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author | Matt Johnston <matt@ucc.asn.au> | 2006-03-08 13:16:18 +0000 |
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committer | Matt Johnston <matt@ucc.asn.au> | 2006-03-08 13:16:18 +0000 |
commit | 1c5fda515f96c27d4e3b732d887f418453f1cb14 (patch) | |
tree | bf90196389a9618de48c5acb5ce1d056aa347ce0 /bn_mp_toradix_n.c | |
download | dropbear-libtommath-0.35.tar.gz |
Import of libtommath 0.35libtommath-0.35
From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c
--HG--
branch : libtommath-orig
extra : convert_revision : 2b4b13ac88b2a81e5c86ba868c92c6a452630e02
Diffstat (limited to 'bn_mp_toradix_n.c')
-rw-r--r-- | bn_mp_toradix_n.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/bn_mp_toradix_n.c b/bn_mp_toradix_n.c new file mode 100644 index 0000000..7d43558 --- /dev/null +++ b/bn_mp_toradix_n.c @@ -0,0 +1,85 @@ +#include <tommath.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. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org + */ + +/* 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(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 < 3 || radix < 2 || radix > 64) { + return MP_VAL; + } + + /* quick out if its zero */ + if (mp_iszero(a) == 1) { + *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) == 0) { + if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) { + mp_clear (&t); + return res; + } + *str++ = mp_s_rmap[d]; + ++digs; + + if (--maxlen == 1) { + /* no more room */ + break; + } + } + + /* 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 |