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/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
/* Portions Copyright(c) 1988, Sun Microsystems Inc. */
/* All Rights Reserved */
/*
* Copyright (c) 1997, by Sun Microsystems, Inc.
* All rights reserved.
*/
/*
* Copyright (c) 2018, Joyent, Inc.
*/
/* LINTLIBRARY */
#include <mp.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include "libmp.h"
static void m_div(MINT *, MINT *, MINT *, MINT *);
void
mp_mdiv(MINT *a, MINT *b, MINT *q, MINT *r)
{
MINT x, y;
int sign;
sign = 1;
x.len = y.len = 0;
_mp_move(a, &x);
_mp_move(b, &y);
if (x.len < 0) {
sign = -1;
x.len = -x.len;
}
if (y.len < 0) {
sign = -sign;
y.len = -y.len;
}
_mp_xfree(q);
_mp_xfree(r);
m_div(&x, &y, q, r);
if (sign == -1) {
q->len = -q->len;
r->len = -r->len;
}
_mp_xfree(&x);
_mp_xfree(&y);
}
static int
m_dsb(int qx, int n, short *a, short *b)
{
int borrow;
int s3b2shit;
int j;
short fifteen = 15;
short *aptr, *bptr;
#ifdef DEBUGDSB
(void) printf("m_dsb %d %d %d %d\n", qx, n, *a, *b);
#endif
borrow = 0;
aptr = a;
bptr = b;
for (j = n; j > 0; j--) {
#ifdef DEBUGDSB
(void) printf("1 borrow=%x %d %d %d\n", borrow, (*aptr * qx),
*bptr, *aptr);
#endif
borrow -= (*aptr++) * qx - *bptr;
#ifdef DEBUGDSB
(void) printf("2 borrow=%x %d %d %d\n", borrow, (*aptr * qx),
*bptr, *aptr);
#endif
*bptr++ = (short)(borrow & 077777);
#ifdef DEBUGDSB
(void) printf("3 borrow=%x %d %d %d\n", borrow, (*aptr * qx),
*bptr, *aptr);
#endif
if (borrow >= 0) borrow >>= fifteen; /* 3b2 */
else borrow = 0xfffe0000 | (borrow >> fifteen);
#ifdef DEBUGDSB
(void) printf("4 borrow=%x %d %d %d\n", borrow, (*aptr * qx),
*bptr, *aptr);
#endif
}
borrow += *bptr;
*bptr = (short)(borrow & 077777);
if (borrow >= 0) s3b2shit = borrow >> fifteen; /* 3b2 */
else s3b2shit = 0xfffe0000 | (borrow >> fifteen);
if (s3b2shit == 0) {
#ifdef DEBUGDSB
(void) printf("mdsb 0\n");
#endif
return (0);
}
borrow = 0;
aptr = a;
bptr = b;
for (j = n; j > 0; j--) {
borrow += *aptr++ + *bptr;
*bptr++ = (short)(borrow & 077777);
if (borrow >= 0) borrow >>= fifteen; /* 3b2 */
else borrow = 0xfffe0000 | (borrow >>fifteen);
}
#ifdef DEBUGDSB
(void) printf("mdsb 1\n");
#endif
return (1);
}
static int
m_trq(short v1, short v2, short u1, short u2, short u3)
{
short d;
int x1;
int c1;
c1 = u1 * 0100000 + u2;
if (u1 == v1) {
d = 077777;
} else {
d = (short)(c1 / v1);
}
do {
x1 = c1 - v1 * d;
x1 = x1 * 0100000 + u3 - v2 * d;
--d;
} while (x1 < 0);
#ifdef DEBUGMTRQ
(void) printf("mtrq %d %d %d %d %d %d\n", v1, v2, u1, u2, u3, (d+1));
#endif
return ((int)d + 1);
}
static void
m_div(MINT *a, MINT *b, MINT *q, MINT *r)
{
MINT u, v, x, w;
short d;
short *qval;
short *uval;
int j;
int qq;
int n;
short v1;
short v2;
u.len = v.len = x.len = w.len = 0;
if (b->len == 0) {
_mp_fatal("mdiv divide by zero");
return;
}
if (b->len == 1) {
r->val = _mp_xalloc(1, "m_div1");
mp_sdiv(a, b->val[0], q, r->val);
if (r->val[0] == 0) {
free(r->val);
r->len = 0;
} else {
r->len = 1;
}
return;
}
if (a -> len < b -> len) {
q->len = 0;
r->len = a->len;
r->val = _mp_xalloc(r->len, "m_div2");
for (qq = 0; qq < r->len; qq++) {
r->val[qq] = a->val[qq];
}
return;
}
x.len = 1;
x.val = &d;
n = b->len;
d = 0100000 / (b->val[n - 1] + 1);
mp_mult(a, &x, &u); /* subtle: relies on mult allocing extra space */
mp_mult(b, &x, &v);
#ifdef DEBUG_MDIV
(void) printf(" u=%s\n", mtox(&u));
(void) printf(" v=%s\n", mtox(&v));
#endif
v1 = v.val[n - 1];
v2 = v.val[n - 2];
qval = _mp_xalloc(a -> len - n + 1, "m_div3");
uval = u.val;
for (j = a->len - n; j >= 0; j--) {
qq = m_trq(v1, v2, uval[j + n], uval[j + n - 1],
uval[j + n - 2]);
if (m_dsb(qq, n, v.val, uval + j))
qq -= 1;
qval[j] = (short)qq;
}
x.len = n;
x.val = u.val;
_mp_mcan(&x);
#ifdef DEBUG_MDIV
(void) printf(" x=%s\n", mtox(&x));
(void) printf(" d(in)=%d\n", (d));
#endif
mp_sdiv(&x, d, &w, &d);
#ifdef DEBUG_MDIV
(void) printf(" w=%s\n", mtox(&w));
(void) printf(" d(out)=%d\n", (d));
#endif
r->len = w.len;
r->val = w.val;
q->val = qval;
qq = a->len - n + 1;
if (qq > 0 && qval[qq - 1] == 0)
qq -= 1;
q->len = qq;
if (qq == 0)
free(qval);
if (x.len != 0)
_mp_xfree(&u);
_mp_xfree(&v);
}
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