libc-top-half/musl/src/internal/floatscan.c

   1 #include <stdint.h>
   2 #include <stdio.h>
   3 #include <math.h>
   4 #include <float.h>
   5 #include <limits.h>
   6 #include <errno.h>
   7 #include <ctype.h>
   8 #ifdef __wasilibc_unmodified_upstream // Changes to optimize printf/scanf when long double isn't needed
   9 #else
  10 #include "printscan.h"
  11 #endif
  12
  13 #include "shgetc.h"
  14 #include "floatscan.h"
  15
  16 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
  17
  18 #define LD_B1B_DIG 2
  19 #define LD_B1B_MAX 9007199, 254740991
  20 #define KMAX 128
  21
  22 #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
  23
  24 #define LD_B1B_DIG 3
  25 #define LD_B1B_MAX 18, 446744073, 709551615
  26 #define KMAX 2048
  27
  28 #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
  29
  30 #define LD_B1B_DIG 4
  31 #define LD_B1B_MAX 10384593, 717069655, 257060992, 658440191
  32 #define KMAX 2048
  33
  34 #else
  35 #error Unsupported long double representation
  36 #endif
  37
  38 #define MASK (KMAX-1)
  39
  40 #define CONCAT2(x,y) x ## y
  41 #define CONCAT(x,y) CONCAT2(x,y)
  42
  43 static long long scanexp(FILE *f, int pok)
  44 {
  45         int c;
  46         int x;
  47         long long y;
  48         int neg = 0;
  49
  50         c = shgetc(f);
  51         if (c=='+' || c=='-') {
  52                 neg = (c=='-');
  53                 c = shgetc(f);
  54                 if (c-'0'>=10U && pok) shunget(f);
  55         }
  56         if (c-'0'>=10U) {
  57                 shunget(f);
  58                 return LLONG_MIN;
  59         }
  60         for (x=0; c-'0'<10U && x<INT_MAX/10; c = shgetc(f))
  61                 x = 10*x + c-'0';
  62         for (y=x; c-'0'<10U && y<LLONG_MAX/100; c = shgetc(f))
  63                 y = 10*y + c-'0';
  64         for (; c-'0'<10U; c = shgetc(f));
  65         shunget(f);
  66         return neg ? -y : y;
  67 }
  68
  69
  70 #if defined(__wasilibc_printscan_no_long_double)
  71 static long_double decfloat(FILE *f, int c, int bits, int emin, int sign, int pok)
  72 #else
  73 static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int pok)
  74 #endif
  75 {
  76         uint32_t x[KMAX];
  77         static const uint32_t th[] = { LD_B1B_MAX };
  78         int i, j, k, a, z;
  79         long long lrp=0, dc=0;
  80         long long e10=0;
  81         int lnz = 0;
  82         int gotdig = 0, gotrad = 0;
  83         int rp;
  84         int e2;
  85         int emax = -emin-bits+3;
  86         int denormal = 0;
  87 #if defined(__wasilibc_printscan_no_long_double)
  88         long_double y;
  89         long_double frac=0;
  90         long_double bias=0;
  91 #else
  92         long double y;
  93         long double frac=0;
  94         long double bias=0;
  95 #endif
  96         static const int p10s[] = { 10, 100, 1000, 10000,
  97                 100000, 1000000, 10000000, 100000000 };
  98
  99         j=0;
 100         k=0;
 101
 102         /* Don't let leading zeros consume buffer space */
 103         for (; c=='0'; c = shgetc(f)) gotdig=1;
 104         if (c=='.') {
 105                 gotrad = 1;
 106                 for (c = shgetc(f); c=='0'; c = shgetc(f)) gotdig=1, lrp--;
 107         }
 108
 109         x[0] = 0;
 110         for (; c-'0'<10U || c=='.'; c = shgetc(f)) {
 111                 if (c == '.') {
 112                         if (gotrad) break;
 113                         gotrad = 1;
 114                         lrp = dc;
 115                 } else if (k < KMAX-3) {
 116                         dc++;
 117                         if (c!='0') lnz = dc;
 118                         if (j) x[k] = x[k]*10 + c-'0';
 119                         else x[k] = c-'0';
 120                         if (++j==9) {
 121                                 k++;
 122                                 j=0;
 123                         }
 124                         gotdig=1;
 125                 } else {
 126                         dc++;
 127                         if (c!='0') {
 128                                 lnz = (KMAX-4)*9;
 129                                 x[KMAX-4] |= 1;
 130                         }
 131                 }
 132         }
 133         if (!gotrad) lrp=dc;
 134
 135         if (gotdig && (c|32)=='e') {
 136                 e10 = scanexp(f, pok);
 137                 if (e10 == LLONG_MIN) {
 138                         if (pok) {
 139                                 shunget(f);
 140                         } else {
 141                                 shlim(f, 0);
 142                                 return 0;
 143                         }
 144                         e10 = 0;
 145                 }
 146                 lrp += e10;
 147         } else if (c>=0) {
 148                 shunget(f);
 149         }
 150         if (!gotdig) {
 151                 errno = EINVAL;
 152                 shlim(f, 0);
 153                 return 0;
 154         }
 155
 156         /* Handle zero specially to avoid nasty special cases later */
 157         if (!x[0]) return sign * 0.0;
 158
 159         /* Optimize small integers (w/no exponent) and over/under-flow */
 160         if (lrp==dc && dc<10 && (bits>30 || x[0]>>bits==0))
 161 #if defined(__wasilibc_printscan_no_long_double)
 162                 return sign * (long_double)x[0];
 163 #else
 164                 return sign * (long double)x[0];
 165 #endif
 166         if (lrp > -emin/2) {
 167                 errno = ERANGE;
 168                 return sign * LDBL_MAX * LDBL_MAX;
 169         }
 170         if (lrp < emin-2*LDBL_MANT_DIG) {
 171                 errno = ERANGE;
 172                 return sign * LDBL_MIN * LDBL_MIN;
 173         }
 174
 175         /* Align incomplete final B1B digit */
 176         if (j) {
 177                 for (; j<9; j++) x[k]*=10;
 178                 k++;
 179                 j=0;
 180         }
 181
 182         a = 0;
 183         z = k;
 184         e2 = 0;
 185         rp = lrp;
 186
 187         /* Optimize small to mid-size integers (even in exp. notation) */
 188         if (lnz<9 && lnz<=rp && rp < 18) {
 189 #if defined(__wasilibc_printscan_no_long_double)
 190                 if (rp == 9) return sign * (long_double)x[0];
 191                 if (rp < 9) return sign * (long_double)x[0] / p10s[8-rp];
 192 #else
 193                 if (rp == 9) return sign * (long double)x[0];
 194                 if (rp < 9) return sign * (long double)x[0] / p10s[8-rp];
 195 #endif
 196                 int bitlim = bits-3*(int)(rp-9);
 197                 if (bitlim>30 || x[0]>>bitlim==0)
 198 #if defined(__wasilibc_printscan_no_long_double)
 199                         return sign * (long_double)x[0] * p10s[rp-10];
 200 #else
 201                         return sign * (long double)x[0] * p10s[rp-10];
 202 #endif
 203         }
 204
 205         /* Drop trailing zeros */
 206         for (; !x[z-1]; z--);
 207
 208         /* Align radix point to B1B digit boundary */
 209         if (rp % 9) {
 210                 int rpm9 = rp>=0 ? rp%9 : rp%9+9;
 211                 int p10 = p10s[8-rpm9];
 212                 uint32_t carry = 0;
 213                 for (k=a; k!=z; k++) {
 214                         uint32_t tmp = x[k] % p10;
 215                         x[k] = x[k]/p10 + carry;
 216                         carry = 1000000000/p10 * tmp;
 217                         if (k==a && !x[k]) {
 218                                 a = (a+1 & MASK);
 219                                 rp -= 9;
 220                         }
 221                 }
 222                 if (carry) x[z++] = carry;
 223                 rp += 9-rpm9;
 224         }
 225
 226         /* Upscale until desired number of bits are left of radix point */
 227         while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[a]<th[0])) {
 228                 uint32_t carry = 0;
 229                 e2 -= 29;
 230                 for (k=(z-1 & MASK); ; k=(k-1 & MASK)) {
 231                         uint64_t tmp = ((uint64_t)x[k] << 29) + carry;
 232                         if (tmp > 1000000000) {
 233                                 carry = tmp / 1000000000;
 234                                 x[k] = tmp % 1000000000;
 235                         } else {
 236                                 carry = 0;
 237                                 x[k] = tmp;
 238                         }
 239                         if (k==(z-1 & MASK) && k!=a && !x[k]) z = k;
 240                         if (k==a) break;
 241                 }
 242                 if (carry) {
 243                         rp += 9;
 244                         a = (a-1 & MASK);
 245                         if (a == z) {
 246                                 z = (z-1 & MASK);
 247                                 x[z-1 & MASK] |= x[z];
 248                         }
 249                         x[a] = carry;
 250                 }
 251         }
 252
 253         /* Downscale until exactly number of bits are left of radix point */
 254         for (;;) {
 255                 uint32_t carry = 0;
 256                 int sh = 1;
 257                 for (i=0; i<LD_B1B_DIG; i++) {
 258                         k = (a+i & MASK);
 259                         if (k == z || x[k] < th[i]) {
 260                                 i=LD_B1B_DIG;
 261                                 break;
 262                         }
 263                         if (x[a+i & MASK] > th[i]) break;
 264                 }
 265                 if (i==LD_B1B_DIG && rp==9*LD_B1B_DIG) break;
 266                 /* FIXME: find a way to compute optimal sh */
 267                 if (rp > 9+9*LD_B1B_DIG) sh = 9;
 268                 e2 += sh;
 269                 for (k=a; k!=z; k=(k+1 & MASK)) {
 270                         uint32_t tmp = x[k] & (1<<sh)-1;
 271                         x[k] = (x[k]>>sh) + carry;
 272                         carry = (1000000000>>sh) * tmp;
 273                         if (k==a && !x[k]) {
 274                                 a = (a+1 & MASK);
 275                                 i--;
 276                                 rp -= 9;
 277                         }
 278                 }
 279                 if (carry) {
 280                         if ((z+1 & MASK) != a) {
 281                                 x[z] = carry;
 282                                 z = (z+1 & MASK);
 283                         } else x[z-1 & MASK] |= 1;
 284                 }
 285         }
 286
 287         /* Assemble desired bits into floating point variable */
 288         for (y=i=0; i<LD_B1B_DIG; i++) {
 289                 if ((a+i & MASK)==z) x[(z=(z+1 & MASK))-1] = 0;
 290 #if defined(__wasilibc_printscan_no_long_double)
 291                 y = 1000000000.0 * y + x[a+i & MASK];
 292 #else
 293                 y = 1000000000.0L * y + x[a+i & MASK];
 294 #endif
 295         }
 296
 297         y *= sign;
 298
 299         /* Limit precision for denormal results */
 300         if (bits > LDBL_MANT_DIG+e2-emin) {
 301                 bits = LDBL_MANT_DIG+e2-emin;
 302                 if (bits<0) bits=0;
 303                 denormal = 1;
 304         }
 305
 306         /* Calculate bias term to force rounding, move out lower bits */
 307         if (bits < LDBL_MANT_DIG) {
 308                 bias = copysignl(scalbn(1, 2*LDBL_MANT_DIG-bits-1), y);
 309                 frac = fmodl(y, scalbn(1, LDBL_MANT_DIG-bits));
 310                 y -= frac;
 311                 y += bias;
 312         }
 313
 314         /* Process tail of decimal input so it can affect rounding */
 315         if ((a+i & MASK) != z) {
 316                 uint32_t t = x[a+i & MASK];
 317                 if (t < 500000000 && (t || (a+i+1 & MASK) != z))
 318                         frac += 0.25*sign;
 319                 else if (t > 500000000)
 320                         frac += 0.75*sign;
 321                 else if (t == 500000000) {
 322                         if ((a+i+1 & MASK) == z)
 323                                 frac += 0.5*sign;
 324                         else
 325                                 frac += 0.75*sign;
 326                 }
 327                 if (LDBL_MANT_DIG-bits >= 2 && !fmodl(frac, 1))
 328                         frac++;
 329         }
 330
 331         y += frac;
 332         y -= bias;
 333
 334         if ((e2+LDBL_MANT_DIG & INT_MAX) > emax-5) {
 335                 if (fabs(y) >= CONCAT(0x1p, LDBL_MANT_DIG)) {
 336                         if (denormal && bits==LDBL_MANT_DIG+e2-emin)
 337                                 denormal = 0;
 338                         y *= 0.5;
 339                         e2++;
 340                 }
 341                 if (e2+LDBL_MANT_DIG>emax || (denormal && frac))
 342                         errno = ERANGE;
 343         }
 344
 345         return scalbnl(y, e2);
 346 }
 347
 348 #if defined(__wasilibc_printscan_no_long_double)
 349 static long_double hexfloat(FILE *f, int bits, int emin, int sign, int pok)
 350 #else
 351 static long double hexfloat(FILE *f, int bits, int emin, int sign, int pok)
 352 #endif
 353 {
 354         uint32_t x = 0;
 355 #if defined(__wasilibc_printscan_no_long_double)
 356         long_double y = 0;
 357         long_double scale = 1;
 358         long_double bias = 0;
 359 #else
 360         long double y = 0;
 361         long double scale = 1;
 362         long double bias = 0;
 363 #endif
 364         int gottail = 0, gotrad = 0, gotdig = 0;
 365         long long rp = 0;
 366         long long dc = 0;
 367         long long e2 = 0;
 368         int d;
 369         int c;
 370
 371         c = shgetc(f);
 372
 373         /* Skip leading zeros */
 374         for (; c=='0'; c = shgetc(f)) gotdig = 1;
 375
 376         if (c=='.') {
 377                 gotrad = 1;
 378                 c = shgetc(f);
 379                 /* Count zeros after the radix point before significand */
 380                 for (rp=0; c=='0'; c = shgetc(f), rp--) gotdig = 1;
 381         }
 382
 383         for (; c-'0'<10U || (c|32)-'a'<6U || c=='.'; c = shgetc(f)) {
 384                 if (c=='.') {
 385                         if (gotrad) break;
 386                         rp = dc;
 387                         gotrad = 1;
 388                 } else {
 389                         gotdig = 1;
 390                         if (c > '9') d = (c|32)+10-'a';
 391                         else d = c-'0';
 392                         if (dc<8) {
 393                                 x = x*16 + d;
 394                         } else if (dc < LDBL_MANT_DIG/4+1) {
 395                                 y += d*(scale/=16);
 396                         } else if (d && !gottail) {
 397                                 y += 0.5*scale;
 398                                 gottail = 1;
 399                         }
 400                         dc++;
 401                 }
 402         }
 403         if (!gotdig) {
 404                 shunget(f);
 405                 if (pok) {
 406                         shunget(f);
 407                         if (gotrad) shunget(f);
 408                 } else {
 409                         shlim(f, 0);
 410                 }
 411                 return sign * 0.0;
 412         }
 413         if (!gotrad) rp = dc;
 414         while (dc<8) x *= 16, dc++;
 415         if ((c|32)=='p') {
 416                 e2 = scanexp(f, pok);
 417                 if (e2 == LLONG_MIN) {
 418                         if (pok) {
 419                                 shunget(f);
 420                         } else {
 421                                 shlim(f, 0);
 422                                 return 0;
 423                         }
 424                         e2 = 0;
 425                 }
 426         } else {
 427                 shunget(f);
 428         }
 429         e2 += 4*rp - 32;
 430
 431         if (!x) return sign * 0.0;
 432         if (e2 > -emin) {
 433                 errno = ERANGE;
 434                 return sign * LDBL_MAX * LDBL_MAX;
 435         }
 436         if (e2 < emin-2*LDBL_MANT_DIG) {
 437                 errno = ERANGE;
 438                 return sign * LDBL_MIN * LDBL_MIN;
 439         }
 440
 441         while (x < 0x80000000) {
 442                 if (y>=0.5) {
 443                         x += x + 1;
 444                         y += y - 1;
 445                 } else {
 446                         x += x;
 447                         y += y;
 448                 }
 449                 e2--;
 450         }
 451
 452         if (bits > 32+e2-emin) {
 453                 bits = 32+e2-emin;
 454                 if (bits<0) bits=0;
 455         }
 456
 457         if (bits < LDBL_MANT_DIG)
 458                 bias = copysignl(scalbn(1, 32+LDBL_MANT_DIG-bits-1), sign);
 459
 460         if (bits<32 && y && !(x&1)) x++, y=0;
 461
 462 #if defined(__wasilibc_printscan_no_long_double)
 463         y = bias + sign*(long_double)x + sign*y;
 464 #else
 465         y = bias + sign*(long double)x + sign*y;
 466 #endif
 467         y -= bias;
 468
 469         if (!y) errno = ERANGE;
 470
 471         return scalbnl(y, e2);
 472 }
 473
 474 #if defined(__wasilibc_printscan_no_long_double)
 475 long_double __floatscan(FILE *f, int prec, int pok)
 476 #else
 477 long double __floatscan(FILE *f, int prec, int pok)
 478 #endif
 479 {
 480         int sign = 1;
 481         size_t i;
 482         int bits;
 483         int emin;
 484         int c;
 485
 486         switch (prec) {
 487         case 0:
 488                 bits = FLT_MANT_DIG;
 489                 emin = FLT_MIN_EXP-bits;
 490                 break;
 491         case 1:
 492                 bits = DBL_MANT_DIG;
 493                 emin = DBL_MIN_EXP-bits;
 494                 break;
 495         case 2:
 496                 bits = LDBL_MANT_DIG;
 497                 emin = LDBL_MIN_EXP-bits;
 498                 break;
 499         default:
 500                 return 0;
 501         }
 502
 503         while (isspace((c=shgetc(f))));
 504
 505         if (c=='+' || c=='-') {
 506                 sign -= 2*(c=='-');
 507                 c = shgetc(f);
 508         }
 509
 510         for (i=0; i<8 && (c|32)=="infinity"[i]; i++)
 511                 if (i<7) c = shgetc(f);
 512         if (i==3 || i==8 || (i>3 && pok)) {
 513                 if (i!=8) {
 514                         shunget(f);
 515                         if (pok) for (; i>3; i--) shunget(f);
 516                 }
 517                 return sign * INFINITY;
 518         }
 519         if (!i) for (i=0; i<3 && (c|32)=="nan"[i]; i++)
 520                 if (i<2) c = shgetc(f);
 521         if (i==3) {
 522                 if (shgetc(f) != '(') {
 523                         shunget(f);
 524                         return NAN;
 525                 }
 526                 for (i=1; ; i++) {
 527                         c = shgetc(f);
 528                         if (c-'0'<10U || c-'A'<26U || c-'a'<26U || c=='_')
 529                                 continue;
 530                         if (c==')') return NAN;
 531                         shunget(f);
 532                         if (!pok) {
 533                                 errno = EINVAL;
 534                                 shlim(f, 0);
 535                                 return 0;
 536                         }
 537                         while (i--) shunget(f);
 538                         return NAN;
 539                 }
 540                 return NAN;
 541         }
 542
 543         if (i) {
 544                 shunget(f);
 545                 errno = EINVAL;
 546                 shlim(f, 0);
 547                 return 0;
 548         }
 549
 550         if (c=='0') {
 551                 c = shgetc(f);
 552                 if ((c|32) == 'x')
 553                         return hexfloat(f, bits, emin, sign, pok);
 554                 shunget(f);
 555                 c = '0';
 556         }
 557
 558         return decfloat(f, c, bits, emin, sign, pok);
 559 }