43 lines
1.1 KiB
C
43 lines
1.1 KiB
C
/* 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://math.libtomcrypt.org
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*/
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#include <tommath.h>
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/* set a 32-bit const */
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int
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mp_set_int (mp_int * a, unsigned int b)
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{
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int x, res;
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mp_zero (a);
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/* set four bits at a time */
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for (x = 0; x < 8; x++) {
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/* shift the number up four bits */
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if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) {
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return res;
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}
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/* OR in the top four bits of the source */
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a->dp[0] |= (b >> 28) & 15;
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/* shift the source up to the next four bits */
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b <<= 4;
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/* ensure that digits are not clamped off */
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a->used += 32 / DIGIT_BIT + 2;
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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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