diff options
Diffstat (limited to 'libtommath/bn_mp_div_3.c')
-rw-r--r-- | libtommath/bn_mp_div_3.c | 95 |
1 files changed, 48 insertions, 47 deletions
diff --git a/libtommath/bn_mp_div_3.c b/libtommath/bn_mp_div_3.c index 79a9816..c5ca137 100644 --- a/libtommath/bn_mp_div_3.c +++ b/libtommath/bn_mp_div_3.c @@ -1,4 +1,4 @@ -#include <tommath.h> +#include "tommath_private.h" #ifdef BN_MP_DIV_3_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * @@ -11,65 +11,66 @@ * * The library is free for all purposes without any express * guarantee it works. - * - * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com */ /* divide by three (based on routine from MPI and the GMP manual) */ -int -mp_div_3 (mp_int * a, mp_int *c, mp_digit * d) +int mp_div_3(const mp_int *a, mp_int *c, mp_digit *d) { - mp_int q; - mp_word w, t; - mp_digit b; - int res, ix; - - /* b = 2**DIGIT_BIT / 3 */ - b = (((mp_word)1) << ((mp_word)DIGIT_BIT)) / ((mp_word)3); + mp_int q; + mp_word w, t; + mp_digit b; + int res, ix; + + /* b = 2**DIGIT_BIT / 3 */ + b = ((mp_word)1 << (mp_word)DIGIT_BIT) / (mp_word)3; + + if ((res = mp_init_size(&q, a->used)) != MP_OKAY) { + return res; + } - 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]); + 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 >= 3) { - /* multiply w by [1/3] */ - t = (w * ((mp_word)b)) >> ((mp_word)DIGIT_BIT); + if (w >= 3u) { + /* multiply w by [1/3] */ + t = (w * (mp_word)b) >> (mp_word)DIGIT_BIT; - /* now subtract 3 * [w/3] from w, to get the remainder */ - w -= t+t+t; + /* now subtract 3 * [w/3] from w, to get the remainder */ + w -= t+t+t; - /* fixup the remainder as required since - * the optimization is not exact. - */ - while (w >= 3) { - t += 1; - w -= 3; - } + /* fixup the remainder as required since + * the optimization is not exact. + */ + while (w >= 3u) { + t += 1u; + w -= 3u; + } } else { - t = 0; + t = 0; } q.dp[ix] = (mp_digit)t; - } + } - /* [optional] store the remainder */ - if (d != NULL) { - *d = (mp_digit)w; - } + /* [optional] store the remainder */ + if (d != NULL) { + *d = (mp_digit)w; + } - /* [optional] store the quotient */ - if (c != NULL) { - mp_clamp(&q); - mp_exch(&q, c); - } - mp_clear(&q); - - return res; + /* [optional] store the quotient */ + 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: $Format:%ai$ */ |