sdcc/device/lib/_modulonglong.c

   1 /*-------------------------------------------------------------------------
   2    _modulonglong.c - routine for modulus of 64 bit unsigned long long
   3
   4    Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
   5    Bug fixes by Martijn van Balen, aed@iae.nl
   6    Copyright (C) 2014, Philipp Klaus Krause . pkk@spth.de
   7
   8    This library is free software; you can redistribute it and/or modify it
   9    under the terms of the GNU General Public License as published by the
  10    Free Software Foundation; either version 2, or (at your option) any
  11    later version.
  12
  13    This library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this library; see the file COPYING. If not, write to the
  20    Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  21    MA 02110-1301, USA.
  22
  23    As a special exception, if you link this library with other files,
  24    some of which are compiled with SDCC, to produce an executable,
  25    this library does not by itself cause the resulting executable to
  26    be covered by the GNU General Public License. This exception does
  27    not however invalidate any other reasons why the executable file
  28    might be covered by the GNU General Public License.
  29 -------------------------------------------------------------------------*/
  30
  31 #include <stdint.h>
  32
  33 #include <sdcc-lib.h>
  34
  35 #ifdef __SDCC_LONGLONG
  36
  37 #define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)
  38
  39 unsigned long long
  40 _modulonglong (unsigned long long a, unsigned long long b) __SDCC_NONBANKED
  41 {
  42   unsigned char count = 0;
  43
  44   while (!MSB_SET(b))
  45   {
  46      b <<= 1;
  47      if (b > a)
  48      {
  49         b >>=1;
  50         break;
  51      }
  52      count++;
  53   }
  54   do
  55   {
  56     if (a >= b)
  57       a -= b;
  58     b >>= 1;
  59   }
  60   while (count--);
  61
  62   return a;
  63 }
  64 #endif
  65