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