#include "tommath_private.h" #ifdef BN_MP_DIV_D_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * * LibTomMath is a library that provides multiple-precision * integer arithmetic as well as number theoretic functionality. * * The library was designed directly after the MPI library by * Michael Fromberger but has been written from scratch with * additional optimizations in place. * * SPDX-License-Identifier: Unlicense */ /* single digit division (based on routine from MPI) */ int mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d) { mp_int q; mp_word w; mp_digit t; int res, ix; /* cannot divide by zero */ if (b == 0u) { return MP_VAL; } /* quick outs */ if ((b == 1u) || (mp_iszero(a) == MP_YES)) { if (d != NULL) { *d = 0; } if (c != NULL) { return mp_copy(a, c); } return MP_OKAY; } /* power of two ? */ if (((b & (b-1)) == 0)) { for (ix = 1; ix < DIGIT_BIT; ix++) { if (b == (((mp_digit)1)<dp[0] & (((mp_digit)1<<(mp_digit)ix) - 1uL); } if (c != NULL) { return mp_div_2d(a, ix, c, NULL); } return MP_OKAY; } #ifdef BN_MP_DIV_3_C /* three? */ if (b == 3u) { return mp_div_3(a, c, d); } #endif /* no easy answer [c'est la vie]. Just division */ if ((res = mp_init_size(&q, a->used)) != MP_OKAY) { return res; } q.used = a->used; q.sign = a->sign; w = 0; for (ix = a->used - 1; ix >= 0; ix--) { w = (w << (mp_word)DIGIT_BIT) | (mp_word)a->dp[ix]; if (w >= b) { t = (mp_digit)(w / b); w -= (mp_word)t * (mp_word)b; } else { t = 0; } q.dp[ix] = t; } if (d != NULL) { *d = (mp_digit)w; } if (c != NULL) { mp_clamp(&q); mp_exch(&q, c); } mp_clear(&q); return res; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */