311 строки
6.7 KiB
C
311 строки
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see the file COPYING, or write
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* to the Free Software Foundation, Inc.
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*/
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#include <linux/libgcc.h>
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#define count_leading_zeros(COUNT, X) ((COUNT) = __builtin_clz(X))
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#define W_TYPE_SIZE 32
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#define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
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#define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
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#define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))
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/* If we still don't have umul_ppmm, define it using plain C. */
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#if !defined(umul_ppmm)
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#define umul_ppmm(w1, w0, u, v) \
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do { \
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unsigned long __x0, __x1, __x2, __x3; \
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unsigned short __ul, __vl, __uh, __vh; \
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\
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__ul = __ll_lowpart(u); \
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__uh = __ll_highpart(u); \
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__vl = __ll_lowpart(v); \
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__vh = __ll_highpart(v); \
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\
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__x0 = (unsigned long) __ul * __vl; \
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__x1 = (unsigned long) __ul * __vh; \
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__x2 = (unsigned long) __uh * __vl; \
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__x3 = (unsigned long) __uh * __vh; \
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\
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__x1 += __ll_highpart(__x0); \
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__x1 += __x2; \
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if (__x1 < __x2) \
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__x3 += __ll_B; \
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\
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(w1) = __x3 + __ll_highpart(__x1); \
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(w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
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} while (0)
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#endif
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#if !defined(sub_ddmmss)
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#define sub_ddmmss(sh, sl, ah, al, bh, bl) \
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do { \
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unsigned long __x; \
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__x = (al) - (bl); \
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(sh) = (ah) - (bh) - (__x > (al)); \
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(sl) = __x; \
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} while (0)
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#endif
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/* Define this unconditionally, so it can be used for debugging. */
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#define __udiv_qrnnd_c(q, r, n1, n0, d) \
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do { \
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unsigned long __d1, __d0, __q1, __q0; \
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unsigned long __r1, __r0, __m; \
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__d1 = __ll_highpart(d); \
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__d0 = __ll_lowpart(d); \
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\
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__r1 = (n1) % __d1; \
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__q1 = (n1) / __d1; \
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__m = (unsigned long) __q1 * __d0; \
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__r1 = __r1 * __ll_B | __ll_highpart(n0); \
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if (__r1 < __m) { \
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__q1--, __r1 += (d); \
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if (__r1 >= (d)) \
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if (__r1 < __m) \
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__q1--, __r1 += (d); \
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} \
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__r1 -= __m; \
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\
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__r0 = __r1 % __d1; \
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__q0 = __r1 / __d1; \
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__m = (unsigned long) __q0 * __d0; \
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__r0 = __r0 * __ll_B | __ll_lowpart(n0); \
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if (__r0 < __m) { \
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__q0--, __r0 += (d); \
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if (__r0 >= (d)) \
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if (__r0 < __m) \
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__q0--, __r0 += (d); \
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} \
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__r0 -= __m; \
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\
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(q) = (unsigned long) __q1 * __ll_B | __q0; \
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(r) = __r0; \
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} while (0)
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/* If udiv_qrnnd was not defined for this processor, use __udiv_qrnnd_c. */
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#if !defined(udiv_qrnnd)
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#define UDIV_NEEDS_NORMALIZATION 1
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#define udiv_qrnnd __udiv_qrnnd_c
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#endif
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unsigned long long __udivmoddi4(unsigned long long u, unsigned long long v,
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unsigned long long *rp)
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{
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const DWunion nn = {.ll = u };
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const DWunion dd = {.ll = v };
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DWunion rr, ww;
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unsigned long d0, d1, n0, n1, n2;
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unsigned long q0 = 0, q1 = 0;
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unsigned long b, bm;
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d0 = dd.s.low;
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d1 = dd.s.high;
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n0 = nn.s.low;
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n1 = nn.s.high;
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#if !UDIV_NEEDS_NORMALIZATION
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if (d1 == 0) {
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if (d0 > n1) {
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/* 0q = nn / 0D */
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udiv_qrnnd(q0, n0, n1, n0, d0);
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q1 = 0;
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/* Remainder in n0. */
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} else {
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/* qq = NN / 0d */
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if (d0 == 0)
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/* Divide intentionally by zero. */
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d0 = 1 / d0;
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udiv_qrnnd(q1, n1, 0, n1, d0);
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udiv_qrnnd(q0, n0, n1, n0, d0);
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/* Remainder in n0. */
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}
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if (rp != 0) {
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rr.s.low = n0;
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rr.s.high = 0;
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*rp = rr.ll;
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}
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#else /* UDIV_NEEDS_NORMALIZATION */
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if (d1 == 0) {
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if (d0 > n1) {
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/* 0q = nn / 0D */
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count_leading_zeros(bm, d0);
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if (bm != 0) {
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/*
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* Normalize, i.e. make the most significant bit
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* of the denominator set.
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*/
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d0 = d0 << bm;
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n1 = (n1 << bm) | (n0 >> (W_TYPE_SIZE - bm));
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n0 = n0 << bm;
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}
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udiv_qrnnd(q0, n0, n1, n0, d0);
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q1 = 0;
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/* Remainder in n0 >> bm. */
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} else {
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/* qq = NN / 0d */
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if (d0 == 0)
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/* Divide intentionally by zero. */
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d0 = 1 / d0;
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count_leading_zeros(bm, d0);
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if (bm == 0) {
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/*
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* From (n1 >= d0) /\ (the most significant bit
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* of d0 is set), conclude (the most significant
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* bit of n1 is set) /\ (theleading quotient
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* digit q1 = 1).
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*
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* This special case is necessary, not an
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* optimization. (Shifts counts of W_TYPE_SIZE
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* are undefined.)
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*/
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n1 -= d0;
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q1 = 1;
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} else {
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/* Normalize. */
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b = W_TYPE_SIZE - bm;
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d0 = d0 << bm;
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n2 = n1 >> b;
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n1 = (n1 << bm) | (n0 >> b);
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n0 = n0 << bm;
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udiv_qrnnd(q1, n1, n2, n1, d0);
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}
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/* n1 != d0... */
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udiv_qrnnd(q0, n0, n1, n0, d0);
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/* Remainder in n0 >> bm. */
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}
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if (rp != 0) {
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rr.s.low = n0 >> bm;
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rr.s.high = 0;
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*rp = rr.ll;
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}
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#endif /* UDIV_NEEDS_NORMALIZATION */
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} else {
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if (d1 > n1) {
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/* 00 = nn / DD */
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q0 = 0;
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q1 = 0;
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/* Remainder in n1n0. */
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if (rp != 0) {
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rr.s.low = n0;
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rr.s.high = n1;
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*rp = rr.ll;
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}
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} else {
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/* 0q = NN / dd */
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count_leading_zeros(bm, d1);
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if (bm == 0) {
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/*
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* From (n1 >= d1) /\ (the most significant bit
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* of d1 is set), conclude (the most significant
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* bit of n1 is set) /\ (the quotient digit q0 =
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* 0 or 1).
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*
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* This special case is necessary, not an
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* optimization.
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*/
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/*
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* The condition on the next line takes
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* advantage of that n1 >= d1 (true due to
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* program flow).
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*/
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if (n1 > d1 || n0 >= d0) {
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q0 = 1;
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sub_ddmmss(n1, n0, n1, n0, d1, d0);
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} else {
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q0 = 0;
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}
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q1 = 0;
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if (rp != 0) {
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rr.s.low = n0;
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rr.s.high = n1;
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*rp = rr.ll;
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}
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} else {
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unsigned long m1, m0;
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/* Normalize. */
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b = W_TYPE_SIZE - bm;
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d1 = (d1 << bm) | (d0 >> b);
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d0 = d0 << bm;
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n2 = n1 >> b;
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n1 = (n1 << bm) | (n0 >> b);
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n0 = n0 << bm;
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udiv_qrnnd(q0, n1, n2, n1, d1);
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umul_ppmm(m1, m0, q0, d0);
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if (m1 > n1 || (m1 == n1 && m0 > n0)) {
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q0--;
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sub_ddmmss(m1, m0, m1, m0, d1, d0);
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}
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q1 = 0;
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/* Remainder in (n1n0 - m1m0) >> bm. */
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if (rp != 0) {
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sub_ddmmss(n1, n0, n1, n0, m1, m0);
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rr.s.low = (n1 << b) | (n0 >> bm);
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rr.s.high = n1 >> bm;
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*rp = rr.ll;
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}
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}
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}
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}
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ww.s.low = q0;
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ww.s.high = q1;
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return ww.ll;
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}
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