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
60static 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
87static 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
332static 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
444long 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