summaryrefslogtreecommitdiffstats
path: root/lib/udivmoddi4.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/udivmoddi4.c')
-rw-r--r--lib/udivmoddi4.c310
1 files changed, 310 insertions, 0 deletions
diff --git a/lib/udivmoddi4.c b/lib/udivmoddi4.c
new file mode 100644
index 000000000000..c08bc8a5f1cf
--- /dev/null
+++ b/lib/udivmoddi4.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.
+ */
+
+#include <linux/libgcc.h>
+
+#define count_leading_zeros(COUNT, X) ((COUNT) = __builtin_clz(X))
+
+#define W_TYPE_SIZE 32
+
+#define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
+#define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
+#define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))
+
+/* If we still don't have umul_ppmm, define it using plain C. */
+#if !defined(umul_ppmm)
+#define umul_ppmm(w1, w0, u, v) \
+ do { \
+ unsigned long __x0, __x1, __x2, __x3; \
+ unsigned short __ul, __vl, __uh, __vh; \
+ \
+ __ul = __ll_lowpart(u); \
+ __uh = __ll_highpart(u); \
+ __vl = __ll_lowpart(v); \
+ __vh = __ll_highpart(v); \
+ \
+ __x0 = (unsigned long) __ul * __vl; \
+ __x1 = (unsigned long) __ul * __vh; \
+ __x2 = (unsigned long) __uh * __vl; \
+ __x3 = (unsigned long) __uh * __vh; \
+ \
+ __x1 += __ll_highpart(__x0); \
+ __x1 += __x2; \
+ if (__x1 < __x2) \
+ __x3 += __ll_B; \
+ \
+ (w1) = __x3 + __ll_highpart(__x1); \
+ (w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
+ } while (0)
+#endif
+
+#if !defined(sub_ddmmss)
+#define sub_ddmmss(sh, sl, ah, al, bh, bl) \
+ do { \
+ unsigned long __x; \
+ __x = (al) - (bl); \
+ (sh) = (ah) - (bh) - (__x > (al)); \
+ (sl) = __x; \
+ } while (0)
+#endif
+
+/* Define this unconditionally, so it can be used for debugging. */
+#define __udiv_qrnnd_c(q, r, n1, n0, d) \
+ do { \
+ unsigned long __d1, __d0, __q1, __q0; \
+ unsigned long __r1, __r0, __m; \
+ __d1 = __ll_highpart(d); \
+ __d0 = __ll_lowpart(d); \
+ \
+ __r1 = (n1) % __d1; \
+ __q1 = (n1) / __d1; \
+ __m = (unsigned long) __q1 * __d0; \
+ __r1 = __r1 * __ll_B | __ll_highpart(n0); \
+ if (__r1 < __m) { \
+ __q1--, __r1 += (d); \
+ if (__r1 >= (d)) \
+ if (__r1 < __m) \
+ __q1--, __r1 += (d); \
+ } \
+ __r1 -= __m; \
+ \
+ __r0 = __r1 % __d1; \
+ __q0 = __r1 / __d1; \
+ __m = (unsigned long) __q0 * __d0; \
+ __r0 = __r0 * __ll_B | __ll_lowpart(n0); \
+ if (__r0 < __m) { \
+ __q0--, __r0 += (d); \
+ if (__r0 >= (d)) \
+ if (__r0 < __m) \
+ __q0--, __r0 += (d); \
+ } \
+ __r0 -= __m; \
+ \
+ (q) = (unsigned long) __q1 * __ll_B | __q0; \
+ (r) = __r0; \
+ } while (0)
+
+/* If udiv_qrnnd was not defined for this processor, use __udiv_qrnnd_c. */
+#if !defined(udiv_qrnnd)
+#define UDIV_NEEDS_NORMALIZATION 1
+#define udiv_qrnnd __udiv_qrnnd_c
+#endif
+
+unsigned long long __udivmoddi4(unsigned long long u, unsigned long long v,
+ unsigned long long *rp)
+{
+ const DWunion nn = {.ll = u };
+ const DWunion dd = {.ll = v };
+ DWunion rr, ww;
+ unsigned long d0, d1, n0, n1, n2;
+ unsigned long q0 = 0, q1 = 0;
+ unsigned long b, bm;
+
+ d0 = dd.s.low;
+ d1 = dd.s.high;
+ n0 = nn.s.low;
+ n1 = nn.s.high;
+
+#if !UDIV_NEEDS_NORMALIZATION
+
+ if (d1 == 0) {
+ if (d0 > n1) {
+ /* 0q = nn / 0D */
+
+ udiv_qrnnd(q0, n0, n1, n0, d0);
+ q1 = 0;
+
+ /* Remainder in n0. */
+ } else {
+ /* qq = NN / 0d */
+
+ if (d0 == 0)
+ /* Divide intentionally by zero. */
+ d0 = 1 / d0;
+
+ udiv_qrnnd(q1, n1, 0, n1, d0);
+ udiv_qrnnd(q0, n0, n1, n0, d0);
+
+ /* Remainder in n0. */
+ }
+
+ if (rp != 0) {
+ rr.s.low = n0;
+ rr.s.high = 0;
+ *rp = rr.ll;
+ }
+
+#else /* UDIV_NEEDS_NORMALIZATION */
+
+ if (d1 == 0) {
+ if (d0 > n1) {
+ /* 0q = nn / 0D */
+
+ count_leading_zeros(bm, d0);
+
+ if (bm != 0) {
+ /*
+ * Normalize, i.e. make the most significant bit
+ * of the denominator set.
+ */
+
+ d0 = d0 << bm;
+ n1 = (n1 << bm) | (n0 >> (W_TYPE_SIZE - bm));
+ n0 = n0 << bm;
+ }
+
+ udiv_qrnnd(q0, n0, n1, n0, d0);
+ q1 = 0;
+
+ /* Remainder in n0 >> bm. */
+ } else {
+ /* qq = NN / 0d */
+
+ if (d0 == 0)
+ /* Divide intentionally by zero. */
+ d0 = 1 / d0;
+
+ count_leading_zeros(bm, d0);
+
+ if (bm == 0) {
+ /*
+ * From (n1 >= d0) /\ (the most significant bit
+ * of d0 is set), conclude (the most significant
+ * bit of n1 is set) /\ (theleading quotient
+ * digit q1 = 1).
+ *
+ * This special case is necessary, not an
+ * optimization. (Shifts counts of W_TYPE_SIZE
+ * are undefined.)
+ */
+
+ n1 -= d0;
+ q1 = 1;
+ } else {
+ /* Normalize. */
+
+ b = W_TYPE_SIZE - bm;
+
+ d0 = d0 << bm;
+ n2 = n1 >> b;
+ n1 = (n1 << bm) | (n0 >> b);
+ n0 = n0 << bm;
+
+ udiv_qrnnd(q1, n1, n2, n1, d0);
+ }
+
+ /* n1 != d0... */
+
+ udiv_qrnnd(q0, n0, n1, n0, d0);
+
+ /* Remainder in n0 >> bm. */
+ }
+
+ if (rp != 0) {
+ rr.s.low = n0 >> bm;
+ rr.s.high = 0;
+ *rp = rr.ll;
+ }
+
+#endif /* UDIV_NEEDS_NORMALIZATION */
+
+ } else {
+ if (d1 > n1) {
+ /* 00 = nn / DD */
+
+ q0 = 0;
+ q1 = 0;
+
+ /* Remainder in n1n0. */
+ if (rp != 0) {
+ rr.s.low = n0;
+ rr.s.high = n1;
+ *rp = rr.ll;
+ }
+ } else {
+ /* 0q = NN / dd */
+
+ count_leading_zeros(bm, d1);
+ if (bm == 0) {
+ /*
+ * From (n1 >= d1) /\ (the most significant bit
+ * of d1 is set), conclude (the most significant
+ * bit of n1 is set) /\ (the quotient digit q0 =
+ * 0 or 1).
+ *
+ * This special case is necessary, not an
+ * optimization.
+ */
+
+ /*
+ * The condition on the next line takes
+ * advantage of that n1 >= d1 (true due to
+ * program flow).
+ */
+ if (n1 > d1 || n0 >= d0) {
+ q0 = 1;
+ sub_ddmmss(n1, n0, n1, n0, d1, d0);
+ } else {
+ q0 = 0;
+ }
+
+ q1 = 0;
+
+ if (rp != 0) {
+ rr.s.low = n0;
+ rr.s.high = n1;
+ *rp = rr.ll;
+ }
+ } else {
+ unsigned long m1, m0;
+ /* Normalize. */
+
+ b = W_TYPE_SIZE - bm;
+
+ d1 = (d1 << bm) | (d0 >> b);
+ d0 = d0 << bm;
+ n2 = n1 >> b;
+ n1 = (n1 << bm) | (n0 >> b);
+ n0 = n0 << bm;
+
+ udiv_qrnnd(q0, n1, n2, n1, d1);
+ umul_ppmm(m1, m0, q0, d0);
+
+ if (m1 > n1 || (m1 == n1 && m0 > n0)) {
+ q0--;
+ sub_ddmmss(m1, m0, m1, m0, d1, d0);
+ }
+
+ q1 = 0;
+
+ /* Remainder in (n1n0 - m1m0) >> bm. */
+ if (rp != 0) {
+ sub_ddmmss(n1, n0, n1, n0, m1, m0);
+ rr.s.low = (n1 << b) | (n0 >> bm);
+ rr.s.high = n1 >> bm;
+ *rp = rr.ll;
+ }
+ }
+ }
+ }
+
+ ww.s.low = q0;
+ ww.s.high = q1;
+
+ return ww.ll;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-03 18:36:52 +0000