37 lines
867 B
C
37 lines
867 B
C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is library that provides for multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library is designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://libtommath.iahu.ca
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*/
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#include <tommath.h>
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/* d = a - b (mod c) */
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int
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mp_submod (mp_int * a, mp_int * b, mp_int * c, mp_int * d)
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{
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int res;
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mp_int t;
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if ((res = mp_init (&t)) != MP_OKAY) {
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return res;
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}
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if ((res = mp_sub (a, b, &t)) != MP_OKAY) {
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mp_clear (&t);
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return res;
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}
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res = mp_mod (&t, c, d);
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mp_clear (&t);
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return res;
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}
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