tommath/bn_mp_set_int.c

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#include <tommath_private.h>
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#ifdef BN_MP_SET_INT_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
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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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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tstdenis82@gmail.com, http://libtom.org
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*/
/* set a 32-bit const */
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int mp_set_int(mp_int *a, unsigned long 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 */
for (x = 0; x < 8; x++) {
/* shift the number up four bits */
if ((res = mp_mul_2d(a, 4, a)) != MP_OKAY) {
return res;
}
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/* OR in the top four bits of the source */
a->dp[0] |= (b >> 28) & 15;
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/* shift the source up to the next four bits */
b <<= 4;
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/* ensure that digits are not clamped off */
a->used += 1;
}
mp_clamp(a);
return MP_OKAY;
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}
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#endif
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/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */