51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
#include "tommath_private.h"
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#ifdef BN_MP_MUL_SI_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was 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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// multiply bigint a with int d and put the result in c
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// Like mp_mul_d() but with a signed long as the small input
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int mp_mul_si(const mp_int *a, long d, mp_int *c)
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{
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mp_int t;
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int err, neg = 0;
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if ((err = mp_init(&t)) != MP_OKAY) {
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return err;
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}
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if (d < 0) {
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neg = 1;
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d = -d;
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}
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// mp_digit might be smaller than a long, which excludes
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// the use of mp_mul_d() here.
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if ((err = mp_set_int(&t, (unsigned long) d)) != MP_OKAY) {
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goto LBL_MPMULSI_ERR;
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}
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if ((err = mp_mul(a, &t, c)) != MP_OKAY) {
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goto LBL_MPMULSI_ERR;
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}
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if (neg == 1) {
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c->sign = (a->sign == MP_NEG) ? MP_ZPOS: MP_NEG;
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}
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LBL_MPMULSI_ERR:
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mp_clear(&t);
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return err;
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}
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#endif
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