43 lines
886 B
C
43 lines
886 B
C
/* LibTomPoly, Polynomial Basis Math -- Tom St Denis
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*
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* LibTomPoly is a public domain library that provides
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* polynomial basis arithmetic support. It relies on
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* LibTomMath for large integer support.
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*
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* This library is free for all purposes without any
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* express guarantee that it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
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*/
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#include <tompoly.h>
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int pb_lshd(pb_poly *a, int x)
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{
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int err, y;
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if (x <= 0) {
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return MP_OKAY;
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}
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/* grow as required */
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if (a->alloc < (a->used + x)) {
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if ((err = pb_grow(a, a->used + x)) != MP_OKAY) {
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return err;
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}
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}
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/* shift */
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for (y = a->used + x; y >= x; y--) {
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mp_exch(&(a->terms[y-x]), &(a->terms[y]));
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}
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/* zero lower digits */
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for (y = 0; y < x; y++) {
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mp_zero(&(a->terms[y]));
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}
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a->used += x;
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return MP_OKAY;
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}
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