bc/src/library.c

/*
 * *****************************************************************************
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2018-2021 Gavin D. Howard and contributors.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * *****************************************************************************
 *
 * The public functions for libbc.
 *
 */

#if BC_ENABLE_LIBRARY

#include <setjmp.h>
#include <string.h>
#include <time.h>

#include <bcl.h>

#include <library.h>
#include <num.h>
#include <vm.h>

// The asserts in this file are important to testing; in many cases, the test
// would not work without the asserts, so don't remove them without reason.
//
// Also, there are many uses of bc_num_clear() here; that is because numbers are
// being reused, and a clean slate is required.
//
// Also, there are a bunch of BC_UNSETJMP and BC_SETJMP_LOCKED() between calls
// to bc_num_init(). That is because locals are being initialized, and unlike bc
// proper, this code cannot assume that allocation failures are fatal. So we
// have to reset the jumps every time to ensure that the locals will be correct
// after jumping.

void bcl_handleSignal(void) {

	// Signal already in flight, or bc is not executing.
	if (vm.sig || !vm.running) return;

	vm.sig = 1;

	assert(vm.jmp_bufs.len);

	if (!vm.sig_lock) BC_JMP;
}

bool bcl_running(void) {
	return vm.running != 0;
}

BclError bcl_init(void) {

	BclError e = BCL_ERROR_NONE;

	vm.refs += 1;

	if (vm.refs > 1) return e;

	// Setting these to NULL ensures that if an error occurs, we only free what
	// is necessary.
	vm.ctxts.v = NULL;
	vm.jmp_bufs.v = NULL;
	vm.out.v = NULL;

	vm.abrt = false;

	BC_SIG_LOCK;

	// The jmp_bufs always has to be initialized first.
	bc_vec_init(&vm.jmp_bufs, sizeof(sigjmp_buf), BC_DTOR_NONE);

	BC_FUNC_HEADER_INIT(err);

	bc_vm_init();

	bc_vec_init(&vm.ctxts, sizeof(BclContext), BC_DTOR_NONE);
	bc_vec_init(&vm.out, sizeof(uchar), BC_DTOR_NONE);

	// We need to seed this in case /dev/random and /dev/urandm don't work.
	srand((unsigned int) time(NULL));
	bc_rand_init(&vm.rng);

err:
	// This is why we had to set them to NULL.
	if (BC_ERR(vm.err)) {
		if (vm.out.v != NULL) bc_vec_free(&vm.out);
		if (vm.jmp_bufs.v != NULL) bc_vec_free(&vm.jmp_bufs);
		if (vm.ctxts.v != NULL) bc_vec_free(&vm.ctxts);
	}

	BC_FUNC_FOOTER_UNLOCK(e);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return e;
}

BclError bcl_pushContext(BclContext ctxt) {

	BclError e = BCL_ERROR_NONE;

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_push(&vm.ctxts, &ctxt);

err:
	BC_FUNC_FOOTER_UNLOCK(e);
	return e;
}

void bcl_popContext(void) {
	if (vm.ctxts.len) bc_vec_pop(&vm.ctxts);
}

BclContext bcl_context(void) {
	if (!vm.ctxts.len) return NULL;
	return *((BclContext*) bc_vec_top(&vm.ctxts));
}

void bcl_free(void) {

	size_t i;

	vm.refs -= 1;

	if (vm.refs) return;

	BC_SIG_LOCK;

	bc_rand_free(&vm.rng);
	bc_vec_free(&vm.out);

	for (i = 0; i < vm.ctxts.len; ++i) {
		BclContext ctxt = *((BclContext*) bc_vec_item(&vm.ctxts, i));
		bcl_ctxt_free(ctxt);
	}

	bc_vec_free(&vm.ctxts);

	bc_vm_atexit();

	BC_SIG_UNLOCK;

	memset(&vm, 0, sizeof(BcVm));

	assert(!vm.running && !vm.sig && !vm.sig_lock);
}

void bcl_gc(void) {
	BC_SIG_LOCK;
	bc_vm_freeTemps();
	BC_SIG_UNLOCK;
}

bool bcl_abortOnFatalError(void) {
	return vm.abrt;
}

void bcl_setAbortOnFatalError(bool abrt) {
	vm.abrt = abrt;
}

BclContext bcl_ctxt_create(void) {

	BclContext ctxt = NULL;

	BC_FUNC_HEADER_LOCK(err);

	// We want the context to be free of any interference of other parties, so
	// malloc() is appropriate here.
	ctxt = bc_vm_malloc(sizeof(BclCtxt));

	bc_vec_init(&ctxt->nums, sizeof(BcNum), BC_DTOR_BCL_NUM);
	bc_vec_init(&ctxt->free_nums, sizeof(BclNumber), BC_DTOR_NONE);

	ctxt->scale = 0;
	ctxt->ibase = 10;
	ctxt->obase= 10;

err:
	if (BC_ERR(vm.err && ctxt != NULL)) {
		if (ctxt->nums.v != NULL) bc_vec_free(&ctxt->nums);
		free(ctxt);
		ctxt = NULL;
	}

	BC_FUNC_FOOTER_NO_ERR;

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return ctxt;
}

void bcl_ctxt_free(BclContext ctxt) {
	BC_SIG_LOCK;
	bc_vec_free(&ctxt->free_nums);
	bc_vec_free(&ctxt->nums);
	free(ctxt);
	BC_SIG_UNLOCK;
}

void bcl_ctxt_freeNums(BclContext ctxt) {
	bc_vec_popAll(&ctxt->nums);
	bc_vec_popAll(&ctxt->free_nums);
}

size_t bcl_ctxt_scale(BclContext ctxt) {
	return ctxt->scale;
}

void bcl_ctxt_setScale(BclContext ctxt, size_t scale) {
	ctxt->scale = scale;
}

size_t bcl_ctxt_ibase(BclContext ctxt) {
	return ctxt->ibase;
}

void bcl_ctxt_setIbase(BclContext ctxt, size_t ibase) {
	if (ibase < BC_NUM_MIN_BASE) ibase = BC_NUM_MIN_BASE;
	else if (ibase > BC_NUM_MAX_IBASE) ibase = BC_NUM_MAX_IBASE;
	ctxt->ibase = ibase;
}

size_t bcl_ctxt_obase(BclContext ctxt) {
	return ctxt->obase;
}

void bcl_ctxt_setObase(BclContext ctxt, size_t obase) {
	ctxt->obase = obase;
}

BclError bcl_err(BclNumber n) {

	BclContext ctxt;

	BC_CHECK_CTXT_ERR(ctxt);

	// Errors are encoded as (0 - error_code). If the index is in that range, it
	// is an encoded error.
	if (n.i >= ctxt->nums.len) {
		if (n.i > 0 - (size_t) BCL_ERROR_NELEMS) return (BclError) (0 - n.i);
		else return BCL_ERROR_INVALID_NUM;
	}
	else return BCL_ERROR_NONE;
}

/**
 * Inserts a BcNum into a context's list of numbers.
 * @param ctxt  The context to insert into.
 * @param n     The BcNum to insert.
 * @return      The resulting BclNumber from the insert.
 */
static BclNumber bcl_num_insert(BclContext ctxt, BcNum *restrict n) {

	BclNumber idx;

	// If there is a free spot...
	if (ctxt->free_nums.len) {

		BcNum *ptr;

		// Get the index of the free spot and remove it.
		idx = *((BclNumber*) bc_vec_top(&ctxt->free_nums));
		bc_vec_pop(&ctxt->free_nums);

		// Copy the number into the spot.
		ptr = bc_vec_item(&ctxt->nums, idx.i);
		memcpy(ptr, n, sizeof(BcNum));
	}
	else {
		// Just push the number onto the vector.
		idx.i = ctxt->nums.len;
		bc_vec_push(&ctxt->nums, n);
	}

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

BclNumber bcl_num_create(void) {

	BclError e = BCL_ERROR_NONE;
	BcNum n;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	bc_num_init(&n, BC_NUM_DEF_SIZE);

err:
	BC_FUNC_FOOTER_UNLOCK(e);
	BC_MAYBE_SETUP(ctxt, e, n, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

/**
 * Destructs a number and marks its spot as free.
 * @param ctxt  The context.
 * @param n     The index of the number.
 * @param num   The number to destroy.
 */
static void bcl_num_dtor(BclContext ctxt, BclNumber n, BcNum *restrict num) {

	BC_SIG_ASSERT_LOCKED;

	assert(num != NULL && num->num != NULL);

	bcl_num_destruct(num);
	bc_vec_push(&ctxt->free_nums, &n);
}

void bcl_num_free(BclNumber n) {

	BcNum *num;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	BC_SIG_LOCK;

	assert(n.i < ctxt->nums.len);

	num = BC_NUM(ctxt, n);

	bcl_num_dtor(ctxt, n, num);

	BC_SIG_UNLOCK;
}

BclError bcl_copy(BclNumber d, BclNumber s) {

	BclError e = BCL_ERROR_NONE;
	BcNum *dest, *src;
	BclContext ctxt;

	BC_CHECK_CTXT_ERR(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	assert(d.i < ctxt->nums.len && s.i < ctxt->nums.len);

	dest = BC_NUM(ctxt, d);
	src = BC_NUM(ctxt, s);

	assert(dest != NULL && src != NULL);
	assert(dest->num != NULL && src->num != NULL);

	bc_num_copy(dest, src);

err:
	BC_FUNC_FOOTER_UNLOCK(e);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return e;
}

BclNumber bcl_dup(BclNumber s) {

	BclError e = BCL_ERROR_NONE;
	BcNum *src, dest;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(s.i < ctxt->nums.len);

	src = BC_NUM(ctxt, s);

	assert(src != NULL && src->num != NULL);

	// Copy the number.
	bc_num_clear(&dest);
	bc_num_createCopy(&dest, src);

err:
	BC_FUNC_FOOTER_UNLOCK(e);
	BC_MAYBE_SETUP(ctxt, e, dest, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

void bcl_num_destruct(void *num) {

	BcNum *n = (BcNum*) num;

	assert(n != NULL);

	if (n->num == NULL) return;

	bc_num_free(num);
	bc_num_clear(num);
}

bool bcl_num_neg(BclNumber n) {

	BcNum *num;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(n.i < ctxt->nums.len);

	num = BC_NUM(ctxt, n);

	assert(num != NULL && num->num != NULL);

	return BC_NUM_NEG(num) != 0;
}

void bcl_num_setNeg(BclNumber n, bool neg) {

	BcNum *num;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(n.i < ctxt->nums.len);

	num = BC_NUM(ctxt, n);

	assert(num != NULL && num->num != NULL);

	num->rdx = BC_NUM_NEG_VAL(num, neg);
}

size_t bcl_num_scale(BclNumber n) {

	BcNum *num;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(n.i < ctxt->nums.len);

	num = BC_NUM(ctxt, n);

	assert(num != NULL && num->num != NULL);

	return bc_num_scale(num);
}

BclError bcl_num_setScale(BclNumber n, size_t scale) {

	BclError e = BCL_ERROR_NONE;
	BcNum *nptr;
	BclContext ctxt;

	BC_CHECK_CTXT_ERR(ctxt);

	BC_CHECK_NUM_ERR(ctxt, n);

	BC_FUNC_HEADER(err);

	assert(n.i < ctxt->nums.len);

	nptr = BC_NUM(ctxt, n);

	assert(nptr != NULL && nptr->num != NULL);

	if (scale > nptr->scale) bc_num_extend(nptr, scale - nptr->scale);
	else if (scale < nptr->scale) bc_num_truncate(nptr, nptr->scale - scale);

err:
	BC_SIG_MAYLOCK;
	BC_FUNC_FOOTER(e);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return e;
}

size_t bcl_num_len(BclNumber n) {

	BcNum *num;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(n.i < ctxt->nums.len);

	num = BC_NUM(ctxt, n);

	assert(num != NULL && num->num != NULL);

	return bc_num_len(num);
}

BclError bcl_bigdig(BclNumber n, BclBigDig *result) {

	BclError e = BCL_ERROR_NONE;
	BcNum *num;
	BclContext ctxt;

	BC_CHECK_CTXT_ERR(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	assert(n.i < ctxt->nums.len);
	assert(result != NULL);

	num = BC_NUM(ctxt, n);

	assert(num != NULL && num->num != NULL);

	*result = bc_num_bigdig(num);

err:
	bcl_num_dtor(ctxt, n, num);
	BC_FUNC_FOOTER_UNLOCK(e);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return e;
}

BclNumber bcl_bigdig2num(BclBigDig val) {

	BclError e = BCL_ERROR_NONE;
	BcNum n;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	bc_num_createFromBigdig(&n, val);

err:
	BC_FUNC_FOOTER_UNLOCK(e);
	BC_MAYBE_SETUP(ctxt, e, n, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

/**
 * Sets up and executes a binary operator operation.
 * @param a     The first operand.
 * @param b     The second operand.
 * @param op    The operation.
 * @param req   The function to get the size of the result for preallocation.
 * @return      The result of the operation.
 */
static BclNumber bcl_binary(BclNumber a, BclNumber b, const BcNumBinaryOp op,
                            const BcNumBinaryOpReq req)
{
	BclError e = BCL_ERROR_NONE;
	BcNum *aptr, *bptr;
	BcNum c;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_CHECK_NUM(ctxt, a);
	BC_CHECK_NUM(ctxt, b);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(a.i < ctxt->nums.len && b.i < ctxt->nums.len);

	aptr = BC_NUM(ctxt, a);
	bptr = BC_NUM(ctxt, b);

	assert(aptr != NULL && bptr != NULL);
	assert(aptr->num != NULL && bptr->num != NULL);

	// Clear and initialize the result.
	bc_num_clear(&c);
	bc_num_init(&c, req(aptr, bptr, ctxt->scale));

	BC_SIG_UNLOCK;

	op(aptr, bptr, &c, ctxt->scale);

err:

	BC_SIG_MAYLOCK;

	// Eat the operands.
	bcl_num_dtor(ctxt, a, aptr);
	if (b.i != a.i) bcl_num_dtor(ctxt, b, bptr);

	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, c, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

BclNumber bcl_add(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_add, bc_num_addReq);
}

BclNumber bcl_sub(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_sub, bc_num_addReq);
}

BclNumber bcl_mul(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_mul, bc_num_mulReq);
}

BclNumber bcl_div(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_div, bc_num_divReq);
}

BclNumber bcl_mod(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_mod, bc_num_divReq);
}

BclNumber bcl_pow(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_pow, bc_num_powReq);
}

BclNumber bcl_lshift(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_lshift, bc_num_placesReq);
}

BclNumber bcl_rshift(BclNumber a, BclNumber b) {
	return bcl_binary(a, b, bc_num_rshift, bc_num_placesReq);
}

BclNumber bcl_sqrt(BclNumber a) {

	BclError e = BCL_ERROR_NONE;
	BcNum *aptr;
	BcNum b;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_CHECK_NUM(ctxt, a);

	BC_FUNC_HEADER(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(a.i < ctxt->nums.len);

	aptr = BC_NUM(ctxt, a);

	bc_num_sqrt(aptr, &b, ctxt->scale);

err:
	BC_SIG_MAYLOCK;
	bcl_num_dtor(ctxt, a, aptr);
	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, b, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

BclError bcl_divmod(BclNumber a, BclNumber b, BclNumber *c, BclNumber *d) {

	BclError e = BCL_ERROR_NONE;
	size_t req;
	BcNum *aptr, *bptr;
	BcNum cnum, dnum;
	BclContext ctxt;

	BC_CHECK_CTXT_ERR(ctxt);

	BC_CHECK_NUM_ERR(ctxt, a);
	BC_CHECK_NUM_ERR(ctxt, b);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 2);

	assert(c != NULL && d != NULL);

	aptr = BC_NUM(ctxt, a);
	bptr = BC_NUM(ctxt, b);

	assert(aptr != NULL && bptr != NULL);
	assert(aptr->num != NULL && bptr->num != NULL);

	bc_num_clear(&cnum);
	bc_num_clear(&dnum);

	req = bc_num_divReq(aptr, bptr, ctxt->scale);

	// Initialize the numbers.
	bc_num_init(&cnum, req);
	BC_UNSETJMP;
	BC_SETJMP_LOCKED(err);
	bc_num_init(&dnum, req);

	BC_SIG_UNLOCK;

	bc_num_divmod(aptr, bptr, &cnum, &dnum, ctxt->scale);

err:
	BC_SIG_MAYLOCK;

	// Eat the operands.
	bcl_num_dtor(ctxt, a, aptr);
	if (b.i != a.i) bcl_num_dtor(ctxt, b, bptr);

	// If there was an error...
	if (BC_ERR(vm.err)) {

		// Free the results.
		if (cnum.num != NULL) bc_num_free(&cnum);
		if (dnum.num != NULL) bc_num_free(&dnum);

		// Make sure the return values are invalid.
		c->i = 0 - (size_t) BCL_ERROR_INVALID_NUM;
		d->i = c->i;

		BC_FUNC_FOOTER(e);
	}
	else {

		BC_FUNC_FOOTER(e);

		// Insert the results into the context.
		*c = bcl_num_insert(ctxt, &cnum);
		*d = bcl_num_insert(ctxt, &dnum);
	}

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return e;
}

BclNumber bcl_modexp(BclNumber a, BclNumber b, BclNumber c) {

	BclError e = BCL_ERROR_NONE;
	size_t req;
	BcNum *aptr, *bptr, *cptr;
	BcNum d;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_CHECK_NUM(ctxt, a);
	BC_CHECK_NUM(ctxt, b);
	BC_CHECK_NUM(ctxt, c);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(a.i < ctxt->nums.len && b.i < ctxt->nums.len);
	assert(c.i < ctxt->nums.len);

	aptr = BC_NUM(ctxt, a);
	bptr = BC_NUM(ctxt, b);
	cptr = BC_NUM(ctxt, c);

	assert(aptr != NULL && bptr != NULL && cptr != NULL);
	assert(aptr->num != NULL && bptr->num != NULL && cptr->num != NULL);

	// Prepare the result.
	bc_num_clear(&d);

	req = bc_num_divReq(aptr, cptr, 0);

	// Initialize the result.
	bc_num_init(&d, req);

	BC_SIG_UNLOCK;

	bc_num_modexp(aptr, bptr, cptr, &d);

err:
	BC_SIG_MAYLOCK;

	// Eat the operands.
	bcl_num_dtor(ctxt, a, aptr);
	if (b.i != a.i) bcl_num_dtor(ctxt, b, bptr);
	if (c.i != a.i && c.i != b.i) bcl_num_dtor(ctxt, c, cptr);

	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, d, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

ssize_t bcl_cmp(BclNumber a, BclNumber b) {

	BcNum *aptr, *bptr;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(a.i < ctxt->nums.len && b.i < ctxt->nums.len);

	aptr = BC_NUM(ctxt, a);
	bptr = BC_NUM(ctxt, b);

	assert(aptr != NULL && bptr != NULL);
	assert(aptr->num != NULL && bptr->num != NULL);

	return bc_num_cmp(aptr, bptr);
}

void bcl_zero(BclNumber n) {

	BcNum *nptr;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(n.i < ctxt->nums.len);

	nptr = BC_NUM(ctxt, n);

	assert(nptr != NULL && nptr->num != NULL);

	bc_num_zero(nptr);
}

void bcl_one(BclNumber n) {

	BcNum *nptr;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	assert(n.i < ctxt->nums.len);

	nptr = BC_NUM(ctxt, n);

	assert(nptr != NULL && nptr->num != NULL);

	bc_num_one(nptr);
}

BclNumber bcl_parse(const char *restrict val) {

	BclError e = BCL_ERROR_NONE;
	BcNum n;
	BclNumber idx;
	BclContext ctxt;
	bool neg;

	BC_CHECK_CTXT(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(val != NULL);

	// We have to take care of negative here because bc's number parsing does
	// not.
	neg = (val[0] == '-');

	if (neg) val += 1;

	if (!bc_num_strValid(val)) {
		vm.err = BCL_ERROR_PARSE_INVALID_STR;
		goto err;
	}

	// Clear and initialize the number.
	bc_num_clear(&n);
	bc_num_init(&n, BC_NUM_DEF_SIZE);

	BC_SIG_UNLOCK;

	bc_num_parse(&n, val, (BcBigDig) ctxt->ibase);

	// Set the negative.
	n.rdx = BC_NUM_NEG_VAL_NP(n, neg);

err:
	BC_SIG_MAYLOCK;
	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, n, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

char* bcl_string(BclNumber n) {

	BcNum *nptr;
	char *str = NULL;
	BclContext ctxt;

	BC_CHECK_CTXT_ASSERT(ctxt);

	if (BC_ERR(n.i >= ctxt->nums.len)) return str;

	BC_FUNC_HEADER(err);

	assert(n.i < ctxt->nums.len);

	nptr = BC_NUM(ctxt, n);

	assert(nptr != NULL && nptr->num != NULL);

	// Clear the buffer.
	bc_vec_popAll(&vm.out);

	// Print to the buffer.
	bc_num_print(nptr, (BcBigDig) ctxt->obase, false);
	bc_vec_pushByte(&vm.out, '\0');

	BC_SIG_LOCK;

	// Just dup the string; the caller is responsible for it.
	str = bc_vm_strdup(vm.out.v);

err:

	// Eat the operand.
	bcl_num_dtor(ctxt, n, nptr);

	BC_FUNC_FOOTER_NO_ERR;

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return str;
}

BclNumber bcl_irand(BclNumber a) {

	BclError e = BCL_ERROR_NONE;
	BcNum *aptr;
	BcNum b;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_CHECK_NUM(ctxt, a);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(a.i < ctxt->nums.len);

	aptr = BC_NUM(ctxt, a);

	assert(aptr != NULL && aptr->num != NULL);

	// Clear and initialize the result.
	bc_num_clear(&b);
	bc_num_init(&b, BC_NUM_DEF_SIZE);

	BC_SIG_UNLOCK;

	bc_num_irand(aptr, &b, &vm.rng);

err:
	BC_SIG_MAYLOCK;

	// Eat the operand.
	bcl_num_dtor(ctxt, a, aptr);

	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, b, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

/**
 * Helps bcl_frand(). This is separate because the error handling is easier that
 * way. It is also easier to do ifrand that way.
 * @param b       The return parameter.
 * @param places  The number of decimal places to generate.
 */
static void bcl_frandHelper(BcNum *restrict b, size_t places) {

	BcNum exp, pow, ten;
	BcDig exp_digs[BC_NUM_BIGDIG_LOG10];
	BcDig ten_digs[BC_NUM_BIGDIG_LOG10];

	// Set up temporaries.
	bc_num_setup(&exp, exp_digs, BC_NUM_BIGDIG_LOG10);
	bc_num_setup(&ten, ten_digs, BC_NUM_BIGDIG_LOG10);

	ten.num[0] = 10;
	ten.len = 1;

	bc_num_bigdig2num(&exp, (BcBigDig) places);

	// Clear the temporary that might need to grow.
	bc_num_clear(&pow);

	BC_SIG_LOCK;

	// Initialize the temporary that might need to grow.
	bc_num_init(&pow, bc_num_powReq(&ten, &exp, 0));

	BC_SETJMP_LOCKED(err);

	BC_SIG_UNLOCK;

	// Generate the number.
	bc_num_pow(&ten, &exp, &pow, 0);
	bc_num_irand(&pow, b, &vm.rng);

	// Make the number entirely fraction.
	bc_num_shiftRight(b, places);

err:
	BC_SIG_MAYLOCK;
	bc_num_free(&pow);
	BC_LONGJMP_CONT;
}

BclNumber bcl_frand(size_t places) {

	BclError e = BCL_ERROR_NONE;
	BcNum n;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	// Clear and initialize the number.
	bc_num_clear(&n);
	bc_num_init(&n, BC_NUM_DEF_SIZE);

	BC_SIG_UNLOCK;

	bcl_frandHelper(&n, places);

err:
	BC_SIG_MAYLOCK;

	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, n, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

/**
 * Helps bc_ifrand(). This is separate because error handling is easier that
 * way.
 * @param a       The limit for bc_num_irand().
 * @param b       The return parameter.
 * @param places  The number of decimal places to generate.
 */
static void bcl_ifrandHelper(BcNum *restrict a, BcNum *restrict b,
                             size_t places)
{
	BcNum ir, fr;

	// Clear the integer and fractional numbers.
	bc_num_clear(&ir);
	bc_num_clear(&fr);

	BC_SIG_LOCK;

	// Initialize the integer and fractional numbers.
	bc_num_init(&ir, BC_NUM_DEF_SIZE);
	bc_num_init(&fr, BC_NUM_DEF_SIZE);

	BC_SETJMP_LOCKED(err);

	BC_SIG_UNLOCK;

	bc_num_irand(a, &ir, &vm.rng);
	bcl_frandHelper(&fr, places);

	bc_num_add(&ir, &fr, b, 0);

err:
	BC_SIG_MAYLOCK;
	bc_num_free(&fr);
	bc_num_free(&ir);
	BC_LONGJMP_CONT;
}

BclNumber bcl_ifrand(BclNumber a, size_t places) {

	BclError e = BCL_ERROR_NONE;
	BcNum *aptr;
	BcNum b;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);
	BC_CHECK_NUM(ctxt, a);

	BC_FUNC_HEADER_LOCK(err);

	bc_vec_grow(&ctxt->nums, 1);

	assert(a.i < ctxt->nums.len);

	aptr = BC_NUM(ctxt, a);

	assert(aptr != NULL && aptr->num != NULL);

	// Clear and initialize the number.
	bc_num_clear(&b);
	bc_num_init(&b, BC_NUM_DEF_SIZE);

	BC_SIG_UNLOCK;

	bcl_ifrandHelper(aptr, &b, places);

err:
	BC_SIG_MAYLOCK;

	// Eat the oprand.
	bcl_num_dtor(ctxt, a, aptr);

	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, b, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

BclError bcl_rand_seedWithNum(BclNumber n) {

	BclError e = BCL_ERROR_NONE;
	BcNum *nptr;
	BclContext ctxt;

	BC_CHECK_CTXT_ERR(ctxt);
	BC_CHECK_NUM_ERR(ctxt, n);

	BC_FUNC_HEADER(err);

	assert(n.i < ctxt->nums.len);

	nptr = BC_NUM(ctxt, n);

	assert(nptr != NULL && nptr->num != NULL);

	bc_num_rng(nptr, &vm.rng);

err:
	BC_SIG_MAYLOCK;
	BC_FUNC_FOOTER(e);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return e;
}

BclError bcl_rand_seed(unsigned char seed[BCL_SEED_SIZE]) {

	BclError e = BCL_ERROR_NONE;
	size_t i;
	ulong vals[BCL_SEED_ULONGS];

	BC_FUNC_HEADER(err);

	// Fill the array.
	for (i = 0; i < BCL_SEED_SIZE; ++i) {
		ulong val = ((ulong) seed[i]) << (((ulong) CHAR_BIT) *
		                                  (i % sizeof(ulong)));
		vals[i / sizeof(long)] |= val;
	}

	bc_rand_seed(&vm.rng, vals[0], vals[1], vals[2], vals[3]);

err:
	BC_SIG_MAYLOCK;
	BC_FUNC_FOOTER(e);
	return e;
}

void bcl_rand_reseed(void) {
	bc_rand_srand(bc_vec_top(&vm.rng.v));
}

BclNumber bcl_rand_seed2num(void) {

	BclError e = BCL_ERROR_NONE;
	BcNum n;
	BclNumber idx;
	BclContext ctxt;

	BC_CHECK_CTXT(ctxt);

	BC_FUNC_HEADER_LOCK(err);

	// Clear and initialize the number.
	bc_num_clear(&n);
	bc_num_init(&n, BC_NUM_DEF_SIZE);

	BC_SIG_UNLOCK;

	bc_num_createFromRNG(&n, &vm.rng);

err:
	BC_SIG_MAYLOCK;
	BC_FUNC_FOOTER(e);
	BC_MAYBE_SETUP(ctxt, e, n, idx);

	assert(!vm.running && !vm.sig && !vm.sig_lock);

	return idx;
}

BclRandInt bcl_rand_int(void) {
	return (BclRandInt) bc_rand_int(&vm.rng);
}

BclRandInt bcl_rand_bounded(BclRandInt bound) {
	if (bound <= 1) return 0;
	return (BclRandInt) bc_rand_bounded(&vm.rng, (BcRand) bound);
}

#endif // BC_ENABLE_LIBRARY