Fix fencepost bugs in binary radix writing.
[u/mdw/catacomb] / mptext.c
CommitLineData
d3409d5e 1/* -*-c-*-
2 *
afd054c1 3 * $Id: mptext.c,v 1.15 2002/10/15 19:18:15 mdw Exp $
d3409d5e 4 *
5 * Textual representation of multiprecision numbers
6 *
7 * (c) 1999 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of Catacomb.
13 *
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: mptext.c,v $
afd054c1 33 * Revision 1.15 2002/10/15 19:18:15 mdw
34 * Fix fencepost bugs in binary radix writing.
35 *
3db58009 36 * Revision 1.14 2002/10/09 00:33:44 mdw
37 * Allow `0o' and `0b' prefixes for octal and binary (from Haskell)
38 *
6ea6fe51 39 * Revision 1.13 2002/10/09 00:21:06 mdw
40 * Allow user-specified `r_xx' bases to be up to 62.
41 *
631673a1 42 * Revision 1.12 2002/01/13 19:51:18 mdw
43 * Extend the textual format to bases up to 62 by distinguishing case.
44 *
eaa515d8 45 * Revision 1.11 2001/06/16 23:42:17 mdw
46 * Typesetting fixes.
47 *
a951033d 48 * Revision 1.10 2001/06/16 13:22:39 mdw
49 * Added fast-track code for binary output bases, and tests.
50 *
3bc9cb53 51 * Revision 1.9 2001/02/03 16:05:17 mdw
52 * Make flags be unsigned. Improve the write algorithm: recurse until the
53 * parts are one word long and use single-precision arithmetic from there.
54 * Fix off-by-one bug when breaking the number apart.
55 *
9d3838a0 56 * Revision 1.8 2000/12/06 20:32:42 mdw
57 * Reduce binary bytes (to allow marker bits to be ignored). Fix error
58 * message string a bit. Allow leading `+' signs.
59 *
7d45ed6c 60 * Revision 1.7 2000/07/15 10:01:08 mdw
61 * Bug fix in binary input.
62 *
dd9199f0 63 * Revision 1.6 2000/06/25 12:58:23 mdw
64 * Fix the derivation of `depth' commentary.
65 *
2b26f2d7 66 * Revision 1.5 2000/06/17 11:46:19 mdw
67 * New and much faster stack-based algorithm for reading integers. Support
68 * reading and writing binary integers in bases between 2 and 256.
69 *
e360a4f2 70 * Revision 1.4 1999/12/22 15:56:56 mdw
71 * Use clever recursive algorithm for writing numbers out.
72 *
9c3df6c0 73 * Revision 1.3 1999/12/10 23:23:26 mdw
74 * Allocate slightly less memory.
75 *
90b6f0be 76 * Revision 1.2 1999/11/20 22:24:15 mdw
77 * Use function versions of MPX_UMULN and MPX_UADDN.
78 *
d3409d5e 79 * Revision 1.1 1999/11/17 18:02:16 mdw
80 * New multiprecision integer arithmetic suite.
81 *
82 */
83
84/*----- Header files ------------------------------------------------------*/
85
86#include <ctype.h>
2b26f2d7 87#include <limits.h>
d3409d5e 88#include <stdio.h>
89
d3409d5e 90#include "mp.h"
91#include "mptext.h"
e360a4f2 92#include "paranoia.h"
d3409d5e 93
2b26f2d7 94/*----- Magical numbers ---------------------------------------------------*/
95
96/* --- Maximum recursion depth --- *
97 *
98 * This is the number of bits in a @size_t@ object. Why?
99 *
eaa515d8 100 * To see this, let %$b = \textit{MPW\_MAX} + 1$% and let %$Z$% be the
dd9199f0 101 * largest @size_t@ value. Then the largest possible @mp@ is %$M - 1$% where
102 * %$M = b^Z$%. Let %$r$% be a radix to read or write. Since the recursion
103 * squares the radix at each step, the highest number reached by the
104 * recursion is %$d$%, where:
2b26f2d7 105 *
dd9199f0 106 * %$r^{2^d} = b^Z$%.
2b26f2d7 107 *
108 * Solving gives that %$d = \lg \log_r b^Z$%. If %$r = 2$%, this is maximum,
109 * so choosing %$d = \lg \lg b^Z = \lg (Z \lg b) = \lg Z + \lg \lg b$%.
110 *
111 * Expressing %$\lg Z$% as @CHAR_BIT * sizeof(size_t)@ yields an
112 * overestimate, since a @size_t@ representation may contain `holes'.
113 * Choosing to represent %$\lg \lg b$% by 10 is almost certainly sufficient
114 * for `some time to come'.
115 */
116
117#define DEPTH (CHAR_BIT * sizeof(size_t) + 10)
118
d3409d5e 119/*----- Main code ---------------------------------------------------------*/
120
121/* --- @mp_read@ --- *
122 *
123 * Arguments: @mp *m@ = destination multiprecision number
124 * @int radix@ = base to assume for data (or zero to guess)
125 * @const mptext_ops *ops@ = pointer to operations block
126 * @void *p@ = data for the operations block
127 *
128 * Returns: The integer read, or zero if it didn't work.
129 *
130 * Use: Reads an integer from some source. If the @radix@ is
131 * specified, the number is assumed to be given in that radix,
132 * with the letters `a' (either upper- or lower-case) upwards
133 * standing for digits greater than 9. Otherwise, base 10 is
134 * assumed unless the number starts with `0' (octal), `0x' (hex)
135 * or `nnn_' (base `nnn'). An arbitrary amount of whitespace
136 * before the number is ignored.
137 */
138
2b26f2d7 139/* --- About the algorithm --- *
140 *
141 * The algorithm here is rather aggressive. I maintain an array of
142 * successive squarings of the radix, and a stack of partial results, each
143 * with a counter attached indicating which radix square to multiply by.
144 * Once the item at the top of the stack reaches the same counter level as
145 * the next item down, they are combined together and the result is given a
146 * counter level one higher than either of the results.
147 *
148 * Gluing the results together at the end is slightly tricky. Pay attention
149 * to the code.
150 *
151 * This is more complicated because of the need to handle the slightly
152 * bizarre syntax.
153 */
154
d3409d5e 155mp *mp_read(mp *m, int radix, const mptext_ops *ops, void *p)
156{
2b26f2d7 157 int ch; /* Current char being considered */
158 unsigned f = 0; /* Flags about the current number */
159 int r; /* Radix to switch over to */
160 mpw rd; /* Radix as an @mp@ digit */
161 mp rr; /* The @mp@ for the radix */
162 unsigned nf = m ? m->f & MP_BURN : 0; /* New @mp@ flags */
163
164 /* --- Stacks --- */
165
166 mp *pow[DEPTH]; /* List of powers */
167 unsigned pows; /* Next index to fill */
168 struct { unsigned i; mp *m; } s[DEPTH]; /* Main stack */
169 unsigned sp; /* Current stack pointer */
170
171 /* --- Flags --- */
d3409d5e 172
3bc9cb53 173#define f_neg 1u
174#define f_ok 2u
a951033d 175#define f_start 4u
d3409d5e 176
2b26f2d7 177 /* --- Initialize the stacks --- */
178
179 mp_build(&rr, &rd, &rd + 1);
180 pow[0] = &rr;
181 pows = 1;
182
183 sp = 0;
184
d3409d5e 185 /* --- Initialize the destination number --- */
186
2b26f2d7 187 if (m)
188 MP_DROP(m);
d3409d5e 189
190 /* --- Read an initial character --- */
191
192 ch = ops->get(p);
193 while (isspace(ch))
194 ch = ops->get(p);
195
196 /* --- Handle an initial sign --- */
197
9d3838a0 198 if (radix >= 0 && (ch == '-' || ch == '+')) {
199 if (ch == '-')
200 f |= f_neg;
201 do ch = ops->get(p); while isspace(ch);
d3409d5e 202 }
203
204 /* --- If the radix is zero, look for leading zeros --- */
205
2b26f2d7 206 if (radix > 0) {
631673a1 207 assert(((void)"ascii radix must be <= 62", radix <= 62));
2b26f2d7 208 rd = radix;
209 r = -1;
210 } else if (radix < 0) {
211 rd = -radix;
9d3838a0 212 assert(((void)"binary radix must fit in a byte", rd < UCHAR_MAX));
d3409d5e 213 r = -1;
2b26f2d7 214 } else if (ch != '0') {
215 rd = 10;
d3409d5e 216 r = 0;
217 } else {
218 ch = ops->get(p);
3db58009 219 switch (ch) {
220 case 'x':
221 rd = 16;
222 goto prefix;
223 case 'o':
224 rd = 8;
225 goto prefix;
226 case 'b':
227 rd = 2;
228 goto prefix;
229 prefix:
230 ch = ops->get(p);
231 break;
232 default:
233 rd = 8;
234 f |= f_ok;
d3409d5e 235 }
236 r = -1;
237 }
238
a951033d 239 /* --- Use fast algorithm for binary radix --- *
240 *
241 * This is the restart point after having parsed a radix number from the
242 * input. We check whether the radix is binary, and if so use a fast
243 * algorithm which just stacks the bits up in the right order.
244 */
245
246restart:
247 switch (rd) {
248 unsigned bit;
249
250 case 2: bit = 1; goto bin;
251 case 4: bit = 2; goto bin;
252 case 8: bit = 3; goto bin;
253 case 16: bit = 4; goto bin;
254 case 32: bit = 5; goto bin;
255 case 64: bit = 6; goto bin;
256 case 128: bit = 7; goto bin;
257 default:
258 break;
259
260 /* --- The fast binary algorithm --- *
261 *
262 * We stack bits up starting at the top end of a word. When one word is
263 * full, we write it to the integer, and start another with the left-over
264 * bits. When the array in the integer is full, we resize using low-level
265 * calls and copy the current data to the top end. Finally, we do a single
266 * bit-shift when we know where the end of the number is.
267 */
268
269 bin: {
270 mpw a = 0;
271 unsigned b = MPW_BITS;
272 size_t len, n;
273 mpw *v;
274
275 m = mp_dest(MP_NEW, 1, nf);
276 len = n = m->sz;
277 n = len;
278 v = m->v + n;
279 for (;; ch = ops->get(p)) {
280 unsigned x;
281
282 if (ch < 0)
283 break;
284
285 /* --- Check that the character is a digit and in range --- */
286
287 if (radix < 0)
288 x = ch % rd;
289 else {
290 if (!isalnum(ch))
291 break;
292 if (ch >= '0' && ch <= '9')
293 x = ch - '0';
294 else {
631673a1 295 if (rd <= 36)
296 ch = tolower(ch);
a951033d 297 if (ch >= 'a' && ch <= 'z') /* ASCII dependent! */
298 x = ch - 'a' + 10;
631673a1 299 else if (ch >= 'A' && ch <= 'Z')
300 x = ch - 'A' + 36;
a951033d 301 else
302 break;
303 }
304 }
305 if (x >= rd)
306 break;
307
308 /* --- Feed the digit into the accumulator --- */
309
310 f |= f_ok;
311 if (!x && !(f & f_start))
312 continue;
313 f |= f_start;
314 if (b > bit) {
315 b -= bit;
316 a |= MPW(x) << b;
317 } else {
318 a |= MPW(x) >> (bit - b);
319 b += MPW_BITS - bit;
320 *--v = MPW(a);
321 n--;
322 if (!n) {
323 n = len;
324 len <<= 1;
325 v = mpalloc(m->a, len);
326 memcpy(v + n, m->v, MPWS(n));
327 mpfree(m->a, m->v);
328 m->v = v;
329 v = m->v + n;
330 }
331 a = (b < MPW_BITS) ? MPW(x) << b : 0;
332 }
333 }
334
335 /* --- Finish up --- */
336
337 if (!(f & f_ok)) {
338 mp_drop(m);
339 m = 0;
340 } else {
341 *--v = MPW(a);
342 n--;
343 m->sz = len;
344 m->vl = m->v + len;
345 m->f &= ~MP_UNDEF;
346 m = mp_lsr(m, m, (unsigned long)n * MPW_BITS + b);
347 }
348 goto done;
349 }}
350
d3409d5e 351 /* --- Time to start --- */
352
353 for (;; ch = ops->get(p)) {
a951033d 354 unsigned x;
d3409d5e 355
7d45ed6c 356 if (ch < 0)
357 break;
358
d3409d5e 359 /* --- An underscore indicates a numbered base --- */
360
6ea6fe51 361 if (ch == '_' && r > 0 && r <= 62) {
2b26f2d7 362 unsigned i;
363
364 /* --- Clear out the stacks --- */
365
366 for (i = 1; i < pows; i++)
367 MP_DROP(pow[i]);
368 pows = 1;
369 for (i = 0; i < sp; i++)
370 MP_DROP(s[i].m);
371 sp = 0;
372
373 /* --- Restart the search --- */
374
375 rd = r;
d3409d5e 376 r = -1;
377 f &= ~f_ok;
a951033d 378 ch = ops->get(p);
379 goto restart;
d3409d5e 380 }
381
382 /* --- Check that the character is a digit and in range --- */
383
2b26f2d7 384 if (radix < 0)
9d3838a0 385 x = ch % rd;
d3409d5e 386 else {
2b26f2d7 387 if (!isalnum(ch))
d3409d5e 388 break;
2b26f2d7 389 if (ch >= '0' && ch <= '9')
390 x = ch - '0';
391 else {
631673a1 392 if (rd <= 36)
393 ch = tolower(ch);
2b26f2d7 394 if (ch >= 'a' && ch <= 'z') /* ASCII dependent! */
395 x = ch - 'a' + 10;
631673a1 396 else if (ch >= 'A' && ch <= 'Z')
397 x = ch - 'A' + 36;
2b26f2d7 398 else
399 break;
400 }
d3409d5e 401 }
402
403 /* --- Sort out what to do with the character --- */
404
405 if (x >= 10 && r >= 0)
406 r = -1;
2b26f2d7 407 if (x >= rd)
d3409d5e 408 break;
409
410 if (r >= 0)
411 r = r * 10 + x;
412
413 /* --- Stick the character on the end of my integer --- */
414
2b26f2d7 415 assert(((void)"Number is too unimaginably huge", sp < DEPTH));
416 s[sp].m = m = mp_new(1, nf);
417 m->v[0] = x;
418 s[sp].i = 0;
419
420 /* --- Now grind through the stack --- */
421
422 while (sp > 0 && s[sp - 1].i == s[sp].i) {
423
424 /* --- Combine the top two items --- */
425
426 sp--;
427 m = s[sp].m;
428 m = mp_mul(m, m, pow[s[sp].i]);
429 m = mp_add(m, m, s[sp + 1].m);
430 s[sp].m = m;
431 MP_DROP(s[sp + 1].m);
432 s[sp].i++;
433
434 /* --- Make a new radix power if necessary --- */
435
436 if (s[sp].i >= pows) {
437 assert(((void)"Number is too unimaginably huge", pows < DEPTH));
438 pow[pows] = mp_sqr(MP_NEW, pow[pows - 1]);
439 pows++;
440 }
441 }
d3409d5e 442 f |= f_ok;
2b26f2d7 443 sp++;
d3409d5e 444 }
445
446 ops->unget(ch, p);
447
2b26f2d7 448 /* --- If we're done, compute the rest of the number --- */
449
450 if (f & f_ok) {
451 if (!sp)
452 return (MP_ZERO);
453 else {
454 mp *z = MP_ONE;
455 sp--;
456
457 while (sp > 0) {
458
459 /* --- Combine the top two items --- */
460
461 sp--;
462 m = s[sp].m;
463 z = mp_mul(z, z, pow[s[sp + 1].i]);
464 m = mp_mul(m, m, z);
465 m = mp_add(m, m, s[sp + 1].m);
466 s[sp].m = m;
467 MP_DROP(s[sp + 1].m);
468
469 /* --- Make a new radix power if necessary --- */
470
471 if (s[sp].i >= pows) {
472 assert(((void)"Number is too unimaginably huge", pows < DEPTH));
473 pow[pows] = mp_sqr(MP_NEW, pow[pows - 1]);
474 pows++;
475 }
476 }
477 MP_DROP(z);
478 m = s[0].m;
479 }
480 } else {
481 unsigned i;
482 for (i = 0; i < sp; i++)
483 MP_DROP(s[i].m);
484 }
485
486 /* --- Clear the radix power list --- */
487
488 {
489 unsigned i;
490 for (i = 1; i < pows; i++)
491 MP_DROP(pow[i]);
492 }
493
d3409d5e 494 /* --- Bail out if the number was bad --- */
495
a951033d 496done:
2b26f2d7 497 if (!(f & f_ok))
d3409d5e 498 return (0);
d3409d5e 499
500 /* --- Set the sign and return --- */
501
d3409d5e 502 if (f & f_neg)
503 m->f |= MP_NEG;
504 return (m);
3bc9cb53 505
a951033d 506#undef f_start
3bc9cb53 507#undef f_neg
508#undef f_ok
d3409d5e 509}
510
511/* --- @mp_write@ --- *
512 *
513 * Arguments: @mp *m@ = pointer to a multi-precision integer
514 * @int radix@ = radix to use when writing the number out
515 * @const mptext_ops *ops@ = pointer to an operations block
516 * @void *p@ = data for the operations block
517 *
518 * Returns: Zero if it worked, nonzero otherwise.
519 *
520 * Use: Writes a large integer in textual form.
521 */
522
e360a4f2 523/* --- Simple case --- *
524 *
3bc9cb53 525 * Use a fixed-sized buffer and single-precision arithmetic to pick off
526 * low-order digits. Put each digit in a buffer, working backwards from the
527 * end. If the buffer becomes full, recurse to get another one. Ensure that
528 * there are at least @z@ digits by writing leading zeroes if there aren't
529 * enough real digits.
e360a4f2 530 */
531
3bc9cb53 532static int simple(mpw n, int radix, unsigned z,
e360a4f2 533 const mptext_ops *ops, void *p)
534{
535 int rc = 0;
536 char buf[64];
537 unsigned i = sizeof(buf);
2b26f2d7 538 int rd = radix > 0 ? radix : -radix;
e360a4f2 539
540 do {
541 int ch;
542 mpw x;
543
3bc9cb53 544 x = n % rd;
545 n /= rd;
2b26f2d7 546 if (radix < 0)
547 ch = x;
3bc9cb53 548 else if (x < 10)
549 ch = '0' + x;
631673a1 550 else if (x < 36) /* Ascii specific */
3bc9cb53 551 ch = 'a' + x - 10;
631673a1 552 else
553 ch = 'A' + x - 36;
e360a4f2 554 buf[--i] = ch;
555 if (z)
556 z--;
3bc9cb53 557 } while (i && n);
e360a4f2 558
3bc9cb53 559 if (n)
560 rc = simple(n, radix, z, ops, p);
e360a4f2 561 else {
a951033d 562 char zbuf[32];
563 memset(zbuf, (radix < 0) ? 0 : '0', sizeof(zbuf));
564 while (!rc && z >= sizeof(zbuf)) {
565 rc = ops->put(zbuf, sizeof(zbuf), p);
566 z -= sizeof(zbuf);
e360a4f2 567 }
568 if (!rc && z)
a951033d 569 rc = ops->put(zbuf, z, p);
e360a4f2 570 }
571 if (!rc)
3bc9cb53 572 rc = ops->put(buf + i, sizeof(buf) - i, p);
573 BURN(buf);
e360a4f2 574 return (rc);
575}
576
577/* --- Complicated case --- *
578 *
579 * If the number is small, fall back to the simple case above. Otherwise
580 * divide and take remainder by current large power of the radix, and emit
581 * each separately. Don't emit a zero quotient. Be very careful about
582 * leading zeroes on the remainder part, because they're deeply significant.
583 */
584
585static int complicated(mp *m, int radix, mp **pr, unsigned i, unsigned z,
586 const mptext_ops *ops, void *p)
587{
588 int rc = 0;
589 mp *q = MP_NEW;
590 unsigned d = 1 << i;
591
3bc9cb53 592 if (MP_LEN(m) < 2)
593 return (simple(MP_LEN(m) ? m->v[0] : 0, radix, z, ops, p));
e360a4f2 594
3bc9cb53 595 assert(i);
e360a4f2 596 mp_div(&q, &m, m, pr[i]);
597 if (!MP_LEN(q))
598 d = z;
599 else {
600 if (z > d)
601 z -= d;
602 else
603 z = 0;
604 rc = complicated(q, radix, pr, i - 1, z, ops, p);
605 }
606 if (!rc)
607 rc = complicated(m, radix, pr, i - 1, d, ops, p);
608 mp_drop(q);
609 return (rc);
610}
611
a951033d 612/* --- Binary case --- *
613 *
614 * Special case for binary output. Goes much faster.
615 */
616
617static int binary(mp *m, int bit, int radix, const mptext_ops *ops, void *p)
618{
619 mpw *v;
620 mpw a;
621 int rc = 0;
622 unsigned b;
623 unsigned mask;
624 unsigned long n;
625 unsigned f = 0;
626 char buf[8], *q;
627 unsigned x;
628 int ch;
629
630#define f_out 1u
631
632 /* --- Work out where to start --- */
633
634 n = mp_bits(m);
afd054c1 635 if (n % bit)
636 n += bit - (n % bit);
a951033d 637 b = n % MPW_BITS;
638 n /= MPW_BITS;
afd054c1 639
640 if (n >= MP_LEN(m)) {
a951033d 641 n--;
642 b += MPW_BITS;
643 }
644
645 v = m->v + n;
646 a = *v;
647 mask = (1 << bit) - 1;
648 q = buf;
649
650 /* --- Main code --- */
651
652 for (;;) {
653 if (b > bit) {
654 b -= bit;
655 x = a >> b;
656 } else {
657 x = a << (bit - b);
658 b += MPW_BITS - bit;
659 if (v == m->v)
660 break;
661 a = *--v;
662 if (b < MPW_BITS)
663 x |= a >> b;
664 }
665 x &= mask;
666 if (!x && !(f & f_out))
667 continue;
668
669 if (radix < 0)
670 ch = x;
671 else if (x < 10)
672 ch = '0' + x;
631673a1 673 else if (x < 36)
674 ch = 'a' + x - 10; /* Ascii specific */
a951033d 675 else
631673a1 676 ch = 'A' + x - 36;
a951033d 677 *q++ = ch;
678 if (q >= buf + sizeof(buf)) {
679 if ((rc = ops->put(buf, sizeof(buf), p)) != 0)
680 goto done;
681 q = buf;
682 }
683 f |= f_out;
684 }
685
686 x &= mask;
687 if (radix < 0)
688 ch = x;
689 else if (x < 10)
690 ch = '0' + x;
631673a1 691 else if (x < 36)
692 ch = 'a' + x - 10; /* Ascii specific */
a951033d 693 else
631673a1 694 ch = 'A' + x - 36;
a951033d 695 *q++ = ch;
696 rc = ops->put(buf, q - buf, p);
697
698done:
699 mp_drop(m);
700 return (rc);
701
702#undef f_out
703}
704
e360a4f2 705/* --- Main driver code --- */
706
d3409d5e 707int mp_write(mp *m, int radix, const mptext_ops *ops, void *p)
708{
e360a4f2 709 int rc;
d3409d5e 710
afd054c1 711 if (MP_EQ(m, MP_ZERO))
712 return (ops->put("0", 1, p));
713
d3409d5e 714 /* --- Set various things up --- */
715
716 m = MP_COPY(m);
e360a4f2 717 MP_SPLIT(m);
d3409d5e 718
2b26f2d7 719 /* --- Check the radix for sensibleness --- */
720
721 if (radix > 0)
631673a1 722 assert(((void)"ascii radix must be <= 62", radix <= 62));
2b26f2d7 723 else if (radix < 0)
724 assert(((void)"binary radix must fit in a byte", -radix < UCHAR_MAX));
725 else
726 assert(((void)"radix can't be zero in mp_write", 0));
727
d3409d5e 728 /* --- If the number is negative, sort that out --- */
729
730 if (m->f & MP_NEG) {
731 if (ops->put("-", 1, p))
732 return (EOF);
2b26f2d7 733 m->f &= ~MP_NEG;
d3409d5e 734 }
735
a951033d 736 /* --- Handle binary radix --- */
737
738 switch (radix) {
739 case 2: case -2: return (binary(m, 1, radix, ops, p));
740 case 4: case -4: return (binary(m, 2, radix, ops, p));
741 case 8: case -8: return (binary(m, 3, radix, ops, p));
742 case 16: case -16: return (binary(m, 4, radix, ops, p));
743 case 32: case -32: return (binary(m, 5, radix, ops, p));
744 case -64: return (binary(m, 6, radix, ops, p));
745 case -128: return (binary(m, 7, radix, ops, p));
746 }
747
e360a4f2 748 /* --- If the number is small, do it the easy way --- */
749
3bc9cb53 750 if (MP_LEN(m) < 2)
751 rc = simple(MP_LEN(m) ? m->v[0] : 0, radix, 0, ops, p);
e360a4f2 752
753 /* --- Use a clever algorithm --- *
754 *
755 * Square the radix repeatedly, remembering old results, until I get
756 * something more than half the size of the number @m@. Use this to divide
757 * the number: the quotient and remainder will be approximately the same
758 * size, and I'll have split them on a digit boundary, so I can just emit
759 * the quotient and remainder recursively, in order.
e360a4f2 760 */
761
762 else {
2b26f2d7 763 mp *pr[DEPTH];
3bc9cb53 764 size_t target = (MP_LEN(m) + 1) / 2;
e360a4f2 765 unsigned i = 0;
2b26f2d7 766 mp *z = mp_new(1, 0);
e360a4f2 767
768 /* --- Set up the exponent table --- */
769
2b26f2d7 770 z->v[0] = (radix > 0 ? radix : -radix);
e360a4f2 771 z->f = 0;
772 for (;;) {
2b26f2d7 773 assert(((void)"Number is too unimaginably huge", i < DEPTH));
e360a4f2 774 pr[i++] = z;
775 if (MP_LEN(z) > target)
776 break;
777 z = mp_sqr(MP_NEW, z);
778 }
d3409d5e 779
e360a4f2 780 /* --- Write out the answer --- */
d3409d5e 781
e360a4f2 782 rc = complicated(m, radix, pr, i - 1, 0, ops, p);
d3409d5e 783
e360a4f2 784 /* --- Tidy away the array --- */
d3409d5e 785
e360a4f2 786 while (i > 0)
787 mp_drop(pr[--i]);
d3409d5e 788 }
e360a4f2 789
790 /* --- Tidying up code --- */
791
792 MP_DROP(m);
793 return (rc);
d3409d5e 794}
795
796/*----- Test rig ----------------------------------------------------------*/
797
798#ifdef TEST_RIG
799
800#include <mLib/testrig.h>
801
802static int verify(dstr *v)
803{
804 int ok = 1;
805 int ib = *(int *)v[0].buf, ob = *(int *)v[2].buf;
806 dstr d = DSTR_INIT;
807 mp *m = mp_readdstr(MP_NEW, &v[1], 0, ib);
808 if (m) {
809 if (!ob) {
810 fprintf(stderr, "*** unexpected successful parse\n"
a951033d 811 "*** input [%2i] = ", ib);
2b26f2d7 812 if (ib < 0)
813 type_hex.dump(&v[1], stderr);
814 else
815 fputs(v[1].buf, stderr);
d3409d5e 816 mp_writedstr(m, &d, 10);
2b26f2d7 817 fprintf(stderr, "\n*** (value = %s)\n", d.buf);
d3409d5e 818 ok = 0;
819 } else {
820 mp_writedstr(m, &d, ob);
821 if (d.len != v[3].len || memcmp(d.buf, v[3].buf, d.len) != 0) {
822 fprintf(stderr, "*** failed read or write\n"
a951033d 823 "*** input [%2i] = ", ib);
2b26f2d7 824 if (ib < 0)
825 type_hex.dump(&v[1], stderr);
826 else
827 fputs(v[1].buf, stderr);
a951033d 828 fprintf(stderr, "\n*** output [%2i] = ", ob);
2b26f2d7 829 if (ob < 0)
830 type_hex.dump(&d, stderr);
831 else
832 fputs(d.buf, stderr);
a951033d 833 fprintf(stderr, "\n*** expected [%2i] = ", ob);
2b26f2d7 834 if (ob < 0)
835 type_hex.dump(&v[3], stderr);
836 else
837 fputs(v[3].buf, stderr);
838 fputc('\n', stderr);
d3409d5e 839 ok = 0;
840 }
841 }
842 mp_drop(m);
843 } else {
844 if (ob) {
845 fprintf(stderr, "*** unexpected parse failure\n"
2b26f2d7 846 "*** input [%i] = ", ib);
847 if (ib < 0)
848 type_hex.dump(&v[1], stderr);
849 else
850 fputs(v[1].buf, stderr);
851 fprintf(stderr, "\n*** expected [%i] = ", ob);
852 if (ob < 0)
853 type_hex.dump(&v[3], stderr);
854 else
855 fputs(v[3].buf, stderr);
856 fputc('\n', stderr);
d3409d5e 857 ok = 0;
858 }
859 }
860
861 dstr_destroy(&d);
9c3df6c0 862 assert(mparena_count(MPARENA_GLOBAL) == 0);
d3409d5e 863 return (ok);
864}
865
866static test_chunk tests[] = {
2b26f2d7 867 { "mptext-ascii", verify,
d3409d5e 868 { &type_int, &type_string, &type_int, &type_string, 0 } },
2b26f2d7 869 { "mptext-bin-in", verify,
870 { &type_int, &type_hex, &type_int, &type_string, 0 } },
871 { "mptext-bin-out", verify,
872 { &type_int, &type_string, &type_int, &type_hex, 0 } },
d3409d5e 873 { 0, 0, { 0 } }
874};
875
876int main(int argc, char *argv[])
877{
878 sub_init();
879 test_run(argc, argv, tests, SRCDIR "/tests/mptext");
880 return (0);
881}
882
883#endif
884
885/*----- That's all, folks -------------------------------------------------*/