additional functions mp_incr and mp_decr

bn_mp_decr.c

@@ -0,0 +1,48 @@
+#include "tommath_private.h"
+#ifdef BN_MP_DECR_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.
+ *
+ * SPDX-License-Identifier: Unlicense
+ */
+
+
+/* Decrement "a" by one like "a--". Changes input! */
+int mp_decr(mp_int *a)
+{
+   int e = MP_OKAY;
+   if (IS_ZERO(a)) {
+      mp_set(a,1uL);
+      a->sign = MP_NEG;
+      return MP_OKAY;
+   } else if (a->sign == MP_NEG) {
+      a->sign = MP_ZPOS;
+      if ((e = mp_incr(a)) != MP_OKAY) {
+         return e;
+      }
+      /* There is no -0 in LTM */
+      if (!IS_ZERO(a)) {
+         a->sign = MP_NEG;
+      }
+      return MP_OKAY;
+   } else if (a->dp[0] > 1uL) {
+      a->dp[0]--;
+      if (a->dp[0] == 0) {
+         mp_zero(a);
+      }
+      return MP_OKAY;
+   }
+   return mp_sub_d(a, 1uL,a);
+}
+
+
+#endif
+/* ref:         \$Format:\%D$ */
+/* git commit:  \$Format:\%H$ */
+/* commit time: \$Format:\%ai$ */

bn_mp_incr.c

@@ -0,0 +1,42 @@
+#include "tommath_private.h"
+#ifdef BN_MP_INCR_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.
+ *
+ * SPDX-License-Identifier: Unlicense
+ */
+
+/* Increment "a" by one like "a++". Changes input! */
+int mp_incr(mp_int *a)
+{
+   int e = MP_OKAY;
+   if (IS_ZERO(a)) {
+      mp_set(a,1uL);
+      return MP_OKAY;
+   } else if (a->sign == MP_NEG) {
+      a->sign = MP_ZPOS;
+      if ((e = mp_decr(a)) != MP_OKAY) {
+         return e;
+      }
+      /* There is no -0 in LTM */
+      if (!IS_ZERO(a)) {
+         a->sign = MP_NEG;
+      }
+      return MP_OKAY;
+   } else if (a->dp[0] < MP_MASK) {
+      a->dp[0]++;
+      return MP_OKAY;
+   }
+   return mp_add_d(a, 1uL,a);
+}
+
+#endif
+/* ref:         \$Format:\%D$ */
+/* git commit:  \$Format:\%H$ */
+/* commit time: \$Format:\%ai$ */

callgraph.txt

@@ -256,6 +256,23 @@ BN_MP_COPY_C
 BN_MP_COUNT_BITS_C
 
 
+BN_MP_DECR_C
++--->BN_MP_SET_C
+|   +--->BN_MP_ZERO_C
++--->BN_MP_INCR_C
+|   +--->BN_MP_ADD_D_C
+|   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_SUB_D_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_CLAMP_C
++--->BN_MP_ZERO_C
++--->BN_MP_SUB_D_C
+|   +--->BN_MP_GROW_C
+|   +--->BN_MP_ADD_D_C
+|   |   +--->BN_MP_CLAMP_C
+|   +--->BN_MP_CLAMP_C
+
+
 BN_MP_DIV_2D_C
 +--->BN_MP_COPY_C
 |   +--->BN_MP_GROW_C
@@ -2357,6 +2374,23 @@ BN_MP_IMPORT_C
 +--->BN_MP_CLAMP_C
 
 
+BN_MP_INCR_C
++--->BN_MP_SET_C
+|   +--->BN_MP_ZERO_C
++--->BN_MP_DECR_C
+|   +--->BN_MP_ZERO_C
+|   +--->BN_MP_SUB_D_C
+|   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_ADD_D_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_CLAMP_C
++--->BN_MP_ADD_D_C
+|   +--->BN_MP_GROW_C
+|   +--->BN_MP_SUB_D_C
+|   |   +--->BN_MP_CLAMP_C
+|   +--->BN_MP_CLAMP_C
+
+
 BN_MP_INIT_C
 
 

demo/test.c

@@ -1230,6 +1230,138 @@ static int test_mp_reduce_2k_l(void)
 #   endif /* LTM_DEMO_TEST_REDUCE_2K_L */
 }
 
+static int test_mp_incr(void)
+{
+   mp_int a, b;
+   int e = MP_OKAY;
+
+   if ((e = mp_init_multi(&a, &b, NULL)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+
+   /* Does it increment inside the limits of a MP_xBIT limb? */
+   mp_set(&a, MP_MASK/2);
+   if ((e = mp_incr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (mp_cmp_d(&a, (MP_MASK/2uL) + 1uL) != MP_EQ) {
+      goto LTM_ERR;
+   }
+
+   /* Does it increment outside of the limits of a MP_xBIT limb? */
+   mp_set(&a, MP_MASK);
+   mp_set(&b, MP_MASK);
+   if ((e = mp_incr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if ((e = mp_add_d(&b, 1uL, &b)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (mp_cmp(&a, &b) != MP_EQ) {
+      goto LTM_ERR;
+   }
+
+   /* Does it increment from -1 to 0? */
+   mp_set(&a, 1uL);
+   a.sign = MP_NEG;
+   if ((e = mp_incr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (mp_cmp_d(&a, 0uL) != MP_EQ) {
+      goto LTM_ERR;
+   }
+
+   /* Does it increment from -(MP_MASK + 1) to -MP_MASK? */
+   mp_set(&a, MP_MASK);
+   if ((e = mp_add_d(&a, 1uL, &a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   a.sign = MP_NEG;
+   if ((e = mp_incr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (a.sign != MP_NEG) {
+      goto LTM_ERR;
+   }
+   a.sign = MP_ZPOS;
+   if (mp_cmp_d(&a, MP_MASK) != MP_EQ) {puts("DDD");
+      goto LTM_ERR;
+   }
+
+   mp_clear_multi(&a, &b, NULL);
+   return EXIT_SUCCESS;
+LTM_ERR:
+   mp_clear_multi(&a, &b, NULL);
+   return EXIT_FAILURE;
+}
+
+static int test_mp_decr(void)
+{
+   mp_int a, b;
+   int e = MP_OKAY;
+
+   if ((e = mp_init_multi(&a, &b, NULL)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+
+   /* Does it decrement inside the limits of a MP_xBIT limb? */
+   mp_set(&a, MP_MASK/2);
+   if ((e = mp_decr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (mp_cmp_d(&a, (MP_MASK/2uL) - 1uL) != MP_EQ) {
+      goto LTM_ERR;
+   }
+
+   /* Does it decrement outside of the limits of a MP_xBIT limb? */
+   mp_set(&a, MP_MASK);
+   if ((e = mp_add_d(&a, 1uL, &a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if ((e = mp_decr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (mp_cmp_d(&a, MP_MASK) != MP_EQ) {
+      goto LTM_ERR;
+   }
+
+   /* Does it decrement from 0 to -1? */
+   mp_zero(&a);
+   if ((e = mp_decr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (a.sign == MP_NEG) {
+      a.sign = MP_ZPOS;
+      if (mp_cmp_d(&a, 1uL) != MP_EQ) {
+         goto LTM_ERR;
+      }
+   } else {
+      goto LTM_ERR;
+   }
+
+
+   /* Does it decrement from -MP_MASK to -(MP_MASK + 1)? */
+   mp_set(&a, MP_MASK);
+   a.sign = MP_NEG;
+   mp_set(&b, MP_MASK);
+   b.sign = MP_NEG;
+   if ((e = mp_sub_d(&b, 1uL, &b)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if ((e = mp_decr(&a)) != MP_OKAY) {
+      goto LTM_ERR;
+   }
+   if (mp_cmp(&a, &b) != MP_EQ) {
+      goto LTM_ERR;
+   }
+
+   mp_clear_multi(&a, &b, NULL);
+   return EXIT_SUCCESS;
+LTM_ERR:
+   mp_clear_multi(&a, &b, NULL);
+   return EXIT_FAILURE;
+}
+
 int unit_tests(void)
 {
    static const struct {
@@ -1262,6 +1394,8 @@ int unit_tests(void)
       T(mp_tc_div_2d),
       T(mp_tc_or),
       T(mp_tc_xor),
+      T(mp_incr),
+      T(mp_decr)
 #undef T
    };
    unsigned long i;

doc/bn.tex

@@ -2284,6 +2284,12 @@ \section{Single Digit Functions}
 functions fairly handy if you have to work with relatively small numbers since you will not have to allocate
 an entire mp\_int to store a number like $1$ or $2$.
 
+The functions \texttt{mp\_incr} and \texttt{mp\_decr} mimic the postfix operators \texttt{++} and \texttt{--} respectively, to increment the input by one. They call the full single-digit functions if the addition would carry. Both functions need to be included in a minimized library because they call each other in case of a negative input, These functions change the inputs!
+\begin{alltt}
+int mp_incr(mp_int *a);
+int mp_decr(mp_int *a);
+\end{alltt}
+
 
 The division by three can be made faster by replacing the division with a multiplication by the multiplicative inverse of three.
 

libtommath_VS2008.vcproj

@@ -400,6 +400,10 @@
 			RelativePath="bn_mp_count_bits.c"
 			>
 		</File>
+		<File
+			RelativePath="bn_mp_decr.c"
+			>
+		</File>
 		<File
 			RelativePath="bn_mp_div.c"
 			>
@@ -500,6 +504,10 @@
 			RelativePath="bn_mp_import.c"
 			>
 		</File>
+		<File
+			RelativePath="bn_mp_incr.c"
+			>
+		</File>
 		<File
 			RelativePath="bn_mp_init.c"
 			>

makefile

@@ -29,17 +29,17 @@ LCOV_ARGS=--directory .
 OBJECTS=bn_error.o bn_fast_mp_invmod.o bn_fast_mp_montgomery_reduce.o bn_fast_s_mp_mul_digs.o \
 bn_fast_s_mp_mul_high_digs.o bn_fast_s_mp_sqr.o bn_mp_2expt.o bn_mp_abs.o bn_mp_add.o bn_mp_add_d.o \
 bn_mp_addmod.o bn_mp_and.o bn_mp_clamp.o bn_mp_clear.o bn_mp_clear_multi.o bn_mp_cmp.o bn_mp_cmp_d.o \
-bn_mp_cmp_mag.o bn_mp_cnt_lsb.o bn_mp_complement.o bn_mp_copy.o bn_mp_count_bits.o bn_mp_div.o \
-bn_mp_div_2.o bn_mp_div_2d.o bn_mp_div_3.o bn_mp_div_d.o bn_mp_dr_is_modulus.o bn_mp_dr_reduce.o \
-bn_mp_dr_setup.o bn_mp_exch.o bn_mp_export.o bn_mp_expt_d.o bn_mp_expt_d_ex.o bn_mp_exptmod.o \
-bn_mp_exptmod_fast.o bn_mp_exteuclid.o bn_mp_fread.o bn_mp_fwrite.o bn_mp_gcd.o bn_mp_get_bit.o \
-bn_mp_get_double.o bn_mp_get_int.o bn_mp_get_long.o bn_mp_get_long_long.o bn_mp_grow.o bn_mp_import.o \
-bn_mp_init.o bn_mp_init_copy.o bn_mp_init_multi.o bn_mp_init_set.o bn_mp_init_set_int.o bn_mp_init_size.o \
-bn_mp_invmod.o bn_mp_invmod_slow.o bn_mp_is_square.o bn_mp_iseven.o bn_mp_isodd.o bn_mp_jacobi.o \
-bn_mp_karatsuba_mul.o bn_mp_karatsuba_sqr.o bn_mp_kronecker.o bn_mp_lcm.o bn_mp_lshd.o bn_mp_mod.o \
-bn_mp_mod_2d.o bn_mp_mod_d.o bn_mp_montgomery_calc_normalization.o bn_mp_montgomery_reduce.o \
-bn_mp_montgomery_setup.o bn_mp_mul.o bn_mp_mul_2.o bn_mp_mul_2d.o bn_mp_mul_d.o bn_mp_mulmod.o \
-bn_mp_n_root.o bn_mp_n_root_ex.o bn_mp_neg.o bn_mp_or.o bn_mp_prime_fermat.o \
+bn_mp_cmp_mag.o bn_mp_cnt_lsb.o bn_mp_complement.o bn_mp_copy.o bn_mp_count_bits.o bn_mp_decr.o \
+bn_mp_div.o bn_mp_div_2.o bn_mp_div_2d.o bn_mp_div_3.o bn_mp_div_d.o bn_mp_dr_is_modulus.o \
+bn_mp_dr_reduce.o bn_mp_dr_setup.o bn_mp_exch.o bn_mp_export.o bn_mp_expt_d.o bn_mp_expt_d_ex.o \
+bn_mp_exptmod.o bn_mp_exptmod_fast.o bn_mp_exteuclid.o bn_mp_fread.o bn_mp_fwrite.o bn_mp_gcd.o \
+bn_mp_get_bit.o bn_mp_get_double.o bn_mp_get_int.o bn_mp_get_long.o bn_mp_get_long_long.o bn_mp_grow.o \
+bn_mp_import.o bn_mp_incr.o bn_mp_init.o bn_mp_init_copy.o bn_mp_init_multi.o bn_mp_init_set.o \
+bn_mp_init_set_int.o bn_mp_init_size.o bn_mp_invmod.o bn_mp_invmod_slow.o bn_mp_is_square.o \
+bn_mp_iseven.o bn_mp_isodd.o bn_mp_jacobi.o bn_mp_karatsuba_mul.o bn_mp_karatsuba_sqr.o bn_mp_kronecker.o \
+bn_mp_lcm.o bn_mp_lshd.o bn_mp_mod.o bn_mp_mod_2d.o bn_mp_mod_d.o bn_mp_montgomery_calc_normalization.o \
+bn_mp_montgomery_reduce.o bn_mp_montgomery_setup.o bn_mp_mul.o bn_mp_mul_2.o bn_mp_mul_2d.o bn_mp_mul_d.o \
+bn_mp_mulmod.o bn_mp_n_root.o bn_mp_n_root_ex.o bn_mp_neg.o bn_mp_or.o bn_mp_prime_fermat.o \
 bn_mp_prime_frobenius_underwood.o bn_mp_prime_is_divisible.o bn_mp_prime_is_prime.o \
 bn_mp_prime_miller_rabin.o bn_mp_prime_next_prime.o bn_mp_prime_rabin_miller_trials.o \
 bn_mp_prime_random_ex.o bn_mp_prime_strong_lucas_selfridge.o bn_mp_radix_size.o bn_mp_radix_smap.o \

makefile.mingw

@@ -32,17 +32,17 @@ LIBMAIN_D =libtommath.dll
 OBJECTS=bn_error.o bn_fast_mp_invmod.o bn_fast_mp_montgomery_reduce.o bn_fast_s_mp_mul_digs.o \
 bn_fast_s_mp_mul_high_digs.o bn_fast_s_mp_sqr.o bn_mp_2expt.o bn_mp_abs.o bn_mp_add.o bn_mp_add_d.o \
 bn_mp_addmod.o bn_mp_and.o bn_mp_clamp.o bn_mp_clear.o bn_mp_clear_multi.o bn_mp_cmp.o bn_mp_cmp_d.o \
-bn_mp_cmp_mag.o bn_mp_cnt_lsb.o bn_mp_complement.o bn_mp_copy.o bn_mp_count_bits.o bn_mp_div.o \
-bn_mp_div_2.o bn_mp_div_2d.o bn_mp_div_3.o bn_mp_div_d.o bn_mp_dr_is_modulus.o bn_mp_dr_reduce.o \
-bn_mp_dr_setup.o bn_mp_exch.o bn_mp_export.o bn_mp_expt_d.o bn_mp_expt_d_ex.o bn_mp_exptmod.o \
-bn_mp_exptmod_fast.o bn_mp_exteuclid.o bn_mp_fread.o bn_mp_fwrite.o bn_mp_gcd.o bn_mp_get_bit.o \
-bn_mp_get_double.o bn_mp_get_int.o bn_mp_get_long.o bn_mp_get_long_long.o bn_mp_grow.o bn_mp_import.o \
-bn_mp_init.o bn_mp_init_copy.o bn_mp_init_multi.o bn_mp_init_set.o bn_mp_init_set_int.o bn_mp_init_size.o \
-bn_mp_invmod.o bn_mp_invmod_slow.o bn_mp_is_square.o bn_mp_iseven.o bn_mp_isodd.o bn_mp_jacobi.o \
-bn_mp_karatsuba_mul.o bn_mp_karatsuba_sqr.o bn_mp_kronecker.o bn_mp_lcm.o bn_mp_lshd.o bn_mp_mod.o \
-bn_mp_mod_2d.o bn_mp_mod_d.o bn_mp_montgomery_calc_normalization.o bn_mp_montgomery_reduce.o \
-bn_mp_montgomery_setup.o bn_mp_mul.o bn_mp_mul_2.o bn_mp_mul_2d.o bn_mp_mul_d.o bn_mp_mulmod.o \
-bn_mp_n_root.o bn_mp_n_root_ex.o bn_mp_neg.o bn_mp_or.o bn_mp_prime_fermat.o \
+bn_mp_cmp_mag.o bn_mp_cnt_lsb.o bn_mp_complement.o bn_mp_copy.o bn_mp_count_bits.o bn_mp_decr.o \
+bn_mp_div.o bn_mp_div_2.o bn_mp_div_2d.o bn_mp_div_3.o bn_mp_div_d.o bn_mp_dr_is_modulus.o \
+bn_mp_dr_reduce.o bn_mp_dr_setup.o bn_mp_exch.o bn_mp_export.o bn_mp_expt_d.o bn_mp_expt_d_ex.o \
+bn_mp_exptmod.o bn_mp_exptmod_fast.o bn_mp_exteuclid.o bn_mp_fread.o bn_mp_fwrite.o bn_mp_gcd.o \
+bn_mp_get_bit.o bn_mp_get_double.o bn_mp_get_int.o bn_mp_get_long.o bn_mp_get_long_long.o bn_mp_grow.o \
+bn_mp_import.o bn_mp_incr.o bn_mp_init.o bn_mp_init_copy.o bn_mp_init_multi.o bn_mp_init_set.o \
+bn_mp_init_set_int.o bn_mp_init_size.o bn_mp_invmod.o bn_mp_invmod_slow.o bn_mp_is_square.o \
+bn_mp_iseven.o bn_mp_isodd.o bn_mp_jacobi.o bn_mp_karatsuba_mul.o bn_mp_karatsuba_sqr.o bn_mp_kronecker.o \
+bn_mp_lcm.o bn_mp_lshd.o bn_mp_mod.o bn_mp_mod_2d.o bn_mp_mod_d.o bn_mp_montgomery_calc_normalization.o \
+bn_mp_montgomery_reduce.o bn_mp_montgomery_setup.o bn_mp_mul.o bn_mp_mul_2.o bn_mp_mul_2d.o bn_mp_mul_d.o \
+bn_mp_mulmod.o bn_mp_n_root.o bn_mp_n_root_ex.o bn_mp_neg.o bn_mp_or.o bn_mp_prime_fermat.o \
 bn_mp_prime_frobenius_underwood.o bn_mp_prime_is_divisible.o bn_mp_prime_is_prime.o \
 bn_mp_prime_miller_rabin.o bn_mp_prime_next_prime.o bn_mp_prime_rabin_miller_trials.o \
 bn_mp_prime_random_ex.o bn_mp_prime_strong_lucas_selfridge.o bn_mp_radix_size.o bn_mp_radix_smap.o \