Mercurial > dropbear
annotate bn_mp_read_radix.c @ 190:d8254fc979e9 libtommath-orig LTM_0.35
Initial import of libtommath 0.35
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Fri, 06 May 2005 08:59:30 +0000 |
| parents | d29b64170cf0 |
| children |
| rev | line source |
|---|---|
| 142 | 1 #include <tommath.h> |
| 2 #ifdef BN_MP_READ_RADIX_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 /* read a string [ASCII] in a given radix */ | |
|
190
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
19 int mp_read_radix (mp_int * a, const char *str, int radix) |
| 2 | 20 { |
| 21 int y, res, neg; | |
| 22 char ch; | |
| 23 | |
| 24 /* make sure the radix is ok */ | |
| 25 if (radix < 2 || radix > 64) { | |
| 26 return MP_VAL; | |
| 27 } | |
| 28 | |
| 29 /* if the leading digit is a | |
| 30 * minus set the sign to negative. | |
| 31 */ | |
| 32 if (*str == '-') { | |
| 33 ++str; | |
| 34 neg = MP_NEG; | |
| 35 } else { | |
| 36 neg = MP_ZPOS; | |
| 37 } | |
| 38 | |
| 39 /* set the integer to the default of zero */ | |
| 40 mp_zero (a); | |
| 41 | |
| 42 /* process each digit of the string */ | |
| 43 while (*str) { | |
| 44 /* if the radix < 36 the conversion is case insensitive | |
| 45 * this allows numbers like 1AB and 1ab to represent the same value | |
| 46 * [e.g. in hex] | |
| 47 */ | |
| 48 ch = (char) ((radix < 36) ? toupper (*str) : *str); | |
| 49 for (y = 0; y < 64; y++) { | |
| 50 if (ch == mp_s_rmap[y]) { | |
| 51 break; | |
| 52 } | |
| 53 } | |
| 54 | |
| 55 /* if the char was found in the map | |
| 56 * and is less than the given radix add it | |
| 57 * to the number, otherwise exit the loop. | |
| 58 */ | |
| 59 if (y < radix) { | |
| 60 if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) { | |
| 61 return res; | |
| 62 } | |
| 63 if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) { | |
| 64 return res; | |
| 65 } | |
| 66 } else { | |
| 67 break; | |
| 68 } | |
| 69 ++str; | |
| 70 } | |
| 71 | |
| 72 /* set the sign only if a != 0 */ | |
| 73 if (mp_iszero(a) != 1) { | |
| 74 a->sign = neg; | |
| 75 } | |
| 76 return MP_OKAY; | |
| 77 } | |
| 142 | 78 #endif |