Addition of faster to_radix function

Author: czurnieden

demo/test.c

@@ -1016,9 +1016,10 @@ static int test_mp_read_radix(void)
 {
    char buf[4096];
    size_t written;
+   int bignum, i;
 
-   mp_int a;
-   DOR(mp_init_multi(&a, NULL));
+   mp_int a, b;
+   DOR(mp_init_multi(&a, &b, NULL));
 
    DO(mp_read_radix(&a, "123456", 10));
 
@@ -1044,6 +1045,30 @@ static int test_mp_read_radix(void)
    DO(mp_to_radix(&a, buf, sizeof(buf), &written, 10));
    printf("\r '0' a == %s, length = %zu", buf, written);
 
+   /* Test the fast method with a slightly larger number */
+
+   /* Must be bigger than the cut-off value, of course */
+   bignum = 2* (2 * s_mp_radix_exponent_y[2] * MP_RADIX_BARRETT_START_MULTIPLICATOR);
+   printf("Size of bignum_size = %d\n", bignum);
+   /* Check if "bignum" is small enough for the result to fit into "buf"
+      otherwise lead tester to this function */
+   if (bignum >= 4096) {
+      fprintf(stderr, "Buffer too small, please check function \"test_mp_read_radix\" in \"test.c\"");
+      goto LBL_ERR;
+   }
+   /* Produce a random number */
+   bignum /= MP_DIGIT_BIT;
+   DO(mp_rand(&b, bignum));
+   /* Check if it makes the round */
+   printf("Number of limbs in &b = %d, bit_count of &b = %d\n", bignum, mp_count_bits(&b));
+   for (i = 2; i < 65; i++) {
+      DO(mp_to_radix(&b, buf, sizeof(buf), &written, i));
+      DO(mp_read_radix(&a, buf, i));
+      EXPECT(mp_cmp(&a, &b) == MP_EQ);
+      /* fprintf(stderr,"radix = %d\n",i); */
+   }
+
+
    while (0) {
       char *s = fgets(buf, sizeof(buf), stdin);
       if (s != buf) break;
@@ -1053,10 +1078,10 @@ static int test_mp_read_radix(void)
       printf("%s, %lu\n", buf, (unsigned long)a.dp[0] & 3uL);
    }
 
-   mp_clear(&a);
+   mp_clear_multi(&a, &b, NULL);
    return EXIT_SUCCESS;
 LBL_ERR:
-   mp_clear(&a);
+   mp_clear_multi(&a, &b, NULL);
    return EXIT_FAILURE;
 }
 

libtommath_VS2008.vcproj

@@ -824,6 +824,10 @@
 			RelativePath="s_mp_exptmod_fast.c"
 			>
 		</File>
+		<File
+			RelativePath="s_mp_faster_to_radix.c"
+			>
+		</File>
 		<File
 			RelativePath="s_mp_get_bit.c"
 			>
@@ -900,6 +904,10 @@
 			RelativePath="s_mp_rand_platform.c"
 			>
 		</File>
+		<File
+			RelativePath="s_mp_slower_to_radix.c"
+			>
+		</File>
 		<File
 			RelativePath="s_mp_sqr.c"
 			>

makefile

@@ -44,12 +44,12 @@ mp_reduce_setup.o mp_root_n.o mp_rshd.o mp_sbin_size.o mp_set.o mp_set_double.o
 mp_set_l.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_shrink.o mp_signed_rsh.o 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_copy_digs.o s_mp_div_3.o s_mp_div_recursive.o \
-s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod.o \
-s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o s_mp_montgomery_reduce_comba.o s_mp_mul.o \
-s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o s_mp_mul_high_comba.o s_mp_mul_karatsuba.o \
-s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o s_mp_radix_map.o \
-s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_sqr.o s_mp_sqr_comba.o s_mp_sqr_karatsuba.o \
-s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
+s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_faster_to_radix.o \
+s_mp_get_bit.o s_mp_invmod.o s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o \
+s_mp_montgomery_reduce_comba.o s_mp_mul.o s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o \
+s_mp_mul_high_comba.o s_mp_mul_karatsuba.o s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o \
+s_mp_radix_map.o s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_slower_to_radix.o s_mp_sqr.o \
+s_mp_sqr_comba.o s_mp_sqr_karatsuba.o s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
 
 #END_INS
 

makefile.mingw

@@ -46,12 +46,12 @@ mp_reduce_setup.o mp_root_n.o mp_rshd.o mp_sbin_size.o mp_set.o mp_set_double.o
 mp_set_l.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_shrink.o mp_signed_rsh.o 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_copy_digs.o s_mp_div_3.o s_mp_div_recursive.o \
-s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod.o \
-s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o s_mp_montgomery_reduce_comba.o s_mp_mul.o \
-s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o s_mp_mul_high_comba.o s_mp_mul_karatsuba.o \
-s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o s_mp_radix_map.o \
-s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_sqr.o s_mp_sqr_comba.o s_mp_sqr_karatsuba.o \
-s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
+s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_faster_to_radix.o \
+s_mp_get_bit.o s_mp_invmod.o s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o \
+s_mp_montgomery_reduce_comba.o s_mp_mul.o s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o \
+s_mp_mul_high_comba.o s_mp_mul_karatsuba.o s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o \
+s_mp_radix_map.o s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_slower_to_radix.o s_mp_sqr.o \
+s_mp_sqr_comba.o s_mp_sqr_karatsuba.o s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
 
 HEADERS_PUB=tommath.h
 HEADERS=tommath_private.h tommath_class.h tommath_superclass.h tommath_cutoffs.h $(HEADERS_PUB)

makefile.msvc

@@ -42,12 +42,12 @@ mp_reduce_setup.obj mp_root_n.obj mp_rshd.obj mp_sbin_size.obj mp_set.obj mp_set
 mp_set_l.obj mp_set_u32.obj mp_set_u64.obj mp_set_ul.obj mp_shrink.obj mp_signed_rsh.obj 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_copy_digs.obj s_mp_div_3.obj s_mp_div_recursive.obj \
-s_mp_div_school.obj s_mp_div_small.obj s_mp_exptmod.obj s_mp_exptmod_fast.obj s_mp_get_bit.obj s_mp_invmod.obj \
-s_mp_invmod_odd.obj s_mp_log.obj s_mp_log_2expt.obj s_mp_log_d.obj s_mp_montgomery_reduce_comba.obj s_mp_mul.obj \
-s_mp_mul_balance.obj s_mp_mul_comba.obj s_mp_mul_high.obj s_mp_mul_high_comba.obj s_mp_mul_karatsuba.obj \
-s_mp_mul_toom.obj s_mp_prime_is_divisible.obj s_mp_prime_tab.obj s_mp_radix_map.obj \
-s_mp_radix_size_overestimate.obj s_mp_rand_platform.obj s_mp_sqr.obj s_mp_sqr_comba.obj s_mp_sqr_karatsuba.obj \
-s_mp_sqr_toom.obj s_mp_sub.obj s_mp_zero_buf.obj s_mp_zero_digs.obj
+s_mp_div_school.obj s_mp_div_small.obj s_mp_exptmod.obj s_mp_exptmod_fast.obj s_mp_faster_to_radix.obj \
+s_mp_get_bit.obj s_mp_invmod.obj s_mp_invmod_odd.obj s_mp_log.obj s_mp_log_2expt.obj s_mp_log_d.obj \
+s_mp_montgomery_reduce_comba.obj s_mp_mul.obj s_mp_mul_balance.obj s_mp_mul_comba.obj s_mp_mul_high.obj \
+s_mp_mul_high_comba.obj s_mp_mul_karatsuba.obj s_mp_mul_toom.obj s_mp_prime_is_divisible.obj s_mp_prime_tab.obj \
+s_mp_radix_map.obj s_mp_radix_size_overestimate.obj s_mp_rand_platform.obj s_mp_slower_to_radix.obj s_mp_sqr.obj \
+s_mp_sqr_comba.obj s_mp_sqr_karatsuba.obj s_mp_sqr_toom.obj s_mp_sub.obj s_mp_zero_buf.obj s_mp_zero_digs.obj
 
 HEADERS_PUB=tommath.h
 HEADERS=tommath_private.h tommath_class.h tommath_superclass.h tommath_cutoffs.h $(HEADERS_PUB)

makefile.shared

@@ -41,12 +41,12 @@ mp_reduce_setup.o mp_root_n.o mp_rshd.o mp_sbin_size.o mp_set.o mp_set_double.o
 mp_set_l.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_shrink.o mp_signed_rsh.o 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_copy_digs.o s_mp_div_3.o s_mp_div_recursive.o \
-s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod.o \
-s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o s_mp_montgomery_reduce_comba.o s_mp_mul.o \
-s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o s_mp_mul_high_comba.o s_mp_mul_karatsuba.o \
-s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o s_mp_radix_map.o \
-s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_sqr.o s_mp_sqr_comba.o s_mp_sqr_karatsuba.o \
-s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
+s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_faster_to_radix.o \
+s_mp_get_bit.o s_mp_invmod.o s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o \
+s_mp_montgomery_reduce_comba.o s_mp_mul.o s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o \
+s_mp_mul_high_comba.o s_mp_mul_karatsuba.o s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o \
+s_mp_radix_map.o s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_slower_to_radix.o s_mp_sqr.o \
+s_mp_sqr_comba.o s_mp_sqr_karatsuba.o s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
 
 #END_INS
 

makefile.unix

@@ -47,12 +47,12 @@ mp_reduce_setup.o mp_root_n.o mp_rshd.o mp_sbin_size.o mp_set.o mp_set_double.o
 mp_set_l.o mp_set_u32.o mp_set_u64.o mp_set_ul.o mp_shrink.o mp_signed_rsh.o 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_copy_digs.o s_mp_div_3.o s_mp_div_recursive.o \
-s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_get_bit.o s_mp_invmod.o \
-s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o s_mp_montgomery_reduce_comba.o s_mp_mul.o \
-s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o s_mp_mul_high_comba.o s_mp_mul_karatsuba.o \
-s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o s_mp_radix_map.o \
-s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_sqr.o s_mp_sqr_comba.o s_mp_sqr_karatsuba.o \
-s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
+s_mp_div_school.o s_mp_div_small.o s_mp_exptmod.o s_mp_exptmod_fast.o s_mp_faster_to_radix.o \
+s_mp_get_bit.o s_mp_invmod.o s_mp_invmod_odd.o s_mp_log.o s_mp_log_2expt.o s_mp_log_d.o \
+s_mp_montgomery_reduce_comba.o s_mp_mul.o s_mp_mul_balance.o s_mp_mul_comba.o s_mp_mul_high.o \
+s_mp_mul_high_comba.o s_mp_mul_karatsuba.o s_mp_mul_toom.o s_mp_prime_is_divisible.o s_mp_prime_tab.o \
+s_mp_radix_map.o s_mp_radix_size_overestimate.o s_mp_rand_platform.o s_mp_slower_to_radix.o s_mp_sqr.o \
+s_mp_sqr_comba.o s_mp_sqr_karatsuba.o s_mp_sqr_toom.o s_mp_sub.o s_mp_zero_buf.o s_mp_zero_digs.o
 
 
 HEADERS_PUB=tommath.h

mp_to_radix.c

@@ -3,29 +3,16 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-/* reverse an array, used for radix code */
-static void s_reverse(char *s, size_t len)
-{
-   size_t ix = 0, iy = len - 1u;
-   while (ix < iy) {
-      MP_EXCH(char, s[ix], s[iy]);
-      ++ix;
-      --iy;
-   }
-}
-
 /* stores a bignum as a ASCII string in a given radix (2..64)
  *
  * Stores upto "size - 1" chars and always a NULL byte, puts the number of characters
  * written, including the '\0', in "written".
  */
 mp_err mp_to_radix(const mp_int *a, char *str, size_t maxlen, size_t *written, int radix)
 {
-   size_t  digs;
-   mp_err  err;
-   mp_int  t;
-   mp_digit d;
-   char   *_s = str;
+   mp_err err;
+   mp_int a_bar = *a;
+   size_t part_written = 0;
 
    /* check range of radix and size*/
    if (maxlen < 2u) {
@@ -45,50 +32,36 @@ mp_err mp_to_radix(const mp_int *a, char *str, size_t maxlen, size_t *written, i
       return MP_OKAY;
    }
 
-   if ((err = mp_init_copy(&t, a)) != MP_OKAY) {
-      return err;
-   }
-
    /* if it is negative output a - */
-   if (mp_isneg(&t)) {
-      /* we have to reverse our digits later... but not the - sign!! */
-      ++_s;
-
+   if (mp_isneg(a)) {
       /* store the flag and mark the number as positive */
       *str++ = '-';
-      t.sign = MP_ZPOS;
+      a_bar.sign = MP_ZPOS;
 
       /* subtract a char */
       --maxlen;
    }
-   digs = 0u;
-   while (!mp_iszero(&t)) {
-      if (--maxlen < 1u) {
-         /* no more room */
-         err = MP_BUF;
-         goto LBL_ERR;
-      }
-      if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
-         goto LBL_ERR;
+
+   /* TODO: check if it can be done better */
+   if (MP_HAS(S_MP_FASTER_TO_RADIX)) {
+      if ((err = s_mp_faster_to_radix(&a_bar, str, maxlen, &part_written, radix)) != MP_OKAY)            goto LBL_ERR;
+   } else {
+      if (MP_HAS(S_MP_SLOWER_TO_RADIX)) {
+         if ((err = s_mp_slower_to_radix(&a_bar, &str, &maxlen, &part_written, radix, false)) != MP_OKAY) goto LBL_ERR;
+         /* part_written does not count EOS */
+         part_written++;
       }
-      *str++ = s_mp_radix_map[d];
-      ++digs;
    }
-   /* reverse the digits of the string.  In this case _s points
-    * to the first digit [excluding the sign] of the number
-    */
-   s_reverse(_s, digs);
 
-   /* append a NULL so the string is properly terminated */
-   *str = '\0';
-   digs++;
+   /* TODO: Think about adding a function for base-2 radices only although
+            s_faster_to_radix is rather quick with such radices. */
 
    if (written != NULL) {
-      *written = mp_isneg(a) ? (digs + 1u): digs;
+      part_written += mp_isneg(a) ? 1: 0;
+      *written = part_written;
    }
 
 LBL_ERR:
-   mp_clear(&t);
    return err;
 }