andre@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
andre@0: /* This Source Code Form is subject to the terms of the Mozilla Public
andre@0: * License, v. 2.0. If a copy of the MPL was not distributed with this
andre@0: * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
andre@0:
andre@0: #include "prlong.h"
andre@0:
andre@0: static PRInt64 ll_zero = LL_INIT( 0x00000000,0x00000000 );
andre@0: static PRInt64 ll_maxint = LL_INIT( 0x7fffffff, 0xffffffff );
andre@0: static PRInt64 ll_minint = LL_INIT( 0x80000000, 0x00000000 );
andre@0: static PRUint64 ll_maxuint = LL_INIT( 0xffffffff, 0xffffffff );
andre@0:
andre@0: PR_IMPLEMENT(PRInt64) LL_Zero(void) { return ll_zero; }
andre@0: PR_IMPLEMENT(PRInt64) LL_MaxInt(void) { return ll_maxint; }
andre@0: PR_IMPLEMENT(PRInt64) LL_MinInt(void) { return ll_minint; }
andre@0: PR_IMPLEMENT(PRUint64) LL_MaxUint(void) { return ll_maxuint; }
andre@0:
andre@0: #ifndef HAVE_LONG_LONG
andre@0: /*
andre@0: ** Divide 64-bit a by 32-bit b, which must be normalized so its high bit is 1.
andre@0: */
andre@0: static void norm_udivmod32(PRUint32 *qp, PRUint32 *rp, PRUint64 a, PRUint32 b)
andre@0: {
andre@0: PRUint32 d1, d0, q1, q0;
andre@0: PRUint32 r1, r0, m;
andre@0:
andre@0: d1 = _hi16(b);
andre@0: d0 = _lo16(b);
andre@0: r1 = a.hi % d1;
andre@0: q1 = a.hi / d1;
andre@0: m = q1 * d0;
andre@0: r1 = (r1 << 16) | _hi16(a.lo);
andre@0: if (r1 < m) {
andre@0: q1--, r1 += b;
andre@0: if (r1 >= b /* i.e., we didn't get a carry when adding to r1 */
andre@0: && r1 < m) {
andre@0: q1--, r1 += b;
andre@0: }
andre@0: }
andre@0: r1 -= m;
andre@0: r0 = r1 % d1;
andre@0: q0 = r1 / d1;
andre@0: m = q0 * d0;
andre@0: r0 = (r0 << 16) | _lo16(a.lo);
andre@0: if (r0 < m) {
andre@0: q0--, r0 += b;
andre@0: if (r0 >= b
andre@0: && r0 < m) {
andre@0: q0--, r0 += b;
andre@0: }
andre@0: }
andre@0: *qp = (q1 << 16) | q0;
andre@0: *rp = r0 - m;
andre@0: }
andre@0:
andre@0: static PRUint32 CountLeadingZeros(PRUint32 a)
andre@0: {
andre@0: PRUint32 t;
andre@0: PRUint32 r = 32;
andre@0:
andre@0: if ((t = a >> 16) != 0)
andre@0: r -= 16, a = t;
andre@0: if ((t = a >> 8) != 0)
andre@0: r -= 8, a = t;
andre@0: if ((t = a >> 4) != 0)
andre@0: r -= 4, a = t;
andre@0: if ((t = a >> 2) != 0)
andre@0: r -= 2, a = t;
andre@0: if ((t = a >> 1) != 0)
andre@0: r -= 1, a = t;
andre@0: if (a & 1)
andre@0: r--;
andre@0: return r;
andre@0: }
andre@0:
andre@0: PR_IMPLEMENT(void) ll_udivmod(PRUint64 *qp, PRUint64 *rp, PRUint64 a, PRUint64 b)
andre@0: {
andre@0: PRUint32 n0, n1, n2;
andre@0: PRUint32 q0, q1;
andre@0: PRUint32 rsh, lsh;
andre@0:
andre@0: n0 = a.lo;
andre@0: n1 = a.hi;
andre@0:
andre@0: if (b.hi == 0) {
andre@0: if (b.lo > n1) {
andre@0: /* (0 q0) = (n1 n0) / (0 D0) */
andre@0:
andre@0: lsh = CountLeadingZeros(b.lo);
andre@0:
andre@0: if (lsh) {
andre@0: /*
andre@0: * Normalize, i.e. make the most significant bit of the
andre@0: * denominator be set.
andre@0: */
andre@0: b.lo = b.lo << lsh;
andre@0: n1 = (n1 << lsh) | (n0 >> (32 - lsh));
andre@0: n0 = n0 << lsh;
andre@0: }
andre@0:
andre@0: a.lo = n0, a.hi = n1;
andre@0: norm_udivmod32(&q0, &n0, a, b.lo);
andre@0: q1 = 0;
andre@0:
andre@0: /* remainder is in n0 >> lsh */
andre@0: } else {
andre@0: /* (q1 q0) = (n1 n0) / (0 d0) */
andre@0:
andre@0: if (b.lo == 0) /* user wants to divide by zero! */
andre@0: b.lo = 1 / b.lo; /* so go ahead and crash */
andre@0:
andre@0: lsh = CountLeadingZeros(b.lo);
andre@0:
andre@0: if (lsh == 0) {
andre@0: /*
andre@0: * From (n1 >= b.lo)
andre@0: * && (the most significant bit of b.lo is set),
andre@0: * conclude that
andre@0: * (the most significant bit of n1 is set)
andre@0: * && (the leading quotient digit q1 = 1).
andre@0: *
andre@0: * This special case is necessary, not an optimization
andre@0: * (Shifts counts of 32 are undefined).
andre@0: */
andre@0: n1 -= b.lo;
andre@0: q1 = 1;
andre@0: } else {
andre@0: /*
andre@0: * Normalize.
andre@0: */
andre@0: rsh = 32 - lsh;
andre@0:
andre@0: b.lo = b.lo << lsh;
andre@0: n2 = n1 >> rsh;
andre@0: n1 = (n1 << lsh) | (n0 >> rsh);
andre@0: n0 = n0 << lsh;
andre@0:
andre@0: a.lo = n1, a.hi = n2;
andre@0: norm_udivmod32(&q1, &n1, a, b.lo);
andre@0: }
andre@0:
andre@0: /* n1 != b.lo... */
andre@0:
andre@0: a.lo = n0, a.hi = n1;
andre@0: norm_udivmod32(&q0, &n0, a, b.lo);
andre@0:
andre@0: /* remainder in n0 >> lsh */
andre@0: }
andre@0:
andre@0: if (rp) {
andre@0: rp->lo = n0 >> lsh;
andre@0: rp->hi = 0;
andre@0: }
andre@0: } else {
andre@0: if (b.hi > n1) {
andre@0: /* (0 0) = (n1 n0) / (D1 d0) */
andre@0:
andre@0: q0 = 0;
andre@0: q1 = 0;
andre@0:
andre@0: /* remainder in (n1 n0) */
andre@0: if (rp) {
andre@0: rp->lo = n0;
andre@0: rp->hi = n1;
andre@0: }
andre@0: } else {
andre@0: /* (0 q0) = (n1 n0) / (d1 d0) */
andre@0:
andre@0: lsh = CountLeadingZeros(b.hi);
andre@0: if (lsh == 0) {
andre@0: /*
andre@0: * From (n1 >= b.hi)
andre@0: * && (the most significant bit of b.hi is set),
andre@0: * conclude that
andre@0: * (the most significant bit of n1 is set)
andre@0: * && (the quotient digit q0 = 0 or 1).
andre@0: *
andre@0: * This special case is necessary, not an optimization.
andre@0: */
andre@0:
andre@0: /*
andre@0: * The condition on the next line takes advantage of that
andre@0: * n1 >= b.hi (true due to control flow).
andre@0: */
andre@0: if (n1 > b.hi || n0 >= b.lo) {
andre@0: q0 = 1;
andre@0: a.lo = n0, a.hi = n1;
andre@0: LL_SUB(a, a, b);
andre@0: } else {
andre@0: q0 = 0;
andre@0: }
andre@0: q1 = 0;
andre@0:
andre@0: if (rp) {
andre@0: rp->lo = n0;
andre@0: rp->hi = n1;
andre@0: }
andre@0: } else {
andre@0: PRInt64 m;
andre@0:
andre@0: /*
andre@0: * Normalize.
andre@0: */
andre@0: rsh = 32 - lsh;
andre@0:
andre@0: b.hi = (b.hi << lsh) | (b.lo >> rsh);
andre@0: b.lo = b.lo << lsh;
andre@0: n2 = n1 >> rsh;
andre@0: n1 = (n1 << lsh) | (n0 >> rsh);
andre@0: n0 = n0 << lsh;
andre@0:
andre@0: a.lo = n1, a.hi = n2;
andre@0: norm_udivmod32(&q0, &n1, a, b.hi);
andre@0: LL_MUL32(m, q0, b.lo);
andre@0:
andre@0: if ((m.hi > n1) || ((m.hi == n1) && (m.lo > n0))) {
andre@0: q0--;
andre@0: LL_SUB(m, m, b);
andre@0: }
andre@0:
andre@0: q1 = 0;
andre@0:
andre@0: /* Remainder is ((n1 n0) - (m1 m0)) >> lsh */
andre@0: if (rp) {
andre@0: a.lo = n0, a.hi = n1;
andre@0: LL_SUB(a, a, m);
andre@0: rp->lo = (a.hi << rsh) | (a.lo >> lsh);
andre@0: rp->hi = a.hi >> lsh;
andre@0: }
andre@0: }
andre@0: }
andre@0: }
andre@0:
andre@0: if (qp) {
andre@0: qp->lo = q0;
andre@0: qp->hi = q1;
andre@0: }
andre@0: }
andre@0: #endif /* !HAVE_LONG_LONG */