arch/arm/lib/udivdi3.c

   1 /* More subroutines needed by GCC output code on some machines.  */
   2 /* Compile this one with gcc.  */
   3 /* Copyright (C) 1989, 92-98, 1999 Free Software Foundation, Inc.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 /* As a special exception, if you link this library with other files,
  23    some of which are compiled with GCC, to produce an executable,
  24    this library does not by itself cause the resulting executable
  25    to be covered by the GNU General Public License.
  26    This exception does not however invalidate any other reasons why
  27    the executable file might be covered by the GNU General Public License.
  28  */
  29 /* support functions required by the kernel. based on code from gcc-2.95.3 */
  30 /* I Molton     29/07/01 */
  31
  32 #include "gcclib.h"
  33 #include "longlong.h"
  34
  35 static const u8 __clz_tab[] = {
  36         0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5,
  37             5, 5, 5, 5, 5, 5, 5, 5,
  38         6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
  39             6, 6, 6, 6, 6, 6, 6, 6,
  40         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
  41             7, 7, 7, 7, 7, 7, 7, 7,
  42         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
  43             7, 7, 7, 7, 7, 7, 7, 7,
  44         8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
  45             8, 8, 8, 8, 8, 8, 8, 8,
  46         8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
  47             8, 8, 8, 8, 8, 8, 8, 8,
  48         8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
  49             8, 8, 8, 8, 8, 8, 8, 8,
  50         8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
  51             8, 8, 8, 8, 8, 8, 8, 8,
  52 };
  53
  54 u64 __udivmoddi4(u64 n, u64 d, u64 * rp)
  55 {
  56         DIunion ww;
  57         DIunion nn, dd;
  58         DIunion rr;
  59         u32 d0, d1, n0, n1, n2;
  60         u32 q0, q1;
  61         u32 b, bm;
  62
  63         nn.ll = n;
  64         dd.ll = d;
  65
  66         d0 = dd.s.low;
  67         d1 = dd.s.high;
  68         n0 = nn.s.low;
  69         n1 = nn.s.high;
  70
  71         if (d1 == 0) {
  72                 if (d0 > n1) {
  73                         /* 0q = nn / 0D */
  74
  75                         count_leading_zeros(bm, d0);
  76
  77                         if (bm != 0) {
  78                                 /* Normalize, i.e. make the most significant bit of the
  79                                    denominator set.  */
  80
  81                                 d0 = d0 << bm;
  82                                 n1 = (n1 << bm) | (n0 >> (SI_TYPE_SIZE - bm));
  83                                 n0 = n0 << bm;
  84                         }
  85
  86                         udiv_qrnnd(q0, n0, n1, n0, d0);
  87                         q1 = 0;
  88
  89                         /* Remainder in n0 >> bm.  */
  90                 } else {
  91                         /* qq = NN / 0d */
  92
  93                         if (d0 == 0)
  94                                 d0 = 1 / d0;    /* Divide intentionally by zero.  */
  95
  96                         count_leading_zeros(bm, d0);
  97
  98                         if (bm == 0) {
  99                                 /* From (n1 >= d0) /\ (the most significant bit of d0 is set),
 100                                    conclude (the most significant bit of n1 is set) /\ (the
 101                                    leading quotient digit q1 = 1).
 102
 103                                    This special case is necessary, not an optimization.
 104                                    (Shifts counts of SI_TYPE_SIZE are undefined.)  */
 105
 106                                 n1 -= d0;
 107                                 q1 = 1;
 108                         } else {
 109                                 /* Normalize.  */
 110
 111                                 b = SI_TYPE_SIZE - bm;
 112
 113                                 d0 = d0 << bm;
 114                                 n2 = n1 >> b;
 115                                 n1 = (n1 << bm) | (n0 >> b);
 116                                 n0 = n0 << bm;
 117
 118                                 udiv_qrnnd(q1, n1, n2, n1, d0);
 119                         }
 120
 121                         /* n1 != d0...  */
 122
 123                         udiv_qrnnd(q0, n0, n1, n0, d0);
 124
 125                         /* Remainder in n0 >> bm.  */
 126                 }
 127
 128                 if (rp != 0) {
 129                         rr.s.low = n0 >> bm;
 130                         rr.s.high = 0;
 131                         *rp = rr.ll;
 132                 }
 133         } else {
 134                 if (d1 > n1) {
 135                         /* 00 = nn / DD */
 136
 137                         q0 = 0;
 138                         q1 = 0;
 139
 140                         /* Remainder in n1n0.  */
 141                         if (rp != 0) {
 142                                 rr.s.low = n0;
 143                                 rr.s.high = n1;
 144                                 *rp = rr.ll;
 145                         }
 146                 } else {
 147                         /* 0q = NN / dd */
 148
 149                         count_leading_zeros(bm, d1);
 150                         if (bm == 0) {
 151                                 /* From (n1 >= d1) /\ (the most significant bit of d1 is set),
 152                                    conclude (the most significant bit of n1 is set) /\ (the
 153                                    quotient digit q0 = 0 or 1).
 154
 155                                    This special case is necessary, not an optimization.  */
 156
 157                                 /* The condition on the next line takes advantage of that
 158                                    n1 >= d1 (true due to program flow).  */
 159                                 if (n1 > d1 || n0 >= d0) {
 160                                         q0 = 1;
 161                                         sub_ddmmss(n1, n0, n1, n0, d1, d0);
 162                                 } else
 163                                         q0 = 0;
 164
 165                                 q1 = 0;
 166
 167                                 if (rp != 0) {
 168                                         rr.s.low = n0;
 169                                         rr.s.high = n1;
 170                                         *rp = rr.ll;
 171                                 }
 172                         } else {
 173                                 u32 m1, m0;
 174                                 /* Normalize.  */
 175
 176                                 b = SI_TYPE_SIZE - bm;
 177
 178                                 d1 = (d1 << bm) | (d0 >> b);
 179                                 d0 = d0 << bm;
 180                                 n2 = n1 >> b;
 181                                 n1 = (n1 << bm) | (n0 >> b);
 182                                 n0 = n0 << bm;
 183
 184                                 udiv_qrnnd(q0, n1, n2, n1, d1);
 185                                 umul_ppmm(m1, m0, q0, d0);
 186
 187                                 if (m1 > n1 || (m1 == n1 && m0 > n0)) {
 188                                         q0--;
 189                                         sub_ddmmss(m1, m0, m1, m0, d1, d0);
 190                                 }
 191
 192                                 q1 = 0;
 193
 194                                 /* Remainder in (n1n0 - m1m0) >> bm.  */
 195                                 if (rp != 0) {
 196                                         sub_ddmmss(n1, n0, n1, n0, m1, m0);
 197                                         rr.s.low = (n1 << b) | (n0 >> bm);
 198                                         rr.s.high = n1 >> bm;
 199                                         *rp = rr.ll;
 200                                 }
 201                         }
 202                 }
 203         }
 204
 205         ww.s.low = q0;
 206         ww.s.high = q1;
 207         return ww.ll;
 208 }
 209
 210 u64 __udivdi3(u64 n, u64 d)
 211 {
 212         return __udivmoddi4(n, d, (u64 *) 0);
 213 }
 214
 215 u64 __umoddi3(u64 u, u64 v)
 216 {
 217         u64 w;
 218
 219         (void)__udivmoddi4(u, v, &w);
 220
 221         return w;
 222 }