add s_mp_log10

demo/test.c

@@ -1524,8 +1524,8 @@ static int test_mp_reduce_2k_l(void)
    return EXIT_SUCCESS;
 #   endif /* LTM_DEMO_TEST_REDUCE_2K_L */
 }
-/* stripped down version of mp_radix_size. The faster version can be off by up t
-o +3  */
+
+/* stripped down version of mp_radix_size. The faster version can be off by up to +3  */
 /* TODO: This function should be removed, replaced by mp_radix_size, mp_radix_size_overestimate in 2.0 */
 static mp_err s_rs(const mp_int *a, int radix, uint32_t *size)
 {
@@ -1559,6 +1559,8 @@ static mp_err s_rs(const mp_int *a, int radix, uint32_t *size)
 }
 static int test_mp_log_u32(void)
 {
+        int z;
+        for (z = 0; z < 100; ++z) {
    mp_int a;
    mp_digit d;
    uint32_t base, lb, size;
@@ -1644,6 +1646,7 @@ static int test_mp_log_u32(void)
       /* radix_size includes the memory needed for '\0', too*/
       size -= 2;
       if (lb != size) {
+              printf("NE1 %d\n", base);
          goto LBL_ERR;
       }
    }
@@ -1664,6 +1667,7 @@ static int test_mp_log_u32(void)
       }
       size -= 2;
       if (lb != size) {
+              printf("NE2 %d %d %d\n", base, lb, size);
          goto LBL_ERR;
       }
    }
@@ -1684,10 +1688,12 @@ static int test_mp_log_u32(void)
    }
 
    mp_clear(&a);
-   return EXIT_SUCCESS;
+   continue;
 LBL_ERR:
    mp_clear(&a);
    return EXIT_FAILURE;
+        }
+        return EXIT_SUCCESS;
 }
 
 static int test_mp_incr(void)
@@ -2279,14 +2285,14 @@ static int test_mp_radix_size(void)
    size_t size;
 /* *INDENT-OFF* */
    size_t results[65] = {
-       0, 0, 1627, 1027, 814, 702, 630, 581, 543,
-       514, 491, 471, 455, 441, 428, 418, 408, 399,
-       391, 384, 378, 372, 366, 361, 356, 352, 347,
-       343, 340, 336, 333, 330, 327, 324, 321, 318,
-       316, 314, 311, 309, 307, 305, 303, 301, 299,
-       298, 296, 294, 293, 291, 290, 288, 287, 285,
-       284, 283, 281, 280, 279, 278, 277, 276, 275,
-       273, 272
+       0u, 0u, 1627u, 1027u, 814u, 702u, 630u, 581u, 543u,
+       514u, 491u, 471u, 455u, 441u, 428u, 418u, 408u, 399u,
+       391u, 384u, 378u, 372u, 366u, 361u, 356u, 352u, 347u,
+       343u, 340u, 336u, 333u, 330u, 327u, 324u, 321u, 318u,
+       316u, 314u, 311u, 309u, 307u, 305u, 303u, 301u, 299u,
+       298u, 296u, 294u, 293u, 291u, 290u, 288u, 287u, 285u,
+       284u, 283u, 281u, 280u, 279u, 278u, 277u, 276u, 275u,
+       273u, 272u
    };
 /* *INDENT-ON* */
 
@@ -2326,8 +2332,6 @@ static int test_mp_radix_size(void)
    return EXIT_FAILURE;
 }
 
-
-
 static int test_mp_read_write_ubin(void)
 {
    mp_int a, b, c;

libtommath_VS2008.vcproj

@@ -884,10 +884,18 @@
 			RelativePath="s_mp_log.c"
 			>
 		</File>
+		<File
+			RelativePath="s_mp_log10.c"
+			>
+		</File>
 		<File
 			RelativePath="s_mp_log_d.c"
 			>
 		</File>
+		<File
+			RelativePath="s_mp_log_pow2.c"
+			>
+		</File>
 		<File
 			RelativePath="s_mp_montgomery_reduce_fast.c"
 			>

makefile

@@ -46,10 +46,10 @@ mp_set_ll.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_set_ull.o mp_shrink.o mp_si
 mp_sqrmod.o mp_sqrt.o mp_sqrtmod_prime.o mp_sub.o mp_sub_d.o mp_submod.o mp_to_radix.o mp_to_sbin.o \
 mp_to_ubin.o mp_ubin_size.o mp_unpack.o mp_xor.o mp_zero.o s_mp_add.o s_mp_balance_mul.o s_mp_exptmod.o \
 s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod_fast.o s_mp_invmod_slow.o s_mp_karatsuba_mul.o \
-s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log_d.o s_mp_montgomery_reduce_fast.o s_mp_mul_digs.o \
-s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o s_mp_prime_is_divisible.o \
-s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o s_mp_sqr_fast.o s_mp_sub.o \
-s_mp_toom_mul.o s_mp_toom_sqr.o
+s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log10.o s_mp_log_d.o s_mp_log_pow2.o s_mp_montgomery_reduce_fast.o \
+s_mp_mul_digs.o s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o \
+s_mp_prime_is_divisible.o s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o \
+s_mp_sqr_fast.o s_mp_sub.o s_mp_toom_mul.o s_mp_toom_sqr.o
 
 #END_INS
 

makefile.mingw

@@ -49,10 +49,10 @@ mp_set_ll.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_set_ull.o mp_shrink.o mp_si
 mp_sqrmod.o mp_sqrt.o mp_sqrtmod_prime.o mp_sub.o mp_sub_d.o mp_submod.o mp_to_radix.o mp_to_sbin.o \
 mp_to_ubin.o mp_ubin_size.o mp_unpack.o mp_xor.o mp_zero.o s_mp_add.o s_mp_balance_mul.o s_mp_exptmod.o \
 s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod_fast.o s_mp_invmod_slow.o s_mp_karatsuba_mul.o \
-s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log_d.o s_mp_montgomery_reduce_fast.o s_mp_mul_digs.o \
-s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o s_mp_prime_is_divisible.o \
-s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o s_mp_sqr_fast.o s_mp_sub.o \
-s_mp_toom_mul.o s_mp_toom_sqr.o
+s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log10.o s_mp_log_d.o s_mp_log_pow2.o s_mp_montgomery_reduce_fast.o \
+s_mp_mul_digs.o s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o \
+s_mp_prime_is_divisible.o s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o \
+s_mp_sqr_fast.o s_mp_sub.o s_mp_toom_mul.o s_mp_toom_sqr.o
 
 HEADERS_PUB=tommath.h
 HEADERS=tommath_private.h tommath_class.h tommath_superclass.h tommath_cutoffs.h $(HEADERS_PUB)

makefile.msvc

@@ -41,10 +41,10 @@ mp_set_ll.obj mp_set_u32.obj mp_set_u64.obj mp_set_ul.obj mp_set_ull.obj mp_shri
 mp_sqrmod.obj mp_sqrt.obj mp_sqrtmod_prime.obj mp_sub.obj mp_sub_d.obj mp_submod.obj mp_to_radix.obj mp_to_sbin.obj \
 mp_to_ubin.obj mp_ubin_size.obj mp_unpack.obj mp_xor.obj mp_zero.obj s_mp_add.obj s_mp_balance_mul.obj s_mp_exptmod.obj \
 s_mp_exptmod_fast.obj s_mp_get_bit.obj s_mp_invmod_fast.obj s_mp_invmod_slow.obj s_mp_karatsuba_mul.obj \
-s_mp_karatsuba_sqr.obj s_mp_log.obj s_mp_log_d.obj s_mp_montgomery_reduce_fast.obj s_mp_mul_digs.obj \
-s_mp_mul_digs_fast.obj s_mp_mul_high_digs.obj s_mp_mul_high_digs_fast.obj s_mp_prime_is_divisible.obj \
-s_mp_rand_jenkins.obj s_mp_rand_platform.obj s_mp_reverse.obj s_mp_sqr.obj s_mp_sqr_fast.obj s_mp_sub.obj \
-s_mp_toom_mul.obj s_mp_toom_sqr.obj
+s_mp_karatsuba_sqr.obj s_mp_log.obj s_mp_log10.obj s_mp_log_d.obj s_mp_log_pow2.obj s_mp_montgomery_reduce_fast.obj \
+s_mp_mul_digs.obj s_mp_mul_digs_fast.obj s_mp_mul_high_digs.obj s_mp_mul_high_digs_fast.obj \
+s_mp_prime_is_divisible.obj s_mp_rand_jenkins.obj s_mp_rand_platform.obj s_mp_reverse.obj s_mp_sqr.obj \
+s_mp_sqr_fast.obj s_mp_sub.obj s_mp_toom_mul.obj s_mp_toom_sqr.obj
 
 HEADERS_PUB=tommath.h
 HEADERS=tommath_private.h tommath_class.h tommath_superclass.h tommath_cutoffs.h $(HEADERS_PUB)

makefile.shared

@@ -43,10 +43,10 @@ mp_set_ll.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_set_ull.o mp_shrink.o mp_si
 mp_sqrmod.o mp_sqrt.o mp_sqrtmod_prime.o mp_sub.o mp_sub_d.o mp_submod.o mp_to_radix.o mp_to_sbin.o \
 mp_to_ubin.o mp_ubin_size.o mp_unpack.o mp_xor.o mp_zero.o s_mp_add.o s_mp_balance_mul.o s_mp_exptmod.o \
 s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod_fast.o s_mp_invmod_slow.o s_mp_karatsuba_mul.o \
-s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log_d.o s_mp_montgomery_reduce_fast.o s_mp_mul_digs.o \
-s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o s_mp_prime_is_divisible.o \
-s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o s_mp_sqr_fast.o s_mp_sub.o \
-s_mp_toom_mul.o s_mp_toom_sqr.o
+s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log10.o s_mp_log_d.o s_mp_log_pow2.o s_mp_montgomery_reduce_fast.o \
+s_mp_mul_digs.o s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o \
+s_mp_prime_is_divisible.o s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o \
+s_mp_sqr_fast.o s_mp_sub.o s_mp_toom_mul.o s_mp_toom_sqr.o
 
 #END_INS
 

makefile.unix

@@ -50,10 +50,10 @@ mp_set_ll.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_set_ull.o mp_shrink.o mp_si
 mp_sqrmod.o mp_sqrt.o mp_sqrtmod_prime.o mp_sub.o mp_sub_d.o mp_submod.o mp_to_radix.o mp_to_sbin.o \
 mp_to_ubin.o mp_ubin_size.o mp_unpack.o mp_xor.o mp_zero.o s_mp_add.o s_mp_balance_mul.o s_mp_exptmod.o \
 s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod_fast.o s_mp_invmod_slow.o s_mp_karatsuba_mul.o \
-s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log_d.o s_mp_montgomery_reduce_fast.o s_mp_mul_digs.o \
-s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o s_mp_prime_is_divisible.o \
-s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o s_mp_sqr_fast.o s_mp_sub.o \
-s_mp_toom_mul.o s_mp_toom_sqr.o
+s_mp_karatsuba_sqr.o s_mp_log.o s_mp_log10.o s_mp_log_d.o s_mp_log_pow2.o s_mp_montgomery_reduce_fast.o \
+s_mp_mul_digs.o s_mp_mul_digs_fast.o s_mp_mul_high_digs.o s_mp_mul_high_digs_fast.o \
+s_mp_prime_is_divisible.o s_mp_rand_jenkins.o s_mp_rand_platform.o s_mp_reverse.o s_mp_sqr.o \
+s_mp_sqr_fast.o s_mp_sub.o s_mp_toom_mul.o s_mp_toom_sqr.o
 
 HEADERS_PUB=tommath.h
 HEADERS=tommath_private.h tommath_class.h tommath_superclass.h tommath_cutoffs.h $(HEADERS_PUB)

mp_log_u32.c

@@ -17,14 +17,12 @@ mp_err mp_log_u32(const mp_int *a, uint32_t base, uint32_t *c)
       return MP_VAL;
    }
 
-   /* A small shortcut for bases that are powers of two. */
-   if ((base & (base - 1u)) == 0u) {
-      int y, bit_count;
-      for (y=0; (y < 7) && ((base & 1u) == 0u); y++) {
-         base >>= 1;
-      }
-      bit_count = mp_count_bits(a) - 1;
-      *c = (uint32_t)(bit_count/y);
+   if (MP_HAS(S_MP_LOG10) && (base == 10u)) {
+      return s_mp_log10(a, c);
+   }
+
+   if (MP_HAS(S_MP_LOG_POW2) && (base & (base - 1u)) == 0u) {
+      *c = s_mp_log_pow2(a, base);
       return MP_OKAY;
    }
 

s_mp_log10.c

@@ -0,0 +1,70 @@
+#include "tommath_private.h"
+#ifdef S_MP_LOG10_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+#ifdef MP_16BIT
+static mp_err s_mp_add_u32(mp_int *a, uint32_t x)
+{
+   mp_int t;
+   mp_err err;
+   if ((err = mp_init_u32(&t, x)) != MP_OKAY) {
+      return err;
+   }
+   err = mp_add(a, &t, a);
+   mp_clear(&t);
+   return err;
+}
+#endif
+
+mp_err s_mp_log10(const mp_int *a, uint32_t *c)
+{
+   /*
+       floor(2^64/log_2(10)) = 5553023288523357132
+
+       We need that much precision. Example:
+
+         log_2(x) = log(x)/log(2)
+         198096465/log_2(10) = 59632978.000000002598316594477929217520
+
+        Which are more than 16 decimal digits, so with BINARY_64 (C's "double")
+        a 'ceil(198096465/log_2(10))' would result wrongly in 59632978.0.
+    */
+   mp_err err;
+   mp_int bit_count, k;
+
+#ifdef MP_16BIT
+   if ((err = mp_init_u32(&k, 0x4d104d42UL)) != MP_OKAY) {
+      return err;
+   }
+   if ((err = mp_mul_2d(&k, 32, &k)) != MP_OKAY) {
+      goto LBL_ERR1;
+   }
+   if ((err = s_mp_add32(&k, 0x7de7fbccUL)) != MP_OKAY) {
+      goto LBL_ERR1;
+   }
+#else
+   if ((err = mp_init_u64(&k, 0x4d104d427de7fbccULL)) != MP_OKAY) {
+      return err;
+   }
+#endif
+
+   if ((err = mp_init_l(&bit_count, mp_count_bits(a) - 1))  != MP_OKAY) {
+      goto LBL_ERR1;
+   }
+   if ((err = mp_mul(&bit_count, &k, &k)) != MP_OKAY) {
+      goto LBL_ERR2;
+   }
+   if ((err = mp_div_2d(&k, 64, &k, NULL)) != MP_OKAY) {
+      goto LBL_ERR2;
+   }
+   *c = mp_get_u32(&k);
+
+LBL_ERR2:
+   mp_clear(&bit_count);
+LBL_ERR1:
+   mp_clear(&k);
+   return err;
+}
+
+#endif

s_mp_log_pow2.c

@@ -0,0 +1,12 @@
+#include "tommath_private.h"
+#ifdef S_MP_LOG_POW2_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+uint32_t s_mp_log_pow2(const mp_int *a, uint32_t base)
+{
+   int y;
+   for (y = 0; (base & 1u) == 0u; y++, base >>= 1) {}
+   return (uint32_t)((mp_count_bits(a) - 1) / y);
+}
+#endif

tommath_class.h

@@ -154,7 +154,9 @@
 #   define S_MP_KARATSUBA_MUL_C
 #   define S_MP_KARATSUBA_SQR_C
 #   define S_MP_LOG_C
+#   define S_MP_LOG10_C
 #   define S_MP_LOG_D_C
+#   define S_MP_LOG_POW2_C
 #   define S_MP_MONTGOMERY_REDUCE_FAST_C
 #   define S_MP_MUL_DIGS_C
 #   define S_MP_MUL_DIGS_FAST_C
@@ -531,9 +533,10 @@
 #endif
 
 #if defined(MP_LOG_U32_C)
-#   define MP_COUNT_BITS_C
+#   define S_MP_LOG10_C
 #   define S_MP_LOG_C
 #   define S_MP_LOG_D_C
+#   define S_MP_LOG_POW2_C
 #endif
 
 #if defined(MP_LSHD_C)
@@ -1127,9 +1130,23 @@
 #   define MP_SQR_C
 #endif
 
+#if defined(S_MP_LOG10_C)
+#   define MP_CLEAR_C
+#   define MP_COUNT_BITS_C
+#   define MP_DIV_2D_C
+#   define MP_GET_I32_C
+#   define MP_INIT_L_C
+#   define MP_INIT_U64_C
+#   define MP_MUL_C
+#endif
+
 #if defined(S_MP_LOG_D_C)
 #endif
 
+#if defined(S_MP_LOG_POW2_C)
+#   define MP_COUNT_BITS_C
+#endif
+
 #if defined(S_MP_MONTGOMERY_REDUCE_FAST_C)
 #   define MP_CLAMP_C
 #   define MP_CMP_MAG_C

tommath_private.h

@@ -212,6 +212,8 @@ MP_PRIVATE void s_mp_reverse(unsigned char *s, size_t len);
 MP_PRIVATE mp_err s_mp_prime_is_divisible(const mp_int *a, mp_bool *result);
 MP_PRIVATE mp_digit s_mp_log_d(mp_digit base, mp_digit n);
 MP_PRIVATE mp_err s_mp_log(const mp_int *a, uint32_t base, uint32_t *c);
+MP_PRIVATE mp_err s_mp_log10(const mp_int *a, uint32_t *c);
+MP_PRIVATE uint32_t s_mp_log_pow2(const mp_int *a, uint32_t base);
 
 /* TODO: jenkins prng is not thread safe as of now */
 MP_PRIVATE mp_err s_mp_rand_jenkins(void *p, size_t n) MP_WUR;