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diff --git a/lib/libc/quad/qdivrem.c b/lib/libc/quad/qdivrem.c
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-/*-
- * Copyright (c) 1992, 1993
- * The Regents of the University of California. All rights reserved.
- *
- * This software was developed by the Computer Systems Engineering group
- * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
- * contributed to Berkeley.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. 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.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)qdivrem.c 8.1 (Berkeley) 6/4/93";
-#endif /* LIBC_SCCS and not lint */
-
-/*
- * Multiprecision divide. This algorithm is from Knuth vol. 2 (2nd ed),
- * section 4.3.1, pp. 257--259.
- */
-
-#include "quad.h"
-
-#define B (1 << HALF_BITS) /* digit base */
-
-/* Combine two `digits' to make a single two-digit number. */
-#define COMBINE(a, b) (((u_long)(a) << HALF_BITS) | (b))
-
-/* select a type for digits in base B: use unsigned short if they fit */
-#if ULONG_MAX == 0xffffffff && USHRT_MAX >= 0xffff
-typedef unsigned short digit;
-#else
-typedef u_long digit;
-#endif
-
-/*
- * Shift p[0]..p[len] left `sh' bits, ignoring any bits that
- * `fall out' the left (there never will be any such anyway).
- * We may assume len >= 0. NOTE THAT THIS WRITES len+1 DIGITS.
- */
-static void
-shl(register digit *p, register int len, register int sh)
-{
- register int i;
-
- for (i = 0; i < len; i++)
- p[i] = LHALF(p[i] << sh) | (p[i + 1] >> (HALF_BITS - sh));
- p[i] = LHALF(p[i] << sh);
-}
-
-/*
- * __qdivrem(u, v, rem) returns u/v and, optionally, sets *rem to u%v.
- *
- * We do this in base 2-sup-HALF_BITS, so that all intermediate products
- * fit within u_long. As a consequence, the maximum length dividend and
- * divisor are 4 `digits' in this base (they are shorter if they have
- * leading zeros).
- */
-u_quad_t
-__qdivrem(uq, vq, arq)
- u_quad_t uq, vq, *arq;
-{
- union uu tmp;
- digit *u, *v, *q;
- register digit v1, v2;
- u_long qhat, rhat, t;
- int m, n, d, j, i;
- digit uspace[5], vspace[5], qspace[5];
-
- /*
- * Take care of special cases: divide by zero, and u < v.
- */
- if (vq == 0) {
- /* divide by zero. */
- static volatile const unsigned int zero = 0;
-
- tmp.ul[H] = tmp.ul[L] = 1 / zero;
- if (arq)
- *arq = uq;
- return (tmp.q);
- }
- if (uq < vq) {
- if (arq)
- *arq = uq;
- return (0);
- }
- u = &uspace[0];
- v = &vspace[0];
- q = &qspace[0];
-
- /*
- * Break dividend and divisor into digits in base B, then
- * count leading zeros to determine m and n. When done, we
- * will have:
- * u = (u[1]u[2]...u[m+n]) sub B
- * v = (v[1]v[2]...v[n]) sub B
- * v[1] != 0
- * 1 < n <= 4 (if n = 1, we use a different division algorithm)
- * m >= 0 (otherwise u < v, which we already checked)
- * m + n = 4
- * and thus
- * m = 4 - n <= 2
- */
- tmp.uq = uq;
- u[0] = 0;
- u[1] = HHALF(tmp.ul[H]);
- u[2] = LHALF(tmp.ul[H]);
- u[3] = HHALF(tmp.ul[L]);
- u[4] = LHALF(tmp.ul[L]);
- tmp.uq = vq;
- v[1] = HHALF(tmp.ul[H]);
- v[2] = LHALF(tmp.ul[H]);
- v[3] = HHALF(tmp.ul[L]);
- v[4] = LHALF(tmp.ul[L]);
- for (n = 4; v[1] == 0; v++) {
- if (--n == 1) {
- u_long rbj; /* r*B+u[j] (not root boy jim) */
- digit q1, q2, q3, q4;
-
- /*
- * Change of plan, per exercise 16.
- * r = 0;
- * for j = 1..4:
- * q[j] = floor((r*B + u[j]) / v),
- * r = (r*B + u[j]) % v;
- * We unroll this completely here.
- */
- t = v[2]; /* nonzero, by definition */
- q1 = u[1] / t;
- rbj = COMBINE(u[1] % t, u[2]);
- q2 = rbj / t;
- rbj = COMBINE(rbj % t, u[3]);
- q3 = rbj / t;
- rbj = COMBINE(rbj % t, u[4]);
- q4 = rbj / t;
- if (arq)
- *arq = rbj % t;
- tmp.ul[H] = COMBINE(q1, q2);
- tmp.ul[L] = COMBINE(q3, q4);
- return (tmp.q);
- }
- }
-
- /*
- * By adjusting q once we determine m, we can guarantee that
- * there is a complete four-digit quotient at &qspace[1] when
- * we finally stop.
- */
- for (m = 4 - n; u[1] == 0; u++)
- m--;
- for (i = 4 - m; --i >= 0;)
- q[i] = 0;
- q += 4 - m;
-
- /*
- * Here we run Program D, translated from MIX to C and acquiring
- * a few minor changes.
- *
- * D1: choose multiplier 1 << d to ensure v[1] >= B/2.
- */
- d = 0;
- for (t = v[1]; t < B / 2; t <<= 1)
- d++;
- if (d > 0) {
- shl(&u[0], m + n, d); /* u <<= d */
- shl(&v[1], n - 1, d); /* v <<= d */
- }
- /*
- * D2: j = 0.
- */
- j = 0;
- v1 = v[1]; /* for D3 -- note that v[1..n] are constant */
- v2 = v[2]; /* for D3 */
- do {
- register digit uj0, uj1, uj2;
-
- /*
- * D3: Calculate qhat (\^q, in TeX notation).
- * Let qhat = min((u[j]*B + u[j+1])/v[1], B-1), and
- * let rhat = (u[j]*B + u[j+1]) mod v[1].
- * While rhat < B and v[2]*qhat > rhat*B+u[j+2],
- * decrement qhat and increase rhat correspondingly.
- * Note that if rhat >= B, v[2]*qhat < rhat*B.
- */
- uj0 = u[j + 0]; /* for D3 only -- note that u[j+...] change */
- uj1 = u[j + 1]; /* for D3 only */
- uj2 = u[j + 2]; /* for D3 only */
- if (uj0 == v1) {
- qhat = B;
- rhat = uj1;
- goto qhat_too_big;
- } else {
- u_long n = COMBINE(uj0, uj1);
- qhat = n / v1;
- rhat = n % v1;
- }
- while (v2 * qhat > COMBINE(rhat, uj2)) {
- qhat_too_big:
- qhat--;
- if ((rhat += v1) >= B)
- break;
- }
- /*
- * D4: Multiply and subtract.
- * The variable `t' holds any borrows across the loop.
- * We split this up so that we do not require v[0] = 0,
- * and to eliminate a final special case.
- */
- for (t = 0, i = n; i > 0; i--) {
- t = u[i + j] - v[i] * qhat - t;
- u[i + j] = LHALF(t);
- t = (B - HHALF(t)) & (B - 1);
- }
- t = u[j] - t;
- u[j] = LHALF(t);
- /*
- * D5: test remainder.
- * There is a borrow if and only if HHALF(t) is nonzero;
- * in that (rare) case, qhat was too large (by exactly 1).
- * Fix it by adding v[1..n] to u[j..j+n].
- */
- if (HHALF(t)) {
- qhat--;
- for (t = 0, i = n; i > 0; i--) { /* D6: add back. */
- t += u[i + j] + v[i];
- u[i + j] = LHALF(t);
- t = HHALF(t);
- }
- u[j] = LHALF(u[j] + t);
- }
- q[j] = qhat;
- } while (++j <= m); /* D7: loop on j. */
-
- /*
- * If caller wants the remainder, we have to calculate it as
- * u[m..m+n] >> d (this is at most n digits and thus fits in
- * u[m+1..m+n], but we may need more source digits).
- */
- if (arq) {
- if (d) {
- for (i = m + n; i > m; --i)
- u[i] = (u[i] >> d) |
- LHALF(u[i - 1] << (HALF_BITS - d));
- u[i] = 0;
- }
- tmp.ul[H] = COMBINE(uspace[1], uspace[2]);
- tmp.ul[L] = COMBINE(uspace[3], uspace[4]);
- *arq = tmp.q;
- }
-
- tmp.ul[H] = COMBINE(qspace[1], qspace[2]);
- tmp.ul[L] = COMBINE(qspace[3], qspace[4]);
- return (tmp.q);
-}
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