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;
}