47 lines
1.1 KiB
C
47 lines
1.1 KiB
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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/* shift left a certain amount of digits */
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int
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mp_lshd (mp_int * a, int b)
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{
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int x, res;
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/* if its less than zero return */
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if (b <= 0) {
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return MP_OKAY;
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}
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/* grow to fit the new digits */
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if ((res = mp_grow (a, a->used + b)) != MP_OKAY) {
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return res;
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}
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/* increment the used by the shift amount than copy upwards */
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a->used += b;
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for (x = a->used - 1; x >= b; x--) {
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a->dp[x] = a->dp[x - b];
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}
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/* zero the lower digits */
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for (x = 0; x < b; x++) {
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a->dp[x] = 0;
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}
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mp_clamp (a);
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return MP_OKAY;
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}
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