3 SPDX-License-Identifier: BSD-2-Clause
5 Copyright (c) 2018-2023 Gavin D. Howard and contributors.
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33 bcl - library of arbitrary precision decimal arithmetic
41 Link with *-lbcl*, and on POSIX systems, *-lpthread* is also required.
45 These items allow clients to set up bcl(3).
47 **BclError bcl_start(**_void_**);**
49 **void bcl_end(**_void_**);**
51 **BclError bcl_init(**_void_**);**
53 **void bcl_free(**_void_**);**
55 **bool bcl_abortOnFatalError(**_void_**);**
57 **void bcl_setAbortOnFatalError(bool** _abrt_**);**
59 **bool bcl_leadingZeroes(**_void_**);**
61 **void bcl_setLeadingZeroes(bool** _leadingZeroes_**);**
63 **void bcl_gc(**_void_**);**
65 **bool bcl_digitClamp(**_void_**);**
67 **void bcl_setDigitClamp(bool** _digitClamp_**);**
71 These items will allow clients to handle contexts, which are isolated from each
72 other. This allows more than one client to use bcl(3) in the same program.
76 **typedef struct BclCtxt\* BclContext;**
78 **BclContext bcl_ctxt_create(**_void_**);**
80 **void bcl_ctxt_free(BclContext** _ctxt_**);**
82 **BclError bcl_pushContext(BclContext** _ctxt_**);**
84 **void bcl_popContext(**_void_**);**
86 **BclContext bcl_context(**_void_**);**
88 **void bcl_ctxt_freeNums(BclContext** _ctxt_**);**
90 **size_t bcl_ctxt_scale(BclContext** _ctxt_**);**
92 **void bcl_ctxt_setScale(BclContext** _ctxt_**, size_t** _scale_**);**
94 **size_t bcl_ctxt_ibase(BclContext** _ctxt_**);**
96 **void bcl_ctxt_setIbase(BclContext** _ctxt_**, size_t** _ibase_**);**
98 **size_t bcl_ctxt_obase(BclContext** _ctxt_**);**
100 **void bcl_ctxt_setObase(BclContext** _ctxt_**, size_t** _obase_**);**
104 These items allow clients to handle errors.
106 **typedef enum BclError BclError;**
108 **BclError bcl_err(BclNumber** _n_**);**
112 These items allow clients to manipulate and query the arbitrary-precision
113 numbers managed by bcl(3).
115 **typedef struct { size_t i; } BclNumber;**
117 **BclNumber bcl_num_create(**_void_**);**
119 **void bcl_num_free(BclNumber** _n_**);**
121 **bool bcl_num_neg(BclNumber** _n_**);**
123 **void bcl_num_setNeg(BclNumber** _n_**, bool** _neg_**);**
125 **size_t bcl_num_scale(BclNumber** _n_**);**
127 **BclError bcl_num_setScale(BclNumber** _n_**, size_t** _scale_**);**
129 **size_t bcl_num_len(BclNumber** _n_**);**
133 These items allow clients to convert numbers into and from strings and integers.
135 **BclNumber bcl_parse(const char \*restrict** _val_**);**
137 **char\* bcl_string(BclNumber** _n_**);**
139 **char\* bcl_string_keep(BclNumber** _n_**);**
141 **BclError bcl_bigdig(BclNumber** _n_**, BclBigDig \***_result_**);**
143 **BclError bcl_bigdig_keep(BclNumber** _n_**, BclBigDig \***_result_**);**
145 **BclNumber bcl_bigdig2num(BclBigDig** _val_**);**
149 These items allow clients to run math on numbers.
151 **BclNumber bcl_add(BclNumber** _a_**, BclNumber** _b_**);**
153 **BclNumber bcl_add_keep(BclNumber** _a_**, BclNumber** _b_**);**
155 **BclNumber bcl_sub(BclNumber** _a_**, BclNumber** _b_**);**
157 **BclNumber bcl_sub_keep(BclNumber** _a_**, BclNumber** _b_**);**
159 **BclNumber bcl_mul(BclNumber** _a_**, BclNumber** _b_**);**
161 **BclNumber bcl_mul_keep(BclNumber** _a_**, BclNumber** _b_**);**
163 **BclNumber bcl_div(BclNumber** _a_**, BclNumber** _b_**);**
165 **BclNumber bcl_div_keep(BclNumber** _a_**, BclNumber** _b_**);**
167 **BclNumber bcl_mod(BclNumber** _a_**, BclNumber** _b_**);**
169 **BclNumber bcl_mod_keep(BclNumber** _a_**, BclNumber** _b_**);**
171 **BclNumber bcl_pow(BclNumber** _a_**, BclNumber** _b_**);**
173 **BclNumber bcl_pow_keep(BclNumber** _a_**, BclNumber** _b_**);**
175 **BclNumber bcl_lshift(BclNumber** _a_**, BclNumber** _b_**);**
177 **BclNumber bcl_lshift_keep(BclNumber** _a_**, BclNumber** _b_**);**
179 **BclNumber bcl_rshift(BclNumber** _a_**, BclNumber** _b_**);**
181 **BclNumber bcl_rshift_keep(BclNumber** _a_**, BclNumber** _b_**);**
183 **BclNumber bcl_sqrt(BclNumber** _a_**);**
185 **BclNumber bcl_sqrt_keep(BclNumber** _a_**);**
187 **BclError bcl_divmod(BclNumber** _a_**, BclNumber** _b_**, BclNumber \***_c_**, BclNumber \***_d_**);**
189 **BclError bcl_divmod_keep(BclNumber** _a_**, BclNumber** _b_**, BclNumber \***_c_**, BclNumber \***_d_**);**
191 **BclNumber bcl_modexp(BclNumber** _a_**, BclNumber** _b_**, BclNumber** _c_**);**
193 **BclNumber bcl_modexp_keep(BclNumber** _a_**, BclNumber** _b_**, BclNumber** _c_**);**
197 These items are miscellaneous.
199 **void bcl_zero(BclNumber** _n_**);**
201 **void bcl_one(BclNumber** _n_**);**
203 **ssize_t bcl_cmp(BclNumber** _a_**, BclNumber** _b_**);**
205 **BclError bcl_copy(BclNumber** _d_**, BclNumber** _s_**);**
207 **BclNumber bcl_dup(BclNumber** _s_**);**
209 ## Pseudo-Random Number Generator
211 These items allow clients to manipulate the seeded pseudo-random number
214 **#define BCL_SEED_ULONGS**
216 **#define BCL_SEED_SIZE**
218 **typedef unsigned long BclBigDig;**
220 **typedef unsigned long BclRandInt;**
222 **BclNumber bcl_irand(BclNumber** _a_**);**
224 **BclNumber bcl_irand_keep(BclNumber** _a_**);**
226 **BclNumber bcl_frand(size_t** _places_**);**
228 **BclNumber bcl_ifrand(BclNumber** _a_**, size_t** _places_**);**
230 **BclNumber bcl_ifrand_keep(BclNumber** _a_**, size_t** _places_**);**
232 **BclError bcl_rand_seedWithNum(BclNumber** _n_**);**
234 **BclError bcl_rand_seedWithNum_keep(BclNumber** _n_**);**
236 **BclError bcl_rand_seed(unsigned char** _seed_**[**_BCL_SEED_SIZE_**]);**
238 **void bcl_rand_reseed(**_void_**);**
240 **BclNumber bcl_rand_seed2num(**_void_**);**
242 **BclRandInt bcl_rand_int(**_void_**);**
244 **BclRandInt bcl_rand_bounded(BclRandInt** _bound_**);**
248 bcl(3) is a library that implements arbitrary-precision decimal math, as
249 standardized by POSIX
250 (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html) in bc(1).
252 bcl(3) assumes that it is allowed to use the **bcl**, **Bcl**, **bc**, and
253 **Bc** prefixes for symbol names without collision.
255 All of the items in its interface are described below. See the documentation for
256 each function for what each function can return.
260 **BclError bcl_start(**_void_**)**
262 : Initializes this library. This function can be called multiple times, but
263 **bcl_end()** must only be called *once*. This is to make it possible for
264 multiple libraries and applications to initialize bcl(3) without problem.
266 It is suggested that client libraries call this function, but do not call
267 **bcl_end()**, and client applications should call both.
269 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
272 * **BCL_ERROR_FATAL_ALLOC_ERR**
274 This function must be the first one clients call. Calling any other
275 function without calling this one first is undefined behavior.
277 **void bcl_end(**_void_**)**
279 : Deinitializes this library. This function must only be called *once*.
281 All data must have been freed before calling this function.
283 This function must be the last one clients call. Calling this function
284 before calling any other function is undefined behavior.
286 **BclError bcl_init(**_void_**)**
288 : Initializes the library for the current thread. This function can be called
289 multiple times, but each call must be matched by a call to
290 **bcl_free(**_void_**)**. This is to make it possible for multiple libraries
291 and applications to initialize threads for bcl(3) without problem.
293 This function *must* be called from the thread that it is supposed to
296 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
299 * **BCL_ERROR_FATAL_ALLOC_ERR**
301 This function must be the second one clients call. Calling any other
302 function without calling **bcl_start()** and then this one first is
303 undefined behavior, except in the case of new threads. New threads can
304 safely call this function without calling **bcl_start()** if another thread
305 has previously called **bcl_start()**. But this function must still be the
306 first function in bcl(3) called by that new thread.
308 **void bcl_free(**_void_**)**
310 : Decrements bcl(3)'s reference count and frees the data associated with it if
311 the reference count is **0**.
313 This function *must* be called from the thread that it is supposed to
316 This function must be the second to last one clients call. Calling this
317 function before calling any other function besides **bcl_end()** is
320 **bool bcl_abortOnFatalError(**_void_**)**
322 : Queries and returns the current state of calling **abort()** on fatal
323 errors. If **true** is returned, bcl(3) will cause a **SIGABRT** if a fatal
326 If activated, clients do not need to check for fatal errors.
328 This value is *thread-local*; it applies to just the thread it is read on.
330 The default is **false**.
332 **void bcl_setAbortOnFatalError(bool** _abrt_**)**
334 : Sets the state of calling **abort()** on fatal errors. If *abrt* is
335 **false**, bcl(3) will not cause a **SIGABRT** on fatal errors after the
336 call. If *abrt* is **true**, bcl(3) will cause a **SIGABRT** on fatal errors
339 This value is *thread-local*; it applies to just the thread it is set on.
341 If activated, clients do not need to check for fatal errors.
343 **bool bcl_leadingZeroes(**_void_**)**
345 : Queries and returns the state of whether leading zeroes are added to strings
346 returned by **bcl_string()** when numbers are greater than **-1**, less than
347 **1**, and not equal to **0**. If **true** is returned, then leading zeroes
350 This value is *thread-local*; it applies to just the thread it is read on.
352 The default is **false**.
354 **void bcl_setLeadingZeroes(bool** _leadingZeroes_**)**
356 : Sets the state of whether leading zeroes are added to strings returned by
357 **bcl_string()** when numbers are greater than **-1**, less than **1**, and
358 not equal to **0**. If *leadingZeroes* is **true**, leading zeroes will be
359 added to strings returned by **bcl_string()**.
361 This value is *thread-local*; it applies to just the thread it is set on.
363 **bool bcl_digitClamp(**_void_**)**
365 : Queries and returns the state of whether digits in number strings that are
366 greater than or equal to the current **ibase** are clamped or not.
368 If **true** is returned, then digits are treated as though they are equal to
369 the value of **ibase** minus **1**. If this is *not* true, then digits are
370 treated as though they are equal to the value they would have if **ibase**
371 was large enough. They are then multiplied by the appropriate power of
374 For example, with clamping off and an **ibase** of **3**, the string "AB"
375 would equal **3\^1\*A+3\^0\*B**, which is **3** times **10** plus **11**, or
376 **41**, while with clamping on and an **ibase** of **3**, the string "AB"
377 would be equal to **3\^1\*2+3\^0\*2**, which is **3** times **2** plus
380 This value is *thread-local*; it applies to just the thread it is read on.
382 The default is **true**.
384 **void bcl_setDigitClamp(bool** _digitClamp_**)**
386 : Sets the state of whether digits in number strings that are greater than or
387 equal to the current **ibase** are clamped or not. For more information, see
388 the **bcl_digitClamp(**_void_**)** function.
390 This value is *thread-local*; it applies to just the thread it is set on.
392 **void bcl_gc(**_void_**)**
394 : Garbage collects cached instances of arbitrary-precision numbers. This only
395 frees the memory of numbers that are *not* in use, so it is safe to call at
400 All procedures that take a **BclContext** parameter a require a valid context as
405 : A forward declaration for a hidden **struct** type. Clients cannot access
406 the internals of the **struct** type directly. All interactions with the
407 type are done through pointers. See **BclContext** below.
411 : A typedef to a pointer of **struct BclCtxt**. This is the only handle
412 clients can get to **struct BclCtxt**.
414 A **BclContext** contains the values **scale**, **ibase**, and **obase**, as
415 well as a list of numbers.
417 **scale** is a value used to control how many decimal places calculations
418 should use. A value of **0** means that calculations are done on integers
419 only, where applicable, and a value of 20, for example, means that all
420 applicable calculations return results with 20 decimal places. The default
423 **ibase** is a value used to control the input base. The minimum **ibase**
424 is **2**, and the maximum is **36**. If **ibase** is **2**, numbers are
425 parsed as though they are in binary, and any digits larger than **1** are
426 clamped. Likewise, a value of **10** means that numbers are parsed as though
427 they are decimal, and any larger digits are clamped. The default is **10**.
429 **obase** is a value used to control the output base. The minimum **obase**
430 is **0** and the maximum is **BC_BASE_MAX** (see the **LIMITS** section).
432 Numbers created in one context are not valid in another context. It is
433 undefined behavior to use a number created in a different context. Contexts
434 are meant to isolate the numbers used by different clients in the same
437 Different threads also have different contexts, so any numbers created in
438 one thread are not valid in another thread. To pass values between contexts
439 and threads, use **bcl_string()** to produce a string to pass around, and
440 use **bcl_parse()** to parse the string. It is suggested that the **obase**
441 used to create the string be passed around with the string and used as the
442 **ibase** for **bcl_parse()** to ensure that the number will be the same.
444 **BclContext bcl_ctxt_create(**_void_**)**
446 : Creates a context and returns it. Returns **NULL** if there was an error.
448 **void bcl_ctxt_free(BclContext** _ctxt_**)**
450 : Frees *ctxt*, after which it is no longer valid. It is undefined behavior to
451 attempt to use an invalid context.
453 **BclError bcl_pushContext(BclContext** _ctxt_**)**
455 : Pushes *ctxt* onto bcl(3)'s stack of contexts. *ctxt* must have been created
456 with **bcl_ctxt_create(**_void_**)**.
458 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
461 * **BCL_ERROR_FATAL_ALLOC_ERR**
463 There *must* be a valid context to do any arithmetic.
465 **void bcl_popContext(**_void_**)**
467 : Pops the current context off of the stack, if one exists.
469 **BclContext bcl_context(**_void_**)**
471 : Returns the current context, or **NULL** if no context exists.
473 **void bcl_ctxt_freeNums(BclContext** _ctxt_**)**
475 : Frees all numbers in use that are associated with *ctxt*. It is undefined
476 behavior to attempt to use a number associated with *ctxt* after calling
477 this procedure unless such numbers have been created with
478 **bcl_num_create(**_void_**)** after calling this procedure.
480 **size_t bcl_ctxt_scale(BclContext** _ctxt_**)**
482 : Returns the **scale** for given context.
484 **void bcl_ctxt_setScale(BclContext** _ctxt_**, size_t** _scale_**)**
486 : Sets the **scale** for the given context to the argument *scale*.
488 **size_t bcl_ctxt_ibase(BclContext** _ctxt_**)**
490 : Returns the **ibase** for the given context.
492 **void bcl_ctxt_setIbase(BclContext** _ctxt_**, size_t** _ibase_**)**
494 : Sets the **ibase** for the given context to the argument *ibase*. If the
495 argument *ibase* is invalid, it clamped, so an *ibase* of **0** or **1** is
496 clamped to **2**, and any values above **36** are clamped to **36**.
498 **size_t bcl_ctxt_obase(BclContext** _ctxt_**)**
500 : Returns the **obase** for the given context.
502 **void bcl_ctxt_setObase(BclContext** _ctxt_**, size_t** _obase_**)**
504 : Sets the **obase** for the given context to the argument *obase*.
510 : An **enum** of possible error codes. See the **ERRORS** section for a
511 complete listing the codes.
513 **BclError bcl_err(BclNumber** _n_**)**
515 : Checks for errors in a **BclNumber**. All functions that can return a
516 **BclNumber** can encode an error in the number, and this function will
517 return the error, if any. If there was no error, it will return
520 There must be a valid current context.
524 All procedures in this section require a valid current context.
528 : A handle to an arbitrary-precision number. The actual number type is not
529 exposed; the **BclNumber** handle is the only way clients can refer to
530 instances of arbitrary-precision numbers.
532 **BclNumber bcl_num_create(**_void_**)**
534 : Creates and returns a **BclNumber**.
536 bcl(3) will encode an error in the return value, if there was one. The error
537 can be queried with **bcl_err(BclNumber)**. Possible errors include:
539 * **BCL_ERROR_INVALID_CONTEXT**
540 * **BCL_ERROR_FATAL_ALLOC_ERR**
542 **void bcl_num_free(BclNumber** _n_**)**
544 : Frees *n*. It is undefined behavior to use *n* after calling this function.
546 **bool bcl_num_neg(BclNumber** _n_**)**
548 : Returns **true** if *n* is negative, **false** otherwise.
550 **void bcl_num_setNeg(BclNumber** _n_**, bool** _neg_**)**
552 : Sets *n*'s sign to *neg*, where **true** is negative, and **false** is
555 **size_t bcl_num_scale(BclNumber** _n_**)**
557 : Returns the *scale* of *n*.
559 The *scale* of a number is the number of decimal places it has after the
560 radix (decimal point).
562 **BclError bcl_num_setScale(BclNumber** _n_**, size_t** _scale_**)**
564 : Sets the *scale* of *n* to the argument *scale*. If the argument *scale* is
565 greater than the *scale* of *n*, *n* is extended. If the argument *scale* is
566 less than the *scale* of *n*, *n* is truncated.
568 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
571 * **BCL_ERROR_INVALID_NUM**
572 * **BCL_ERROR_INVALID_CONTEXT**
573 * **BCL_ERROR_FATAL_ALLOC_ERR**
575 **size_t bcl_num_len(BclNumber** _n_**)**
577 : Returns the number of *significant decimal digits* in *n*.
581 All procedures in this section require a valid current context.
583 All procedures in this section without the **_keep** suffix in their name
584 consume the given **BclNumber** arguments that are not given to pointer
585 arguments. See the **Consumption and Propagation** subsection below.
587 **BclNumber bcl_parse(const char \*restrict** _val_**)**
589 : Parses a number string according to the current context's **ibase** and
590 returns the resulting number.
592 *val* must be non-**NULL** and a valid string. See
593 **BCL_ERROR_PARSE_INVALID_STR** in the **ERRORS** section for more
596 bcl(3) will encode an error in the return value, if there was one. The error
597 can be queried with **bcl_err(BclNumber)**. Possible errors include:
599 * **BCL_ERROR_INVALID_NUM**
600 * **BCL_ERROR_INVALID_CONTEXT**
601 * **BCL_ERROR_PARSE_INVALID_STR**
602 * **BCL_ERROR_FATAL_ALLOC_ERR**
604 **char\* bcl_string(BclNumber** _n_**)**
606 : Returns a string representation of *n* according the the current context's
607 **ibase**. The string is dynamically allocated and must be freed by the
610 *n* is consumed; it cannot be used after the call. See the
611 **Consumption and Propagation** subsection below.
613 **char\* bcl_string_keep(BclNumber** _n_**)**
615 : Returns a string representation of *n* according the the current context's
616 **ibase**. The string is dynamically allocated and must be freed by the
619 **BclError bcl_bigdig(BclNumber** _n_**, BclBigDig \***_result_**)**
621 : Converts *n* into a **BclBigDig** and returns the result in the space
622 pointed to by *result*.
624 *a* must be smaller than **BC_OVERFLOW_MAX**. See the **LIMITS** section.
626 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
629 * **BCL_ERROR_INVALID_NUM**
630 * **BCL_ERROR_INVALID_CONTEXT**
631 * **BCL_ERROR_MATH_OVERFLOW**
633 *n* is consumed; it cannot be used after the call. See the
634 **Consumption and Propagation** subsection below.
636 **BclError bcl_bigdig_keep(BclNumber** _n_**, BclBigDig \***_result_**)**
638 : Converts *n* into a **BclBigDig** and returns the result in the space
639 pointed to by *result*.
641 *a* must be smaller than **BC_OVERFLOW_MAX**. See the **LIMITS** section.
643 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
646 * **BCL_ERROR_INVALID_NUM**
647 * **BCL_ERROR_INVALID_CONTEXT**
648 * **BCL_ERROR_MATH_OVERFLOW**
650 **BclNumber bcl_bigdig2num(BclBigDig** _val_**)**
652 : Creates a **BclNumber** from *val*.
654 bcl(3) will encode an error in the return value, if there was one. The error
655 can be queried with **bcl_err(BclNumber)**. Possible errors include:
657 * **BCL_ERROR_INVALID_CONTEXT**
658 * **BCL_ERROR_FATAL_ALLOC_ERR**
662 All procedures in this section require a valid current context.
664 All procedures in this section without the **_keep** suffix in their name
665 consume the given **BclNumber** arguments that are not given to pointer
666 arguments. See the **Consumption and Propagation** subsection below.
668 All procedures in this section can return the following errors:
670 * **BCL_ERROR_INVALID_NUM**
671 * **BCL_ERROR_INVALID_CONTEXT**
672 * **BCL_ERROR_FATAL_ALLOC_ERR**
674 **BclNumber bcl_add(BclNumber** _a_**, BclNumber** _b_**)**
676 : Adds *a* and *b* and returns the result. The *scale* of the result is the
677 max of the *scale*s of *a* and *b*.
679 *a* and *b* are consumed; they cannot be used after the call. See the
680 **Consumption and Propagation** subsection below.
682 *a* and *b* can be the same number.
684 bcl(3) will encode an error in the return value, if there was one. The error
685 can be queried with **bcl_err(BclNumber)**. Possible errors include:
687 * **BCL_ERROR_INVALID_NUM**
688 * **BCL_ERROR_INVALID_CONTEXT**
689 * **BCL_ERROR_FATAL_ALLOC_ERR**
691 **BclNumber bcl_add_keep(BclNumber** _a_**, BclNumber** _b_**)**
693 : Adds *a* and *b* and returns the result. The *scale* of the result is the
694 max of the *scale*s of *a* and *b*.
696 *a* and *b* can be the same number.
698 bcl(3) will encode an error in the return value, if there was one. The error
699 can be queried with **bcl_err(BclNumber)**. Possible errors include:
701 * **BCL_ERROR_INVALID_NUM**
702 * **BCL_ERROR_INVALID_CONTEXT**
703 * **BCL_ERROR_FATAL_ALLOC_ERR**
705 **BclNumber bcl_sub(BclNumber** _a_**, BclNumber** _b_**)**
707 : Subtracts *b* from *a* and returns the result. The *scale* of the result is
708 the max of the *scale*s of *a* and *b*.
710 *a* and *b* are consumed; they cannot be used after the call. See the
711 **Consumption and Propagation** subsection below.
713 *a* and *b* can be the same number.
715 bcl(3) will encode an error in the return value, if there was one. The error
716 can be queried with **bcl_err(BclNumber)**. Possible errors include:
718 * **BCL_ERROR_INVALID_NUM**
719 * **BCL_ERROR_INVALID_CONTEXT**
720 * **BCL_ERROR_FATAL_ALLOC_ERR**
722 **BclNumber bcl_sub_keep(BclNumber** _a_**, BclNumber** _b_**)**
724 : Subtracts *b* from *a* and returns the result. The *scale* of the result is
725 the max of the *scale*s of *a* and *b*.
727 *a* and *b* can be the same number.
729 bcl(3) will encode an error in the return value, if there was one. The error
730 can be queried with **bcl_err(BclNumber)**. Possible errors include:
732 * **BCL_ERROR_INVALID_NUM**
733 * **BCL_ERROR_INVALID_CONTEXT**
734 * **BCL_ERROR_FATAL_ALLOC_ERR**
736 **BclNumber bcl_mul(BclNumber** _a_**, BclNumber** _b_**)**
738 : Multiplies *a* and *b* and returns the result. If *ascale* is the *scale* of
739 *a* and *bscale* is the *scale* of *b*, the *scale* of the result is equal
740 to **min(ascale+bscale,max(scale,ascale,bscale))**, where **min()** and
741 **max()** return the obvious values.
743 *a* and *b* are consumed; they cannot be used after the call. See the
744 **Consumption and Propagation** subsection below.
746 *a* and *b* can be the same number.
748 bcl(3) will encode an error in the return value, if there was one. The error
749 can be queried with **bcl_err(BclNumber)**. Possible errors include:
751 * **BCL_ERROR_INVALID_NUM**
752 * **BCL_ERROR_INVALID_CONTEXT**
753 * **BCL_ERROR_FATAL_ALLOC_ERR**
755 **BclNumber bcl_mul_keep(BclNumber** _a_**, BclNumber** _b_**)**
757 : Multiplies *a* and *b* and returns the result. If *ascale* is the *scale* of
758 *a* and *bscale* is the *scale* of *b*, the *scale* of the result is equal
759 to **min(ascale+bscale,max(scale,ascale,bscale))**, where **min()** and
760 **max()** return the obvious values.
762 *a* and *b* can be the same number.
764 bcl(3) will encode an error in the return value, if there was one. The error
765 can be queried with **bcl_err(BclNumber)**. Possible errors include:
767 * **BCL_ERROR_INVALID_NUM**
768 * **BCL_ERROR_INVALID_CONTEXT**
769 * **BCL_ERROR_FATAL_ALLOC_ERR**
771 **BclNumber bcl_div(BclNumber** _a_**, BclNumber** _b_**)**
773 : Divides *a* by *b* and returns the result. The *scale* of the result is the
774 *scale* of the current context.
778 *a* and *b* are consumed; they cannot be used after the call. See the
779 **Consumption and Propagation** subsection below.
781 *a* and *b* can be the same number.
783 bcl(3) will encode an error in the return value, if there was one. The error
784 can be queried with **bcl_err(BclNumber)**. Possible errors include:
786 * **BCL_ERROR_INVALID_NUM**
787 * **BCL_ERROR_INVALID_CONTEXT**
788 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
789 * **BCL_ERROR_FATAL_ALLOC_ERR**
791 **BclNumber bcl_div_keep(BclNumber** _a_**, BclNumber** _b_**)**
793 : Divides *a* by *b* and returns the result. The *scale* of the result is the
794 *scale* of the current context.
798 *a* and *b* can be the same number.
800 bcl(3) will encode an error in the return value, if there was one. The error
801 can be queried with **bcl_err(BclNumber)**. Possible errors include:
803 * **BCL_ERROR_INVALID_NUM**
804 * **BCL_ERROR_INVALID_CONTEXT**
805 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
806 * **BCL_ERROR_FATAL_ALLOC_ERR**
808 **BclNumber bcl_mod(BclNumber** _a_**, BclNumber** _b_**)**
810 : Divides *a* by *b* to the *scale* of the current context, computes the
811 modulus **a-(a/b)\*b**, and returns the modulus.
815 *a* and *b* are consumed; they cannot be used after the call. See the
816 **Consumption and Propagation** subsection below.
818 *a* and *b* can be the same number.
820 bcl(3) will encode an error in the return value, if there was one. The error
821 can be queried with **bcl_err(BclNumber)**. Possible errors include:
823 * **BCL_ERROR_INVALID_NUM**
824 * **BCL_ERROR_INVALID_CONTEXT**
825 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
826 * **BCL_ERROR_FATAL_ALLOC_ERR**
828 **BclNumber bcl_mod_keep(BclNumber** _a_**, BclNumber** _b_**)**
830 : Divides *a* by *b* to the *scale* of the current context, computes the
831 modulus **a-(a/b)\*b**, and returns the modulus.
835 *a* and *b* can be the same number.
837 bcl(3) will encode an error in the return value, if there was one. The error
838 can be queried with **bcl_err(BclNumber)**. Possible errors include:
840 * **BCL_ERROR_INVALID_NUM**
841 * **BCL_ERROR_INVALID_CONTEXT**
842 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
843 * **BCL_ERROR_FATAL_ALLOC_ERR**
845 **BclNumber bcl_pow(BclNumber** _a_**, BclNumber** _b_**)**
847 : Calculates *a* to the power of *b* to the *scale* of the current context.
848 *b* must be an integer, but can be negative. If it is negative, *a* must
851 *b* must be an integer. If *b* is negative, *a* must not be **0**.
853 *a* must be smaller than **BC_OVERFLOW_MAX**. See the **LIMITS** section.
855 *a* and *b* are consumed; they cannot be used after the call. See the
856 **Consumption and Propagation** subsection below.
858 *a* and *b* can be the same number.
860 bcl(3) will encode an error in the return value, if there was one. The error
861 can be queried with **bcl_err(BclNumber)**. Possible errors include:
863 * **BCL_ERROR_INVALID_NUM**
864 * **BCL_ERROR_INVALID_CONTEXT**
865 * **BCL_ERROR_MATH_NON_INTEGER**
866 * **BCL_ERROR_MATH_OVERFLOW**
867 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
868 * **BCL_ERROR_FATAL_ALLOC_ERR**
870 **BclNumber bcl_pow_keep(BclNumber** _a_**, BclNumber** _b_**)**
872 : Calculates *a* to the power of *b* to the *scale* of the current context.
873 *b* must be an integer, but can be negative. If it is negative, *a* must
876 *b* must be an integer. If *b* is negative, *a* must not be **0**.
878 *a* must be smaller than **BC_OVERFLOW_MAX**. See the **LIMITS** section.
880 *a* and *b* can be the same number.
882 bcl(3) will encode an error in the return value, if there was one. The error
883 can be queried with **bcl_err(BclNumber)**. Possible errors include:
885 * **BCL_ERROR_INVALID_NUM**
886 * **BCL_ERROR_INVALID_CONTEXT**
887 * **BCL_ERROR_MATH_NON_INTEGER**
888 * **BCL_ERROR_MATH_OVERFLOW**
889 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
890 * **BCL_ERROR_FATAL_ALLOC_ERR**
892 **BclNumber bcl_lshift(BclNumber** _a_**, BclNumber** _b_**)**
894 : Shifts *a* left (moves the radix right) by *b* places and returns the
895 result. This is done in decimal. *b* must be an integer.
897 *b* must be an integer.
899 *a* and *b* are consumed; they cannot be used after the call. See the
900 **Consumption and Propagation** subsection below.
902 *a* and *b* can be the same number.
904 bcl(3) will encode an error in the return value, if there was one. The error
905 can be queried with **bcl_err(BclNumber)**. Possible errors include:
907 * **BCL_ERROR_INVALID_NUM**
908 * **BCL_ERROR_INVALID_CONTEXT**
909 * **BCL_ERROR_MATH_NON_INTEGER**
910 * **BCL_ERROR_FATAL_ALLOC_ERR**
912 **BclNumber bcl_lshift_keep(BclNumber** _a_**, BclNumber** _b_**)**
914 : Shifts *a* left (moves the radix right) by *b* places and returns the
915 result. This is done in decimal. *b* must be an integer.
917 *b* must be an integer.
919 *a* and *b* can be the same number.
921 bcl(3) will encode an error in the return value, if there was one. The error
922 can be queried with **bcl_err(BclNumber)**. Possible errors include:
924 * **BCL_ERROR_INVALID_NUM**
925 * **BCL_ERROR_INVALID_CONTEXT**
926 * **BCL_ERROR_MATH_NON_INTEGER**
927 * **BCL_ERROR_FATAL_ALLOC_ERR**
929 **BclNumber bcl_rshift(BclNumber** _a_**, BclNumber** _b_**)**
931 : Shifts *a* right (moves the radix left) by *b* places and returns the
932 result. This is done in decimal. *b* must be an integer.
934 *b* must be an integer.
936 *a* and *b* are consumed; they cannot be used after the call. See the
937 **Consumption and Propagation** subsection below.
939 *a* and *b* can be the same number.
941 bcl(3) will encode an error in the return value, if there was one. The error
942 can be queried with **bcl_err(BclNumber)**. Possible errors include:
944 * **BCL_ERROR_INVALID_NUM**
945 * **BCL_ERROR_INVALID_CONTEXT**
946 * **BCL_ERROR_MATH_NON_INTEGER**
947 * **BCL_ERROR_FATAL_ALLOC_ERR**
949 **BclNumber bcl_rshift_keep(BclNumber** _a_**, BclNumber** _b_**)**
951 : Shifts *a* right (moves the radix left) by *b* places and returns the
952 result. This is done in decimal. *b* must be an integer.
954 *b* must be an integer.
956 *a* and *b* can be the same number.
958 bcl(3) will encode an error in the return value, if there was one. The error
959 can be queried with **bcl_err(BclNumber)**. Possible errors include:
961 * **BCL_ERROR_INVALID_NUM**
962 * **BCL_ERROR_INVALID_CONTEXT**
963 * **BCL_ERROR_MATH_NON_INTEGER**
964 * **BCL_ERROR_FATAL_ALLOC_ERR**
966 **BclNumber bcl_sqrt(BclNumber** _a_**)**
968 : Calculates the square root of *a* and returns the result. The *scale* of the
969 result is equal to the **scale** of the current context.
971 *a* cannot be negative.
973 *a* is consumed; it cannot be used after the call. See the
974 **Consumption and Propagation** subsection below.
976 bcl(3) will encode an error in the return value, if there was one. The error
977 can be queried with **bcl_err(BclNumber)**. Possible errors include:
979 * **BCL_ERROR_INVALID_NUM**
980 * **BCL_ERROR_INVALID_CONTEXT**
981 * **BCL_ERROR_MATH_NEGATIVE**
982 * **BCL_ERROR_FATAL_ALLOC_ERR**
984 **BclNumber bcl_sqrt_keep(BclNumber** _a_**)**
986 : Calculates the square root of *a* and returns the result. The *scale* of the
987 result is equal to the **scale** of the current context.
989 *a* cannot be negative.
991 bcl(3) will encode an error in the return value, if there was one. The error
992 can be queried with **bcl_err(BclNumber)**. Possible errors include:
994 * **BCL_ERROR_INVALID_NUM**
995 * **BCL_ERROR_INVALID_CONTEXT**
996 * **BCL_ERROR_MATH_NEGATIVE**
997 * **BCL_ERROR_FATAL_ALLOC_ERR**
999 **BclError bcl_divmod(BclNumber** _a_**, BclNumber** _b_**, BclNumber \***_c_**, BclNumber \***_d_**)**
1001 : Divides *a* by *b* and returns the quotient in a new number which is put
1002 into the space pointed to by *c*, and puts the modulus in a new number which
1003 is put into the space pointed to by *d*.
1005 *b* cannot be **0**.
1007 *a* and *b* are consumed; they cannot be used after the call. See the
1008 **Consumption and Propagation** subsection below.
1010 *c* and *d* cannot point to the same place, nor can they point to the space
1011 occupied by *a* or *b*.
1013 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
1014 function can return:
1016 * **BCL_ERROR_INVALID_NUM**
1017 * **BCL_ERROR_INVALID_CONTEXT**
1018 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
1019 * **BCL_ERROR_FATAL_ALLOC_ERR**
1021 **BclError bcl_divmod_keep(BclNumber** _a_**, BclNumber** _b_**, BclNumber \***_c_**, BclNumber \***_d_**)**
1023 : Divides *a* by *b* and returns the quotient in a new number which is put
1024 into the space pointed to by *c*, and puts the modulus in a new number which
1025 is put into the space pointed to by *d*.
1027 *b* cannot be **0**.
1029 *c* and *d* cannot point to the same place, nor can they point to the space
1030 occupied by *a* or *b*.
1032 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
1033 function can return:
1035 * **BCL_ERROR_INVALID_NUM**
1036 * **BCL_ERROR_INVALID_CONTEXT**
1037 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
1038 * **BCL_ERROR_FATAL_ALLOC_ERR**
1040 **BclNumber bcl_modexp(BclNumber** _a_**, BclNumber** _b_**, BclNumber** _c_**)**
1042 : Computes a modular exponentiation where *a* is the base, *b* is the
1043 exponent, and *c* is the modulus, and returns the result. The *scale* of the
1044 result is equal to the **scale** of the current context.
1046 *a*, *b*, and *c* must be integers. *c* must not be **0**. *b* must not be
1049 *a*, *b*, and *c* are consumed; they cannot be used after the call. See the
1050 **Consumption and Propagation** subsection below.
1052 bcl(3) will encode an error in the return value, if there was one. The error
1053 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1055 * **BCL_ERROR_INVALID_NUM**
1056 * **BCL_ERROR_INVALID_CONTEXT**
1057 * **BCL_ERROR_MATH_NEGATIVE**
1058 * **BCL_ERROR_MATH_NON_INTEGER**
1059 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
1060 * **BCL_ERROR_FATAL_ALLOC_ERR**
1062 **BclNumber bcl_modexp_keep(BclNumber** _a_**, BclNumber** _b_**, BclNumber** _c_**)**
1064 : Computes a modular exponentiation where *a* is the base, *b* is the
1065 exponent, and *c* is the modulus, and returns the result. The *scale* of the
1066 result is equal to the **scale** of the current context.
1068 *a*, *b*, and *c* must be integers. *c* must not be **0**. *b* must not be
1071 bcl(3) will encode an error in the return value, if there was one. The error
1072 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1074 * **BCL_ERROR_INVALID_NUM**
1075 * **BCL_ERROR_INVALID_CONTEXT**
1076 * **BCL_ERROR_MATH_NEGATIVE**
1077 * **BCL_ERROR_MATH_NON_INTEGER**
1078 * **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
1079 * **BCL_ERROR_FATAL_ALLOC_ERR**
1083 **void bcl_zero(BclNumber** _n_**)**
1085 : Sets *n* to **0**.
1087 **void bcl_one(BclNumber** _n_**)**
1089 : Sets *n* to **1**.
1091 **ssize_t bcl_cmp(BclNumber** _a_**, BclNumber** _b_**)**
1093 : Compares *a* and *b* and returns **0** if *a* and *b* are equal, **<0** if
1094 *a* is less than *b*, and **>0** if *a* is greater than *b*.
1096 **BclError bcl_copy(BclNumber** _d_**, BclNumber** _s_**)**
1098 : Copies *s* into *d*.
1100 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
1101 function can return:
1103 * **BCL_ERROR_INVALID_NUM**
1104 * **BCL_ERROR_INVALID_CONTEXT**
1105 * **BCL_ERROR_FATAL_ALLOC_ERR**
1107 **BclNumber bcl_dup(BclNumber** _s_**)**
1109 : Creates and returns a new **BclNumber** that is a copy of *s*.
1111 bcl(3) will encode an error in the return value, if there was one. The error
1112 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1114 * **BCL_ERROR_INVALID_NUM**
1115 * **BCL_ERROR_INVALID_CONTEXT**
1116 * **BCL_ERROR_FATAL_ALLOC_ERR**
1118 ## Pseudo-Random Number Generator
1120 The pseudo-random number generator in bcl(3) is a *seeded* PRNG. Given the same
1121 seed twice, it will produce the same sequence of pseudo-random numbers twice.
1123 By default, bcl(3) attempts to seed the PRNG with data from **/dev/urandom**. If
1124 that fails, it seeds itself with by calling **libc**'s **srand(time(NULL))** and
1125 then calling **rand()** for each byte, since **rand()** is only guaranteed to
1128 This should provide fairly good seeding in the standard case while also
1129 remaining fairly portable.
1131 If necessary, the PRNG can be reseeded with one of the following functions:
1133 * **bcl_rand_seedWithNum(BclNumber)**
1134 * **bcl_rand_seed(unsigned char[**_BCL_SEED_SIZE_**])**
1135 * **bcl_rand_reseed(**_void_**)**
1137 All procedures in this section without the **_keep** suffix in their name
1138 consume the given **BclNumber** arguments that are not given to pointer
1139 arguments. See the **Consumption and Propagation** subsection below.
1141 The following items allow clients to use the pseudo-random number generator. All
1142 procedures require a valid current context.
1146 : The number of **unsigned long**'s in a seed for bcl(3)'s random number
1151 : The size, in **char**'s, of a seed for bcl(3)'s random number generator.
1155 : bcl(3)'s overflow type (see the **PERFORMANCE** section).
1159 : An unsigned integer type returned by bcl(3)'s random number generator.
1161 **BclNumber bcl_irand(BclNumber** _a_**)**
1163 : Returns a random number that is not larger than *a* in a new number. If *a*
1164 is **0** or **1**, the new number is equal to **0**. The bound is unlimited,
1165 so it is not bound to the size of **BclRandInt**. This is done by generating
1166 as many random numbers as necessary, multiplying them by certain exponents,
1167 and adding them all together.
1169 *a* must be an integer and non-negative.
1171 *a* is consumed; it cannot be used after the call. See the **Consumption and
1172 Propagation** subsection below.
1174 This procedure requires a valid current context.
1176 bcl(3) will encode an error in the return value, if there was one. The error
1177 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1179 * **BCL_ERROR_INVALID_NUM**
1180 * **BCL_ERROR_INVALID_CONTEXT**
1181 * **BCL_ERROR_MATH_NEGATIVE**
1182 * **BCL_ERROR_MATH_NON_INTEGER**
1183 * **BCL_ERROR_FATAL_ALLOC_ERR**
1185 **BclNumber bcl_irand_keep(BclNumber** _a_**)**
1187 : Returns a random number that is not larger than *a* in a new number. If *a*
1188 is **0** or **1**, the new number is equal to **0**. The bound is unlimited,
1189 so it is not bound to the size of **BclRandInt**. This is done by generating
1190 as many random numbers as necessary, multiplying them by certain exponents,
1191 and adding them all together.
1193 *a* must be an integer and non-negative.
1195 This procedure requires a valid current context.
1197 bcl(3) will encode an error in the return value, if there was one. The error
1198 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1200 * **BCL_ERROR_INVALID_NUM**
1201 * **BCL_ERROR_INVALID_CONTEXT**
1202 * **BCL_ERROR_MATH_NEGATIVE**
1203 * **BCL_ERROR_MATH_NON_INTEGER**
1204 * **BCL_ERROR_FATAL_ALLOC_ERR**
1206 **BclNumber bcl_frand(size_t** _places_**)**
1208 : Returns a random number between **0** (inclusive) and **1** (exclusive) that
1209 has *places* decimal digits after the radix (decimal point). There are no
1212 This procedure requires a valid current context.
1214 bcl(3) will encode an error in the return value, if there was one. The error
1215 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1217 * **BCL_ERROR_INVALID_CONTEXT**
1218 * **BCL_ERROR_FATAL_ALLOC_ERR**
1220 **BclNumber bcl_ifrand(BclNumber** _a_**, size_t** _places_**)**
1222 : Returns a random number less than *a* with *places* decimal digits after the
1223 radix (decimal point). There are no limits on *a* or *places*.
1225 *a* must be an integer and non-negative.
1227 *a* is consumed; it cannot be used after the call. See the **Consumption and
1228 Propagation** subsection below.
1230 This procedure requires a valid current context.
1232 bcl(3) will encode an error in the return value, if there was one. The error
1233 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1235 * **BCL_ERROR_INVALID_NUM**
1236 * **BCL_ERROR_INVALID_CONTEXT**
1237 * **BCL_ERROR_MATH_NEGATIVE**
1238 * **BCL_ERROR_MATH_NON_INTEGER**
1239 * **BCL_ERROR_FATAL_ALLOC_ERR**
1241 **BclNumber bcl_ifrand_keep(BclNumber** _a_**, size_t** _places_**)**
1243 : Returns a random number less than *a* with *places* decimal digits after the
1244 radix (decimal point). There are no limits on *a* or *places*.
1246 *a* must be an integer and non-negative.
1248 This procedure requires a valid current context.
1250 bcl(3) will encode an error in the return value, if there was one. The error
1251 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1253 * **BCL_ERROR_INVALID_NUM**
1254 * **BCL_ERROR_INVALID_CONTEXT**
1255 * **BCL_ERROR_MATH_NEGATIVE**
1256 * **BCL_ERROR_MATH_NON_INTEGER**
1257 * **BCL_ERROR_FATAL_ALLOC_ERR**
1259 **BclError bcl_rand_seedWithNum(BclNumber** _n_**)**
1261 : Seeds the PRNG with *n*.
1265 This procedure requires a valid current context.
1267 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
1268 function can return:
1270 * **BCL_ERROR_INVALID_NUM**
1271 * **BCL_ERROR_INVALID_CONTEXT**
1273 Note that if **bcl_rand_seed2num(**_void_**)** or
1274 **bcl_rand_seed2num_err(BclNumber)** are called right after this function,
1275 they are not guaranteed to return a number equal to *n*.
1277 **BclError bcl_rand_seedWithNum_keep(BclNumber** _n_**)**
1279 : Seeds the PRNG with *n*.
1281 This procedure requires a valid current context.
1283 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
1284 function can return:
1286 * **BCL_ERROR_INVALID_NUM**
1287 * **BCL_ERROR_INVALID_CONTEXT**
1289 Note that if **bcl_rand_seed2num(**_void_**)** or
1290 **bcl_rand_seed2num_err(BclNumber)** are called right after this function,
1291 they are not guaranteed to return a number equal to *n*.
1293 **BclError bcl_rand_seed(unsigned char** _seed_**[**_BCL_SEED_SIZE_**])**
1295 : Seeds the PRNG with the bytes in *seed*.
1297 If there was no error, **BCL_ERROR_NONE** is returned. Otherwise, this
1298 function can return:
1300 * **BCL_ERROR_INVALID_CONTEXT**
1302 **void bcl_rand_reseed(**_void_**)**
1304 : Reseeds the PRNG with the default reseeding behavior. First, it attempts to
1305 read data from **/dev/urandom** and falls back to **libc**'s **rand()**.
1307 This procedure cannot fail.
1309 **BclNumber bcl_rand_seed2num(**_void_**)**
1311 : Returns the current seed of the PRNG as a **BclNumber**.
1313 This procedure requires a valid current context.
1315 bcl(3) will encode an error in the return value, if there was one. The error
1316 can be queried with **bcl_err(BclNumber)**. Possible errors include:
1318 * **BCL_ERROR_INVALID_CONTEXT**
1319 * **BCL_ERROR_FATAL_ALLOC_ERR**
1321 **BclRandInt bcl_rand_int(**_void_**)**
1323 : Returns a random integer between **0** and **BC_RAND_MAX** (inclusive).
1325 This procedure cannot fail.
1327 **BclRandInt bcl_rand_bounded(BclRandInt** _bound_**)**
1329 : Returns a random integer between **0** and *bound* (exclusive). Bias is
1330 removed before returning the integer.
1332 This procedure cannot fail.
1334 ## Consumption and Propagation
1336 Some functions are listed as consuming some or all of their arguments. This
1337 means that the arguments are freed, regardless of if there were errors or not.
1339 This is to enable compact code like the following:
1341 BclNumber n = bcl_num_add(bcl_num_mul(a, b), bcl_num_div(c, d));
1343 If arguments to those functions were not consumed, memory would be leaked until
1344 reclaimed with **bcl_ctxt_freeNums(BclContext)**.
1346 When errors occur, they are propagated through. The result should always be
1347 checked with **bcl_err(BclNumber)**, so the example above should properly
1350 BclNumber n = bcl_num_add(bcl_num_mul(a, b), bcl_num_div(c, d));
1351 if (bcl_err(n) != BCL_ERROR_NONE) {
1352 // Handle the error.
1357 Most functions in bcl(3) return, directly or indirectly, any one of the error
1358 codes defined in **BclError**. The complete list of codes is the following:
1362 : Success; no error occurred.
1364 **BCL_ERROR_INVALID_NUM**
1366 : An invalid **BclNumber** was given as a parameter.
1368 **BCL_ERROR_INVALID_CONTEXT**
1370 : An invalid **BclContext** is being used.
1372 **BCL_ERROR_MATH_NEGATIVE**
1374 : A negative number was given as an argument to a parameter that cannot accept
1375 negative numbers, such as for square roots.
1377 **BCL_ERROR_MATH_NON_INTEGER**
1379 : A non-integer was given as an argument to a parameter that cannot accept
1380 non-integer numbers, such as for the second parameter of **bcl_num_pow()**.
1382 **BCL_ERROR_MATH_OVERFLOW**
1384 : A number that would overflow its result was given as an argument, such as
1385 for converting a **BclNumber** to a **BclBigDig**.
1387 **BCL_ERROR_MATH_DIVIDE_BY_ZERO**
1389 : A divide by zero occurred.
1391 **BCL_ERROR_PARSE_INVALID_STR**
1393 : An invalid number string was passed to a parsing function.
1395 A valid number string can only be one radix (period). In addition, any
1396 lowercase ASCII letters, symbols, or non-ASCII characters are invalid. It is
1397 allowed for the first character to be a dash. In that case, the number is
1398 considered to be negative.
1400 There is one exception to the above: one lowercase **e** is allowed in the
1401 number, after the radix, if it exists. If the letter **e** exists, the
1402 number is considered to be in scientific notation, where the part before the
1403 **e** is the number, and the part after, which must be an integer, is the
1404 exponent. There can be a dash right after the **e** to indicate a negative
1407 **WARNING**: Both the number and the exponent in scientific notation are
1408 interpreted according to the current **ibase**, but the number is still
1409 multiplied by **10\^exponent** regardless of the current **ibase**. For
1410 example, if **ibase** is **16** and bcl(3) is given the number string
1411 **FFeA**, the resulting decimal number will be **2550000000000**, and if
1412 bcl(3) is given the number string **10e-4**, the resulting decimal number
1415 **BCL_ERROR_FATAL_ALLOC_ERR**
1417 : bcl(3) failed to allocate memory.
1419 If clients call **bcl_setAbortOnFatalError()** with an **true** argument,
1420 this error will cause bcl(3) to throw a **SIGABRT**. This behavior can also
1421 be turned off later by calling that same function with a **false** argument.
1422 By default, this behavior is off.
1424 It is highly recommended that client libraries do *not* activate this
1427 **BCL_ERROR_FATAL_UNKNOWN_ERR**
1429 : An unknown error occurred.
1431 If clients call **bcl_setAbortOnFatalError()** with an **true** argument,
1432 this error will cause bcl(3) to throw a **SIGABRT**. This behavior can also
1433 be turned off later by calling that same function with a **false** argument.
1434 By default, this behavior is off.
1436 It is highly recommended that client libraries do *not* activate this
1441 bcl(3) is *MT-Safe*: it is safe to call any functions from more than one thread.
1442 However, is is *not* safe to pass any data between threads except for strings
1443 returned by **bcl_string()**.
1445 bcl(3) is not *async-signal-safe*. It was not possible to make bcl(3) safe with
1446 signals and also make it safe with multiple threads. If it is necessary to be
1447 able to interrupt bcl(3), spawn a separate thread to run the calculation.
1451 Most bc(1) implementations use **char** types to calculate the value of **1**
1452 decimal digit at a time, but that can be slow. bcl(3) does something
1455 It uses large integers to calculate more than **1** decimal digit at a time. If
1456 built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
1457 **64**, then each integer has **9** decimal digits. If built in an environment
1458 where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
1459 value (the number of decimal digits per large integer) is called
1462 In addition, this bcl(3) uses an even larger integer for overflow checking. This
1463 integer type depends on the value of **BC_LONG_BIT**, but is always at least
1464 twice as large as the integer type used to store digits.
1468 The following are the limits on bcl(3):
1472 : The number of bits in the **long** type in the environment where bcl(3) was
1473 built. This determines how many decimal digits can be stored in a single
1474 large integer (see the **PERFORMANCE** section).
1478 : The number of decimal digits per large integer (see the **PERFORMANCE**
1479 section). Depends on **BC_LONG_BIT**.
1483 : The max decimal number that each large integer can store (see
1484 **BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
1488 : The max number that the overflow type (see the **PERFORMANCE** section) can
1489 hold. Depends on **BC_LONG_BIT**.
1493 : The maximum output base. Set at **BC_BASE_POW**.
1497 : The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
1501 : The maximum length of a number (in decimal digits), which includes digits
1502 after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
1506 : The maximum integer (inclusive) returned by the **bcl_rand_int()** function.
1507 Set at **2\^BC_LONG_BIT-1**.
1511 : The maximum allowable exponent (positive or negative). Set at
1512 **BC_OVERFLOW_MAX**.
1514 These limits are meant to be effectively non-existent; the limits are so large
1515 (at least on 64-bit machines) that there should not be any point at which they
1516 become a problem. In fact, memory should be exhausted before these limits should
1525 bcl(3) is compliant with the arithmetic defined in the IEEE Std 1003.1-2017
1526 (“POSIX.1-2017”) specification at
1527 https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html for bc(1).
1529 Note that the specification explicitly says that bc(1) only accepts numbers that
1530 use a period (**.**) as a radix point, regardless of the value of
1531 **LC_NUMERIC**. This is also true of bcl(3).
1535 None are known. Report bugs at https://git.gavinhoward.com/gavin/bc.
1539 Gavin D. Howard <gavin@gavinhoward.com> and contributors.