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56 lines
1.8 KiB
C
56 lines
1.8 KiB
C
/*-------------------------------------------------------------------------
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_modulong.c - routine for modulus of 32 bit unsigned long
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Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
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Bug fixes by Martijn van Balen, aed@iae.nl
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This library is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this library; see the file COPYING. If not, write to the
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Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA.
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As a special exception, if you link this library with other files,
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some of which are compiled with SDCC, to produce an executable,
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this library does not by itself cause the resulting executable to
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be covered by the GNU General Public License. This exception does
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not however invalidate any other reasons why the executable file
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might be covered by the GNU General Public License.
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-------------------------------------------------------------------------*/
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#define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)
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unsigned long _modulong (unsigned long a, unsigned long b)
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{
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unsigned char count = 0;
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while (!MSB_SET(b))
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{
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b <<= 1;
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if (b > a)
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{
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b >>=1;
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break;
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}
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count++;
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}
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do
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{
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if (a >= b)
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a -= b;
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b >>= 1;
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}
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while (count--);
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return a;
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}
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