1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/nsprpub/pr/src/misc/prlong.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,239 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#include "prlong.h"
1.10 +
1.11 +static PRInt64 ll_zero = LL_INIT( 0x00000000,0x00000000 );
1.12 +static PRInt64 ll_maxint = LL_INIT( 0x7fffffff, 0xffffffff );
1.13 +static PRInt64 ll_minint = LL_INIT( 0x80000000, 0x00000000 );
1.14 +static PRUint64 ll_maxuint = LL_INIT( 0xffffffff, 0xffffffff );
1.15 +
1.16 +PR_IMPLEMENT(PRInt64) LL_Zero(void) { return ll_zero; }
1.17 +PR_IMPLEMENT(PRInt64) LL_MaxInt(void) { return ll_maxint; }
1.18 +PR_IMPLEMENT(PRInt64) LL_MinInt(void) { return ll_minint; }
1.19 +PR_IMPLEMENT(PRUint64) LL_MaxUint(void) { return ll_maxuint; }
1.20 +
1.21 +#ifndef HAVE_LONG_LONG
1.22 +/*
1.23 +** Divide 64-bit a by 32-bit b, which must be normalized so its high bit is 1.
1.24 +*/
1.25 +static void norm_udivmod32(PRUint32 *qp, PRUint32 *rp, PRUint64 a, PRUint32 b)
1.26 +{
1.27 + PRUint32 d1, d0, q1, q0;
1.28 + PRUint32 r1, r0, m;
1.29 +
1.30 + d1 = _hi16(b);
1.31 + d0 = _lo16(b);
1.32 + r1 = a.hi % d1;
1.33 + q1 = a.hi / d1;
1.34 + m = q1 * d0;
1.35 + r1 = (r1 << 16) | _hi16(a.lo);
1.36 + if (r1 < m) {
1.37 + q1--, r1 += b;
1.38 + if (r1 >= b /* i.e., we didn't get a carry when adding to r1 */
1.39 + && r1 < m) {
1.40 + q1--, r1 += b;
1.41 + }
1.42 + }
1.43 + r1 -= m;
1.44 + r0 = r1 % d1;
1.45 + q0 = r1 / d1;
1.46 + m = q0 * d0;
1.47 + r0 = (r0 << 16) | _lo16(a.lo);
1.48 + if (r0 < m) {
1.49 + q0--, r0 += b;
1.50 + if (r0 >= b
1.51 + && r0 < m) {
1.52 + q0--, r0 += b;
1.53 + }
1.54 + }
1.55 + *qp = (q1 << 16) | q0;
1.56 + *rp = r0 - m;
1.57 +}
1.58 +
1.59 +static PRUint32 CountLeadingZeros(PRUint32 a)
1.60 +{
1.61 + PRUint32 t;
1.62 + PRUint32 r = 32;
1.63 +
1.64 + if ((t = a >> 16) != 0)
1.65 + r -= 16, a = t;
1.66 + if ((t = a >> 8) != 0)
1.67 + r -= 8, a = t;
1.68 + if ((t = a >> 4) != 0)
1.69 + r -= 4, a = t;
1.70 + if ((t = a >> 2) != 0)
1.71 + r -= 2, a = t;
1.72 + if ((t = a >> 1) != 0)
1.73 + r -= 1, a = t;
1.74 + if (a & 1)
1.75 + r--;
1.76 + return r;
1.77 +}
1.78 +
1.79 +PR_IMPLEMENT(void) ll_udivmod(PRUint64 *qp, PRUint64 *rp, PRUint64 a, PRUint64 b)
1.80 +{
1.81 + PRUint32 n0, n1, n2;
1.82 + PRUint32 q0, q1;
1.83 + PRUint32 rsh, lsh;
1.84 +
1.85 + n0 = a.lo;
1.86 + n1 = a.hi;
1.87 +
1.88 + if (b.hi == 0) {
1.89 + if (b.lo > n1) {
1.90 + /* (0 q0) = (n1 n0) / (0 D0) */
1.91 +
1.92 + lsh = CountLeadingZeros(b.lo);
1.93 +
1.94 + if (lsh) {
1.95 + /*
1.96 + * Normalize, i.e. make the most significant bit of the
1.97 + * denominator be set.
1.98 + */
1.99 + b.lo = b.lo << lsh;
1.100 + n1 = (n1 << lsh) | (n0 >> (32 - lsh));
1.101 + n0 = n0 << lsh;
1.102 + }
1.103 +
1.104 + a.lo = n0, a.hi = n1;
1.105 + norm_udivmod32(&q0, &n0, a, b.lo);
1.106 + q1 = 0;
1.107 +
1.108 + /* remainder is in n0 >> lsh */
1.109 + } else {
1.110 + /* (q1 q0) = (n1 n0) / (0 d0) */
1.111 +
1.112 + if (b.lo == 0) /* user wants to divide by zero! */
1.113 + b.lo = 1 / b.lo; /* so go ahead and crash */
1.114 +
1.115 + lsh = CountLeadingZeros(b.lo);
1.116 +
1.117 + if (lsh == 0) {
1.118 + /*
1.119 + * From (n1 >= b.lo)
1.120 + * && (the most significant bit of b.lo is set),
1.121 + * conclude that
1.122 + * (the most significant bit of n1 is set)
1.123 + * && (the leading quotient digit q1 = 1).
1.124 + *
1.125 + * This special case is necessary, not an optimization
1.126 + * (Shifts counts of 32 are undefined).
1.127 + */
1.128 + n1 -= b.lo;
1.129 + q1 = 1;
1.130 + } else {
1.131 + /*
1.132 + * Normalize.
1.133 + */
1.134 + rsh = 32 - lsh;
1.135 +
1.136 + b.lo = b.lo << lsh;
1.137 + n2 = n1 >> rsh;
1.138 + n1 = (n1 << lsh) | (n0 >> rsh);
1.139 + n0 = n0 << lsh;
1.140 +
1.141 + a.lo = n1, a.hi = n2;
1.142 + norm_udivmod32(&q1, &n1, a, b.lo);
1.143 + }
1.144 +
1.145 + /* n1 != b.lo... */
1.146 +
1.147 + a.lo = n0, a.hi = n1;
1.148 + norm_udivmod32(&q0, &n0, a, b.lo);
1.149 +
1.150 + /* remainder in n0 >> lsh */
1.151 + }
1.152 +
1.153 + if (rp) {
1.154 + rp->lo = n0 >> lsh;
1.155 + rp->hi = 0;
1.156 + }
1.157 + } else {
1.158 + if (b.hi > n1) {
1.159 + /* (0 0) = (n1 n0) / (D1 d0) */
1.160 +
1.161 + q0 = 0;
1.162 + q1 = 0;
1.163 +
1.164 + /* remainder in (n1 n0) */
1.165 + if (rp) {
1.166 + rp->lo = n0;
1.167 + rp->hi = n1;
1.168 + }
1.169 + } else {
1.170 + /* (0 q0) = (n1 n0) / (d1 d0) */
1.171 +
1.172 + lsh = CountLeadingZeros(b.hi);
1.173 + if (lsh == 0) {
1.174 + /*
1.175 + * From (n1 >= b.hi)
1.176 + * && (the most significant bit of b.hi is set),
1.177 + * conclude that
1.178 + * (the most significant bit of n1 is set)
1.179 + * && (the quotient digit q0 = 0 or 1).
1.180 + *
1.181 + * This special case is necessary, not an optimization.
1.182 + */
1.183 +
1.184 + /*
1.185 + * The condition on the next line takes advantage of that
1.186 + * n1 >= b.hi (true due to control flow).
1.187 + */
1.188 + if (n1 > b.hi || n0 >= b.lo) {
1.189 + q0 = 1;
1.190 + a.lo = n0, a.hi = n1;
1.191 + LL_SUB(a, a, b);
1.192 + } else {
1.193 + q0 = 0;
1.194 + }
1.195 + q1 = 0;
1.196 +
1.197 + if (rp) {
1.198 + rp->lo = n0;
1.199 + rp->hi = n1;
1.200 + }
1.201 + } else {
1.202 + PRInt64 m;
1.203 +
1.204 + /*
1.205 + * Normalize.
1.206 + */
1.207 + rsh = 32 - lsh;
1.208 +
1.209 + b.hi = (b.hi << lsh) | (b.lo >> rsh);
1.210 + b.lo = b.lo << lsh;
1.211 + n2 = n1 >> rsh;
1.212 + n1 = (n1 << lsh) | (n0 >> rsh);
1.213 + n0 = n0 << lsh;
1.214 +
1.215 + a.lo = n1, a.hi = n2;
1.216 + norm_udivmod32(&q0, &n1, a, b.hi);
1.217 + LL_MUL32(m, q0, b.lo);
1.218 +
1.219 + if ((m.hi > n1) || ((m.hi == n1) && (m.lo > n0))) {
1.220 + q0--;
1.221 + LL_SUB(m, m, b);
1.222 + }
1.223 +
1.224 + q1 = 0;
1.225 +
1.226 + /* Remainder is ((n1 n0) - (m1 m0)) >> lsh */
1.227 + if (rp) {
1.228 + a.lo = n0, a.hi = n1;
1.229 + LL_SUB(a, a, m);
1.230 + rp->lo = (a.hi << rsh) | (a.lo >> lsh);
1.231 + rp->hi = a.hi >> lsh;
1.232 + }
1.233 + }
1.234 + }
1.235 + }
1.236 +
1.237 + if (qp) {
1.238 + qp->lo = q0;
1.239 + qp->hi = q1;
1.240 + }
1.241 +}
1.242 +#endif /* !HAVE_LONG_LONG */
