Mercurial > dropbear
annotate bn_mp_radix_size.c @ 201:c0bf626ee437 libtommath
Bringing back the original ltc 0.35 makefile
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Wed, 11 May 2005 16:23:24 +0000 |
| parents | d8254fc979e9 |
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| rev | line source |
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| 142 | 1 #include <tommath.h> |
| 2 #ifdef BN_MP_RADIX_SIZE_C | |
| 2 | 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
| 4 * | |
| 5 * LibTomMath is a library that provides multiple-precision | |
| 6 * integer arithmetic as well as number theoretic functionality. | |
| 7 * | |
| 8 * The library was designed directly after the MPI library by | |
| 9 * Michael Fromberger but has been written from scratch with | |
| 10 * additional optimizations in place. | |
| 11 * | |
| 12 * The library is free for all purposes without any express | |
| 13 * guarantee it works. | |
| 14 * | |
| 15 * Tom St Denis, [email protected], http://math.libtomcrypt.org | |
| 16 */ | |
| 17 | |
| 18 /* returns size of ASCII reprensentation */ | |
| 19 int mp_radix_size (mp_int * a, int radix, int *size) | |
| 20 { | |
| 21 int res, digs; | |
| 22 mp_int t; | |
| 23 mp_digit d; | |
| 24 | |
| 25 *size = 0; | |
| 26 | |
| 27 /* special case for binary */ | |
| 28 if (radix == 2) { | |
| 29 *size = mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1; | |
| 30 return MP_OKAY; | |
| 31 } | |
| 32 | |
| 33 /* make sure the radix is in range */ | |
| 34 if (radix < 2 || radix > 64) { | |
| 35 return MP_VAL; | |
| 36 } | |
| 37 | |
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38 if (mp_iszero(a) == MP_YES) { |
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39 *size = 2; |
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40 return MP_OKAY; |
| 2 | 41 } |
| 42 | |
| 43 /* digs is the digit count */ | |
| 44 digs = 0; | |
| 45 | |
| 46 /* if it's negative add one for the sign */ | |
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47 if (a->sign == MP_NEG) { |
| 2 | 48 ++digs; |
| 49 } | |
| 50 | |
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51 /* init a copy of the input */ |
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52 if ((res = mp_init_copy (&t, a)) != MP_OKAY) { |
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53 return res; |
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54 } |
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55 |
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56 /* force temp to positive */ |
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57 t.sign = MP_ZPOS; |
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58 |
| 2 | 59 /* fetch out all of the digits */ |
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60 while (mp_iszero (&t) == MP_NO) { |
| 2 | 61 if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) { |
| 62 mp_clear (&t); | |
| 63 return res; | |
| 64 } | |
| 65 ++digs; | |
| 66 } | |
| 67 mp_clear (&t); | |
| 68 | |
| 69 /* return digs + 1, the 1 is for the NULL byte that would be required. */ | |
| 70 *size = digs + 1; | |
| 71 return MP_OKAY; | |
| 72 } | |
| 73 | |
| 142 | 74 #endif |