libgcc/multi3.c

   1 /* muldi3.c extracted from gcc-2.7.2.3/libgcc2.c and
   2                            gcc-2.7.2.3/longlong.h which is: */
   3 /* Copyright (C) 1989, 1992, 1993, 1994, 1995 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, 51 Franklin St, Fifth Floor, Boston,
  20 MA 02110-1301, USA. */
  21
  22 #include "libgcc.h"
  23
  24 #define BITS_PER_UNIT 8
  25 #define DI_TYPE_SIZE 64
  26
  27 #define __BITS4 (DI_TYPE_SIZE / 4)
  28 #define __ll_B (1L << (DI_TYPE_SIZE / 2))
  29 #define __ll_lowpart(t) ((UDItype) (t) % __ll_B)
  30 #define __ll_highpart(t) ((UDItype) (t) / __ll_B)
  31
  32 #define umul_ppmm(w1, w0, u, v)                                         \
  33   do {                                                                  \
  34     UDItype __x0, __x1, __x2, __x3;                                     \
  35     UDItype __ul, __vl, __uh, __vh;                                     \
  36                                                                         \
  37     __ul = __ll_lowpart (u);                                            \
  38     __uh = __ll_highpart (u);                                           \
  39     __vl = __ll_lowpart (v);                                            \
  40     __vh = __ll_highpart (v);                                           \
  41                                                                         \
  42     __x0 = (UDItype) __ul * __vl;                                       \
  43     __x1 = (UDItype) __ul * __vh;                                       \
  44     __x2 = (UDItype) __uh * __vl;                                       \
  45     __x3 = (UDItype) __uh * __vh;                                       \
  46                                                                         \
  47     __x1 += __ll_highpart (__x0);/* this can't give carry */            \
  48     __x1 += __x2;               /* but this indeed can */               \
  49     if (__x1 < __x2)            /* did we get it? */                    \
  50       __x3 += __ll_B;           /* yes, add it in the proper pos. */    \
  51                                                                         \
  52     (w1) = __x3 + __ll_highpart (__x1);                                 \
  53     (w0) = __ll_lowpart (__x1) * __ll_B + __ll_lowpart (__x0);          \
  54   } while (0)
  55
  56 #define __umulsidi3(u, v) \
  57   ({TIunion __w;                                                        \
  58     umul_ppmm (__w.s.high, __w.s.low, u, v);                            \
  59     __w.ll; })
  60
  61 struct TIstruct {DItype high, low;};
  62
  63 typedef union
  64 {
  65   struct TIstruct s;
  66   TItype ll;
  67 } TIunion;
  68
  69 TItype
  70 __multi3 (TItype u, TItype v)
  71 {
  72   TIunion w;
  73   TIunion uu, vv;
  74
  75   uu.ll = u,
  76   vv.ll = v;
  77
  78   w.ll = __umulsidi3 (uu.s.low, vv.s.low);
  79   w.s.high += ((UDItype) uu.s.low * (UDItype) vv.s.high
  80                + (UDItype) uu.s.high * (UDItype) vv.s.low);
  81
  82   return w.ll;
  83 }