1 // ----------------------------------------------------------------------
2 // Copyright © 2005-2014 Rich Felker, et al.
3 // Copyright 2014 The Android Open Source Project.
4 //
5 // Permission is hereby granted, free of charge, to any person obtaining
6 // a copy of this software and associated documentation files (the
7 // "Software"), to deal in the Software without restriction, including
8 // without limitation the rights to use, copy, modify, merge, publish,
9 // distribute, sublicense, and/or sell copies of the Software, and to
10 // permit persons to whom the Software is furnished to do so, subject to
11 // the following conditions:
12 //
13 // The above copyright notice and this permission notice shall be
14 // included in all copies or substantial portions of the Software.
15 //
16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 // IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 // CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 // TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 // SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 // ----------------------------------------------------------------------
24
25 #include <stdint.h>
26 #include <stdio.h>
27 #include <math.h>
28 #include <float.h>
29 #include <limits.h>
30 #include <errno.h>
31 #include <ctype.h>
32
33 #include "shgetc.h"
34 #include "floatscan.h"
35
36 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
37
38 #define LD_B1B_DIG 2
39 #define LD_B1B_MAX 9007199, 254740991
40 #define KMAX 128
41
42 #else /* LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384 */
43
44 #define LD_B1B_DIG 3
45 #define LD_B1B_MAX 18, 446744073, 709551615
46 #define KMAX 2048
47
48 #endif
49
50 #define MASK (KMAX-1)
51
52 #define CONCAT2(x,y) x ## y
53 #define CONCAT(x,y) CONCAT2(x,y)
54
55 // ANDROID: The original Musl sources use a FILE* handle, but redefine the
56 // type to match our custom fake_file_t from shgetc.h
57 #undef FILE
58 #define FILE struct fake_file_t
59
scanexp(FILE * f,int pok)60 static long long scanexp(FILE *f, int pok)
61 {
62 int c;
63 int x;
64 long long y;
65 int neg = 0;
66
67 c = shgetc(f);
68 if (c=='+' || c=='-') {
69 neg = (c=='-');
70 c = shgetc(f);
71 if (c-'0'>=10U && pok) shunget(f);
72 }
73 if (c-'0'>=10U) {
74 shunget(f);
75 return LLONG_MIN;
76 }
77 for (x=0; c-'0'<10U && x<INT_MAX/10; c = shgetc(f))
78 x = 10*x + c-'0';
79 for (y=x; c-'0'<10U && y<LLONG_MAX/100; c = shgetc(f))
80 y = 10*y + c-'0';
81 for (; c-'0'<10U; c = shgetc(f));
82 shunget(f);
83 return neg ? -y : y;
84 }
85
86
decfloat(FILE * f,int c,int bits,int emin,int sign,int pok)87 static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int pok)
88 {
89 uint32_t x[KMAX];
90 static const uint32_t th[] = { LD_B1B_MAX };
91 int i, j, k, a, z;
92 long long lrp=0, dc=0;
93 long long e10=0;
94 int lnz = 0;
95 int gotdig = 0, gotrad = 0;
96 int rp;
97 int e2;
98 int emax = -emin-bits+3;
99 int denormal = 0;
100 long double y;
101 long double frac=0;
102 long double bias=0;
103 static const int p10s[] = { 10, 100, 1000, 10000,
104 100000, 1000000, 10000000, 100000000 };
105
106 j=0;
107 k=0;
108
109 /* Don't let leading zeros consume buffer space */
110 for (; c=='0'; c = shgetc(f)) gotdig=1;
111 if (c=='.') {
112 gotrad = 1;
113 for (c = shgetc(f); c=='0'; c = shgetc(f)) gotdig=1, lrp--;
114 }
115
116 x[0] = 0;
117 for (; c-'0'<10U || c=='.'; c = shgetc(f)) {
118 if (c == '.') {
119 if (gotrad) break;
120 gotrad = 1;
121 lrp = dc;
122 } else if (k < KMAX-3) {
123 dc++;
124 if (c!='0') lnz = dc;
125 if (j) x[k] = x[k]*10 + c-'0';
126 else x[k] = c-'0';
127 if (++j==9) {
128 k++;
129 j=0;
130 }
131 gotdig=1;
132 } else {
133 dc++;
134 if (c!='0') x[KMAX-4] |= 1;
135 }
136 }
137 if (!gotrad) lrp=dc;
138
139 if (gotdig && (c|32)=='e') {
140 e10 = scanexp(f, pok);
141 if (e10 == LLONG_MIN) {
142 if (pok) {
143 shunget(f);
144 } else {
145 shlim(f, 0);
146 return 0;
147 }
148 e10 = 0;
149 }
150 lrp += e10;
151 } else if (c>=0) {
152 shunget(f);
153 }
154 if (!gotdig) {
155 errno = EINVAL;
156 shlim(f, 0);
157 return 0;
158 }
159
160 /* Handle zero specially to avoid nasty special cases later */
161 if (!x[0]) return sign * 0.0;
162
163 /* Optimize small integers (w/no exponent) and over/under-flow */
164 if (lrp==dc && dc<10 && (bits>30 || x[0]>>bits==0))
165 return sign * (long double)x[0];
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 (rp == 9) return sign * (long double)x[0];
190 if (rp < 9) return sign * (long double)x[0] / p10s[8-rp];
191 int bitlim = bits-3*(int)(rp-9);
192 if (bitlim>30 || x[0]>>bitlim==0)
193 return sign * (long double)x[0] * p10s[rp-10];
194 }
195
196 /* Align radix point to B1B digit boundary */
197 if (rp % 9) {
198 int rpm9 = rp>=0 ? rp%9 : rp%9+9;
199 int p10 = p10s[8-rpm9];
200 uint32_t carry = 0;
201 for (k=a; k!=z; k++) {
202 uint32_t tmp = x[k] % p10;
203 x[k] = x[k]/p10 + carry;
204 carry = 1000000000/p10 * tmp;
205 if (k==a && !x[k]) {
206 a = (a+1 & MASK);
207 rp -= 9;
208 }
209 }
210 if (carry) x[z++] = carry;
211 rp += 9-rpm9;
212 }
213
214 /* Upscale until desired number of bits are left of radix point */
215 while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[a]<th[0])) {
216 uint32_t carry = 0;
217 e2 -= 29;
218 for (k=(z-1 & MASK); ; k=(k-1 & MASK)) {
219 uint64_t tmp = ((uint64_t)x[k] << 29) + carry;
220 if (tmp > 1000000000) {
221 carry = tmp / 1000000000;
222 x[k] = tmp % 1000000000;
223 } else {
224 carry = 0;
225 x[k] = tmp;
226 }
227 if (k==(z-1 & MASK) && k!=a && !x[k]) z = k;
228 if (k==a) break;
229 }
230 if (carry) {
231 rp += 9;
232 a = (a-1 & MASK);
233 if (a == z) {
234 z = (z-1 & MASK);
235 x[z-1 & MASK] |= x[z];
236 }
237 x[a] = carry;
238 }
239 }
240
241 /* Downscale until exactly number of bits are left of radix point */
242 for (;;) {
243 uint32_t carry = 0;
244 int sh = 1;
245 for (i=0; i<LD_B1B_DIG; i++) {
246 k = (a+i & MASK);
247 if (k == z || x[k] < th[i]) {
248 i=LD_B1B_DIG;
249 break;
250 }
251 if (x[a+i & MASK] > th[i]) break;
252 }
253 if (i==LD_B1B_DIG && rp==9*LD_B1B_DIG) break;
254 /* FIXME: find a way to compute optimal sh */
255 if (rp > 9+9*LD_B1B_DIG) sh = 9;
256 e2 += sh;
257 for (k=a; k!=z; k=(k+1 & MASK)) {
258 uint32_t tmp = x[k] & (1<<sh)-1;
259 x[k] = (x[k]>>sh) + carry;
260 carry = (1000000000>>sh) * tmp;
261 if (k==a && !x[k]) {
262 a = (a+1 & MASK);
263 i--;
264 rp -= 9;
265 }
266 }
267 if (carry) {
268 if ((z+1 & MASK) != a) {
269 x[z] = carry;
270 z = (z+1 & MASK);
271 } else x[z-1 & MASK] |= 1;
272 }
273 }
274
275 /* Assemble desired bits into floating point variable */
276 for (y=i=0; i<LD_B1B_DIG; i++) {
277 if ((a+i & MASK)==z) x[(z=(z+1 & MASK))-1] = 0;
278 y = 1000000000.0L * y + x[a+i & MASK];
279 }
280
281 y *= sign;
282
283 /* Limit precision for denormal results */
284 if (bits > LDBL_MANT_DIG+e2-emin) {
285 bits = LDBL_MANT_DIG+e2-emin;
286 if (bits<0) bits=0;
287 denormal = 1;
288 }
289
290 /* Calculate bias term to force rounding, move out lower bits */
291 if (bits < LDBL_MANT_DIG) {
292 bias = copysignl(scalbn(1, 2*LDBL_MANT_DIG-bits-1), y);
293 frac = fmodl(y, scalbn(1, LDBL_MANT_DIG-bits));
294 y -= frac;
295 y += bias;
296 }
297
298 /* Process tail of decimal input so it can affect rounding */
299 if ((a+i & MASK) != z) {
300 uint32_t t = x[a+i & MASK];
301 if (t < 500000000 && (t || (a+i+1 & MASK) != z))
302 frac += 0.25*sign;
303 else if (t > 500000000)
304 frac += 0.75*sign;
305 else if (t == 500000000) {
306 if ((a+i+1 & MASK) == z)
307 frac += 0.5*sign;
308 else
309 frac += 0.75*sign;
310 }
311 if (LDBL_MANT_DIG-bits >= 2 && !fmodl(frac, 1))
312 frac++;
313 }
314
315 y += frac;
316 y -= bias;
317
318 if ((e2+LDBL_MANT_DIG & INT_MAX) > emax-5) {
319 if (fabs(y) >= CONCAT(0x1p, LDBL_MANT_DIG)) {
320 if (denormal && bits==LDBL_MANT_DIG+e2-emin)
321 denormal = 0;
322 y *= 0.5;
323 e2++;
324 }
325 if (e2+LDBL_MANT_DIG>emax || (denormal && frac))
326 errno = ERANGE;
327 }
328
329 return scalbnl(y, e2);
330 }
331
hexfloat(FILE * f,int bits,int emin,int sign,int pok)332 static long double hexfloat(FILE *f, int bits, int emin, int sign, int pok)
333 {
334 uint32_t x = 0;
335 long double y = 0;
336 long double scale = 1;
337 long double bias = 0;
338 int gottail = 0, gotrad = 0, gotdig = 0;
339 long long rp = 0;
340 long long dc = 0;
341 long long e2 = 0;
342 int d;
343 int c;
344
345 c = shgetc(f);
346
347 /* Skip leading zeros */
348 for (; c=='0'; c = shgetc(f)) gotdig = 1;
349
350 if (c=='.') {
351 gotrad = 1;
352 c = shgetc(f);
353 /* Count zeros after the radix point before significand */
354 for (rp=0; c=='0'; c = shgetc(f), rp--) gotdig = 1;
355 }
356
357 for (; c-'0'<10U || (c|32)-'a'<6U || c=='.'; c = shgetc(f)) {
358 if (c=='.') {
359 if (gotrad) break;
360 rp = dc;
361 gotrad = 1;
362 } else {
363 gotdig = 1;
364 if (c > '9') d = (c|32)+10-'a';
365 else d = c-'0';
366 if (dc<8) {
367 x = x*16 + d;
368 } else if (dc < LDBL_MANT_DIG/4+1) {
369 y += d*(scale/=16);
370 } else if (d && !gottail) {
371 y += 0.5*scale;
372 gottail = 1;
373 }
374 dc++;
375 }
376 }
377 if (!gotdig) {
378 shunget(f);
379 if (pok) {
380 shunget(f);
381 if (gotrad) shunget(f);
382 } else {
383 shlim(f, 0);
384 }
385 return sign * 0.0;
386 }
387 if (!gotrad) rp = dc;
388 while (dc<8) x *= 16, dc++;
389 if ((c|32)=='p') {
390 e2 = scanexp(f, pok);
391 if (e2 == LLONG_MIN) {
392 if (pok) {
393 shunget(f);
394 } else {
395 shlim(f, 0);
396 return 0;
397 }
398 e2 = 0;
399 }
400 } else {
401 shunget(f);
402 }
403 e2 += 4*rp - 32;
404
405 if (!x) return sign * 0.0;
406 if (e2 > -emin) {
407 errno = ERANGE;
408 return sign * LDBL_MAX * LDBL_MAX;
409 }
410 if (e2 < emin-2*LDBL_MANT_DIG) {
411 errno = ERANGE;
412 return sign * LDBL_MIN * LDBL_MIN;
413 }
414
415 while (x < 0x80000000) {
416 if (y>=0.5) {
417 x += x + 1;
418 y += y - 1;
419 } else {
420 x += x;
421 y += y;
422 }
423 e2--;
424 }
425
426 if (bits > 32+e2-emin) {
427 bits = 32+e2-emin;
428 if (bits<0) bits=0;
429 }
430
431 if (bits < LDBL_MANT_DIG)
432 bias = copysignl(scalbn(1, 32+LDBL_MANT_DIG-bits-1), sign);
433
434 if (bits<32 && y && !(x&1)) x++, y=0;
435
436 y = bias + sign*(long double)x + sign*y;
437 y -= bias;
438
439 if (!y) errno = ERANGE;
440
441 return scalbnl(y, e2);
442 }
443
__floatscan(FILE * f,int prec,int pok)444 long double __floatscan(FILE *f, int prec, int pok)
445 {
446 int sign = 1;
447 size_t i;
448 int bits;
449 int emin;
450 int c;
451
452 switch (prec) {
453 case 0:
454 bits = FLT_MANT_DIG;
455 emin = FLT_MIN_EXP-bits;
456 break;
457 case 1:
458 bits = DBL_MANT_DIG;
459 emin = DBL_MIN_EXP-bits;
460 break;
461 case 2:
462 bits = LDBL_MANT_DIG;
463 emin = LDBL_MIN_EXP-bits;
464 break;
465 default:
466 return 0;
467 }
468
469 while (isspace((c=shgetc(f))));
470
471 if (c=='+' || c=='-') {
472 sign -= 2*(c=='-');
473 c = shgetc(f);
474 }
475
476 for (i=0; i<8 && (c|32)=="infinity"[i]; i++)
477 if (i<7) c = shgetc(f);
478 if (i==3 || i==8 || (i>3 && pok)) {
479 if (i!=8) {
480 shunget(f);
481 if (pok) for (; i>3; i--) shunget(f);
482 }
483 return sign * INFINITY;
484 }
485 if (!i) for (i=0; i<3 && (c|32)=="nan"[i]; i++)
486 if (i<2) c = shgetc(f);
487 if (i==3) {
488 if (shgetc(f) != '(') {
489 shunget(f);
490 return NAN;
491 }
492 for (i=1; ; i++) {
493 c = shgetc(f);
494 if (c-'0'<10U || c-'A'<26U || c-'a'<26U || c=='_')
495 continue;
496 if (c==')') return NAN;
497 shunget(f);
498 if (!pok) {
499 errno = EINVAL;
500 shlim(f, 0);
501 return 0;
502 }
503 while (i--) shunget(f);
504 return NAN;
505 }
506 return NAN;
507 }
508
509 if (i) {
510 shunget(f);
511 errno = EINVAL;
512 shlim(f, 0);
513 return 0;
514 }
515
516 if (c=='0') {
517 c = shgetc(f);
518 if ((c|32) == 'x')
519 return hexfloat(f, bits, emin, sign, pok);
520 shunget(f);
521 c = '0';
522 }
523
524 return decfloat(f, c, bits, emin, sign, pok);
525 }
526