * d64, decNumber * dn) 193 { 194 uInt msd; /* coefficient MSD */ 195 decimal64 wk; /* working copy, if needed */ 196 uInt top = d64->bytes[0] & 0x7f; /* top byte, less sign bit */ 197 decNumberZero (dn); /* clean target */ 198 /* set the sign if negative */ 199 if (decimal64Sign (d64)) 200 dn->bits = DECNEG; 201 202 if (top >= 0x78) 203 { /* is a special */ 204 if ((top & 0x7c) == (DECIMAL_Inf & 0x7c)) 205 dn->bits |= DECINF; 206 else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e)) 207 dn->bits |= DECNAN; 208 else 209 dn->bits |= DECSNAN; 210 msd = 0; /* no top digit */ 211 } 212 else 213 { /* have a finite number */ 214 uInt comb = top >> 2; /* combination field */ 215 uInt exp; /* exponent */ 216 217 if (comb >= 0x18) 218 { 219 msd = 8 + (comb & 0x01); 220 exp = (comb & 0x06) << 7; /* MSBs */ 221 } 222 else 223 { 224 msd = comb & 0x07; 225 exp = (comb & 0x18) << 5; 226 } 227 dn->exponent = exp + decimal64ExpCon (d64) - DECIMAL64_Bias; /* remove bias */ 228 } 229 230 /* get the coefficient, unless infinite */ 231 if (!(dn->bits & DECINF)) 232 { 233 Int bunches = DECIMAL64_Pmax / 3; /* coefficient full bunches to convert */ 234 Int odd = 0; /* assume MSD is 0 (no odd bunch) */ 235 if (msd != 0) 236 { /* coefficient has leading non-0 digit */ 237 /* make a copy of the decimal64, with an extra bunch which has */ 238 /* the top digit ready for conversion */ 239 wk = *d64; /* take a copy */ 240 wk.bytes[0] = 0; /* clear all but coecon */ 241 wk.bytes[1] &= 0x03; /* .. */ 242 wk.bytes[1] |= (msd << 2); /* and prefix MSD */ 243 odd++; /* indicate the extra */ 244 d64 = &wk; /* use the work copy */ 245 } 246 decDenseUnpackCoeff (d64->bytes, sizeof (d64->bytes), dn, bunches, odd); 247 } 248 return dn; 249 } 250 251 /* ------------------------------------------------------------------ */ 252 /* to-scientific-string -- conversion to numeric string */ 253 /* to-engineering-string -- conversion to numeric string */ 254 /* */ 255 /* decimal64ToString(d64, string); */ 256 /* decimal64ToEngString(d64, string); */ 257 /* */ 258 /* d64 is the decimal64 format number to convert */ 259 /* string is the string where the result will be laid out */ 260 /* */ 261 /* string must be at least 24 characters */ 262 /* */ 263 /* No error is possible, and no status can be set. */ 264 /* ------------------------------------------------------------------ */ 265 char * 266 decimal64ToString (const decimal64 * d64, char *string) 267 { 268 decNumber dn; /* work */ 269 decimal64ToNumber (d64, &dn); 270 decNumberToString (&dn, string); 271 return string; 272 } 273 274 char * 275 decimal64ToEngString (const decimal64 * d64, char *string) 276 { 277 decNumber dn; /* work */ 278 decimal64ToNumber (d64, &dn); 279 decNumberToEngString (&dn, string); 280 return string; 281 } 282 283 /* ------------------------------------------------------------------ */ 284 /* to-number -- conversion from numeric string */ 285 /* */ 286 /* decimal64FromString(result, string, set); */ 287 /* */ 288 /* result is the decimal64 format number which gets the result of */ 289 /* the conversion */ 290 /* *string is the character string which should contain a valid */ 291 /* number (which may be a special value) */ 292 /* set is the context */ 293 /* */ 294 /* The context is supplied to this routine is used for error handling */ 295 /* (setting of status and traps) and for the rounding mode, only. */ 296 /* If an error occurs, the result will be a valid decimal64 NaN. */ 297 /* ------------------------------------------------------------------ */ 298 decimal64 * 299 decimal64FromString (decimal64 * result, const char *string, decContext * set) 300 { 301 decContext dc; /* work */ 302 decNumber dn; /* .. */ 303 304 decContextDefault (&dc, DEC_INIT_DECIMAL64); /* no traps, please */ 305 dc.round = set->round; /* use supplied rounding */ 306 307 decNumberFromString (&dn, string, &dc); /* will round if needed */ 308 309 decimal64FromNumber (result, &dn, &dc); 310 if (dc.status != 0) 311 { /* something happened */ 312 decContextSetStatus (set, dc.status); /* .. pass it on */ 313 } 314 return result; 315 } 316 317 #if DECTRACE || DECCHECK 318 /* ------------------------------------------------------------------ */ 319 /* decimal64Show -- display a single in hexadecimal [debug aid] */ 320 /* d64 -- the number to show */ 321 /* ------------------------------------------------------------------ */ 322 /* Also shows sign/cob/expconfields extracted */ 323 void 324 decimal64Show (const decimal64 * d64) 325 { 326 char buf[DECIMAL64_Bytes * 2 + 1]; 327 Int i, j; 328 j = 0; 329 for (i = 0; i < DECIMAL64_Bytes; i++) 330 { 331 sprintf (&buf[j], "%02x", d64->bytes[i]); 332 j = j + 2; 333 } 334 printf (" D64> %s [S:%d Cb:%02x E:%d]\n", buf, 335 decimal64Sign (d64), decimal64Comb (d64), decimal64ExpCon (d64)); 336 } 337 #endif 338