mp_n_root: add mp_n_root_ex() with parameter 'fast' for mp_expt_d_ex() This change is introduced to be able to choose the underlying implementation of mp_expt_d_ex() The implementation of the root_n functionality is now implemented in the mp_n_root_ex() function. The parameter 'fast' is just passed over to mp_expt_d_ex(). mp_n_root() defaults to the pre 921be35779f7d71080ad85c27ed58671602d59b3 implementation
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diff --git a/bn_mp_n_root.c b/bn_mp_n_root.c
index 11b878b..56f1586 100644
--- a/bn_mp_n_root.c
+++ b/bn_mp_n_root.c
@@ -15,116 +15,14 @@
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
-/* find the n'th root of an integer
- *
- * Result found such that (c)**b <= a and (c+1)**b > a
- *
- * This algorithm uses Newton's approximation
- * x[i+1] = x[i] - f(x[i])/f'(x[i])
- * which will find the root in log(N) time where
- * each step involves a fair bit. This is not meant to
- * find huge roots [square and cube, etc].
+/* wrapper function for mp_n_root_ex()
+ * computes c = (a)**(1/b) such that (c)**b <= a and (c+1)**b > a
*/
int mp_n_root (mp_int * a, mp_digit b, mp_int * c)
{
- mp_int t1, t2, t3;
- int res, neg;
-
- /* input must be positive if b is even */
- if ((b & 1) == 0 && a->sign == MP_NEG) {
- return MP_VAL;
- }
-
- if ((res = mp_init (&t1)) != MP_OKAY) {
- return res;
- }
-
- if ((res = mp_init (&t2)) != MP_OKAY) {
- goto LBL_T1;
- }
-
- if ((res = mp_init (&t3)) != MP_OKAY) {
- goto LBL_T2;
- }
-
- /* if a is negative fudge the sign but keep track */
- neg = a->sign;
- a->sign = MP_ZPOS;
-
- /* t2 = 2 */
- mp_set (&t2, 2);
-
- do {
- /* t1 = t2 */
- if ((res = mp_copy (&t2, &t1)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- /* t2 = t1 - ((t1**b - a) / (b * t1**(b-1))) */
-
- /* t3 = t1**(b-1) */
- if ((res = mp_expt_d (&t1, b - 1, &t3)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- /* numerator */
- /* t2 = t1**b */
- if ((res = mp_mul (&t3, &t1, &t2)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- /* t2 = t1**b - a */
- if ((res = mp_sub (&t2, a, &t2)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- /* denominator */
- /* t3 = t1**(b-1) * b */
- if ((res = mp_mul_d (&t3, b, &t3)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- /* t3 = (t1**b - a)/(b * t1**(b-1)) */
- if ((res = mp_div (&t2, &t3, &t3, NULL)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- if ((res = mp_sub (&t1, &t3, &t2)) != MP_OKAY) {
- goto LBL_T3;
- }
- } while (mp_cmp (&t1, &t2) != MP_EQ);
-
- /* result can be off by a few so check */
- for (;;) {
- if ((res = mp_expt_d (&t1, b, &t2)) != MP_OKAY) {
- goto LBL_T3;
- }
-
- if (mp_cmp (&t2, a) == MP_GT) {
- if ((res = mp_sub_d (&t1, 1, &t1)) != MP_OKAY) {
- goto LBL_T3;
- }
- } else {
- break;
- }
- }
-
- /* reset the sign of a first */
- a->sign = neg;
-
- /* set the result */
- mp_exch (&t1, c);
-
- /* set the sign of the result */
- c->sign = neg;
-
- res = MP_OKAY;
-
-LBL_T3:mp_clear (&t3);
-LBL_T2:mp_clear (&t2);
-LBL_T1:mp_clear (&t1);
- return res;
+ return mp_n_root_ex(a, b, c, 0);
}
+
#endif
/* $Source$ */
diff --git a/bn_mp_n_root_ex.c b/bn_mp_n_root_ex.c
new file mode 100644
index 0000000..6b42643
--- /dev/null
+++ b/bn_mp_n_root_ex.c
@@ -0,0 +1,132 @@
+#include <tommath.h>
+#ifdef BN_MP_N_ROOT_EX_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@gmail.com, http://libtom.org
+ */
+
+/* find the n'th root of an integer
+ *
+ * Result found such that (c)**b <= a and (c+1)**b > a
+ *
+ * This algorithm uses Newton's approximation
+ * x[i+1] = x[i] - f(x[i])/f'(x[i])
+ * which will find the root in log(N) time where
+ * each step involves a fair bit. This is not meant to
+ * find huge roots [square and cube, etc].
+ */
+int mp_n_root_ex (mp_int * a, mp_digit b, mp_int * c, int fast)
+{
+ mp_int t1, t2, t3;
+ int res, neg;
+
+ /* input must be positive if b is even */
+ if ((b & 1) == 0 && a->sign == MP_NEG) {
+ return MP_VAL;
+ }
+
+ if ((res = mp_init (&t1)) != MP_OKAY) {
+ return res;
+ }
+
+ if ((res = mp_init (&t2)) != MP_OKAY) {
+ goto LBL_T1;
+ }
+
+ if ((res = mp_init (&t3)) != MP_OKAY) {
+ goto LBL_T2;
+ }
+
+ /* if a is negative fudge the sign but keep track */
+ neg = a->sign;
+ a->sign = MP_ZPOS;
+
+ /* t2 = 2 */
+ mp_set (&t2, 2);
+
+ do {
+ /* t1 = t2 */
+ if ((res = mp_copy (&t2, &t1)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ /* t2 = t1 - ((t1**b - a) / (b * t1**(b-1))) */
+
+ /* t3 = t1**(b-1) */
+ if ((res = mp_expt_d_ex (&t1, b - 1, &t3, fast)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ /* numerator */
+ /* t2 = t1**b */
+ if ((res = mp_mul (&t3, &t1, &t2)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ /* t2 = t1**b - a */
+ if ((res = mp_sub (&t2, a, &t2)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ /* denominator */
+ /* t3 = t1**(b-1) * b */
+ if ((res = mp_mul_d (&t3, b, &t3)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ /* t3 = (t1**b - a)/(b * t1**(b-1)) */
+ if ((res = mp_div (&t2, &t3, &t3, NULL)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ if ((res = mp_sub (&t1, &t3, &t2)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+ } while (mp_cmp (&t1, &t2) != MP_EQ);
+
+ /* result can be off by a few so check */
+ for (;;) {
+ if ((res = mp_expt_d_ex (&t1, b, &t2, fast)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+
+ if (mp_cmp (&t2, a) == MP_GT) {
+ if ((res = mp_sub_d (&t1, 1, &t1)) != MP_OKAY) {
+ goto LBL_T3;
+ }
+ } else {
+ break;
+ }
+ }
+
+ /* reset the sign of a first */
+ a->sign = neg;
+
+ /* set the result */
+ mp_exch (&t1, c);
+
+ /* set the sign of the result */
+ c->sign = neg;
+
+ res = MP_OKAY;
+
+LBL_T3:mp_clear (&t3);
+LBL_T2:mp_clear (&t2);
+LBL_T1:mp_clear (&t1);
+ return res;
+}
+#endif
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */
diff --git a/makefile b/makefile
index e9b2eab..6ef47b7 100644
--- a/makefile
+++ b/makefile
@@ -96,7 +96,7 @@ bn_mp_init_multi.o bn_mp_clear_multi.o bn_mp_exteuclid.o bn_mp_toradix_n.o \
bn_mp_prime_random_ex.o bn_mp_get_int.o bn_mp_sqrt.o bn_mp_is_square.o bn_mp_init_set.o \
bn_mp_init_set_int.o bn_mp_invmod_slow.o bn_mp_prime_rabin_miller_trials.o \
bn_mp_to_signed_bin_n.o bn_mp_to_unsigned_bin_n.o bn_mp_import.o bn_mp_export.o \
-bn_mp_balance_mul.o bn_mp_expt_d_ex.o
+bn_mp_balance_mul.o bn_mp_expt_d_ex.o bn_mp_n_root_ex.o
$(LIBNAME): $(OBJECTS)
$(AR) $(ARFLAGS) $@ $(OBJECTS)
diff --git a/tommath.h b/tommath.h
index 7b5a703..13cc64a 100644
--- a/tommath.h
+++ b/tommath.h
@@ -400,6 +400,7 @@ int mp_lcm(mp_int *a, mp_int *b, mp_int *c);
* returns error if a < 0 and b is even
*/
int mp_n_root(mp_int *a, mp_digit b, mp_int *c);
+int mp_n_root_ex (mp_int * a, mp_digit b, mp_int * c, int fast);
/* special sqrt algo */
int mp_sqrt(mp_int *arg, mp_int *ret);
diff --git a/tommath_class.h b/tommath_class.h
index 6569f18..afd08a4 100644
--- a/tommath_class.h
+++ b/tommath_class.h
@@ -77,6 +77,7 @@
#define BN_MP_MUL_D_C
#define BN_MP_MULMOD_C
#define BN_MP_N_ROOT_C
+#define BN_MP_N_ROOT_EX_C
#define BN_MP_NEG_C
#define BN_MP_OR_C
#define BN_MP_PRIME_FERMAT_C
@@ -614,10 +615,14 @@
#endif
#if defined(BN_MP_N_ROOT_C)
+ #define BN_MP_N_ROOT_EX_C
+#endif
+
+#if defined(BN_MP_N_ROOT_EX_C)
#define BN_MP_INIT_C
#define BN_MP_SET_C
#define BN_MP_COPY_C
- #define BN_MP_EXPT_D_C
+ #define BN_MP_EXPT_D_EX_C
#define BN_MP_MUL_C
#define BN_MP_SUB_C
#define BN_MP_MUL_D_C
@@ -1023,7 +1028,3 @@
#else
#define LTM_LAST
#endif
-
-/* $Source$ */
-/* $Revision$ */
-/* $Date$ */