Mercurial > dropbear
view libtommath/bn_mp_toradix_n.c @ 1664:871484eac157
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 14 Mar 2020 23:33:30 +0800 |
parents | f52919ffd3b1 |
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#include "tommath_private.h" #ifdef BN_MP_TORADIX_N_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 */ /* stores a bignum as a ASCII string in a given radix (2..64) * * Stores upto maxlen-1 chars and always a NULL byte */ int mp_toradix_n(const mp_int *a, char *str, int radix, int maxlen) { int res, digs; mp_int t; mp_digit d; char *_s = str; /* check range of the maxlen, radix */ if ((maxlen < 2) || (radix < 2) || (radix > 64)) { return MP_VAL; } /* quick out if its zero */ if (mp_iszero(a) == MP_YES) { *str++ = '0'; *str = '\0'; return MP_OKAY; } if ((res = mp_init_copy(&t, a)) != MP_OKAY) { return res; } /* if it is negative output a - */ if (t.sign == MP_NEG) { /* we have to reverse our digits later... but not the - sign!! */ ++_s; /* store the flag and mark the number as positive */ *str++ = '-'; t.sign = MP_ZPOS; /* subtract a char */ --maxlen; } digs = 0; while (mp_iszero(&t) == MP_NO) { if (--maxlen < 1) { /* no more room */ break; } if ((res = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) { mp_clear(&t); return res; } *str++ = mp_s_rmap[d]; ++digs; } /* reverse the digits of the string. In this case _s points * to the first digit [exluding the sign] of the number */ bn_reverse((unsigned char *)_s, digs); /* append a NULL so the string is properly terminated */ *str = '\0'; mp_clear(&t); return MP_OKAY; } #endif /* ref: HEAD -> master, tag: v1.1.0 */ /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ /* commit time: 2019-01-28 20:32:32 +0100 */