summaryrefslogtreecommitdiffstats
path: root/nsprpub/pr/src/misc/prlong.c
diff options
context:
space:
mode:
Diffstat (limited to 'nsprpub/pr/src/misc/prlong.c')
-rw-r--r--nsprpub/pr/src/misc/prlong.c239
1 files changed, 239 insertions, 0 deletions
diff --git a/nsprpub/pr/src/misc/prlong.c b/nsprpub/pr/src/misc/prlong.c
new file mode 100644
index 000000000..185fa5cd4
--- /dev/null
+++ b/nsprpub/pr/src/misc/prlong.c
@@ -0,0 +1,239 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "prlong.h"
+
+static PRInt64 ll_zero = PR_INT64(0x0000000000000000);
+static PRInt64 ll_maxint = PR_INT64(0x7fffffffffffffff);
+static PRInt64 ll_minint = PR_INT64(0x8000000000000000);
+static PRUint64 ll_maxuint = PR_UINT64(0xffffffffffffffff);
+
+PR_IMPLEMENT(PRInt64) LL_Zero(void) { return ll_zero; }
+PR_IMPLEMENT(PRInt64) LL_MaxInt(void) { return ll_maxint; }
+PR_IMPLEMENT(PRInt64) LL_MinInt(void) { return ll_minint; }
+PR_IMPLEMENT(PRUint64) LL_MaxUint(void) { return ll_maxuint; }
+
+#ifndef HAVE_LONG_LONG
+/*
+** Divide 64-bit a by 32-bit b, which must be normalized so its high bit is 1.
+*/
+static void norm_udivmod32(PRUint32 *qp, PRUint32 *rp, PRUint64 a, PRUint32 b)
+{
+ PRUint32 d1, d0, q1, q0;
+ PRUint32 r1, r0, m;
+
+ d1 = _hi16(b);
+ d0 = _lo16(b);
+ r1 = a.hi % d1;
+ q1 = a.hi / d1;
+ m = q1 * d0;
+ r1 = (r1 << 16) | _hi16(a.lo);
+ if (r1 < m) {
+ q1--, r1 += b;
+ if (r1 >= b /* i.e., we didn't get a carry when adding to r1 */
+ && r1 < m) {
+ q1--, r1 += b;
+ }
+ }
+ r1 -= m;
+ r0 = r1 % d1;
+ q0 = r1 / d1;
+ m = q0 * d0;
+ r0 = (r0 << 16) | _lo16(a.lo);
+ if (r0 < m) {
+ q0--, r0 += b;
+ if (r0 >= b
+ && r0 < m) {
+ q0--, r0 += b;
+ }
+ }
+ *qp = (q1 << 16) | q0;
+ *rp = r0 - m;
+}
+
+static PRUint32 CountLeadingZeros(PRUint32 a)
+{
+ PRUint32 t;
+ PRUint32 r = 32;
+
+ if ((t = a >> 16) != 0)
+ r -= 16, a = t;
+ if ((t = a >> 8) != 0)
+ r -= 8, a = t;
+ if ((t = a >> 4) != 0)
+ r -= 4, a = t;
+ if ((t = a >> 2) != 0)
+ r -= 2, a = t;
+ if ((t = a >> 1) != 0)
+ r -= 1, a = t;
+ if (a & 1)
+ r--;
+ return r;
+}
+
+PR_IMPLEMENT(void) ll_udivmod(PRUint64 *qp, PRUint64 *rp, PRUint64 a, PRUint64 b)
+{
+ PRUint32 n0, n1, n2;
+ PRUint32 q0, q1;
+ PRUint32 rsh, lsh;
+
+ n0 = a.lo;
+ n1 = a.hi;
+
+ if (b.hi == 0) {
+ if (b.lo > n1) {
+ /* (0 q0) = (n1 n0) / (0 D0) */
+
+ lsh = CountLeadingZeros(b.lo);
+
+ if (lsh) {
+ /*
+ * Normalize, i.e. make the most significant bit of the
+ * denominator be set.
+ */
+ b.lo = b.lo << lsh;
+ n1 = (n1 << lsh) | (n0 >> (32 - lsh));
+ n0 = n0 << lsh;
+ }
+
+ a.lo = n0, a.hi = n1;
+ norm_udivmod32(&q0, &n0, a, b.lo);
+ q1 = 0;
+
+ /* remainder is in n0 >> lsh */
+ } else {
+ /* (q1 q0) = (n1 n0) / (0 d0) */
+
+ if (b.lo == 0) /* user wants to divide by zero! */
+ b.lo = 1 / b.lo; /* so go ahead and crash */
+
+ lsh = CountLeadingZeros(b.lo);
+
+ if (lsh == 0) {
+ /*
+ * From (n1 >= b.lo)
+ * && (the most significant bit of b.lo is set),
+ * conclude that
+ * (the most significant bit of n1 is set)
+ * && (the leading quotient digit q1 = 1).
+ *
+ * This special case is necessary, not an optimization
+ * (Shifts counts of 32 are undefined).
+ */
+ n1 -= b.lo;
+ q1 = 1;
+ } else {
+ /*
+ * Normalize.
+ */
+ rsh = 32 - lsh;
+
+ b.lo = b.lo << lsh;
+ n2 = n1 >> rsh;
+ n1 = (n1 << lsh) | (n0 >> rsh);
+ n0 = n0 << lsh;
+
+ a.lo = n1, a.hi = n2;
+ norm_udivmod32(&q1, &n1, a, b.lo);
+ }
+
+ /* n1 != b.lo... */
+
+ a.lo = n0, a.hi = n1;
+ norm_udivmod32(&q0, &n0, a, b.lo);
+
+ /* remainder in n0 >> lsh */
+ }
+
+ if (rp) {
+ rp->lo = n0 >> lsh;
+ rp->hi = 0;
+ }
+ } else {
+ if (b.hi > n1) {
+ /* (0 0) = (n1 n0) / (D1 d0) */
+
+ q0 = 0;
+ q1 = 0;
+
+ /* remainder in (n1 n0) */
+ if (rp) {
+ rp->lo = n0;
+ rp->hi = n1;
+ }
+ } else {
+ /* (0 q0) = (n1 n0) / (d1 d0) */
+
+ lsh = CountLeadingZeros(b.hi);
+ if (lsh == 0) {
+ /*
+ * From (n1 >= b.hi)
+ * && (the most significant bit of b.hi is set),
+ * conclude that
+ * (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 >= b.hi (true due to control flow).
+ */
+ if (n1 > b.hi || n0 >= b.lo) {
+ q0 = 1;
+ a.lo = n0, a.hi = n1;
+ LL_SUB(a, a, b);
+ } else {
+ q0 = 0;
+ }
+ q1 = 0;
+
+ if (rp) {
+ rp->lo = n0;
+ rp->hi = n1;
+ }
+ } else {
+ PRInt64 m;
+
+ /*
+ * Normalize.
+ */
+ rsh = 32 - lsh;
+
+ b.hi = (b.hi << lsh) | (b.lo >> rsh);
+ b.lo = b.lo << lsh;
+ n2 = n1 >> rsh;
+ n1 = (n1 << lsh) | (n0 >> rsh);
+ n0 = n0 << lsh;
+
+ a.lo = n1, a.hi = n2;
+ norm_udivmod32(&q0, &n1, a, b.hi);
+ LL_MUL32(m, q0, b.lo);
+
+ if ((m.hi > n1) || ((m.hi == n1) && (m.lo > n0))) {
+ q0--;
+ LL_SUB(m, m, b);
+ }
+
+ q1 = 0;
+
+ /* Remainder is ((n1 n0) - (m1 m0)) >> lsh */
+ if (rp) {
+ a.lo = n0, a.hi = n1;
+ LL_SUB(a, a, m);
+ rp->lo = (a.hi << rsh) | (a.lo >> lsh);
+ rp->hi = a.hi >> lsh;
+ }
+ }
+ }
+ }
+
+ if (qp) {
+ qp->lo = q0;
+ qp->hi = q1;
+ }
+}
+#endif /* !HAVE_LONG_LONG */