LCOV - app.info - nsprpub/pr/src/misc/prlong.c

LCOV - code coverage report
| Current view: | directory - nsprpub/pr/src/misc - prlong.c (source / functions) |  | Found | Hit | Coverage |
| Test: | app.info | Lines: | 4 | 0 | 0.0 %
| Date: | 2012-04-07 | Functions: | 4 | 0 | 0.0 %

           1                 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
           2                 : /* ***** BEGIN LICENSE BLOCK *****
           3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
           4                 :  *
           5                 :  * The contents of this file are subject to the Mozilla Public License Version
           6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
           7                 :  * the License. You may obtain a copy of the License at
           8                 :  * http://www.mozilla.org/MPL/
           9                 :  *
          10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
          11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
          12                 :  * for the specific language governing rights and limitations under the
          13                 :  * License.
          14                 :  *
          15                 :  * The Original Code is the Netscape Portable Runtime (NSPR).
          16                 :  *
          17                 :  * The Initial Developer of the Original Code is
          18                 :  * Netscape Communications Corporation.
          19                 :  * Portions created by the Initial Developer are Copyright (C) 1998-2000
          20                 :  * the Initial Developer. All Rights Reserved.
          21                 :  *
          22                 :  * Contributor(s):
          23                 :  *
          24                 :  * Alternatively, the contents of this file may be used under the terms of
          25                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
          26                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
          27                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
          28                 :  * of those above. If you wish to allow use of your version of this file only
          29                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
          30                 :  * use your version of this file under the terms of the MPL, indicate your
          31                 :  * decision by deleting the provisions above and replace them with the notice
          32                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
          33                 :  * the provisions above, a recipient may use your version of this file under
          34                 :  * the terms of any one of the MPL, the GPL or the LGPL.
          35                 :  *
          36                 :  * ***** END LICENSE BLOCK ***** */
          37                 :
          38                 : #include "primpl.h"
          39                 :
          40                 : static PRInt64 ll_zero = LL_INIT( 0x00000000,0x00000000 );
          41                 : static PRInt64 ll_maxint = LL_INIT( 0x7fffffff, 0xffffffff );
          42                 : static PRInt64 ll_minint = LL_INIT( 0x80000000, 0x00000000 );
          43                 : static PRUint64 ll_maxuint = LL_INIT( 0xffffffff, 0xffffffff );
          44                 :
          45               0 : PR_IMPLEMENT(PRInt64) LL_Zero(void) { return ll_zero; }
          46               0 : PR_IMPLEMENT(PRInt64) LL_MaxInt(void) { return ll_maxint; }
          47               0 : PR_IMPLEMENT(PRInt64) LL_MinInt(void) { return ll_minint; }
          48               0 : PR_IMPLEMENT(PRUint64) LL_MaxUint(void) { return ll_maxuint; }
          49                 :
          50                 : #ifndef HAVE_LONG_LONG
          51                 : /*
          52                 : ** Divide 64-bit a by 32-bit b, which must be normalized so its high bit is 1.
          53                 : */
          54                 : static void norm_udivmod32(PRUint32 *qp, PRUint32 *rp, PRUint64 a, PRUint32 b)
          55                 : {
          56                 :     PRUint32 d1, d0, q1, q0;
          57                 :     PRUint32 r1, r0, m;
          58                 :
          59                 :     d1 = _hi16(b);
          60                 :     d0 = _lo16(b);
          61                 :     r1 = a.hi % d1;
          62                 :     q1 = a.hi / d1;
          63                 :     m = q1 * d0;
          64                 :     r1 = (r1 << 16) | _hi16(a.lo);
          65                 :     if (r1 < m) {
          66                 :         q1--, r1 += b;
          67                 :         if (r1 >= b  /* i.e., we didn't get a carry when adding to r1 */
          68                 :             && r1 < m) {
          69                 :             q1--, r1 += b;
          70                 :         }
          71                 :     }
          72                 :     r1 -= m;
          73                 :     r0 = r1 % d1;
          74                 :     q0 = r1 / d1;
          75                 :     m = q0 * d0;
          76                 :     r0 = (r0 << 16) | _lo16(a.lo);
          77                 :     if (r0 < m) {
          78                 :         q0--, r0 += b;
          79                 :         if (r0 >= b
          80                 :             && r0 < m) {
          81                 :             q0--, r0 += b;
          82                 :         }
          83                 :     }
          84                 :     *qp = (q1 << 16) | q0;
          85                 :     *rp = r0 - m;
          86                 : }
          87                 :
          88                 : static PRUint32 CountLeadingZeros(PRUint32 a)
          89                 : {
          90                 :     PRUint32 t;
          91                 :     PRUint32 r = 32;
          92                 :
          93                 :     if ((t = a >> 16) != 0)
          94                 :         r -= 16, a = t;
          95                 :     if ((t = a >> 8) != 0)
          96                 :         r -= 8, a = t;
          97                 :     if ((t = a >> 4) != 0)
          98                 :         r -= 4, a = t;
          99                 :     if ((t = a >> 2) != 0)
         100                 :         r -= 2, a = t;
         101                 :     if ((t = a >> 1) != 0)
         102                 :         r -= 1, a = t;
         103                 :     if (a & 1)
         104                 :         r--;
         105                 :     return r;
         106                 : }
         107                 :
         108                 : PR_IMPLEMENT(void) ll_udivmod(PRUint64 *qp, PRUint64 *rp, PRUint64 a, PRUint64 b)
         109                 : {
         110                 :     PRUint32 n0, n1, n2;
         111                 :     PRUint32 q0, q1;
         112                 :     PRUint32 rsh, lsh;
         113                 :
         114                 :     n0 = a.lo;
         115                 :     n1 = a.hi;
         116                 :
         117                 :     if (b.hi == 0) {
         118                 :         if (b.lo > n1) {
         119                 :             /* (0 q0) = (n1 n0) / (0 D0) */
         120                 :
         121                 :             lsh = CountLeadingZeros(b.lo);
         122                 :
         123                 :             if (lsh) {
         124                 :                 /*
         125                 :                  * Normalize, i.e. make the most significant bit of the
         126                 :                  * denominator be set.
         127                 :                  */
         128                 :                 b.lo = b.lo << lsh;
         129                 :                 n1 = (n1 << lsh) | (n0 >> (32 - lsh));
         130                 :                 n0 = n0 << lsh;
         131                 :             }
         132                 :
         133                 :             a.lo = n0, a.hi = n1;
         134                 :             norm_udivmod32(&q0, &n0, a, b.lo);
         135                 :             q1 = 0;
         136                 :
         137                 :             /* remainder is in n0 >> lsh */
         138                 :         } else {
         139                 :             /* (q1 q0) = (n1 n0) / (0 d0) */
         140                 :
         141                 :             if (b.lo == 0)              /* user wants to divide by zero! */
         142                 :                 b.lo = 1 / b.lo;        /* so go ahead and crash */
         143                 :
         144                 :             lsh = CountLeadingZeros(b.lo);
         145                 :
         146                 :             if (lsh == 0) {
         147                 :                 /*
         148                 :                  * From (n1 >= b.lo)
         149                 :                  *   && (the most significant bit of b.lo is set),
         150                 :                  * conclude that
         151                 :                  *      (the most significant bit of n1 is set)
         152                 :                  *   && (the leading quotient digit q1 = 1).
         153                 :                  *
         154                 :                  * This special case is necessary, not an optimization
         155                 :                  * (Shifts counts of 32 are undefined).
         156                 :                  */
         157                 :                 n1 -= b.lo;
         158                 :                 q1 = 1;
         159                 :             } else {
         160                 :                 /*
         161                 :                  * Normalize.
         162                 :                  */
         163                 :                 rsh = 32 - lsh;
         164                 :
         165                 :                 b.lo = b.lo << lsh;
         166                 :                 n2 = n1 >> rsh;
         167                 :                 n1 = (n1 << lsh) | (n0 >> rsh);
         168                 :                 n0 = n0 << lsh;
         169                 :
         170                 :                 a.lo = n1, a.hi = n2;
         171                 :                 norm_udivmod32(&q1, &n1, a, b.lo);
         172                 :             }
         173                 :
         174                 :             /* n1 != b.lo... */
         175                 :
         176                 :             a.lo = n0, a.hi = n1;
         177                 :             norm_udivmod32(&q0, &n0, a, b.lo);
         178                 :
         179                 :             /* remainder in n0 >> lsh */
         180                 :         }
         181                 :
         182                 :         if (rp) {
         183                 :             rp->lo = n0 >> lsh;
         184                 :             rp->hi = 0;
         185                 :         }
         186                 :     } else {
         187                 :         if (b.hi > n1) {
         188                 :             /* (0 0) = (n1 n0) / (D1 d0) */
         189                 :
         190                 :             q0 = 0;
         191                 :             q1 = 0;
         192                 :
         193                 :             /* remainder in (n1 n0) */
         194                 :             if (rp) {
         195                 :                 rp->lo = n0;
         196                 :                 rp->hi = n1;
         197                 :             }
         198                 :         } else {
         199                 :             /* (0 q0) = (n1 n0) / (d1 d0) */
         200                 :
         201                 :             lsh = CountLeadingZeros(b.hi);
         202                 :             if (lsh == 0) {
         203                 :                 /*
         204                 :                  * From (n1 >= b.hi)
         205                 :                  *   && (the most significant bit of b.hi is set),
         206                 :                  * conclude that
         207                 :                  *      (the most significant bit of n1 is set)
         208                 :                  *   && (the quotient digit q0 = 0 or 1).
         209                 :                  *
         210                 :                  * This special case is necessary, not an optimization.
         211                 :                  */
         212                 :
         213                 :                 /*
         214                 :                  * The condition on the next line takes advantage of that
         215                 :                  * n1 >= b.hi (true due to control flow).
         216                 :                  */
         217                 :                 if (n1 > b.hi || n0 >= b.lo) {
         218                 :                     q0 = 1;
         219                 :                     a.lo = n0, a.hi = n1;
         220                 :                     LL_SUB(a, a, b);
         221                 :                 } else {
         222                 :                     q0 = 0;
         223                 :                 }
         224                 :                 q1 = 0;
         225                 :
         226                 :                 if (rp) {
         227                 :                     rp->lo = n0;
         228                 :                     rp->hi = n1;
         229                 :                 }
         230                 :             } else {
         231                 :                 PRInt64 m;
         232                 :
         233                 :                 /*
         234                 :                  * Normalize.
         235                 :                  */
         236                 :                 rsh = 32 - lsh;
         237                 :
         238                 :                 b.hi = (b.hi << lsh) | (b.lo >> rsh);
         239                 :                 b.lo = b.lo << lsh;
         240                 :                 n2 = n1 >> rsh;
         241                 :                 n1 = (n1 << lsh) | (n0 >> rsh);
         242                 :                 n0 = n0 << lsh;
         243                 :
         244                 :                 a.lo = n1, a.hi = n2;
         245                 :                 norm_udivmod32(&q0, &n1, a, b.hi);
         246                 :                 LL_MUL32(m, q0, b.lo);
         247                 :
         248                 :                 if ((m.hi > n1) || ((m.hi == n1) && (m.lo > n0))) {
         249                 :                     q0--;
         250                 :                     LL_SUB(m, m, b);
         251                 :                 }
         252                 :
         253                 :                 q1 = 0;
         254                 :
         255                 :                 /* Remainder is ((n1 n0) - (m1 m0)) >> lsh */
         256                 :                 if (rp) {
         257                 :                     a.lo = n0, a.hi = n1;
         258                 :                     LL_SUB(a, a, m);
         259                 :                     rp->lo = (a.hi << rsh) | (a.lo >> lsh);
         260                 :                     rp->hi = a.hi >> lsh;
         261                 :                 }
         262                 :             }
         263                 :         }
         264                 :     }
         265                 :
         266                 :     if (qp) {
         267                 :         qp->lo = q0;
         268                 :         qp->hi = q1;
         269                 :     }
         270                 : }
         271                 : #endif /* !HAVE_LONG_LONG */

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