bigd.c


/* BIGD "bd" wrapper functions around BigDigits "mp" functions */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "bigd.h"
#include "bigdigits.h"

/* Required for opaque pointers */
#define T BIGD
struct T
{
	DIGIT_T *digits;	/* Ptr to array of digits, least sig. first */
	size_t ndigits;		/* No of non-zero significant digits */
	size_t maxdigits;	/* Max size allocated */
	/*int is_signed;*/	/* (for future use) */
};

/* 
All these functions MUST make sure that there are always
enough digits before doing anything, and SHOULD reset <ndigits>
afterwards to reflect the final significant size.
-- <maxdigits> is the size allocated (at least one).
-- <ndigits> may be zero.
-- <ndigits> may be too long if MS digits compute to zero so
   consider it an upper bound on significant digits, not gospel.

It is an error to pass a NULL BIGD parameter except to bdFree.
*/

#ifdef _DEBUG
static int debug = 0; /* <= change this to > 0 for console debugging */
#else
static int debug = 0; /* <= ALWAYS ZERO */
#endif

/* Useful definitions */
#ifndef FALSE
#define FALSE               0
#endif
#ifndef TRUE
#define TRUE                1
#endif
#ifndef max
#define max(a,b)            (((a) > (b)) ? (a) : (b))
#endif
#ifndef min
#define min(a,b)            (((a) < (b)) ? (a) : (b))
#endif


T bdNew(void)
{
	struct T *p;
	p = calloc(1, (long)sizeof(*p));
	if (!p)
	{
		mpFail("bdNew: Failed to calloc memory.");
	}
	copyright_notice();	
	/* set up with single zero digit */
	p->digits = mpAlloc(1);
	p->digits[0] = 0;
	p->ndigits = 0;
	p->maxdigits = 1;
	//p->sign = 0;
	return p;
}

void bdFree(T *p)
/* Zeroise and free memory. Set ptr to NULL. */
{
	T bd = *p;
	if (*p)
	{
		/* Zeroise them all, just in case */
		if (bd->digits)
		{
			mpSetZero(bd->digits, bd->maxdigits);
			free(bd->digits);
		}
		bd->maxdigits = 0;
		bd->ndigits = 0;
		free(*p);
	}
	*p = NULL;
}

static int bd_resize(T b, size_t newsize)
{
/* 
Internal fn to re-size a BIGD structure before a calc.
Use carefully!
1. If growing, it allocs more digits and increases maxdigits
2. If shrinking, it decreases ndigits and zeroises the excess.
3. It does not increase b->ndigits; that's up to you later.
4. It does not release excess digits; use bdFree.

In other words, it's like middle-aged spread: 
you go from a 32" waist to a 38 but can never go backwards.

Be careful doing the following:-
	n = new_size_we_expect;
	bd_resize(b, n);
	mpFunctionOfSorts(b->digits, n);
	b->ndigits = mpSizeof(b->digits, b->ndigits); // NO!

b->ndigits may be set too short

Better:
	n = new_size_we_expect;
	bd_resize(b, n);
	mpFunctionOfSorts(b->digits, n);
	b->ndigits = mpSizeof(b->digits, n);  // Yes.

*/

	size_t i;

	/* Check just in case NULL */
	assert(b);
	assert(b->digits);

	/* If we are shrinking, clear high digits */
	if (newsize < b->ndigits)
	{
		for (i = newsize; i < b->ndigits; i++)
			b->digits[i] = 0;
		b->ndigits = newsize;
		return 0;
	}

	/* We need more room */
	if (b->maxdigits < newsize)
	{
		DIGIT_T *newp, *oldp;
		size_t oldsize = b->maxdigits;
		/* Increase size of digit array */
		//b->digits = (DIGIT_T *)realloc(b->digits, newsize * sizeof(DIGIT_T));
		/* -- [v2.2] changed [2008-03-30] to avoid realloc */
		newp = (DIGIT_T *)malloc(newsize * sizeof(DIGIT_T));
		oldp = b->digits;
		
		/* Check for failure */
		if (!newp)
		{
			mpSetZero(oldp, oldsize);
			free(oldp);
			mpFail("bd_resize: Failed to realloc memory.");
		}

		memcpy(newp, oldp, oldsize * sizeof(DIGIT_T));
		mpSetZero(oldp, oldsize);
		free(oldp);
		b->digits = newp;

		b->maxdigits = newsize;	/* Remember new allocated size */
	}

	/* Make sure new digits are zero */
	for (i = b->ndigits; i < newsize; i++)
		b->digits[i] = 0;

	return 0;
}

size_t bdConvFromOctets(T b, const unsigned char *c, size_t nbytes)
/* Converts nbytes octets into big digit b, resizing if necessary */
{
	size_t ndigits, n;

	assert(b);
	ndigits = (nbytes + OCTETS_PER_DIGIT - 1) / OCTETS_PER_DIGIT;

	bd_resize(b, ndigits);
	
	n = mpConvFromOctets(b->digits, ndigits, c, nbytes);
	b->ndigits = mpSizeof(b->digits, n);

	return n;
}

size_t bdConvToOctets(T b, unsigned char *c, size_t nbytes)
/* Convert big digit b into string of octets, in big-endian order,
   padding to nbytes or truncating if necessary.
   Returns # significant bytes. 
   If c is NULL or nbytes == 0 then just return required size.
*/
{
	size_t noctets, nbits, n;

	assert(b);

	nbits = mpBitLength(b->digits, b->ndigits);
	noctets = (nbits + 7) / 8;
	/* [2008-05-23] always return at least 1 */
	if (0 == noctets) noctets = 1;

	if (!c || 0 == nbytes)
	{
		return noctets;
	}

	n = mpConvToOctets(b->digits, b->ndigits, c, nbytes);

	return noctets;
}

size_t bdConvFromHex(T b, const char *s)
/* Converts a hex string into big digit b */
{
	size_t ndigits, n;

	assert(b);

	/* Revision [2006-02-21] */
	/* EDIT: ndigits = (strlen(s) / 2 + OCTETS_PER_DIGIT - 1) / OCTETS_PER_DIGIT; */
	ndigits = ((strlen(s) + 1) / 2 + OCTETS_PER_DIGIT - 1) / OCTETS_PER_DIGIT;
	bd_resize(b, ndigits);

	n = mpConvFromHex(b->digits, ndigits, s);
	b->ndigits = mpSizeof(b->digits, n);

	return n;
}

size_t bdConvToHex(T b, char *s, size_t smax)
{
	assert(b);
	return mpConvToHex(b->digits, b->ndigits, s, smax);
}

size_t bdConvFromDecimal(BIGD b, const char *s)
{
	size_t ndigits, n;

	assert(b);
	/* approx size but never too small */
	ndigits = (strlen(s) / 2 + OCTETS_PER_DIGIT) / OCTETS_PER_DIGIT;
	bd_resize(b, ndigits);

	n = mpConvFromDecimal(b->digits, ndigits, s);
	b->ndigits = n;

	return n;
}

size_t bdConvToDecimal(BIGD b, char *s, size_t smax)
{
	assert(b);
	return mpConvToDecimal(b->digits, b->ndigits, s, smax);
}

int bdSetShort(T b, bdigit_t value)
	/* Converts value into a (single-digit) big digit b */
{
	assert(b);
	bd_resize(b, 1);
	b->digits[0] = (DIGIT_T)value;
	b->ndigits = (value ? 1 : 0);
	return 0;
}

size_t bdBitLength(T b)
	/* Returns base-1 index to most significant bit in b */
{
	assert(b);
	return mpBitLength(b->digits, b->ndigits);
}

size_t bdSizeof(T b)
	/* Returns number of significant non-zero bytes in b */
{
	assert(b);
	return mpSizeof(b->digits, b->ndigits);
}

/* Print function for bigdigit_t structures */

void bdPrint(T p, size_t flags)
{
	size_t n;

	assert(p);
	n = p->ndigits;
	if (n == 0) n = 1;

	if (flags & BD_PRINT_TRIM)	/* Trim leading zeroes */
	{
		if (flags & BD_PRINT_NL)	/* add newlines */
			mpPrintTrimNL(p->digits, n);
		else
			mpPrintTrim(p->digits, n);
	}
	else
	{
		if (flags & BD_PRINT_NL)	/* add newlines */
			mpPrintNL(p->digits, n);
		else
			mpPrint(p->digits, n);
	}
}

void bdPrintHex(const char *prefix, T p, const char *suffix)
{
	size_t n;

	assert(p);
	n = p->ndigits;
	if (n == 0) n = 1;
	mpPrintHex(prefix, p->digits, n, suffix);
}

void bdPrintDecimal(const char *prefix, T p, const char *suffix)
{
	size_t n;

	assert(p);
	n = p->ndigits;
	if (n == 0) n = 1;
	mpPrintDecimal(prefix, p->digits, n, suffix);
}

int bdIsEqual(T a, T b)
{
	/*	Returns true if a == b, else false */
	size_t n, na, nb;

	assert(a && b);
	/* We can't trust ndigits */
	na = mpSizeof(a->digits, a->ndigits);
	nb = mpSizeof(b->digits, b->ndigits);
	
	if (na != nb)
		return FALSE;
	if (na == 0 && nb == 0)
		return TRUE;

	/* Otherwise we have equal lengths */
	n = na;
	while (n--)
	{
		if (a->digits[n] != b->digits[n])
			return FALSE;
	}

	return TRUE;
}

int bdIsZero(T a)
	/* Returns true if a == 0, else false */
{
	assert(a);
	return mpIsZero(a->digits, a->ndigits);
}

int bdShortCmp(T a, bdigit_t d)
	/* Returns sign of (a-d) */
{
	assert(a);
	return mpShortCmp(a->digits, d, a->ndigits);
}

int bdCompare(T a, T b)
	/*	Returns sign of (a-b) */
{
	size_t n, na, nb;

	assert(a && b);
	if (a->ndigits != b->ndigits)
	{
		na = mpSizeof(a->digits, a->ndigits);
		nb = mpSizeof(b->digits, b->ndigits);
		if (na > nb) return 1;
		if (na < nb) return -1;
		n = na;
	}
	else
		n = a->ndigits;

	return mpCompare(a->digits, b->digits, n);
}

int bdIsEven(T a)
{
	assert(a);
	return ISEVEN(a->digits[0]);
}

int bdIsOdd(T a)
{
	assert(a);
	return ISODD(a->digits[0]);
}


int bdSetEqual(T a, T b)
	/*	Sets a = b */
{
	assert(a && b);
	bd_resize(a, b->ndigits);
	mpSetEqual(a->digits, b->digits, b->ndigits);
	a->ndigits = b->ndigits;
	return 0;
}

int bdSetZero(T a)
	/* Sets a = 0 */
{
	assert(a);
	mpSetZero(a->digits, a->ndigits);
	a->ndigits = 0;
	return 0;
}

int bdShortAdd(T w, T u, bdigit_t d)
	/* Compute w = u + d, 
	returns 1 if we had a carry */
{
	DIGIT_T carry;
	size_t dig_size = max(u->ndigits, 1);

	assert(w && u);
	bd_resize(w, dig_size + 1);

	carry = mpShortAdd(w->digits, u->digits, d, dig_size);

	/* Cope with overflow */
	if (carry)
	{
		w->digits[dig_size] = carry;
		w->ndigits = dig_size + 1;
	}
	else
		w->ndigits = dig_size;	

	return carry;
}

int bdAdd(T w, T u, T v)
	/* Compute w = u + v, w#v*/
{
	size_t dig_size;
	DIGIT_T carry;

	assert(w && u && v);
	/* Check for cheaper option */
	if (v->ndigits == 1)
		return bdShortAdd(w, u, v->digits[0]);

	/* Make sure u and v are the same size */
	dig_size = max(u->ndigits, v->ndigits);
	bd_resize(v, dig_size);
	bd_resize(u, dig_size);
	/* Now make sure w is big enough for sum (incl carry) */
	bd_resize(w, dig_size + 1);

	/* Finally, do the business */
	carry = mpAdd(w->digits, u->digits, v->digits, dig_size);

	/* Make sure we've set the right size for w */
	if (carry)
	{
		w->digits[dig_size] = carry;
		w->ndigits = dig_size + 1;
	}
	else
		w->ndigits = mpSizeof(w->digits, dig_size);	

	return carry;
}

int bdAdd_s(T w, T u, T v)
	/* Compute w = u + v (safe) */
{
	DIGIT_T carry;
	T ww;

	assert(w && u && v);
	/* Use temp */
	ww = bdNew();
	bdSetEqual(ww, w);

	carry = bdAdd(ww, u, v);

	bdSetEqual(w, ww);
	bdFree(&ww);

	return carry;
}

int bdShortSub(T w, T u, bdigit_t d)
	/* Compute w = u - d, return borrow */
{
	DIGIT_T borrow;
	size_t dig_size = max(u->ndigits, 1);

	assert(w && u);
	bd_resize(w, dig_size);

	borrow = mpShortSub(w->digits, u->digits, d, dig_size);

	w->ndigits = dig_size;	

	return borrow;
}

int bdSubtract(T w, T u, T v)
	/* Compute w = u - v, return borrow, w#v */
{
	size_t dig_size;
	DIGIT_T borrow;

	assert(w && u && v);
	/* Check for cheaper option */
	if (v->ndigits == 1)
		return bdShortSub(w, u, v->digits[0]);

	/* Make sure u and v are the same size */
	dig_size = max(u->ndigits, v->ndigits);
	bd_resize(v, dig_size);
	bd_resize(u, dig_size);
	bd_resize(w, dig_size);

	/* Finally, do the business */
	borrow = mpSubtract(w->digits, u->digits, v->digits, dig_size);

	/* Make sure we've set the right size for w */
	w->ndigits = mpSizeof(w->digits, dig_size);	

	return borrow;
}

int bdSubtract_s(T w, T u, T v)
	/* Compute w = u - v (safe) */
{
	DIGIT_T carry;
	T ww;

	assert(w && u && v);
	/* Use temp */
	ww = bdNew();
	bdSetEqual(ww, w);

	carry = bdSubtract(ww, u, v);

	bdSetEqual(w, ww);
	bdFree(&ww);

	return carry;
}

int bdIncrement(T a)
	/* Sets a = a + 1, returns carry */
{
	assert(a);
	return bdShortAdd(a, a, 1);
}

int bdDecrement(T a)
	/* Sets a = a - 1, returns borrow */
{
	assert(a);
	return bdShortSub(a, a, 1);
}

int bdShortMult(T w, T u, bdigit_t d)
	/* Compute w = u * d */
{
	DIGIT_T overflow;
	size_t dig_size = u->ndigits;

	assert(w && u);
	bd_resize(w, dig_size+1);

	overflow = mpShortMult(w->digits, u->digits, d, dig_size);

	/* Cope with overflow */
	if (overflow)
	{
		w->digits[dig_size] = overflow;
		w->ndigits = dig_size + 1;
	}
	else
		w->ndigits = mpSizeof(w->digits, dig_size);	

	return 0;
}

int bdMultiply(T w, T u, T v)
	/* Compute w = u * v 
	   -- no overlap permitted
	*/
{
	size_t dig_size;

	assert(w && u && v);
	/* Check for cheaper option */
	if (v->ndigits == 1)
		return bdShortMult(w, u, v->digits[0]);

	/* Make sure u and v are the same size */
	dig_size = max(u->ndigits, v->ndigits);
	bd_resize(v, dig_size);
	bd_resize(u, dig_size);
	/* Now make sure w is big enough for product */
	bd_resize(w, 2 * dig_size);

	/* Finally, do the business */
	mpMultiply(w->digits, u->digits, v->digits, dig_size);

	/* Make sure we've set the right size for w */
	w->ndigits = mpSizeof(w->digits, 2 * dig_size);	

	return 0;
}

int bdMultiply_s(T w, T u, T v)
	/* Compute w = u * v (safe) */
{
	T ww;

	assert(w && u && v);
	/* Use temp */
	ww = bdNew();
	bdSetEqual(ww, w);

	bdMultiply(ww, u, v);

	bdSetEqual(w, ww);
	bdFree(&ww);

	return 0;
}

int bdSquare(T w, T x)
	/* Computes w = x^2, w#x */
{
	size_t dig_size;

	assert(w && x);

	dig_size = max(x->ndigits, 1);
	/* Make sure w is big enough for product */
	bd_resize(w, 2 * dig_size);

	/* Finally, do the business */
	mpSquare(w->digits, x->digits, dig_size);

	/* Make sure we've set the right size for w */
	w->ndigits = mpSizeof(w->digits, 2 * dig_size);	

	return 0;
}

int bdSquare_s(T w, T x)
	/* Compute w = x^2 (safe) */
{
	T ww;

	assert(w && x);
	/* Use temp */
	ww = bdNew();
	bdSetEqual(ww, w);

	bdSquare(ww, x);

	bdSetEqual(w, ww);
	bdFree(&ww);

	return 0;
}

int bdPower(BIGD y, BIGD g, unsigned short int n)
/* Computes y = g^n (up to available memory!) */
{
	BIGD z;
	z = bdNew();
	/* Use Right-Left Binary */
	/* 1. Set y <-- 1, z <-- g */
	bdSetShort(y, 1);
	bdSetEqual(z, g);
	/* If n = 0, output y and stop */
	while (n > 0)
	{
		/* 2. If n is odd, set y <-- z.y */
		if (n & 0x1)
			bdMultiply_s(y, z, y);
		/* 3. Set n <-- [n/2]. If n = 0, output y and stop */
		n >>= 1;
		if (n > 0)
			/* 3b. Otherwise set z <-- z.z and go to step 2 */
			bdSquare_s(z, z);
	}
	bdFree(&z);
	/* Result is in y */
	return 0;
}

int bdSqrt(BIGD s, BIGD x)
	/* Computes integer square root s = floor(sqrt(x)) */
{
	size_t dig_size;
	int r;

	assert(s && x);
	dig_size = x->ndigits;
	bd_resize(s, dig_size);
	r = mpSqrt(s->digits, x->digits, dig_size);
	s->ndigits = mpSizeof(s->digits, dig_size);

	return r;
}

int bdCubeRoot(BIGD s, BIGD x)
	/* Computes integer cube root s = floor(cuberoot(x)) */
{
	size_t dig_size;
	int r;

	assert(s && x);
	dig_size = x->ndigits;
	bd_resize(s, dig_size);
	r = mpCubeRoot(s->digits, x->digits, dig_size);
	s->ndigits = mpSizeof(s->digits, dig_size);

	return r;
}

int bdShortDiv(T q, T r, T u, bdigit_t d)
	/* Computes quotient q = u / d and remainder r = u mod d */
{
	DIGIT_T rem;
	size_t dig_size;

	assert(q && r && u);
	dig_size = u->ndigits;
	bd_resize(q, dig_size);

	rem = mpShortDiv(q->digits, u->digits, d, dig_size);
	bdSetShort(r, rem);

	q->ndigits = mpSizeof(q->digits, dig_size);

	return 0;
}

int bdDivide(T q, T r, T u, T v)
	/* Computes quotient q = u / v and remainder r = u mod v 
	   trashes q and r first
	*/
{
	size_t dig_size;

	assert(q && r && u && v);
	dig_size = u->ndigits;
	bd_resize(q, dig_size);
	bd_resize(r, dig_size);

	/* Do the business */
	mpDivide(q->digits, r->digits, u->digits, dig_size, v->digits, v->ndigits);

	/* Set final sizes */
	q->ndigits = mpSizeof(q->digits, dig_size);
	r->ndigits = mpSizeof(r->digits, dig_size);

	return 0;
}

int bdDivide_s(T q, T r, T u, T v)
	/* Computes quotient q = u / v and remainder r = u mod v (safe) */
{
	size_t dig_size;
	BIGD qq, rr;

	assert(q && r && u && v);
	/* Use temps because mpDivide trashes q and r */
	qq = bdNew();
	rr = bdNew();

	dig_size = u->ndigits;
	bd_resize(qq, dig_size);
	bd_resize(rr, dig_size);

	/* Do the business */
	mpDivide(qq->digits, rr->digits, u->digits, dig_size, v->digits, v->ndigits);

	/* Copy temps */
	qq->ndigits = dig_size;
	rr->ndigits = dig_size;
	bdSetEqual(q, qq);
	bdSetEqual(r, rr);

	/* Set final sizes */
	q->ndigits = mpSizeof(q->digits, dig_size);
	r->ndigits = mpSizeof(r->digits, dig_size);

	/* Free temps */
	bdFree(&qq);
	bdFree(&rr);

	return 0;
}

bdigit_t bdShortMod(T r, T u, bdigit_t d)
	/* Returns r = u mod d */
{
	DIGIT_T rr;

	assert(r && u);
	rr = mpShortMod(u->digits, d, u->ndigits);
	bdSetShort(r, rr);

	return rr;
}

int bdModulo(T r, T u, T v)
	/* Computes r = u mod v, r#u */
{
	size_t nr;

	assert(r && u && v);

	/* NB r is only vdigits long at most */
	nr = v->ndigits;
	bd_resize(r, nr);

	/* Do the business */
	mpModulo(r->digits, u->digits, u->ndigits, v->digits, v->ndigits);

	/* Set final size */
	r->ndigits = mpSizeof(r->digits, nr);

	return 0;
}

int bdModulo_s(T r, T u, T v)
	/* Computes r = u mod v (safe) */
{
	T rr;

	assert(r && u && v);
	/* Use temp */
	rr = bdNew();
	bdSetEqual(rr, r);

	bdModulo(rr, u, v);

	bdSetEqual(r, rr);
	bdFree(&rr);

	return 0;
}

int bdSetBit(T a, size_t ibit, int value)
/* Set bit ibit (0..nbits-1) with value 1 or 0 
   -- increases size if a too small but does not shrink */
{
	size_t idigit;

	assert(a);
	/* Which digit? (0-based) */
	idigit = ibit / BITS_PER_DIGIT;
	/* Check size */
	/* [EDIT v2.1:] change a->maxdigits to a->ndigits */
	if (idigit >= a->ndigits)
	{
		bd_resize(a, idigit+1);
		a->ndigits = idigit+1;
	}

	/* [v2.2] use mp function */
	mpSetBit(a->digits, a->ndigits, ibit, value);

	/* Set the right size */
	a->ndigits = mpSizeof(a->digits, a->ndigits);

	return 0;
}

int bdGetBit(T a, size_t ibit)
/* Returns value 1 or 0 of bit ibit (0..nbits-1) */
{
	size_t idigit;

	assert(a);
	/* Which digit? (0-based) */
	idigit = ibit / BITS_PER_DIGIT;
	/* Check size */
	if (idigit >= a->maxdigits)
		return 0;

	/* [v2.2] use mp function */
	return mpGetBit(a->digits, a->ndigits, ibit);
}

void bdShiftLeft(T a, T b, size_t s)
	/* Computes a = b << s */
{ 
	/* Increases the size of a if necessary. */
	/* [v2.1.0] modified to allow any size of shift */

	size_t dig_size = b->ndigits;
	
	assert(a && b);

	if (s >= BITS_PER_DIGIT)
		dig_size += (s / BITS_PER_DIGIT);
	
	/* Assume overflow */
	dig_size++;
	/* Make sure both big enough */
	bd_resize(a, dig_size);
	bd_resize(b, dig_size);

	/* Set the final size */
	mpShiftLeft(a->digits, b->digits, s, dig_size);

	a->ndigits = mpSizeof(a->digits, dig_size);

}

void bdShiftRight(T a, T b, size_t n)
	/* Computes a = b >> n */
{ 
	/* Throws away shifted bits */
	/* [v2.1.0] modified to allow any size of shift */

	size_t dig_size = b->ndigits;
	
	assert(a && b);

	bd_resize(a, dig_size);
	mpShiftRight(a->digits, b->digits, n, dig_size);

	/* Set the final size */
	a->ndigits = mpSizeof(a->digits, dig_size);

}

void bdXorBits(T a, T b, T c)
	/* Computes bitwise operation a = b XOR c */
{ 
	size_t n;

	assert(a && b && c);
	/* Make sure all variables are the same size */
	n = max(b->ndigits, c->ndigits);

	bd_resize(a, n);
	bd_resize(b, n);
	bd_resize(c, n);

	/* Do the business */
	mpXorBits(a->digits, b->digits, c->digits, n);

	/* Set the final size */
	a->ndigits = mpSizeof(a->digits, n);

}

void bdOrBits(T a, T b, T c)
	/* Computes bitwise operation a = b OR c */
{ 
	size_t n;

	assert(a && b && c);
	/* Make sure all variables are the same size */
	n = max(b->ndigits, c->ndigits);

	bd_resize(a, n);
	bd_resize(b, n);
	bd_resize(c, n);

	/* Do the business */
	mpOrBits(a->digits, b->digits, c->digits, n);

	/* Set the final size */
	a->ndigits = mpSizeof(a->digits, n);

}

void bdAndBits(T a, T b, T c)
	/* Computes bitwise operation a = b AND c */
{ 
	size_t n;

	assert(a && b && c);
	/* Make sure all variables are the same size */
	n = max(b->ndigits, c->ndigits);

	bd_resize(a, n);
	bd_resize(b, n);
	bd_resize(c, n);

	/* Do the business */
	mpAndBits(a->digits, b->digits, c->digits, n);

	/* Set the final size */
	a->ndigits = mpSizeof(a->digits, n);
}

void bdNotBits(BIGD a, BIGD b)
	/* Computes bitwise a = NOT b */
{
	size_t n;

	assert(a && b);
	/* Make sure all variables are the same size */
	n = b->ndigits;

	bd_resize(a, n);

	/* Do the business */
	mpNotBits(a->digits, b->digits, n);

	/* Set the final size */
	a->ndigits = mpSizeof(a->digits, n);
}

void bdModPowerOf2(BIGD a, size_t L)
	/* Computes a = a mod 2^L */
{
	size_t n;

	assert(a);
	n = a->ndigits;

	/* Do the business */
	mpModPowerOf2(a->digits, n, L);

	/* Set the final size */
	a->ndigits = mpSizeof(a->digits, n);
}

int bdModExp(T y, T x, T e, T m)
{
	/* Compute y = x^e mod m 
	   x,e < m */

	size_t n;
	int status;

	assert(y && x && e && m);
	/* Make sure all variables are the same size */
	n = max(e->ndigits, m->ndigits);
	n = max(x->ndigits, n);

	bd_resize(y, n);
	bd_resize(x, n);
	bd_resize(e, n);
	bd_resize(m, n);

	/* Finally, do the business */
	status = mpModExp(y->digits, x->digits, e->digits, m->digits, n);

	y->ndigits = mpSizeof(y->digits, n);

	return status;
}

int bdModMult(T a, T x, T y, T m)
	/* Compute a = (x * y) mod m */
{
	size_t n;
	int status;

	assert(a && x && y && m);
	/* Make sure all variables are the same size */
	n = max(y->ndigits, m->ndigits);
	n = max(x->ndigits, n);

	bd_resize(a, n);
	bd_resize(y, n);
	bd_resize(x, n);
	bd_resize(m, n);

	/* Do the business */
	status = mpModMult(a->digits, x->digits, y->digits, m->digits, n);

	a->ndigits = mpSizeof(a->digits, n);

	return status;
}


int bdModInv(T x, T a, T m)
	/* Compute x = a^-1 mod m */
{
	size_t n;
	int status;

	assert(x && a && m);
	/* Make sure all variables are the same size */
	n = max(a->ndigits, m->ndigits);

	bd_resize(x, n);
	bd_resize(a, n);
	bd_resize(m, n);

	/* Do the business */
	status = mpModInv(x->digits, a->digits, m->digits, n);

	x->ndigits = mpSizeof(x->digits, n);

	return status;
}

int bdGcd(T g, T x, T y)
	/* Compute g = gcd(x, y) */
{
	size_t n;
	int status;

	assert(g && x && y);
	n = max(x->ndigits, y->ndigits);

	bd_resize(g, n);
	bd_resize(y, n);
	bd_resize(x, n);

	/* Do the business */
	status = mpGcd(g->digits, x->digits, y->digits, n);

	g->ndigits = mpSizeof(g->digits, n);

	return status;
}

int bdJacobi(T a, T m)
	/* Returns Jacobi(a, m) = {0, +1, -1} */
{
	size_t n;	/* Careful with n and m here! */
	int status;

	assert(a && m);
	n = max(a->ndigits, m->ndigits);

	bd_resize(a, n);
	bd_resize(m, n);

	/* Do the business */
	status = mpJacobi(a->digits, m->digits, n);

	return status;
}

int bdIsPrime(T b, size_t ntests)
/* Returns true if passes ntests x Miller-Rabin tests */
{
	assert(b);
	return (mpIsPrime(b->digits, b->ndigits, ntests));
}

int bdRabinMiller(T b, size_t ntests)
/* Returns true if passes ntests x Miller-Rabin tests without trial division */
{
	assert(b);
	return (mpRabinMiller(b->digits, b->ndigits, ntests));
}

/* [Version 2.1: bdRandDigit moved to bdRand.c] */

size_t bdSetRandTest(T a, size_t ndigits)
/* Make a random bigd a of up to ndigits digits 
   -- NB just for testing 
   Return # digits actually set */ 
{
	size_t i, n, bits;
	DIGIT_T mask;

	assert(a);
	/* Pick a random size */
	n = (size_t)spSimpleRand(1, (DIGIT_T)ndigits);
	
	/* Check allocated memory */
	bd_resize(a, n);
	
	/* Now fill with random digits */
	for (i = 0; i < n; i++)
		a->digits[i] = spSimpleRand(0, MAX_DIGIT);

	a->ndigits = n;

	/*	Zero out a random number of bits in leading digit 
		about half the time */
	bits = (size_t)spSimpleRand(0, 2*BITS_PER_DIGIT);
	if (bits != 0 && bits < BITS_PER_DIGIT)
	{
		mask = HIBITMASK;
		for (i = 1; i < bits; i++)
		{
			mask |= (mask >> 1);
		}
		mask = ~mask;
		a->digits[n-1] &= mask;
	}
	return n;
}


int bdRandomSeeded(T a, size_t nbits, const unsigned char *seed, 
	size_t seedlen, BD_RANDFUNC RandFunc)
/* Create a random mp digit at most nbits long
   -- high bit may or may not be set
   -- Uses whatever RNG function the user specifies */
{
	size_t i, hibit, ndigits, nbytes;
	DIGIT_T chop;

	assert(a);
	/* Make sure big enough */
	ndigits = (nbits + BITS_PER_DIGIT - 1) / BITS_PER_DIGIT;
	bd_resize(a, ndigits);
	nbytes = ndigits * sizeof(DIGIT_T);

	/* Generate random bytes using callback function */
	RandFunc((unsigned char *)a->digits, nbytes, seed, seedlen);

	/* Clear unwanted high bits */
	hibit = (nbits-1) % BITS_PER_DIGIT;
	for (chop = 0x01, i = 0; i < hibit; i++)
		chop = (chop << 1) | chop;

	a->digits[ndigits-1] &= chop;

	a->ndigits = ndigits;

	return 0;
}


int bdGeneratePrime(T b, size_t nbits, size_t ntests, 
	const unsigned char *seed, size_t seedlen, BD_RANDFUNC RandFunc)
{
	size_t i, hibit, ndigits, nbytes;
	DIGIT_T mask, chop;
	DIGIT_T *p;
	int done;
	size_t iloop, maxloops, j, maxodd;

	assert(b);
	/* Make sure big enough */
	ndigits = (nbits + BITS_PER_DIGIT - 1) / BITS_PER_DIGIT;
	bd_resize(b, ndigits);
	nbytes = ndigits * sizeof(DIGIT_T);

	/* use a ptr */
	p = b->digits;

	maxloops = 5;
	maxodd = 100 * nbits;
	done = 0;
	for (iloop = 0; !done && iloop < maxloops; iloop++)
	{
		/* Generate random digits using callback function */
		RandFunc((unsigned char *)p, nbytes, seed, seedlen);

		/* Set high and low bits */
		hibit = (nbits-1) % BITS_PER_DIGIT;
		mask = 0x01 << hibit;
		for (chop = 0x01, i = 0; i < hibit; i++)
			chop = (chop << 1) | chop;

		p[ndigits-1] |= mask;
		p[ndigits-1] &= chop;
		p[0] |= 0x01;

		/* Try each odd number until success or too many tries */
		for (j = 0; !done && j < maxodd; j++, mpShortAdd(p, p, 2, ndigits))
		{
			if (!(p[ndigits-1] & mask))
				break;	/* Catch overflow */

			if (debug) mpPrintNL(p, ndigits);

			if (mpIsPrime(p, ndigits, ntests))
			{
				done = 1;
				break;
			}
		}
	}

	if (debug) mpPrintNL(p, ndigits);

	b->ndigits = ndigits;

	return (done ? 0 : 1);
}

/* Version Info - added in ver 2.0.2 */
int bdVersion(void)
{
	return mpVersion();
}