static char rcsid[] = "$Id: H:/drh/idioms/book/RCS/xp.doc,v 1.10 1996/06/26 23:02:01 drh Exp $";#include <ctype.h>#include <string.h>#include "assert.h"#include "xp.h"#define T XP_T#define BASE (1<<8)static char map[] = {	 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,	36, 36, 36, 36, 36, 36, 36,	10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,	23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,	36, 36, 36, 36, 36, 36,	10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,	23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35};unsigned long XP_fromint(int n, T z, unsigned long u) {	int i = 0;	do		z[i++] = u%BASE;	while ((u /= BASE) > 0 && i < n);	for ( ; i < n; i++)		z[i] = 0;	return u;}unsigned long XP_toint(int n, T x) {	unsigned long u = 0;	int i = (int)sizeof u;	if (i > n)		i = n;	while (--i >= 0)		u = BASE*u + x[i];	return u;}int XP_length(int n, T x) {	while (n > 1 && x[n-1] == 0)		n--;	return n;}int XP_add(int n, T z, T x, T y, int carry) {	int i;	for (i = 0; i < n; i++) {		carry += x[i] + y[i];		z[i] = carry%BASE;		carry /= BASE;	}	return carry;}int XP_sub(int n, T z, T x, T y, int borrow) {	int i;	for (i = 0; i < n; i++) {		int d = (x[i] + BASE) - borrow - y[i];		z[i] = d%BASE;		borrow = 1 - d/BASE;	}	return borrow;}int XP_sum(int n, T z, T x, int y) {	int i;	for (i = 0; i < n; i++) {		y += x[i];		z[i] = y%BASE;		y /= BASE;	}	return y;}int XP_diff(int n, T z, T x, int y) {	int i;	for (i = 0; i < n; i++) {		int d = (x[i] + BASE) - y;		z[i] = d%BASE;		y = 1 - d/BASE;	}	return y;}int XP_neg(int n, T z, T x, int carry) {	int i;	for (i = 0; i < n; i++) {		carry += (unsigned char)~x[i];		z[i] = carry%BASE;		carry /= BASE;	}	return carry;}int XP_mul(T z, int n, T x, int m, T y) {	int i, j, carryout = 0;	for (i = 0; i < n; i++) {		unsigned carry = 0;		for (j = 0; j < m; j++) {			carry += x[i]*y[j] + z[i+j];			z[i+j] = carry%BASE;			carry /= BASE;		}		for ( ; j < n + m - i; j++) {			carry += z[i+j];			z[i+j] = carry%BASE;			carry /= BASE;		}		carryout |= carry;	}	return carryout;}int XP_product(int n, T z, T x, int y) {	int i;	unsigned carry = 0;	for (i = 0; i < n; i++) {		carry += x[i]*y;		z[i] = carry%BASE;		carry /= BASE;	}	return carry;}int XP_div(int n, T q, T x, int m, T y, T r, T tmp) {	int nx = n, my = m;	n = XP_length(n, x);	m = XP_length(m, y);	if (m == 1) {		if (y[0] == 0)			return 0;		r[0] = XP_quotient(nx, q, x, y[0]);		memset(r + 1, '\0', my - 1);	} else if (m > n) {		memset(q, '\0', nx);		memcpy(r, x, n);		memset(r + n, '\0', my - n);	} else {		int k;		unsigned char *rem = tmp, *dq = tmp + n + 1;		assert(2 <= m && m <= n);		memcpy(rem, x, n);		rem[n] = 0;		for (k = n - m; k >= 0; k--) {			int qk;			{				int i;				assert(2 <= m && m <= k+m && k+m <= n);				{					int km = k + m;					unsigned long y2 = y[m-1]*BASE + y[m-2];					unsigned long r3 = rem[km]*(BASE*BASE) +						rem[km-1]*BASE + rem[km-2];					qk = r3/y2;					if (qk >= BASE)						qk = BASE - 1;				}				dq[m] = XP_product(m, dq, y, qk);				for (i = m; i > 0; i--)					if (rem[i+k] != dq[i])						break;				if (rem[i+k] < dq[i])					dq[m] = XP_product(m, dq, y, --qk);			}			q[k] = qk;			{				int borrow;				assert(0 <= k && k <= k+m);				borrow = XP_sub(m + 1, &rem[k], &rem[k], dq, 0);				assert(borrow == 0);			}		}		memcpy(r, rem, m);		{			int i;			for (i = n-m+1; i < nx; i++)				q[i] = 0;			for (i = m; i < my; i++)				r[i] = 0;		}	}	return 1;}int XP_quotient(int n, T z, T x, int y) {	int i;	unsigned carry = 0;	for (i = n - 1; i >= 0; i--) {		carry = carry*BASE + x[i];		z[i] = carry/y;		carry %= y;	}	return carry;}int XP_cmp(int n, T x, T y) {	int i = n - 1;	while (i > 0 && x[i] == y[i])		i--;	return x[i] - y[i];}void XP_lshift(int n, T z, int m, T x, int s, int fill) {	fill = fill ? 0xFF : 0;	{		int i, j = n - 1;		if (n > m)			i = m - 1;		else			i = n - s/8 - 1;		for ( ; j >= m + s/8; j--)			z[j] = 0;		for ( ; i >= 0; i--, j--)			z[j] = x[i];		for ( ; j >= 0; j--)			z[j] = fill;	}	s %= 8;	if (s > 0)		{			XP_product(n, z, z, 1<<s);			z[0] |= fill>>(8-s);		}}void XP_rshift(int n, T z, int m, T x, int s, int fill) {	fill = fill ? 0xFF : 0;	{		int i, j = 0;		for (i = s/8; i < m && j < n; i++, j++)			z[j] = x[i];		for ( ; j < n; j++)			z[j] = fill;	}	s %= 8;	if (s > 0)		{			XP_quotient(n, z, z, 1<<s);			z[n-1] |= fill<<(8-s);		}}int XP_fromstr(int n, T z, const char *str,	int base, char **end) {	const char *p = str;	assert(p);	assert(base >= 2 && base <= 36);	while (*p && isspace(*p))		p++;	if ((*p && isalnum(*p) && map[*p-'0'] < base)) {		int carry;		for ( ; (*p && isalnum(*p) && map[*p-'0'] < base); p++) {			carry = XP_product(n, z, z, base);			if (carry)				break;			XP_sum(n, z, z, map[*p-'0']);		}		if (end)			*end = (char *)p;		return carry;	} else {		if (end)			*end = (char *)str;		return 0;	}}char *XP_tostr(char *str, int size, int base,	int n, T x) {	int i = 0;	assert(str);	assert(base >= 2 && base <= 36);	do {		int r = XP_quotient(n, x, x, base);		assert(i < size);		str[i++] =			"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[r];		while (n > 1 && x[n-1] == 0)			n--;	} while (n > 1 || x[0] != 0);	assert(i < size);	str[i] = '\0';	{		int j;		for (j = 0; j < --i; j++) {			char c = str[j];			str[j] = str[i];			str[i] = c;		}	}	return str;}