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| 1 | +/* | |
| 2 | + * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package sun.misc; | |
| 27 | + | |
| 28 | +import sun.misc.FpUtils; | |
| 29 | +import sun.misc.DoubleConsts; | |
| 30 | +import sun.misc.FloatConsts; | |
| 31 | +import java.util.regex.*; | |
| 32 | + | |
| 33 | +public class FormattedFloatingDecimal{ | |
| 34 | + boolean isExceptional; | |
| 35 | + boolean isNegative; | |
| 36 | + int decExponent; // value set at construction, then immutable | |
| 37 | + int decExponentRounded; | |
| 38 | + char digits[]; | |
| 39 | + int nDigits; | |
| 40 | + int bigIntExp; | |
| 41 | + int bigIntNBits; | |
| 42 | + boolean mustSetRoundDir = false; | |
| 43 | + boolean fromHex = false; | |
| 44 | + int roundDir = 0; // set by doubleValue | |
| 45 | + int precision; // number of digits to the right of decimal | |
| 46 | + | |
| 47 | + public enum Form { SCIENTIFIC, COMPATIBLE, DECIMAL_FLOAT, GENERAL }; | |
| 48 | + | |
| 49 | + private Form form; | |
| 50 | + | |
| 51 | + private FormattedFloatingDecimal( boolean negSign, int decExponent, char []digits, int n, boolean e, int precision, Form form ) | |
| 52 | + { | |
| 53 | + isNegative = negSign; | |
| 54 | + isExceptional = e; | |
| 55 | + this.decExponent = decExponent; | |
| 56 | + this.digits = digits; | |
| 57 | + this.nDigits = n; | |
| 58 | + this.precision = precision; | |
| 59 | + this.form = form; | |
| 60 | + } | |
| 61 | + | |
| 62 | + /* | |
| 63 | + * Constants of the implementation | |
| 64 | + * Most are IEEE-754 related. | |
| 65 | + * (There are more really boring constants at the end.) | |
| 66 | + */ | |
| 67 | + static final long signMask = 0x8000000000000000L; | |
| 68 | + static final long expMask = 0x7ff0000000000000L; | |
| 69 | + static final long fractMask= ~(signMask|expMask); | |
| 70 | + static final int expShift = 52; | |
| 71 | + static final int expBias = 1023; | |
| 72 | + static final long fractHOB = ( 1L<<expShift ); // assumed High-Order bit | |
| 73 | + static final long expOne = ((long)expBias)<<expShift; // exponent of 1.0 | |
| 74 | + static final int maxSmallBinExp = 62; | |
| 75 | + static final int minSmallBinExp = -( 63 / 3 ); | |
| 76 | + static final int maxDecimalDigits = 15; | |
| 77 | + static final int maxDecimalExponent = 308; | |
| 78 | + static final int minDecimalExponent = -324; | |
| 79 | + static final int bigDecimalExponent = 324; // i.e. abs(minDecimalExponent) | |
| 80 | + | |
| 81 | + static final long highbyte = 0xff00000000000000L; | |
| 82 | + static final long highbit = 0x8000000000000000L; | |
| 83 | + static final long lowbytes = ~highbyte; | |
| 84 | + | |
| 85 | + static final int singleSignMask = 0x80000000; | |
| 86 | + static final int singleExpMask = 0x7f800000; | |
| 87 | + static final int singleFractMask = ~(singleSignMask|singleExpMask); | |
| 88 | + static final int singleExpShift = 23; | |
| 89 | + static final int singleFractHOB = 1<<singleExpShift; | |
| 90 | + static final int singleExpBias = 127; | |
| 91 | + static final int singleMaxDecimalDigits = 7; | |
| 92 | + static final int singleMaxDecimalExponent = 38; | |
| 93 | + static final int singleMinDecimalExponent = -45; | |
| 94 | + | |
| 95 | + static final int intDecimalDigits = 9; | |
| 96 | + | |
| 97 | + | |
| 98 | + /* | |
| 99 | + * count number of bits from high-order 1 bit to low-order 1 bit, | |
| 100 | + * inclusive. | |
| 101 | + */ | |
| 102 | + private static int | |
| 103 | + countBits( long v ){ | |
| 104 | + // | |
| 105 | + // the strategy is to shift until we get a non-zero sign bit | |
| 106 | + // then shift until we have no bits left, counting the difference. | |
| 107 | + // we do byte shifting as a hack. Hope it helps. | |
| 108 | + // | |
| 109 | + if ( v == 0L ) return 0; | |
| 110 | + | |
| 111 | + while ( ( v & highbyte ) == 0L ){ | |
| 112 | + v <<= 8; | |
| 113 | + } | |
| 114 | + while ( v > 0L ) { // i.e. while ((v&highbit) == 0L ) | |
| 115 | + v <<= 1; | |
| 116 | + } | |
| 117 | + | |
| 118 | + int n = 0; | |
| 119 | + while (( v & lowbytes ) != 0L ){ | |
| 120 | + v <<= 8; | |
| 121 | + n += 8; | |
| 122 | + } | |
| 123 | + while ( v != 0L ){ | |
| 124 | + v <<= 1; | |
| 125 | + n += 1; | |
| 126 | + } | |
| 127 | + return n; | |
| 128 | + } | |
| 129 | + | |
| 130 | + /* | |
| 131 | + * Keep big powers of 5 handy for future reference. | |
| 132 | + */ | |
| 133 | + private static FDBigInt b5p[]; | |
| 134 | + | |
| 135 | + private static synchronized FDBigInt | |
| 136 | + big5pow( int p ){ | |
| 137 | + assert p >= 0 : p; // negative power of 5 | |
| 138 | + if ( b5p == null ){ | |
| 139 | + b5p = new FDBigInt[ p+1 ]; | |
| 140 | + }else if (b5p.length <= p ){ | |
| 141 | + FDBigInt t[] = new FDBigInt[ p+1 ]; | |
| 142 | + System.arraycopy( b5p, 0, t, 0, b5p.length ); | |
| 143 | + b5p = t; | |
| 144 | + } | |
| 145 | + if ( b5p[p] != null ) | |
| 146 | + return b5p[p]; | |
| 147 | + else if ( p < small5pow.length ) | |
| 148 | + return b5p[p] = new FDBigInt( small5pow[p] ); | |
| 149 | + else if ( p < long5pow.length ) | |
| 150 | + return b5p[p] = new FDBigInt( long5pow[p] ); | |
| 151 | + else { | |
| 152 | + // construct the value. | |
| 153 | + // recursively. | |
| 154 | + int q, r; | |
| 155 | + // in order to compute 5^p, | |
| 156 | + // compute its square root, 5^(p/2) and square. | |
| 157 | + // or, let q = p / 2, r = p -q, then | |
| 158 | + // 5^p = 5^(q+r) = 5^q * 5^r | |
| 159 | + q = p >> 1; | |
| 160 | + r = p - q; | |
| 161 | + FDBigInt bigq = b5p[q]; | |
| 162 | + if ( bigq == null ) | |
| 163 | + bigq = big5pow ( q ); | |
| 164 | + if ( r < small5pow.length ){ | |
| 165 | + return (b5p[p] = bigq.mult( small5pow[r] ) ); | |
| 166 | + }else{ | |
| 167 | + FDBigInt bigr = b5p[ r ]; | |
| 168 | + if ( bigr == null ) | |
| 169 | + bigr = big5pow( r ); | |
| 170 | + return (b5p[p] = bigq.mult( bigr ) ); | |
| 171 | + } | |
| 172 | + } | |
| 173 | + } | |
| 174 | + | |
| 175 | + // | |
| 176 | + // a common operation | |
| 177 | + // | |
| 178 | + private static FDBigInt | |
| 179 | + multPow52( FDBigInt v, int p5, int p2 ){ | |
| 180 | + if ( p5 != 0 ){ | |
| 181 | + if ( p5 < small5pow.length ){ | |
| 182 | + v = v.mult( small5pow[p5] ); | |
| 183 | + } else { | |
| 184 | + v = v.mult( big5pow( p5 ) ); | |
| 185 | + } | |
| 186 | + } | |
| 187 | + if ( p2 != 0 ){ | |
| 188 | + v.lshiftMe( p2 ); | |
| 189 | + } | |
| 190 | + return v; | |
| 191 | + } | |
| 192 | + | |
| 193 | + // | |
| 194 | + // another common operation | |
| 195 | + // | |
| 196 | + private static FDBigInt | |
| 197 | + constructPow52( int p5, int p2 ){ | |
| 198 | + FDBigInt v = new FDBigInt( big5pow( p5 ) ); | |
| 199 | + if ( p2 != 0 ){ | |
| 200 | + v.lshiftMe( p2 ); | |
| 201 | + } | |
| 202 | + return v; | |
| 203 | + } | |
| 204 | + | |
| 205 | + /* | |
| 206 | + * Make a floating double into a FDBigInt. | |
| 207 | + * This could also be structured as a FDBigInt | |
| 208 | + * constructor, but we'd have to build a lot of knowledge | |
| 209 | + * about floating-point representation into it, and we don't want to. | |
| 210 | + * | |
| 211 | + * AS A SIDE EFFECT, THIS METHOD WILL SET THE INSTANCE VARIABLES | |
| 212 | + * bigIntExp and bigIntNBits | |
| 213 | + * | |
| 214 | + */ | |
| 215 | + private FDBigInt | |
| 216 | + doubleToBigInt( double dval ){ | |
| 217 | + long lbits = Double.doubleToLongBits( dval ) & ~signMask; | |
| 218 | + int binexp = (int)(lbits >>> expShift); | |
| 219 | + lbits &= fractMask; | |
| 220 | + if ( binexp > 0 ){ | |
| 221 | + lbits |= fractHOB; | |
| 222 | + } else { | |
| 223 | + assert lbits != 0L : lbits; // doubleToBigInt(0.0) | |
| 224 | + binexp +=1; | |
| 225 | + while ( (lbits & fractHOB ) == 0L){ | |
| 226 | + lbits <<= 1; | |
| 227 | + binexp -= 1; | |
| 228 | + } | |
| 229 | + } | |
| 230 | + binexp -= expBias; | |
| 231 | + int nbits = countBits( lbits ); | |
| 232 | + /* | |
| 233 | + * We now know where the high-order 1 bit is, | |
| 234 | + * and we know how many there are. | |
| 235 | + */ | |
| 236 | + int lowOrderZeros = expShift+1-nbits; | |
| 237 | + lbits >>>= lowOrderZeros; | |
| 238 | + | |
| 239 | + bigIntExp = binexp+1-nbits; | |
| 240 | + bigIntNBits = nbits; | |
| 241 | + return new FDBigInt( lbits ); | |
| 242 | + } | |
| 243 | + | |
| 244 | + /* | |
| 245 | + * Compute a number that is the ULP of the given value, | |
| 246 | + * for purposes of addition/subtraction. Generally easy. | |
| 247 | + * More difficult if subtracting and the argument | |
| 248 | + * is a normalized a power of 2, as the ULP changes at these points. | |
| 249 | + */ | |
| 250 | + private static double ulp( double dval, boolean subtracting ){ | |
| 251 | + long lbits = Double.doubleToLongBits( dval ) & ~signMask; | |
| 252 | + int binexp = (int)(lbits >>> expShift); | |
| 253 | + double ulpval; | |
| 254 | + if ( subtracting && ( binexp >= expShift ) && ((lbits&fractMask) == 0L) ){ | |
| 255 | + // for subtraction from normalized, powers of 2, | |
| 256 | + // use next-smaller exponent | |
| 257 | + binexp -= 1; | |
| 258 | + } | |
| 259 | + if ( binexp > expShift ){ | |
| 260 | + ulpval = Double.longBitsToDouble( ((long)(binexp-expShift))<<expShift ); | |
| 261 | + } else if ( binexp == 0 ){ | |
| 262 | + ulpval = Double.MIN_VALUE; | |
| 263 | + } else { | |
| 264 | + ulpval = Double.longBitsToDouble( 1L<<(binexp-1) ); | |
| 265 | + } | |
| 266 | + if ( subtracting ) ulpval = - ulpval; | |
| 267 | + | |
| 268 | + return ulpval; | |
| 269 | + } | |
| 270 | + | |
| 271 | + /* | |
| 272 | + * Round a double to a float. | |
| 273 | + * In addition to the fraction bits of the double, | |
| 274 | + * look at the class instance variable roundDir, | |
| 275 | + * which should help us avoid double-rounding error. | |
| 276 | + * roundDir was set in hardValueOf if the estimate was | |
| 277 | + * close enough, but not exact. It tells us which direction | |
| 278 | + * of rounding is preferred. | |
| 279 | + */ | |
| 280 | + float | |
| 281 | + stickyRound( double dval ){ | |
| 282 | + long lbits = Double.doubleToLongBits( dval ); | |
| 283 | + long binexp = lbits & expMask; | |
| 284 | + if ( binexp == 0L || binexp == expMask ){ | |
| 285 | + // what we have here is special. | |
| 286 | + // don't worry, the right thing will happen. | |
| 287 | + return (float) dval; | |
| 288 | + } | |
| 289 | + lbits += (long)roundDir; // hack-o-matic. | |
| 290 | + return (float)Double.longBitsToDouble( lbits ); | |
| 291 | + } | |
| 292 | + | |
| 293 | + | |
| 294 | + /* | |
| 295 | + * This is the easy subcase -- | |
| 296 | + * all the significant bits, after scaling, are held in lvalue. | |
| 297 | + * negSign and decExponent tell us what processing and scaling | |
| 298 | + * has already been done. Exceptional cases have already been | |
| 299 | + * stripped out. | |
| 300 | + * In particular: | |
| 301 | + * lvalue is a finite number (not Inf, nor NaN) | |
| 302 | + * lvalue > 0L (not zero, nor negative). | |
| 303 | + * | |
| 304 | + * The only reason that we develop the digits here, rather than | |
| 305 | + * calling on Long.toString() is that we can do it a little faster, | |
| 306 | + * and besides want to treat trailing 0s specially. If Long.toString | |
| 307 | + * changes, we should re-evaluate this strategy! | |
| 308 | + */ | |
| 309 | + private void | |
| 310 | + developLongDigits( int decExponent, long lvalue, long insignificant ){ | |
| 311 | + char digits[]; | |
| 312 | + int ndigits; | |
| 313 | + int digitno; | |
| 314 | + int c; | |
| 315 | + // | |
| 316 | + // Discard non-significant low-order bits, while rounding, | |
| 317 | + // up to insignificant value. | |
| 318 | + int i; | |
| 319 | + for ( i = 0; insignificant >= 10L; i++ ) | |
| 320 | + insignificant /= 10L; | |
| 321 | + if ( i != 0 ){ | |
| 322 | + long pow10 = long5pow[i] << i; // 10^i == 5^i * 2^i; | |
| 323 | + long residue = lvalue % pow10; | |
| 324 | + lvalue /= pow10; | |
| 325 | + decExponent += i; | |
| 326 | + if ( residue >= (pow10>>1) ){ | |
| 327 | + // round up based on the low-order bits we're discarding | |
| 328 | + lvalue++; | |
| 329 | + } | |
| 330 | + } | |
| 331 | + if ( lvalue <= Integer.MAX_VALUE ){ | |
| 332 | + assert lvalue > 0L : lvalue; // lvalue <= 0 | |
| 333 | + // even easier subcase! | |
| 334 | + // can do int arithmetic rather than long! | |
| 335 | + int ivalue = (int)lvalue; | |
| 336 | + ndigits = 10; | |
| 337 | + digits = (char[])(perThreadBuffer.get()); | |
| 338 | + digitno = ndigits-1; | |
| 339 | + c = ivalue%10; | |
| 340 | + ivalue /= 10; | |
| 341 | + while ( c == 0 ){ | |
| 342 | + decExponent++; | |
| 343 | + c = ivalue%10; | |
| 344 | + ivalue /= 10; | |
| 345 | + } | |
| 346 | + while ( ivalue != 0){ | |
| 347 | + digits[digitno--] = (char)(c+'0'); | |
| 348 | + decExponent++; | |
| 349 | + c = ivalue%10; | |
| 350 | + ivalue /= 10; | |
| 351 | + } | |
| 352 | + digits[digitno] = (char)(c+'0'); | |
| 353 | + } else { | |
| 354 | + // same algorithm as above (same bugs, too ) | |
| 355 | + // but using long arithmetic. | |
| 356 | + ndigits = 20; | |
| 357 | + digits = (char[])(perThreadBuffer.get()); | |
| 358 | + digitno = ndigits-1; | |
| 359 | + c = (int)(lvalue%10L); | |
| 360 | + lvalue /= 10L; | |
| 361 | + while ( c == 0 ){ | |
| 362 | + decExponent++; | |
| 363 | + c = (int)(lvalue%10L); | |
| 364 | + lvalue /= 10L; | |
| 365 | + } | |
| 366 | + while ( lvalue != 0L ){ | |
| 367 | + digits[digitno--] = (char)(c+'0'); | |
| 368 | + decExponent++; | |
| 369 | + c = (int)(lvalue%10L); | |
| 370 | + lvalue /= 10; | |
| 371 | + } | |
| 372 | + digits[digitno] = (char)(c+'0'); | |
| 373 | + } | |
| 374 | + char result []; | |
| 375 | + ndigits -= digitno; | |
| 376 | + result = new char[ ndigits ]; | |
| 377 | + System.arraycopy( digits, digitno, result, 0, ndigits ); | |
| 378 | + this.digits = result; | |
| 379 | + this.decExponent = decExponent+1; | |
| 380 | + this.nDigits = ndigits; | |
| 381 | + } | |
| 382 | + | |
| 383 | + // | |
| 384 | + // add one to the least significant digit. | |
| 385 | + // in the unlikely event there is a carry out, | |
| 386 | + // deal with it. | |
| 387 | + // assert that this will only happen where there | |
| 388 | + // is only one digit, e.g. (float)1e-44 seems to do it. | |
| 389 | + // | |
| 390 | + private void | |
| 391 | + roundup(){ | |
| 392 | + int i; | |
| 393 | + int q = digits[ i = (nDigits-1)]; | |
| 394 | + if ( q == '9' ){ | |
| 395 | + while ( q == '9' && i > 0 ){ | |
| 396 | + digits[i] = '0'; | |
| 397 | + q = digits[--i]; | |
| 398 | + } | |
| 399 | + if ( q == '9' ){ | |
| 400 | + // carryout! High-order 1, rest 0s, larger exp. | |
| 401 | + decExponent += 1; | |
| 402 | + digits[0] = '1'; | |
| 403 | + return; | |
| 404 | + } | |
| 405 | + // else fall through. | |
| 406 | + } | |
| 407 | + digits[i] = (char)(q+1); | |
| 408 | + } | |
| 409 | + | |
| 410 | + // Given the desired number of digits predict the result's exponent. | |
| 411 | + private int checkExponent(int length) { | |
| 412 | + if (length >= nDigits || length < 0) | |
| 413 | + return decExponent; | |
| 414 | + | |
| 415 | + for (int i = 0; i < length; i++) | |
| 416 | + if (digits[i] != '9') | |
| 417 | + // a '9' anywhere in digits will absorb the round | |
| 418 | + return decExponent; | |
| 419 | + return decExponent + (digits[length] >= '5' ? 1 : 0); | |
| 420 | + } | |
| 421 | + | |
| 422 | + // Unlike roundup(), this method does not modify digits. It also | |
| 423 | + // rounds at a particular precision. | |
| 424 | + private char [] applyPrecision(int length) { | |
| 425 | + char [] result = new char[nDigits]; | |
| 426 | + for (int i = 0; i < result.length; i++) result[i] = '0'; | |
| 427 | + | |
| 428 | + if (length >= nDigits || length < 0) { | |
| 429 | + // no rounding necessary | |
| 430 | + System.arraycopy(digits, 0, result, 0, nDigits); | |
| 431 | + return result; | |
| 432 | + } | |
| 433 | + if (length == 0) { | |
| 434 | + // only one digit (0 or 1) is returned because the precision | |
| 435 | + // excludes all significant digits | |
| 436 | + if (digits[0] >= '5') { | |
| 437 | + result[0] = '1'; | |
| 438 | + } | |
| 439 | + return result; | |
| 440 | + } | |
| 441 | + | |
| 442 | + int i = length; | |
| 443 | + int q = digits[i]; | |
| 444 | + if (q >= '5' && i > 0) { | |
| 445 | + q = digits[--i]; | |
| 446 | + if ( q == '9' ) { | |
| 447 | + while ( q == '9' && i > 0 ){ | |
| 448 | + q = digits[--i]; | |
| 449 | + } | |
| 450 | + if ( q == '9' ){ | |
| 451 | + // carryout! High-order 1, rest 0s, larger exp. | |
| 452 | + result[0] = '1'; | |
| 453 | + return result; | |
| 454 | + } | |
| 455 | + } | |
| 456 | + result[i] = (char)(q + 1); | |
| 457 | + } | |
| 458 | + while (--i >= 0) { | |
| 459 | + result[i] = digits[i]; | |
| 460 | + } | |
| 461 | + return result; | |
| 462 | + } | |
| 463 | + | |
| 464 | + /* | |
| 465 | + * FIRST IMPORTANT CONSTRUCTOR: DOUBLE | |
| 466 | + */ | |
| 467 | + public FormattedFloatingDecimal( double d ) | |
| 468 | + { | |
| 469 | + this(d, Integer.MAX_VALUE, Form.COMPATIBLE); | |
| 470 | + } | |
| 471 | + | |
| 472 | + public FormattedFloatingDecimal( double d, int precision, Form form ) | |
| 473 | + { | |
| 474 | + long dBits = Double.doubleToLongBits( d ); | |
| 475 | + long fractBits; | |
| 476 | + int binExp; | |
| 477 | + int nSignificantBits; | |
| 478 | + | |
| 479 | + this.precision = precision; | |
| 480 | + this.form = form; | |
| 481 | + | |
| 482 | + // discover and delete sign | |
| 483 | + if ( (dBits&signMask) != 0 ){ | |
| 484 | + isNegative = true; | |
| 485 | + dBits ^= signMask; | |
| 486 | + } else { | |
| 487 | + isNegative = false; | |
| 488 | + } | |
| 489 | + // Begin to unpack | |
| 490 | + // Discover obvious special cases of NaN and Infinity. | |
| 491 | + binExp = (int)( (dBits&expMask) >> expShift ); | |
| 492 | + fractBits = dBits&fractMask; | |
| 493 | + if ( binExp == (int)(expMask>>expShift) ) { | |
| 494 | + isExceptional = true; | |
| 495 | + if ( fractBits == 0L ){ | |
| 496 | + digits = infinity; | |
| 497 | + } else { | |
| 498 | + digits = notANumber; | |
| 499 | + isNegative = false; // NaN has no sign! | |
| 500 | + } | |
| 501 | + nDigits = digits.length; | |
| 502 | + return; | |
| 503 | + } | |
| 504 | + isExceptional = false; | |
| 505 | + // Finish unpacking | |
| 506 | + // Normalize denormalized numbers. | |
| 507 | + // Insert assumed high-order bit for normalized numbers. | |
| 508 | + // Subtract exponent bias. | |
| 509 | + if ( binExp == 0 ){ | |
| 510 | + if ( fractBits == 0L ){ | |
| 511 | + // not a denorm, just a 0! | |
| 512 | + decExponent = 0; | |
| 513 | + digits = zero; | |
| 514 | + nDigits = 1; | |
| 515 | + return; | |
| 516 | + } | |
| 517 | + while ( (fractBits&fractHOB) == 0L ){ | |
| 518 | + fractBits <<= 1; | |
| 519 | + binExp -= 1; | |
| 520 | + } | |
| 521 | + nSignificantBits = expShift + binExp +1; // recall binExp is - shift count. | |
| 522 | + binExp += 1; | |
| 523 | + } else { | |
| 524 | + fractBits |= fractHOB; | |
| 525 | + nSignificantBits = expShift+1; | |
| 526 | + } | |
| 527 | + binExp -= expBias; | |
| 528 | + // call the routine that actually does all the hard work. | |
| 529 | + dtoa( binExp, fractBits, nSignificantBits ); | |
| 530 | + } | |
| 531 | + | |
| 532 | + /* | |
| 533 | + * SECOND IMPORTANT CONSTRUCTOR: SINGLE | |
| 534 | + */ | |
| 535 | + public FormattedFloatingDecimal( float f ) | |
| 536 | + { | |
| 537 | + this(f, Integer.MAX_VALUE, Form.COMPATIBLE); | |
| 538 | + } | |
| 539 | + public FormattedFloatingDecimal( float f, int precision, Form form ) | |
| 540 | + { | |
| 541 | + int fBits = Float.floatToIntBits( f ); | |
| 542 | + int fractBits; | |
| 543 | + int binExp; | |
| 544 | + int nSignificantBits; | |
| 545 | + | |
| 546 | + this.precision = precision; | |
| 547 | + this.form = form; | |
| 548 | + | |
| 549 | + // discover and delete sign | |
| 550 | + if ( (fBits&singleSignMask) != 0 ){ | |
| 551 | + isNegative = true; | |
| 552 | + fBits ^= singleSignMask; | |
| 553 | + } else { | |
| 554 | + isNegative = false; | |
| 555 | + } | |
| 556 | + // Begin to unpack | |
| 557 | + // Discover obvious special cases of NaN and Infinity. | |
| 558 | + binExp = (int)( (fBits&singleExpMask) >> singleExpShift ); | |
| 559 | + fractBits = fBits&singleFractMask; | |
| 560 | + if ( binExp == (int)(singleExpMask>>singleExpShift) ) { | |
| 561 | + isExceptional = true; | |
| 562 | + if ( fractBits == 0L ){ | |
| 563 | + digits = infinity; | |
| 564 | + } else { | |
| 565 | + digits = notANumber; | |
| 566 | + isNegative = false; // NaN has no sign! | |
| 567 | + } | |
| 568 | + nDigits = digits.length; | |
| 569 | + return; | |
| 570 | + } | |
| 571 | + isExceptional = false; | |
| 572 | + // Finish unpacking | |
| 573 | + // Normalize denormalized numbers. | |
| 574 | + // Insert assumed high-order bit for normalized numbers. | |
| 575 | + // Subtract exponent bias. | |
| 576 | + if ( binExp == 0 ){ | |
| 577 | + if ( fractBits == 0 ){ | |
| 578 | + // not a denorm, just a 0! | |
| 579 | + decExponent = 0; | |
| 580 | + digits = zero; | |
| 581 | + nDigits = 1; | |
| 582 | + return; | |
| 583 | + } | |
| 584 | + while ( (fractBits&singleFractHOB) == 0 ){ | |
| 585 | + fractBits <<= 1; | |
| 586 | + binExp -= 1; | |
| 587 | + } | |
| 588 | + nSignificantBits = singleExpShift + binExp +1; // recall binExp is - shift count. | |
| 589 | + binExp += 1; | |
| 590 | + } else { | |
| 591 | + fractBits |= singleFractHOB; | |
| 592 | + nSignificantBits = singleExpShift+1; | |
| 593 | + } | |
| 594 | + binExp -= singleExpBias; | |
| 595 | + // call the routine that actually does all the hard work. | |
| 596 | + dtoa( binExp, ((long)fractBits)<<(expShift-singleExpShift), nSignificantBits ); | |
| 597 | + } | |
| 598 | + | |
| 599 | + private void | |
| 600 | + dtoa( int binExp, long fractBits, int nSignificantBits ) | |
| 601 | + { | |
| 602 | + int nFractBits; // number of significant bits of fractBits; | |
| 603 | + int nTinyBits; // number of these to the right of the point. | |
| 604 | + int decExp; | |
| 605 | + | |
| 606 | + // Examine number. Determine if it is an easy case, | |
| 607 | + // which we can do pretty trivially using float/long conversion, | |
| 608 | + // or whether we must do real work. | |
| 609 | + nFractBits = countBits( fractBits ); | |
| 610 | + nTinyBits = Math.max( 0, nFractBits - binExp - 1 ); | |
| 611 | + if ( binExp <= maxSmallBinExp && binExp >= minSmallBinExp ){ | |
| 612 | + // Look more closely at the number to decide if, | |
| 613 | + // with scaling by 10^nTinyBits, the result will fit in | |
| 614 | + // a long. | |
| 615 | + if ( (nTinyBits < long5pow.length) && ((nFractBits + n5bits[nTinyBits]) < 64 ) ){ | |
| 616 | + /* | |
| 617 | + * We can do this: | |
| 618 | + * take the fraction bits, which are normalized. | |
| 619 | + * (a) nTinyBits == 0: Shift left or right appropriately | |
| 620 | + * to align the binary point at the extreme right, i.e. | |
| 621 | + * where a long int point is expected to be. The integer | |
| 622 | + * result is easily converted to a string. | |
| 623 | + * (b) nTinyBits > 0: Shift right by expShift-nFractBits, | |
| 624 | + * which effectively converts to long and scales by | |
| 625 | + * 2^nTinyBits. Then multiply by 5^nTinyBits to | |
| 626 | + * complete the scaling. We know this won't overflow | |
| 627 | + * because we just counted the number of bits necessary | |
| 628 | + * in the result. The integer you get from this can | |
| 629 | + * then be converted to a string pretty easily. | |
| 630 | + */ | |
| 631 | + long halfULP; | |
| 632 | + if ( nTinyBits == 0 ) { | |
| 633 | + if ( binExp > nSignificantBits ){ | |
| 634 | + halfULP = 1L << ( binExp-nSignificantBits-1); | |
| 635 | + } else { | |
| 636 | + halfULP = 0L; | |
| 637 | + } | |
| 638 | + if ( binExp >= expShift ){ | |
| 639 | + fractBits <<= (binExp-expShift); | |
| 640 | + } else { | |
| 641 | + fractBits >>>= (expShift-binExp) ; | |
| 642 | + } | |
| 643 | + developLongDigits( 0, fractBits, halfULP ); | |
| 644 | + return; | |
| 645 | + } | |
| 646 | + /* | |
| 647 | + * The following causes excess digits to be printed | |
| 648 | + * out in the single-float case. Our manipulation of | |
| 649 | + * halfULP here is apparently not correct. If we | |
| 650 | + * better understand how this works, perhaps we can | |
| 651 | + * use this special case again. But for the time being, | |
| 652 | + * we do not. | |
| 653 | + * else { | |
| 654 | + * fractBits >>>= expShift+1-nFractBits; | |
| 655 | + * fractBits *= long5pow[ nTinyBits ]; | |
| 656 | + * halfULP = long5pow[ nTinyBits ] >> (1+nSignificantBits-nFractBits); | |
| 657 | + * developLongDigits( -nTinyBits, fractBits, halfULP ); | |
| 658 | + * return; | |
| 659 | + * } | |
| 660 | + */ | |
| 661 | + } | |
| 662 | + } | |
| 663 | + /* | |
| 664 | + * This is the hard case. We are going to compute large positive | |
| 665 | + * integers B and S and integer decExp, s.t. | |
| 666 | + * d = ( B / S ) * 10^decExp | |
| 667 | + * 1 <= B / S < 10 | |
| 668 | + * Obvious choices are: | |
| 669 | + * decExp = floor( log10(d) ) | |
| 670 | + * B = d * 2^nTinyBits * 10^max( 0, -decExp ) | |
| 671 | + * S = 10^max( 0, decExp) * 2^nTinyBits | |
| 672 | + * (noting that nTinyBits has already been forced to non-negative) | |
| 673 | + * I am also going to compute a large positive integer | |
| 674 | + * M = (1/2^nSignificantBits) * 2^nTinyBits * 10^max( 0, -decExp ) | |
| 675 | + * i.e. M is (1/2) of the ULP of d, scaled like B. | |
| 676 | + * When we iterate through dividing B/S and picking off the | |
| 677 | + * quotient bits, we will know when to stop when the remainder | |
| 678 | + * is <= M. | |
| 679 | + * | |
| 680 | + * We keep track of powers of 2 and powers of 5. | |
| 681 | + */ | |
| 682 | + | |
| 683 | + /* | |
| 684 | + * Estimate decimal exponent. (If it is small-ish, | |
| 685 | + * we could double-check.) | |
| 686 | + * | |
| 687 | + * First, scale the mantissa bits such that 1 <= d2 < 2. | |
| 688 | + * We are then going to estimate | |
| 689 | + * log10(d2) ~=~ (d2-1.5)/1.5 + log(1.5) | |
| 690 | + * and so we can estimate | |
| 691 | + * log10(d) ~=~ log10(d2) + binExp * log10(2) | |
| 692 | + * take the floor and call it decExp. | |
| 693 | + * FIXME -- use more precise constants here. It costs no more. | |
| 694 | + */ | |
| 695 | + double d2 = Double.longBitsToDouble( | |
| 696 | + expOne | ( fractBits &~ fractHOB ) ); | |
| 697 | + decExp = (int)Math.floor( | |
| 698 | + (d2-1.5D)*0.289529654D + 0.176091259 + (double)binExp * 0.301029995663981 ); | |
| 699 | + int B2, B5; // powers of 2 and powers of 5, respectively, in B | |
| 700 | + int S2, S5; // powers of 2 and powers of 5, respectively, in S | |
| 701 | + int M2, M5; // powers of 2 and powers of 5, respectively, in M | |
| 702 | + int Bbits; // binary digits needed to represent B, approx. | |
| 703 | + int tenSbits; // binary digits needed to represent 10*S, approx. | |
| 704 | + FDBigInt Sval, Bval, Mval; | |
| 705 | + | |
| 706 | + B5 = Math.max( 0, -decExp ); | |
| 707 | + B2 = B5 + nTinyBits + binExp; | |
| 708 | + | |
| 709 | + S5 = Math.max( 0, decExp ); | |
| 710 | + S2 = S5 + nTinyBits; | |
| 711 | + | |
| 712 | + M5 = B5; | |
| 713 | + M2 = B2 - nSignificantBits; | |
| 714 | + | |
| 715 | + /* | |
| 716 | + * the long integer fractBits contains the (nFractBits) interesting | |
| 717 | + * bits from the mantissa of d ( hidden 1 added if necessary) followed | |
| 718 | + * by (expShift+1-nFractBits) zeros. In the interest of compactness, | |
| 719 | + * I will shift out those zeros before turning fractBits into a | |
| 720 | + * FDBigInt. The resulting whole number will be | |
| 721 | + * d * 2^(nFractBits-1-binExp). | |
| 722 | + */ | |
| 723 | + fractBits >>>= (expShift+1-nFractBits); | |
| 724 | + B2 -= nFractBits-1; | |
| 725 | + int common2factor = Math.min( B2, S2 ); | |
| 726 | + B2 -= common2factor; | |
| 727 | + S2 -= common2factor; | |
| 728 | + M2 -= common2factor; | |
| 729 | + | |
| 730 | + /* | |
| 731 | + * HACK!! For exact powers of two, the next smallest number | |
| 732 | + * is only half as far away as we think (because the meaning of | |
| 733 | + * ULP changes at power-of-two bounds) for this reason, we | |
| 734 | + * hack M2. Hope this works. | |
| 735 | + */ | |
| 736 | + if ( nFractBits == 1 ) | |
| 737 | + M2 -= 1; | |
| 738 | + | |
| 739 | + if ( M2 < 0 ){ | |
| 740 | + // oops. | |
| 741 | + // since we cannot scale M down far enough, | |
| 742 | + // we must scale the other values up. | |
| 743 | + B2 -= M2; | |
| 744 | + S2 -= M2; | |
| 745 | + M2 = 0; | |
| 746 | + } | |
| 747 | + /* | |
| 748 | + * Construct, Scale, iterate. | |
| 749 | + * Some day, we'll write a stopping test that takes | |
| 750 | + * account of the assymetry of the spacing of floating-point | |
| 751 | + * numbers below perfect powers of 2 | |
| 752 | + * 26 Sept 96 is not that day. | |
| 753 | + * So we use a symmetric test. | |
| 754 | + */ | |
| 755 | + char digits[] = this.digits = new char[18]; | |
| 756 | + int ndigit = 0; | |
| 757 | + boolean low, high; | |
| 758 | + long lowDigitDifference; | |
| 759 | + int q; | |
| 760 | + | |
| 761 | + /* | |
| 762 | + * Detect the special cases where all the numbers we are about | |
| 763 | + * to compute will fit in int or long integers. | |
| 764 | + * In these cases, we will avoid doing FDBigInt arithmetic. | |
| 765 | + * We use the same algorithms, except that we "normalize" | |
| 766 | + * our FDBigInts before iterating. This is to make division easier, | |
| 767 | + * as it makes our fist guess (quotient of high-order words) | |
| 768 | + * more accurate! | |
| 769 | + * | |
| 770 | + * Some day, we'll write a stopping test that takes | |
| 771 | + * account of the assymetry of the spacing of floating-point | |
| 772 | + * numbers below perfect powers of 2 | |
| 773 | + * 26 Sept 96 is not that day. | |
| 774 | + * So we use a symmetric test. | |
| 775 | + */ | |
| 776 | + Bbits = nFractBits + B2 + (( B5 < n5bits.length )? n5bits[B5] : ( B5*3 )); | |
| 777 | + tenSbits = S2+1 + (( (S5+1) < n5bits.length )? n5bits[(S5+1)] : ( (S5+1)*3 )); | |
| 778 | + if ( Bbits < 64 && tenSbits < 64){ | |
| 779 | + if ( Bbits < 32 && tenSbits < 32){ | |
| 780 | + // wa-hoo! They're all ints! | |
| 781 | + int b = ((int)fractBits * small5pow[B5] ) << B2; | |
| 782 | + int s = small5pow[S5] << S2; | |
| 783 | + int m = small5pow[M5] << M2; | |
| 784 | + int tens = s * 10; | |
| 785 | + /* | |
| 786 | + * Unroll the first iteration. If our decExp estimate | |
| 787 | + * was too high, our first quotient will be zero. In this | |
| 788 | + * case, we discard it and decrement decExp. | |
| 789 | + */ | |
| 790 | + ndigit = 0; | |
| 791 | + q = b / s; | |
| 792 | + b = 10 * ( b % s ); | |
| 793 | + m *= 10; | |
| 794 | + low = (b < m ); | |
| 795 | + high = (b+m > tens ); | |
| 796 | + assert q < 10 : q; // excessively large digit | |
| 797 | + if ( (q == 0) && ! high ){ | |
| 798 | + // oops. Usually ignore leading zero. | |
| 799 | + decExp--; | |
| 800 | + } else { | |
| 801 | + digits[ndigit++] = (char)('0' + q); | |
| 802 | + } | |
| 803 | + /* | |
| 804 | + * HACK! Java spec sez that we always have at least | |
| 805 | + * one digit after the . in either F- or E-form output. | |
| 806 | + * Thus we will need more than one digit if we're using | |
| 807 | + * E-form | |
| 808 | + */ | |
| 809 | + if (! (form == Form.COMPATIBLE && -3 < decExp && decExp < 8)) { | |
| 810 | + high = low = false; | |
| 811 | + } | |
| 812 | + while( ! low && ! high ){ | |
| 813 | + q = b / s; | |
| 814 | + b = 10 * ( b % s ); | |
| 815 | + m *= 10; | |
| 816 | + assert q < 10 : q; // excessively large digit | |
| 817 | + if ( m > 0L ){ | |
| 818 | + low = (b < m ); | |
| 819 | + high = (b+m > tens ); | |
| 820 | + } else { | |
| 821 | + // hack -- m might overflow! | |
| 822 | + // in this case, it is certainly > b, | |
| 823 | + // which won't | |
| 824 | + // and b+m > tens, too, since that has overflowed | |
| 825 | + // either! | |
| 826 | + low = true; | |
| 827 | + high = true; | |
| 828 | + } | |
| 829 | + digits[ndigit++] = (char)('0' + q); | |
| 830 | + } | |
| 831 | + lowDigitDifference = (b<<1) - tens; | |
| 832 | + } else { | |
| 833 | + // still good! they're all longs! | |
| 834 | + long b = (fractBits * long5pow[B5] ) << B2; | |
| 835 | + long s = long5pow[S5] << S2; | |
| 836 | + long m = long5pow[M5] << M2; | |
| 837 | + long tens = s * 10L; | |
| 838 | + /* | |
| 839 | + * Unroll the first iteration. If our decExp estimate | |
| 840 | + * was too high, our first quotient will be zero. In this | |
| 841 | + * case, we discard it and decrement decExp. | |
| 842 | + */ | |
| 843 | + ndigit = 0; | |
| 844 | + q = (int) ( b / s ); | |
| 845 | + b = 10L * ( b % s ); | |
| 846 | + m *= 10L; | |
| 847 | + low = (b < m ); | |
| 848 | + high = (b+m > tens ); | |
| 849 | + assert q < 10 : q; // excessively large digit | |
| 850 | + if ( (q == 0) && ! high ){ | |
| 851 | + // oops. Usually ignore leading zero. | |
| 852 | + decExp--; | |
| 853 | + } else { | |
| 854 | + digits[ndigit++] = (char)('0' + q); | |
| 855 | + } | |
| 856 | + /* | |
| 857 | + * HACK! Java spec sez that we always have at least | |
| 858 | + * one digit after the . in either F- or E-form output. | |
| 859 | + * Thus we will need more than one digit if we're using | |
| 860 | + * E-form | |
| 861 | + */ | |
| 862 | + if (! (form == Form.COMPATIBLE && -3 < decExp && decExp < 8)) { | |
| 863 | + high = low = false; | |
| 864 | + } | |
| 865 | + while( ! low && ! high ){ | |
| 866 | + q = (int) ( b / s ); | |
| 867 | + b = 10 * ( b % s ); | |
| 868 | + m *= 10; | |
| 869 | + assert q < 10 : q; // excessively large digit | |
| 870 | + if ( m > 0L ){ | |
| 871 | + low = (b < m ); | |
| 872 | + high = (b+m > tens ); | |
| 873 | + } else { | |
| 874 | + // hack -- m might overflow! | |
| 875 | + // in this case, it is certainly > b, | |
| 876 | + // which won't | |
| 877 | + // and b+m > tens, too, since that has overflowed | |
| 878 | + // either! | |
| 879 | + low = true; | |
| 880 | + high = true; | |
| 881 | + } | |
| 882 | + digits[ndigit++] = (char)('0' + q); | |
| 883 | + } | |
| 884 | + lowDigitDifference = (b<<1) - tens; | |
| 885 | + } | |
| 886 | + } else { | |
| 887 | + FDBigInt tenSval; | |
| 888 | + int shiftBias; | |
| 889 | + | |
| 890 | + /* | |
| 891 | + * We really must do FDBigInt arithmetic. | |
| 892 | + * Fist, construct our FDBigInt initial values. | |
| 893 | + */ | |
| 894 | + Bval = multPow52( new FDBigInt( fractBits ), B5, B2 ); | |
| 895 | + Sval = constructPow52( S5, S2 ); | |
| 896 | + Mval = constructPow52( M5, M2 ); | |
| 897 | + | |
| 898 | + | |
| 899 | + // normalize so that division works better | |
| 900 | + Bval.lshiftMe( shiftBias = Sval.normalizeMe() ); | |
| 901 | + Mval.lshiftMe( shiftBias ); | |
| 902 | + tenSval = Sval.mult( 10 ); | |
| 903 | + /* | |
| 904 | + * Unroll the first iteration. If our decExp estimate | |
| 905 | + * was too high, our first quotient will be zero. In this | |
| 906 | + * case, we discard it and decrement decExp. | |
| 907 | + */ | |
| 908 | + ndigit = 0; | |
| 909 | + q = Bval.quoRemIteration( Sval ); | |
| 910 | + Mval = Mval.mult( 10 ); | |
| 911 | + low = (Bval.cmp( Mval ) < 0); | |
| 912 | + high = (Bval.add( Mval ).cmp( tenSval ) > 0 ); | |
| 913 | + assert q < 10 : q; // excessively large digit | |
| 914 | + if ( (q == 0) && ! high ){ | |
| 915 | + // oops. Usually ignore leading zero. | |
| 916 | + decExp--; | |
| 917 | + } else { | |
| 918 | + digits[ndigit++] = (char)('0' + q); | |
| 919 | + } | |
| 920 | + /* | |
| 921 | + * HACK! Java spec sez that we always have at least | |
| 922 | + * one digit after the . in either F- or E-form output. | |
| 923 | + * Thus we will need more than one digit if we're using | |
| 924 | + * E-form | |
| 925 | + */ | |
| 926 | + if (! (form == Form.COMPATIBLE && -3 < decExp && decExp < 8)) { | |
| 927 | + high = low = false; | |
| 928 | + } | |
| 929 | + while( ! low && ! high ){ | |
| 930 | + q = Bval.quoRemIteration( Sval ); | |
| 931 | + Mval = Mval.mult( 10 ); | |
| 932 | + assert q < 10 : q; // excessively large digit | |
| 933 | + low = (Bval.cmp( Mval ) < 0); | |
| 934 | + high = (Bval.add( Mval ).cmp( tenSval ) > 0 ); | |
| 935 | + digits[ndigit++] = (char)('0' + q); | |
| 936 | + } | |
| 937 | + if ( high && low ){ | |
| 938 | + Bval.lshiftMe(1); | |
| 939 | + lowDigitDifference = Bval.cmp(tenSval); | |
| 940 | + } else | |
| 941 | + lowDigitDifference = 0L; // this here only for flow analysis! | |
| 942 | + } | |
| 943 | + this.decExponent = decExp+1; | |
| 944 | + this.digits = digits; | |
| 945 | + this.nDigits = ndigit; | |
| 946 | + /* | |
| 947 | + * Last digit gets rounded based on stopping condition. | |
| 948 | + */ | |
| 949 | + if ( high ){ | |
| 950 | + if ( low ){ | |
| 951 | + if ( lowDigitDifference == 0L ){ | |
| 952 | + // it's a tie! | |
| 953 | + // choose based on which digits we like. | |
| 954 | + if ( (digits[nDigits-1]&1) != 0 ) roundup(); | |
| 955 | + } else if ( lowDigitDifference > 0 ){ | |
| 956 | + roundup(); | |
| 957 | + } | |
| 958 | + } else { | |
| 959 | + roundup(); | |
| 960 | + } | |
| 961 | + } | |
| 962 | + } | |
| 963 | + | |
| 964 | + public String | |
| 965 | + toString(){ | |
| 966 | + // most brain-dead version | |
| 967 | + StringBuffer result = new StringBuffer( nDigits+8 ); | |
| 968 | + if ( isNegative ){ result.append( '-' ); } | |
| 969 | + if ( isExceptional ){ | |
| 970 | + result.append( digits, 0, nDigits ); | |
| 971 | + } else { | |
| 972 | + result.append( "0."); | |
| 973 | + result.append( digits, 0, nDigits ); | |
| 974 | + result.append('e'); | |
| 975 | + result.append( decExponent ); | |
| 976 | + } | |
| 977 | + return new String(result); | |
| 978 | + } | |
| 979 | + | |
| 980 | + // returns the exponent before rounding | |
| 981 | + public int getExponent() { | |
| 982 | + return decExponent - 1; | |
| 983 | + } | |
| 984 | + | |
| 985 | + // returns the exponent after rounding has been done by applyPrecision | |
| 986 | + public int getExponentRounded() { | |
| 987 | + return decExponentRounded - 1; | |
| 988 | + } | |
| 989 | + | |
| 990 | + public int getChars(char[] result) { | |
| 991 | + assert nDigits <= 19 : nDigits; // generous bound on size of nDigits | |
| 992 | + int i = 0; | |
| 993 | + if (isNegative) { result[0] = '-'; i = 1; } | |
| 994 | + if (isExceptional) { | |
| 995 | + System.arraycopy(digits, 0, result, i, nDigits); | |
| 996 | + i += nDigits; | |
| 997 | + } else { | |
| 998 | + char digits [] = this.digits; | |
| 999 | + int exp = decExponent; | |
| 1000 | + switch (form) { | |
| 1001 | + case COMPATIBLE: | |
| 1002 | + break; | |
| 1003 | + case DECIMAL_FLOAT: | |
| 1004 | + exp = checkExponent(decExponent + precision); | |
| 1005 | + digits = applyPrecision(decExponent + precision); | |
| 1006 | + break; | |
| 1007 | + case SCIENTIFIC: | |
| 1008 | + exp = checkExponent(precision + 1); | |
| 1009 | + digits = applyPrecision(precision + 1); | |
| 1010 | + break; | |
| 1011 | + case GENERAL: | |
| 1012 | + exp = checkExponent(precision); | |
| 1013 | + digits = applyPrecision(precision); | |
| 1014 | + // adjust precision to be the number of digits to right of decimal | |
| 1015 | + // the real exponent to be output is actually exp - 1, not exp | |
| 1016 | + if (exp - 1 < -4 || exp - 1 >= precision) { | |
| 1017 | + form = Form.SCIENTIFIC; | |
| 1018 | + precision--; | |
| 1019 | + } else { | |
| 1020 | + form = Form.DECIMAL_FLOAT; | |
| 1021 | + precision = precision - exp; | |
| 1022 | + } | |
| 1023 | + break; | |
| 1024 | + default: | |
| 1025 | + assert false; | |
| 1026 | + } | |
| 1027 | + decExponentRounded = exp; | |
| 1028 | + | |
| 1029 | + if (exp > 0 | |
| 1030 | + && ((form == Form.COMPATIBLE && (exp < 8)) | |
| 1031 | + || (form == Form.DECIMAL_FLOAT))) | |
| 1032 | + { | |
| 1033 | + // print digits.digits. | |
| 1034 | + int charLength = Math.min(nDigits, exp); | |
| 1035 | + System.arraycopy(digits, 0, result, i, charLength); | |
| 1036 | + i += charLength; | |
| 1037 | + if (charLength < exp) { | |
| 1038 | + charLength = exp-charLength; | |
| 1039 | + for (int nz = 0; nz < charLength; nz++) | |
| 1040 | + result[i++] = '0'; | |
| 1041 | + // Do not append ".0" for formatted floats since the user | |
| 1042 | + // may request that it be omitted. It is added as necessary | |
| 1043 | + // by the Formatter. | |
| 1044 | + if (form == Form.COMPATIBLE) { | |
| 1045 | + result[i++] = '.'; | |
| 1046 | + result[i++] = '0'; | |
| 1047 | + } | |
| 1048 | + } else { | |
| 1049 | + // Do not append ".0" for formatted floats since the user | |
| 1050 | + // may request that it be omitted. It is added as necessary | |
| 1051 | + // by the Formatter. | |
| 1052 | + if (form == Form.COMPATIBLE) { | |
| 1053 | + result[i++] = '.'; | |
| 1054 | + if (charLength < nDigits) { | |
| 1055 | + int t = Math.min(nDigits - charLength, precision); | |
| 1056 | + System.arraycopy(digits, charLength, result, i, t); | |
| 1057 | + i += t; | |
| 1058 | + } else { | |
| 1059 | + result[i++] = '0'; | |
| 1060 | + } | |
| 1061 | + } else { | |
| 1062 | + int t = Math.min(nDigits - charLength, precision); | |
| 1063 | + if (t > 0) { | |
| 1064 | + result[i++] = '.'; | |
| 1065 | + System.arraycopy(digits, charLength, result, i, t); | |
| 1066 | + i += t; | |
| 1067 | + } | |
| 1068 | + } | |
| 1069 | + } | |
| 1070 | + } else if (exp <= 0 | |
| 1071 | + && ((form == Form.COMPATIBLE && exp > -3) | |
| 1072 | + || (form == Form.DECIMAL_FLOAT))) | |
| 1073 | + { | |
| 1074 | + // print 0.0* digits | |
| 1075 | + result[i++] = '0'; | |
| 1076 | + if (exp != 0) { | |
| 1077 | + // write '0' s before the significant digits | |
| 1078 | + int t = Math.min(-exp, precision); | |
| 1079 | + if (t > 0) { | |
| 1080 | + result[i++] = '.'; | |
| 1081 | + for (int nz = 0; nz < t; nz++) | |
| 1082 | + result[i++] = '0'; | |
| 1083 | + } | |
| 1084 | + } | |
| 1085 | + int t = Math.min(digits.length, precision + exp); | |
| 1086 | + if (t > 0) { | |
| 1087 | + if (i == 1) | |
| 1088 | + result[i++] = '.'; | |
| 1089 | + // copy only when significant digits are within the precision | |
| 1090 | + System.arraycopy(digits, 0, result, i, t); | |
| 1091 | + i += t; | |
| 1092 | + } | |
| 1093 | + } else { | |
| 1094 | + result[i++] = digits[0]; | |
| 1095 | + if (form == Form.COMPATIBLE) { | |
| 1096 | + result[i++] = '.'; | |
| 1097 | + if (nDigits > 1) { | |
| 1098 | + System.arraycopy(digits, 1, result, i, nDigits-1); | |
| 1099 | + i += nDigits-1; | |
| 1100 | + } else { | |
| 1101 | + result[i++] = '0'; | |
| 1102 | + } | |
| 1103 | + result[i++] = 'E'; | |
| 1104 | + } else { | |
| 1105 | + if (nDigits > 1) { | |
| 1106 | + int t = Math.min(nDigits -1, precision); | |
| 1107 | + if (t > 0) { | |
| 1108 | + result[i++] = '.'; | |
| 1109 | + System.arraycopy(digits, 1, result, i, t); | |
| 1110 | + i += t; | |
| 1111 | + } | |
| 1112 | + } | |
| 1113 | + result[i++] = 'e'; | |
| 1114 | + } | |
| 1115 | + int e; | |
| 1116 | + if (exp <= 0) { | |
| 1117 | + result[i++] = '-'; | |
| 1118 | + e = -exp+1; | |
| 1119 | + } else { | |
| 1120 | + if (form != Form.COMPATIBLE) | |
| 1121 | + result[i++] = '+'; | |
| 1122 | + e = exp-1; | |
| 1123 | + } | |
| 1124 | + // decExponent has 1, 2, or 3, digits | |
| 1125 | + if (e <= 9) { | |
| 1126 | + if (form != Form.COMPATIBLE) | |
| 1127 | + result[i++] = '0'; | |
| 1128 | + result[i++] = (char)(e+'0'); | |
| 1129 | + } else if (e <= 99) { | |
| 1130 | + result[i++] = (char)(e/10 +'0'); | |
| 1131 | + result[i++] = (char)(e%10 + '0'); | |
| 1132 | + } else { | |
| 1133 | + result[i++] = (char)(e/100+'0'); | |
| 1134 | + e %= 100; | |
| 1135 | + result[i++] = (char)(e/10+'0'); | |
| 1136 | + result[i++] = (char)(e%10 + '0'); | |
| 1137 | + } | |
| 1138 | + } | |
| 1139 | + } | |
| 1140 | + return i; | |
| 1141 | + } | |
| 1142 | + | |
| 1143 | + // Per-thread buffer for string/stringbuffer conversion | |
| 1144 | + private static ThreadLocal perThreadBuffer = new ThreadLocal() { | |
| 1145 | + protected synchronized Object initialValue() { | |
| 1146 | + return new char[26]; | |
| 1147 | + } | |
| 1148 | + }; | |
| 1149 | + | |
| 1150 | + /* | |
| 1151 | + * Take a FormattedFloatingDecimal, which we presumably just scanned in, | |
| 1152 | + * and find out what its value is, as a double. | |
| 1153 | + * | |
| 1154 | + * AS A SIDE EFFECT, SET roundDir TO INDICATE PREFERRED | |
| 1155 | + * ROUNDING DIRECTION in case the result is really destined | |
| 1156 | + * for a single-precision float. | |
| 1157 | + */ | |
| 1158 | + | |
| 1159 | + public strictfp double doubleValue(){ | |
| 1160 | + int kDigits = Math.min( nDigits, maxDecimalDigits+1 ); | |
| 1161 | + long lValue; | |
| 1162 | + double dValue; | |
| 1163 | + double rValue, tValue; | |
| 1164 | + | |
| 1165 | + // First, check for NaN and Infinity values | |
| 1166 | + if(digits == infinity || digits == notANumber) { | |
| 1167 | + if(digits == notANumber) | |
| 1168 | + return Double.NaN; | |
| 1169 | + else | |
| 1170 | + return (isNegative?Double.NEGATIVE_INFINITY:Double.POSITIVE_INFINITY); | |
| 1171 | + } | |
| 1172 | + else { | |
| 1173 | + if (mustSetRoundDir) { | |
| 1174 | + roundDir = 0; | |
| 1175 | + } | |
| 1176 | + /* | |
| 1177 | + * convert the lead kDigits to a long integer. | |
| 1178 | + */ | |
| 1179 | + // (special performance hack: start to do it using int) | |
| 1180 | + int iValue = (int)digits[0]-(int)'0'; | |
| 1181 | + int iDigits = Math.min( kDigits, intDecimalDigits ); | |
| 1182 | + for ( int i=1; i < iDigits; i++ ){ | |
| 1183 | + iValue = iValue*10 + (int)digits[i]-(int)'0'; | |
| 1184 | + } | |
| 1185 | + lValue = (long)iValue; | |
| 1186 | + for ( int i=iDigits; i < kDigits; i++ ){ | |
| 1187 | + lValue = lValue*10L + (long)((int)digits[i]-(int)'0'); | |
| 1188 | + } | |
| 1189 | + dValue = (double)lValue; | |
| 1190 | + int exp = decExponent-kDigits; | |
| 1191 | + /* | |
| 1192 | + * lValue now contains a long integer with the value of | |
| 1193 | + * the first kDigits digits of the number. | |
| 1194 | + * dValue contains the (double) of the same. | |
| 1195 | + */ | |
| 1196 | + | |
| 1197 | + if ( nDigits <= maxDecimalDigits ){ | |
| 1198 | + /* | |
| 1199 | + * possibly an easy case. | |
| 1200 | + * We know that the digits can be represented | |
| 1201 | + * exactly. And if the exponent isn't too outrageous, | |
| 1202 | + * the whole thing can be done with one operation, | |
| 1203 | + * thus one rounding error. | |
| 1204 | + * Note that all our constructors trim all leading and | |
| 1205 | + * trailing zeros, so simple values (including zero) | |
| 1206 | + * will always end up here | |
| 1207 | + */ | |
| 1208 | + if (exp == 0 || dValue == 0.0) | |
| 1209 | + return (isNegative)? -dValue : dValue; // small floating integer | |
| 1210 | + else if ( exp >= 0 ){ | |
| 1211 | + if ( exp <= maxSmallTen ){ | |
| 1212 | + /* | |
| 1213 | + * Can get the answer with one operation, | |
| 1214 | + * thus one roundoff. | |
| 1215 | + */ | |
| 1216 | + rValue = dValue * small10pow[exp]; | |
| 1217 | + if ( mustSetRoundDir ){ | |
| 1218 | + tValue = rValue / small10pow[exp]; | |
| 1219 | + roundDir = ( tValue == dValue ) ? 0 | |
| 1220 | + :( tValue < dValue ) ? 1 | |
| 1221 | + : -1; | |
| 1222 | + } | |
| 1223 | + return (isNegative)? -rValue : rValue; | |
| 1224 | + } | |
| 1225 | + int slop = maxDecimalDigits - kDigits; | |
| 1226 | + if ( exp <= maxSmallTen+slop ){ | |
| 1227 | + /* | |
| 1228 | + * We can multiply dValue by 10^(slop) | |
| 1229 | + * and it is still "small" and exact. | |
| 1230 | + * Then we can multiply by 10^(exp-slop) | |
| 1231 | + * with one rounding. | |
| 1232 | + */ | |
| 1233 | + dValue *= small10pow[slop]; | |
| 1234 | + rValue = dValue * small10pow[exp-slop]; | |
| 1235 | + | |
| 1236 | + if ( mustSetRoundDir ){ | |
| 1237 | + tValue = rValue / small10pow[exp-slop]; | |
| 1238 | + roundDir = ( tValue == dValue ) ? 0 | |
| 1239 | + :( tValue < dValue ) ? 1 | |
| 1240 | + : -1; | |
| 1241 | + } | |
| 1242 | + return (isNegative)? -rValue : rValue; | |
| 1243 | + } | |
| 1244 | + /* | |
| 1245 | + * Else we have a hard case with a positive exp. | |
| 1246 | + */ | |
| 1247 | + } else { | |
| 1248 | + if ( exp >= -maxSmallTen ){ | |
| 1249 | + /* | |
| 1250 | + * Can get the answer in one division. | |
| 1251 | + */ | |
| 1252 | + rValue = dValue / small10pow[-exp]; | |
| 1253 | + tValue = rValue * small10pow[-exp]; | |
| 1254 | + if ( mustSetRoundDir ){ | |
| 1255 | + roundDir = ( tValue == dValue ) ? 0 | |
| 1256 | + :( tValue < dValue ) ? 1 | |
| 1257 | + : -1; | |
| 1258 | + } | |
| 1259 | + return (isNegative)? -rValue : rValue; | |
| 1260 | + } | |
| 1261 | + /* | |
| 1262 | + * Else we have a hard case with a negative exp. | |
| 1263 | + */ | |
| 1264 | + } | |
| 1265 | + } | |
| 1266 | + | |
| 1267 | + /* | |
| 1268 | + * Harder cases: | |
| 1269 | + * The sum of digits plus exponent is greater than | |
| 1270 | + * what we think we can do with one error. | |
| 1271 | + * | |
| 1272 | + * Start by approximating the right answer by, | |
| 1273 | + * naively, scaling by powers of 10. | |
| 1274 | + */ | |
| 1275 | + if ( exp > 0 ){ | |
| 1276 | + if ( decExponent > maxDecimalExponent+1 ){ | |
| 1277 | + /* | |
| 1278 | + * Lets face it. This is going to be | |
| 1279 | + * Infinity. Cut to the chase. | |
| 1280 | + */ | |
| 1281 | + return (isNegative)? Double.NEGATIVE_INFINITY : Double.POSITIVE_INFINITY; | |
| 1282 | + } | |
| 1283 | + if ( (exp&15) != 0 ){ | |
| 1284 | + dValue *= small10pow[exp&15]; | |
| 1285 | + } | |
| 1286 | + if ( (exp>>=4) != 0 ){ | |
| 1287 | + int j; | |
| 1288 | + for( j = 0; exp > 1; j++, exp>>=1 ){ | |
| 1289 | + if ( (exp&1)!=0) | |
| 1290 | + dValue *= big10pow[j]; | |
| 1291 | + } | |
| 1292 | + /* | |
| 1293 | + * The reason for the weird exp > 1 condition | |
| 1294 | + * in the above loop was so that the last multiply | |
| 1295 | + * would get unrolled. We handle it here. | |
| 1296 | + * It could overflow. | |
| 1297 | + */ | |
| 1298 | + double t = dValue * big10pow[j]; | |
| 1299 | + if ( Double.isInfinite( t ) ){ | |
| 1300 | + /* | |
| 1301 | + * It did overflow. | |
| 1302 | + * Look more closely at the result. | |
| 1303 | + * If the exponent is just one too large, | |
| 1304 | + * then use the maximum finite as our estimate | |
| 1305 | + * value. Else call the result infinity | |
| 1306 | + * and punt it. | |
| 1307 | + * ( I presume this could happen because | |
| 1308 | + * rounding forces the result here to be | |
| 1309 | + * an ULP or two larger than | |
| 1310 | + * Double.MAX_VALUE ). | |
| 1311 | + */ | |
| 1312 | + t = dValue / 2.0; | |
| 1313 | + t *= big10pow[j]; | |
| 1314 | + if ( Double.isInfinite( t ) ){ | |
| 1315 | + return (isNegative)? Double.NEGATIVE_INFINITY : Double.POSITIVE_INFINITY; | |
| 1316 | + } | |
| 1317 | + t = Double.MAX_VALUE; | |
| 1318 | + } | |
| 1319 | + dValue = t; | |
| 1320 | + } | |
| 1321 | + } else if ( exp < 0 ){ | |
| 1322 | + exp = -exp; | |
| 1323 | + if ( decExponent < minDecimalExponent-1 ){ | |
| 1324 | + /* | |
| 1325 | + * Lets face it. This is going to be | |
| 1326 | + * zero. Cut to the chase. | |
| 1327 | + */ | |
| 1328 | + return (isNegative)? -0.0 : 0.0; | |
| 1329 | + } | |
| 1330 | + if ( (exp&15) != 0 ){ | |
| 1331 | + dValue /= small10pow[exp&15]; | |
| 1332 | + } | |
| 1333 | + if ( (exp>>=4) != 0 ){ | |
| 1334 | + int j; | |
| 1335 | + for( j = 0; exp > 1; j++, exp>>=1 ){ | |
| 1336 | + if ( (exp&1)!=0) | |
| 1337 | + dValue *= tiny10pow[j]; | |
| 1338 | + } | |
| 1339 | + /* | |
| 1340 | + * The reason for the weird exp > 1 condition | |
| 1341 | + * in the above loop was so that the last multiply | |
| 1342 | + * would get unrolled. We handle it here. | |
| 1343 | + * It could underflow. | |
| 1344 | + */ | |
| 1345 | + double t = dValue * tiny10pow[j]; | |
| 1346 | + if ( t == 0.0 ){ | |
| 1347 | + /* | |
| 1348 | + * It did underflow. | |
| 1349 | + * Look more closely at the result. | |
| 1350 | + * If the exponent is just one too small, | |
| 1351 | + * then use the minimum finite as our estimate | |
| 1352 | + * value. Else call the result 0.0 | |
| 1353 | + * and punt it. | |
| 1354 | + * ( I presume this could happen because | |
| 1355 | + * rounding forces the result here to be | |
| 1356 | + * an ULP or two less than | |
| 1357 | + * Double.MIN_VALUE ). | |
| 1358 | + */ | |
| 1359 | + t = dValue * 2.0; | |
| 1360 | + t *= tiny10pow[j]; | |
| 1361 | + if ( t == 0.0 ){ | |
| 1362 | + return (isNegative)? -0.0 : 0.0; | |
| 1363 | + } | |
| 1364 | + t = Double.MIN_VALUE; | |
| 1365 | + } | |
| 1366 | + dValue = t; | |
| 1367 | + } | |
| 1368 | + } | |
| 1369 | + | |
| 1370 | + /* | |
| 1371 | + * dValue is now approximately the result. | |
| 1372 | + * The hard part is adjusting it, by comparison | |
| 1373 | + * with FDBigInt arithmetic. | |
| 1374 | + * Formulate the EXACT big-number result as | |
| 1375 | + * bigD0 * 10^exp | |
| 1376 | + */ | |
| 1377 | + FDBigInt bigD0 = new FDBigInt( lValue, digits, kDigits, nDigits ); | |
| 1378 | + exp = decExponent - nDigits; | |
| 1379 | + | |
| 1380 | + correctionLoop: | |
| 1381 | + while(true){ | |
| 1382 | + /* AS A SIDE EFFECT, THIS METHOD WILL SET THE INSTANCE VARIABLES | |
| 1383 | + * bigIntExp and bigIntNBits | |
| 1384 | + */ | |
| 1385 | + FDBigInt bigB = doubleToBigInt( dValue ); | |
| 1386 | + | |
| 1387 | + /* | |
| 1388 | + * Scale bigD, bigB appropriately for | |
| 1389 | + * big-integer operations. | |
| 1390 | + * Naively, we multipy by powers of ten | |
| 1391 | + * and powers of two. What we actually do | |
| 1392 | + * is keep track of the powers of 5 and | |
| 1393 | + * powers of 2 we would use, then factor out | |
| 1394 | + * common divisors before doing the work. | |
| 1395 | + */ | |
| 1396 | + int B2, B5; // powers of 2, 5 in bigB | |
| 1397 | + int D2, D5; // powers of 2, 5 in bigD | |
| 1398 | + int Ulp2; // powers of 2 in halfUlp. | |
| 1399 | + if ( exp >= 0 ){ | |
| 1400 | + B2 = B5 = 0; | |
| 1401 | + D2 = D5 = exp; | |
| 1402 | + } else { | |
| 1403 | + B2 = B5 = -exp; | |
| 1404 | + D2 = D5 = 0; | |
| 1405 | + } | |
| 1406 | + if ( bigIntExp >= 0 ){ | |
| 1407 | + B2 += bigIntExp; | |
| 1408 | + } else { | |
| 1409 | + D2 -= bigIntExp; | |
| 1410 | + } | |
| 1411 | + Ulp2 = B2; | |
| 1412 | + // shift bigB and bigD left by a number s. t. | |
| 1413 | + // halfUlp is still an integer. | |
| 1414 | + int hulpbias; | |
| 1415 | + if ( bigIntExp+bigIntNBits <= -expBias+1 ){ | |
| 1416 | + // This is going to be a denormalized number | |
| 1417 | + // (if not actually zero). | |
| 1418 | + // half an ULP is at 2^-(expBias+expShift+1) | |
| 1419 | + hulpbias = bigIntExp+ expBias + expShift; | |
| 1420 | + } else { | |
| 1421 | + hulpbias = expShift + 2 - bigIntNBits; | |
| 1422 | + } | |
| 1423 | + B2 += hulpbias; | |
| 1424 | + D2 += hulpbias; | |
| 1425 | + // if there are common factors of 2, we might just as well | |
| 1426 | + // factor them out, as they add nothing useful. | |
| 1427 | + int common2 = Math.min( B2, Math.min( D2, Ulp2 ) ); | |
| 1428 | + B2 -= common2; | |
| 1429 | + D2 -= common2; | |
| 1430 | + Ulp2 -= common2; | |
| 1431 | + // do multiplications by powers of 5 and 2 | |
| 1432 | + bigB = multPow52( bigB, B5, B2 ); | |
| 1433 | + FDBigInt bigD = multPow52( new FDBigInt( bigD0 ), D5, D2 ); | |
| 1434 | + // | |
| 1435 | + // to recap: | |
| 1436 | + // bigB is the scaled-big-int version of our floating-point | |
| 1437 | + // candidate. | |
| 1438 | + // bigD is the scaled-big-int version of the exact value | |
| 1439 | + // as we understand it. | |
| 1440 | + // halfUlp is 1/2 an ulp of bigB, except for special cases | |
| 1441 | + // of exact powers of 2 | |
| 1442 | + // | |
| 1443 | + // the plan is to compare bigB with bigD, and if the difference | |
| 1444 | + // is less than halfUlp, then we're satisfied. Otherwise, | |
| 1445 | + // use the ratio of difference to halfUlp to calculate a fudge | |
| 1446 | + // factor to add to the floating value, then go 'round again. | |
| 1447 | + // | |
| 1448 | + FDBigInt diff; | |
| 1449 | + int cmpResult; | |
| 1450 | + boolean overvalue; | |
| 1451 | + if ( (cmpResult = bigB.cmp( bigD ) ) > 0 ){ | |
| 1452 | + overvalue = true; // our candidate is too big. | |
| 1453 | + diff = bigB.sub( bigD ); | |
| 1454 | + if ( (bigIntNBits == 1) && (bigIntExp > -expBias) ){ | |
| 1455 | + // candidate is a normalized exact power of 2 and | |
| 1456 | + // is too big. We will be subtracting. | |
| 1457 | + // For our purposes, ulp is the ulp of the | |
| 1458 | + // next smaller range. | |
| 1459 | + Ulp2 -= 1; | |
| 1460 | + if ( Ulp2 < 0 ){ | |
| 1461 | + // rats. Cannot de-scale ulp this far. | |
| 1462 | + // must scale diff in other direction. | |
| 1463 | + Ulp2 = 0; | |
| 1464 | + diff.lshiftMe( 1 ); | |
| 1465 | + } | |
| 1466 | + } | |
| 1467 | + } else if ( cmpResult < 0 ){ | |
| 1468 | + overvalue = false; // our candidate is too small. | |
| 1469 | + diff = bigD.sub( bigB ); | |
| 1470 | + } else { | |
| 1471 | + // the candidate is exactly right! | |
| 1472 | + // this happens with surprising fequency | |
| 1473 | + break correctionLoop; | |
| 1474 | + } | |
| 1475 | + FDBigInt halfUlp = constructPow52( B5, Ulp2 ); | |
| 1476 | + if ( (cmpResult = diff.cmp( halfUlp ) ) < 0 ){ | |
| 1477 | + // difference is small. | |
| 1478 | + // this is close enough | |
| 1479 | + if (mustSetRoundDir) { | |
| 1480 | + roundDir = overvalue ? -1 : 1; | |
| 1481 | + } | |
| 1482 | + break correctionLoop; | |
| 1483 | + } else if ( cmpResult == 0 ){ | |
| 1484 | + // difference is exactly half an ULP | |
| 1485 | + // round to some other value maybe, then finish | |
| 1486 | + dValue += 0.5*ulp( dValue, overvalue ); | |
| 1487 | + // should check for bigIntNBits == 1 here?? | |
| 1488 | + if (mustSetRoundDir) { | |
| 1489 | + roundDir = overvalue ? -1 : 1; | |
| 1490 | + } | |
| 1491 | + break correctionLoop; | |
| 1492 | + } else { | |
| 1493 | + // difference is non-trivial. | |
| 1494 | + // could scale addend by ratio of difference to | |
| 1495 | + // halfUlp here, if we bothered to compute that difference. | |
| 1496 | + // Most of the time ( I hope ) it is about 1 anyway. | |
| 1497 | + dValue += ulp( dValue, overvalue ); | |
| 1498 | + if ( dValue == 0.0 || dValue == Double.POSITIVE_INFINITY ) | |
| 1499 | + break correctionLoop; // oops. Fell off end of range. | |
| 1500 | + continue; // try again. | |
| 1501 | + } | |
| 1502 | + | |
| 1503 | + } | |
| 1504 | + return (isNegative)? -dValue : dValue; | |
| 1505 | + } | |
| 1506 | + } | |
| 1507 | + | |
| 1508 | + /* | |
| 1509 | + * Take a FormattedFloatingDecimal, which we presumably just scanned in, | |
| 1510 | + * and find out what its value is, as a float. | |
| 1511 | + * This is distinct from doubleValue() to avoid the extremely | |
| 1512 | + * unlikely case of a double rounding error, wherein the converstion | |
| 1513 | + * to double has one rounding error, and the conversion of that double | |
| 1514 | + * to a float has another rounding error, IN THE WRONG DIRECTION, | |
| 1515 | + * ( because of the preference to a zero low-order bit ). | |
| 1516 | + */ | |
| 1517 | + | |
| 1518 | + public strictfp float floatValue(){ | |
| 1519 | + int kDigits = Math.min( nDigits, singleMaxDecimalDigits+1 ); | |
| 1520 | + int iValue; | |
| 1521 | + float fValue; | |
| 1522 | + | |
| 1523 | + // First, check for NaN and Infinity values | |
| 1524 | + if(digits == infinity || digits == notANumber) { | |
| 1525 | + if(digits == notANumber) | |
| 1526 | + return Float.NaN; | |
| 1527 | + else | |
| 1528 | + return (isNegative?Float.NEGATIVE_INFINITY:Float.POSITIVE_INFINITY); | |
| 1529 | + } | |
| 1530 | + else { | |
| 1531 | + /* | |
| 1532 | + * convert the lead kDigits to an integer. | |
| 1533 | + */ | |
| 1534 | + iValue = (int)digits[0]-(int)'0'; | |
| 1535 | + for ( int i=1; i < kDigits; i++ ){ | |
| 1536 | + iValue = iValue*10 + (int)digits[i]-(int)'0'; | |
| 1537 | + } | |
| 1538 | + fValue = (float)iValue; | |
| 1539 | + int exp = decExponent-kDigits; | |
| 1540 | + /* | |
| 1541 | + * iValue now contains an integer with the value of | |
| 1542 | + * the first kDigits digits of the number. | |
| 1543 | + * fValue contains the (float) of the same. | |
| 1544 | + */ | |
| 1545 | + | |
| 1546 | + if ( nDigits <= singleMaxDecimalDigits ){ | |
| 1547 | + /* | |
| 1548 | + * possibly an easy case. | |
| 1549 | + * We know that the digits can be represented | |
| 1550 | + * exactly. And if the exponent isn't too outrageous, | |
| 1551 | + * the whole thing can be done with one operation, | |
| 1552 | + * thus one rounding error. | |
| 1553 | + * Note that all our constructors trim all leading and | |
| 1554 | + * trailing zeros, so simple values (including zero) | |
| 1555 | + * will always end up here. | |
| 1556 | + */ | |
| 1557 | + if (exp == 0 || fValue == 0.0f) | |
| 1558 | + return (isNegative)? -fValue : fValue; // small floating integer | |
| 1559 | + else if ( exp >= 0 ){ | |
| 1560 | + if ( exp <= singleMaxSmallTen ){ | |
| 1561 | + /* | |
| 1562 | + * Can get the answer with one operation, | |
| 1563 | + * thus one roundoff. | |
| 1564 | + */ | |
| 1565 | + fValue *= singleSmall10pow[exp]; | |
| 1566 | + return (isNegative)? -fValue : fValue; | |
| 1567 | + } | |
| 1568 | + int slop = singleMaxDecimalDigits - kDigits; | |
| 1569 | + if ( exp <= singleMaxSmallTen+slop ){ | |
| 1570 | + /* | |
| 1571 | + * We can multiply dValue by 10^(slop) | |
| 1572 | + * and it is still "small" and exact. | |
| 1573 | + * Then we can multiply by 10^(exp-slop) | |
| 1574 | + * with one rounding. | |
| 1575 | + */ | |
| 1576 | + fValue *= singleSmall10pow[slop]; | |
| 1577 | + fValue *= singleSmall10pow[exp-slop]; | |
| 1578 | + return (isNegative)? -fValue : fValue; | |
| 1579 | + } | |
| 1580 | + /* | |
| 1581 | + * Else we have a hard case with a positive exp. | |
| 1582 | + */ | |
| 1583 | + } else { | |
| 1584 | + if ( exp >= -singleMaxSmallTen ){ | |
| 1585 | + /* | |
| 1586 | + * Can get the answer in one division. | |
| 1587 | + */ | |
| 1588 | + fValue /= singleSmall10pow[-exp]; | |
| 1589 | + return (isNegative)? -fValue : fValue; | |
| 1590 | + } | |
| 1591 | + /* | |
| 1592 | + * Else we have a hard case with a negative exp. | |
| 1593 | + */ | |
| 1594 | + } | |
| 1595 | + } else if ( (decExponent >= nDigits) && (nDigits+decExponent <= maxDecimalDigits) ){ | |
| 1596 | + /* | |
| 1597 | + * In double-precision, this is an exact floating integer. | |
| 1598 | + * So we can compute to double, then shorten to float | |
| 1599 | + * with one round, and get the right answer. | |
| 1600 | + * | |
| 1601 | + * First, finish accumulating digits. | |
| 1602 | + * Then convert that integer to a double, multiply | |
| 1603 | + * by the appropriate power of ten, and convert to float. | |
| 1604 | + */ | |
| 1605 | + long lValue = (long)iValue; | |
| 1606 | + for ( int i=kDigits; i < nDigits; i++ ){ | |
| 1607 | + lValue = lValue*10L + (long)((int)digits[i]-(int)'0'); | |
| 1608 | + } | |
| 1609 | + double dValue = (double)lValue; | |
| 1610 | + exp = decExponent-nDigits; | |
| 1611 | + dValue *= small10pow[exp]; | |
| 1612 | + fValue = (float)dValue; | |
| 1613 | + return (isNegative)? -fValue : fValue; | |
| 1614 | + | |
| 1615 | + } | |
| 1616 | + /* | |
| 1617 | + * Harder cases: | |
| 1618 | + * The sum of digits plus exponent is greater than | |
| 1619 | + * what we think we can do with one error. | |
| 1620 | + * | |
| 1621 | + * Start by weeding out obviously out-of-range | |
| 1622 | + * results, then convert to double and go to | |
| 1623 | + * common hard-case code. | |
| 1624 | + */ | |
| 1625 | + if ( decExponent > singleMaxDecimalExponent+1 ){ | |
| 1626 | + /* | |
| 1627 | + * Lets face it. This is going to be | |
| 1628 | + * Infinity. Cut to the chase. | |
| 1629 | + */ | |
| 1630 | + return (isNegative)? Float.NEGATIVE_INFINITY : Float.POSITIVE_INFINITY; | |
| 1631 | + } else if ( decExponent < singleMinDecimalExponent-1 ){ | |
| 1632 | + /* | |
| 1633 | + * Lets face it. This is going to be | |
| 1634 | + * zero. Cut to the chase. | |
| 1635 | + */ | |
| 1636 | + return (isNegative)? -0.0f : 0.0f; | |
| 1637 | + } | |
| 1638 | + | |
| 1639 | + /* | |
| 1640 | + * Here, we do 'way too much work, but throwing away | |
| 1641 | + * our partial results, and going and doing the whole | |
| 1642 | + * thing as double, then throwing away half the bits that computes | |
| 1643 | + * when we convert back to float. | |
| 1644 | + * | |
| 1645 | + * The alternative is to reproduce the whole multiple-precision | |
| 1646 | + * algorythm for float precision, or to try to parameterize it | |
| 1647 | + * for common usage. The former will take about 400 lines of code, | |
| 1648 | + * and the latter I tried without success. Thus the semi-hack | |
| 1649 | + * answer here. | |
| 1650 | + */ | |
| 1651 | + mustSetRoundDir = !fromHex; | |
| 1652 | + double dValue = doubleValue(); | |
| 1653 | + return stickyRound( dValue ); | |
| 1654 | + } | |
| 1655 | + } | |
| 1656 | + | |
| 1657 | + | |
| 1658 | + /* | |
| 1659 | + * All the positive powers of 10 that can be | |
| 1660 | + * represented exactly in double/float. | |
| 1661 | + */ | |
| 1662 | + private static final double small10pow[] = { | |
| 1663 | + 1.0e0, | |
| 1664 | + 1.0e1, 1.0e2, 1.0e3, 1.0e4, 1.0e5, | |
| 1665 | + 1.0e6, 1.0e7, 1.0e8, 1.0e9, 1.0e10, | |
| 1666 | + 1.0e11, 1.0e12, 1.0e13, 1.0e14, 1.0e15, | |
| 1667 | + 1.0e16, 1.0e17, 1.0e18, 1.0e19, 1.0e20, | |
| 1668 | + 1.0e21, 1.0e22 | |
| 1669 | + }; | |
| 1670 | + | |
| 1671 | + private static final float singleSmall10pow[] = { | |
| 1672 | + 1.0e0f, | |
| 1673 | + 1.0e1f, 1.0e2f, 1.0e3f, 1.0e4f, 1.0e5f, | |
| 1674 | + 1.0e6f, 1.0e7f, 1.0e8f, 1.0e9f, 1.0e10f | |
| 1675 | + }; | |
| 1676 | + | |
| 1677 | + private static final double big10pow[] = { | |
| 1678 | + 1e16, 1e32, 1e64, 1e128, 1e256 }; | |
| 1679 | + private static final double tiny10pow[] = { | |
| 1680 | + 1e-16, 1e-32, 1e-64, 1e-128, 1e-256 }; | |
| 1681 | + | |
| 1682 | + private static final int maxSmallTen = small10pow.length-1; | |
| 1683 | + private static final int singleMaxSmallTen = singleSmall10pow.length-1; | |
| 1684 | + | |
| 1685 | + private static final int small5pow[] = { | |
| 1686 | + 1, | |
| 1687 | + 5, | |
| 1688 | + 5*5, | |
| 1689 | + 5*5*5, | |
| 1690 | + 5*5*5*5, | |
| 1691 | + 5*5*5*5*5, | |
| 1692 | + 5*5*5*5*5*5, | |
| 1693 | + 5*5*5*5*5*5*5, | |
| 1694 | + 5*5*5*5*5*5*5*5, | |
| 1695 | + 5*5*5*5*5*5*5*5*5, | |
| 1696 | + 5*5*5*5*5*5*5*5*5*5, | |
| 1697 | + 5*5*5*5*5*5*5*5*5*5*5, | |
| 1698 | + 5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1699 | + 5*5*5*5*5*5*5*5*5*5*5*5*5 | |
| 1700 | + }; | |
| 1701 | + | |
| 1702 | + | |
| 1703 | + private static final long long5pow[] = { | |
| 1704 | + 1L, | |
| 1705 | + 5L, | |
| 1706 | + 5L*5, | |
| 1707 | + 5L*5*5, | |
| 1708 | + 5L*5*5*5, | |
| 1709 | + 5L*5*5*5*5, | |
| 1710 | + 5L*5*5*5*5*5, | |
| 1711 | + 5L*5*5*5*5*5*5, | |
| 1712 | + 5L*5*5*5*5*5*5*5, | |
| 1713 | + 5L*5*5*5*5*5*5*5*5, | |
| 1714 | + 5L*5*5*5*5*5*5*5*5*5, | |
| 1715 | + 5L*5*5*5*5*5*5*5*5*5*5, | |
| 1716 | + 5L*5*5*5*5*5*5*5*5*5*5*5, | |
| 1717 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1718 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1719 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1720 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1721 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1722 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1723 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1724 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1725 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1726 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1727 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1728 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1729 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1730 | + 5L*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5*5, | |
| 1731 | + }; | |
| 1732 | + | |
| 1733 | + // approximately ceil( log2( long5pow[i] ) ) | |
| 1734 | + private static final int n5bits[] = { | |
| 1735 | + 0, | |
| 1736 | + 3, | |
| 1737 | + 5, | |
| 1738 | + 7, | |
| 1739 | + 10, | |
| 1740 | + 12, | |
| 1741 | + 14, | |
| 1742 | + 17, | |
| 1743 | + 19, | |
| 1744 | + 21, | |
| 1745 | + 24, | |
| 1746 | + 26, | |
| 1747 | + 28, | |
| 1748 | + 31, | |
| 1749 | + 33, | |
| 1750 | + 35, | |
| 1751 | + 38, | |
| 1752 | + 40, | |
| 1753 | + 42, | |
| 1754 | + 45, | |
| 1755 | + 47, | |
| 1756 | + 49, | |
| 1757 | + 52, | |
| 1758 | + 54, | |
| 1759 | + 56, | |
| 1760 | + 59, | |
| 1761 | + 61, | |
| 1762 | + }; | |
| 1763 | + | |
| 1764 | + private static final char infinity[] = { 'I', 'n', 'f', 'i', 'n', 'i', 't', 'y' }; | |
| 1765 | + private static final char notANumber[] = { 'N', 'a', 'N' }; | |
| 1766 | + private static final char zero[] = { '0', '0', '0', '0', '0', '0', '0', '0' }; | |
| 1767 | +} | |