c3-lang/libtommath

diff --git a/bn_mp_ilogb.c b/bn_mp_ilogb.c
new file mode 100644
index 0000000..dca0f99
--- /dev/null
+++ b/bn_mp_ilogb.c
@@ -0,0 +1,183 @@
+#include "tommath_private.h"
+#ifdef BN_MP_ILOGB_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+/* Compute log_{base}(a) */
+static mp_word s_pow(mp_word base, mp_word exponent)
+{
+   mp_word result = 1uLL;
+   while (exponent) {
+      if ((exponent & 0x1) == 1) {
+         result *= base;
+      }
+      exponent >>= 1;
+      base *= base;
+   }
+
+   return result;
+}
+
+static mp_digit s_digit_ilogb(mp_digit base, mp_digit n)
+{
+   mp_word bracket_low = 1uLL, bracket_mid, bracket_high, N;
+   mp_digit ret, high = 1uL, low = 0uL, mid;
+
+   if (n < base) {
+      return (mp_digit)0uL;
+   }
+   if (n == base) {
+      return (mp_digit)1uL;
+   }
+
+   bracket_high = (mp_word) base ;
+   N = (mp_word) n;
+
+   while (bracket_high < N) {
+      low = high;
+      bracket_low = bracket_high;
+      high <<= 1;
+      bracket_high *= bracket_high;
+   }
+
+   while (((mp_digit)(high - low)) > 1uL) {
+      mid = (low + high) >> 1;
+      bracket_mid = bracket_low * s_pow(base, mid - low) ;
+
+      if (N < bracket_mid) {
+         high = mid ;
+         bracket_high = bracket_mid ;
+      }
+      if (N > bracket_mid) {
+         low = mid ;
+         bracket_low = bracket_mid ;
+      }
+      if (N == bracket_mid) {
+         return (mp_digit) mid;
+      }
+   }
+
+   if (bracket_high == N) {
+      ret = high;
+   } else {
+      ret = low;
+   }
+
+   return ret;
+}
+
+/* TODO: output could be "int" because the output of mp_radix_size is int, too,
+         as is the output of mp_bitcount.
+         With the same problem: max size is INT_MAX * MP_DIGIT not INT_MAX only!
+*/
+int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
+{
+   int err, cmp;
+   unsigned int high, low, mid;
+   mp_int bracket_low, bracket_high, bracket_mid, t, bi_base;
+   mp_digit tmp;
+
+   err = MP_OKAY;
+   if (a->sign == MP_NEG) {
+      return MP_VAL;
+   }
+   if (IS_ZERO(a)) {
+      return MP_VAL;
+   }
+
+   if (base < 2) {
+      return MP_VAL;
+   } else if (base == 2) {
+      cmp = mp_count_bits(a) - 1;
+      mp_set_int(c, (unsigned long)cmp);
+      return err;
+   } else if (a->used == 1) {
+      tmp = s_digit_ilogb(base, a->dp[0]);
+      mp_set(c, tmp);
+      return err;
+   }
+
+
+   cmp = mp_cmp_d(a, base);
+
+   if (cmp == MP_LT) {
+      mp_zero(c);
+      return err;
+   } else if (cmp == MP_EQ) {
+      mp_set(c, (mp_digit)1uL);
+      return err;
+   }
+
+   if ((err =
+           mp_init_multi(&bracket_low, &bracket_high,
+                         &bracket_mid, &t, &bi_base, NULL)) != MP_OKAY) {
+      return err;
+   }
+
+   low = 0uL;
+   mp_set(&bracket_low, 1uL);
+   high = 1uL;
+
+   mp_set(&bracket_high, base);
+
+   /*
+       A kind of Giant-step/baby-step algorithm.
+       Idea shamelessly stolen from https://programmingpraxis.com/2010/05/07/integer-logarithms/2/
+       The effect is asymptotic, hence needs benchmarks to test if the Giant-step should be skipped
+       for small n.
+    */
+   while (mp_cmp(&bracket_high, a) == MP_LT) {
+      low = high;
+      if ((err = mp_copy(&bracket_high, &bracket_low)) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      high <<= 1;
+      if ((err = mp_sqr(&bracket_high, &bracket_high)) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+   }
+   mp_set(&bi_base, base);
+
+   while ((high - low) > 1) {
+      mid = (high + low) >> 1;
+      /* Difference can be larger then the type behind mp_digit can hold */
+      if ((mid - low) > (unsigned int)(MP_MASK)) {
+         err = MP_VAL;
+         goto LBL_ERR;
+      }
+      if ((err = mp_expt_d(&bi_base, (mid - low), &t)) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      if ((err = mp_mul(&bracket_low, &t, &bracket_mid)) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      cmp = mp_cmp(a, &bracket_mid);
+      if (cmp == MP_LT) {
+         high = mid;
+         mp_exch(&bracket_mid, &bracket_high);
+      }
+      if (cmp == MP_GT) {
+         low = mid;
+         mp_exch(&bracket_mid, &bracket_low);
+      }
+      if (cmp == MP_EQ) {
+         mp_set_int(c, (unsigned long)mid);
+         goto LBL_END;
+      }
+   }
+
+   if (mp_cmp(&bracket_high, a) == MP_EQ) {
+      mp_set_int(c, (unsigned long)high);
+   } else {
+      mp_set_int(c, (unsigned long)low);
+   }
+
+LBL_END:
+LBL_ERR:
+   mp_clear_multi(&bracket_low, &bracket_high, &bracket_mid,
+                  &t, &bi_base, NULL);
+   return err;
+}
+
+
+#endif
diff --git a/callgraph.txt b/callgraph.txt
index eeeea13..2f405b9 100644
--- a/callgraph.txt
+++ b/callgraph.txt
@@ -2616,6 +2616,290 @@ BN_MP_GET_LONG_LONG_C
 BN_MP_GROW_C
 
 
+BN_MP_ILOGB_C
++--->BN_MP_RADIX_SIZE_C
+|   +--->BN_MP_COUNT_BITS_C
+|   +--->BN_MP_INIT_COPY_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   +--->BN_MP_COPY_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_CLEAR_C
+|   +--->BN_MP_DIV_D_C
+|   |   +--->BN_MP_COPY_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_DIV_2D_C
+|   |   |   +--->BN_MP_ZERO_C
+|   |   |   +--->BN_MP_MOD_2D_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_RSHD_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_DIV_3_C
+|   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_EXCH_C
+|   |   |   +--->BN_MP_CLEAR_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_EXCH_C
+|   |   +--->BN_MP_CLEAR_C
+|   +--->BN_MP_CLEAR_C
++--->BN_MP_COUNT_BITS_C
++--->BN_MP_SET_INT_C
+|   +--->BN_MP_SET_LONG_C
++--->BN_MP_SET_C
+|   +--->BN_MP_ZERO_C
++--->BN_MP_CMP_D_C
++--->BN_MP_ZERO_C
++--->BN_MP_INIT_MULTI_C
+|   +--->BN_MP_INIT_C
+|   +--->BN_MP_CLEAR_C
++--->BN_MP_CMP_C
+|   +--->BN_MP_CMP_MAG_C
++--->BN_MP_COPY_C
+|   +--->BN_MP_GROW_C
++--->BN_MP_SQR_C
+|   +--->BN_MP_TOOM_SQR_C
+|   |   +--->BN_MP_MOD_2D_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_RSHD_C
+|   |   +--->BN_MP_MUL_2_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_ADD_C
+|   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_SUB_C
+|   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_DIV_2_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_MUL_2D_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_MUL_D_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_DIV_3_C
+|   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   |   +--->BN_MP_INIT_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_EXCH_C
+|   |   |   +--->BN_MP_CLEAR_C
+|   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_CLEAR_MULTI_C
+|   |   |   +--->BN_MP_CLEAR_C
+|   +--->BN_MP_KARATSUBA_SQR_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_INIT_C
+|   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_S_MP_ADD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_S_MP_SUB_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_RSHD_C
+|   |   +--->BN_MP_ADD_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   +--->BN_MP_CLEAR_C
+|   +--->BN_FAST_S_MP_SQR_C
+|   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_CLAMP_C
+|   +--->BN_S_MP_SQR_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_INIT_C
+|   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_EXCH_C
+|   |   +--->BN_MP_CLEAR_C
++--->BN_MP_EXPT_D_C
+|   +--->BN_MP_EXPT_D_EX_C
+|   |   +--->BN_MP_INIT_COPY_C
+|   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_CLEAR_C
+|   |   +--->BN_MP_MUL_C
+|   |   |   +--->BN_FAST_S_MP_MUL_DIGS_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_BALANCE_MUL_C
+|   |   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   |   +--->BN_MP_CLEAR_C
+|   |   |   |   +--->BN_MP_LSHD_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   +--->BN_MP_RSHD_C
+|   |   |   |   +--->BN_MP_ADD_C
+|   |   |   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_EXCH_C
+|   |   |   |   +--->BN_MP_CLEAR_MULTI_C
+|   |   |   +--->BN_MP_TOOM_MUL_C
+|   |   |   |   +--->BN_MP_MOD_2D_C
+|   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_RSHD_C
+|   |   |   |   +--->BN_MP_MUL_2_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_ADD_C
+|   |   |   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_SUB_C
+|   |   |   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_DIV_2_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_MUL_2D_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   +--->BN_MP_LSHD_C
+|   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_MUL_D_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_DIV_3_C
+|   |   |   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   |   +--->BN_MP_EXCH_C
+|   |   |   |   |   +--->BN_MP_CLEAR_C
+|   |   |   |   +--->BN_MP_LSHD_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLEAR_MULTI_C
+|   |   |   |   |   +--->BN_MP_CLEAR_C
+|   |   |   +--->BN_MP_KARATSUBA_MUL_C
+|   |   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_ADD_C
+|   |   |   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_LSHD_C
+|   |   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   |   +--->BN_MP_RSHD_C
+|   |   |   |   +--->BN_MP_CLEAR_C
+|   |   |   +--->BN_S_MP_MUL_DIGS_C
+|   |   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   |   +--->BN_MP_EXCH_C
+|   |   |   |   +--->BN_MP_CLEAR_C
+|   |   +--->BN_MP_CLEAR_C
++--->BN_MP_MUL_C
+|   +--->BN_FAST_S_MP_MUL_DIGS_C
+|   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_CLAMP_C
+|   +--->BN_MP_BALANCE_MUL_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_INIT_C
+|   |   +--->BN_MP_CLEAR_C
+|   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_RSHD_C
+|   |   +--->BN_MP_ADD_C
+|   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_EXCH_C
+|   |   +--->BN_MP_CLEAR_MULTI_C
+|   +--->BN_MP_TOOM_MUL_C
+|   |   +--->BN_MP_MOD_2D_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_RSHD_C
+|   |   +--->BN_MP_MUL_2_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_ADD_C
+|   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_SUB_C
+|   |   |   +--->BN_S_MP_ADD_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_DIV_2_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_MUL_2D_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_MUL_D_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_DIV_3_C
+|   |   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   |   +--->BN_MP_INIT_C
+|   |   |   +--->BN_MP_CLAMP_C
+|   |   |   +--->BN_MP_EXCH_C
+|   |   |   +--->BN_MP_CLEAR_C
+|   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_CLEAR_MULTI_C
+|   |   |   +--->BN_MP_CLEAR_C
+|   +--->BN_MP_KARATSUBA_MUL_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_INIT_C
+|   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_S_MP_ADD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_ADD_C
+|   |   |   +--->BN_MP_CMP_MAG_C
+|   |   |   +--->BN_S_MP_SUB_C
+|   |   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_S_MP_SUB_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   +--->BN_MP_LSHD_C
+|   |   |   +--->BN_MP_GROW_C
+|   |   |   +--->BN_MP_RSHD_C
+|   |   +--->BN_MP_CLEAR_C
+|   +--->BN_S_MP_MUL_DIGS_C
+|   |   +--->BN_MP_INIT_SIZE_C
+|   |   |   +--->BN_MP_INIT_C
+|   |   +--->BN_MP_CLAMP_C
+|   |   +--->BN_MP_EXCH_C
+|   |   +--->BN_MP_CLEAR_C
++--->BN_MP_EXCH_C
++--->BN_MP_CLEAR_MULTI_C
+|   +--->BN_MP_CLEAR_C
+
+
 BN_MP_IMPORT_C
 +--->BN_MP_ZERO_C
 +--->BN_MP_MUL_2D_C
diff --git a/demo/test.c b/demo/test.c
index 3c61ff5..cb30580 100644
--- a/demo/test.c
+++ b/demo/test.c
@@ -1229,6 +1229,168 @@ LBL_ERR:
    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  */
+static int s_rs(const mp_int *a, int radix, int *size)
+{
+   int     res, digs = 0;
+   mp_int  t;
+   mp_digit d;
+   *size = 0;
+   if (mp_iszero(a) == MP_YES) {
+      *size = 2;
+      return MP_OKAY;
+   }
+   if (radix == 2) {
+      *size = mp_count_bits(a) + 1;
+      return MP_OKAY;
+   }
+   if ((res = mp_init_copy(&t, a)) != MP_OKAY) {
+      return res;
+   }
+   t.sign = MP_ZPOS;
+   while (mp_iszero(&t) == MP_NO) {
+      if ((res = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
+         mp_clear(&t);
+         return res;
+      }
+      ++digs;
+   }
+   mp_clear(&t);
+   *size = digs + 1;
+   return MP_OKAY;
+}
+static int test_mp_ilogb(void)
+{
+   mp_int a, lb;
+   mp_digit d, base;
+   int size;
+
+   if (mp_init_multi(&a, &lb, NULL) != MP_OKAY) {
+      goto LBL_ERR;
+   }
+
+   /*
+     base   a    result
+      0     x    MP_VAL
+      1     x    MP_VAL
+   */
+   mp_set(&a, 42uL);
+   base = 0uL;
+   if (mp_ilogb(&a, base, &lb) != MP_VAL) {
+      goto LBL_ERR;
+   }
+   base = 1uL;
+   if (mp_ilogb(&a, base, &lb) != MP_VAL) {
+      goto LBL_ERR;
+   }
+   /*
+     base   a    result
+      2     0    MP_VAL
+      2     1    0
+      2     2    1
+      2     3    1
+   */
+   base = 2uL;
+   mp_zero(&a);
+   if (mp_ilogb(&a, base, &lb) != MP_VAL) {
+      goto LBL_ERR;
+   }
+
+   for (d = 1; d < 4; d++) {
+      mp_set(&a, d);
+      if (mp_ilogb(&a, base, &lb) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      if (mp_cmp_d(&lb, (d == 1)?0uL:1uL) != MP_EQ) {
+         goto LBL_ERR;
+      }
+   }
+   /*
+    base   a    result
+     3     0    MP_VAL
+     3     1    0
+     3     2    0
+     3     3    1
+   */
+   base = 3uL;
+   mp_zero(&a);
+   if (mp_ilogb(&a, base, &lb) != MP_VAL) {
+      goto LBL_ERR;
+   }
+   for (d = 1; d < 4; d++) {
+      mp_set(&a, d);
+      if (mp_ilogb(&a, base, &lb) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      if (mp_cmp_d(&lb, (d < base)?0uL:1uL) != MP_EQ) {
+         goto LBL_ERR;
+      }
+   }
+
+   /*
+     bases 2..64 with "a" a random large constant.
+     The range of bases tested allows to check with
+     radix_size.
+   */
+   if (mp_rand(&a, 10) != MP_OKAY) {
+      goto LBL_ERR;
+   }
+   for (base = 2uL; base < 65uL; base++) {
+      if (mp_ilogb(&a, base, &lb) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      if (s_rs(&a,(int)base, &size) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      /* radix_size includes the memory needed for '\0', too*/
+      size -= 2;
+      if (mp_cmp_d(&lb, size) != MP_EQ) {
+         goto LBL_ERR;
+      }
+   }
+
+   /*
+     bases 2..64 with "a" a random small constant to
+     test the part of mp_ilogb that uses native types.
+   */
+   if (mp_rand(&a, 1) != MP_OKAY) {
+      goto LBL_ERR;
+   }
+   for (base = 2uL; base < 65uL; base++) {
+      if (mp_ilogb(&a, base, &lb) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      if (s_rs(&a,(int)base, &size) != MP_OKAY) {
+         goto LBL_ERR;
+      }
+      size -= 2;
+      if (mp_cmp_d(&lb, size) != MP_EQ) {
+         goto LBL_ERR;
+      }
+   }
+
+   /*Test upper edgecase with base MP_MASK and number (MP_MASK/2)*MP_MASK^10  */
+   mp_set(&a, MP_MASK);
+   if (mp_expt_d(&a, 10uL, &a) != MP_OKAY) {
+      goto LBL_ERR;
+   }
+   if (mp_add_d(&a, (MP_MASK>>1), &a) != MP_OKAY) {
+      goto LBL_ERR;
+   }
+   if (mp_ilogb(&a, MP_MASK, &lb) != MP_OKAY) {
+      goto LBL_ERR;
+   }
+   if (mp_cmp_d(&lb, 10uL) != MP_EQ) {
+      goto LBL_ERR;
+   }
+
+   mp_clear_multi(&a, &lb, NULL);
+   return EXIT_SUCCESS;
+LBL_ERR:
+   mp_clear_multi(&a, &lb, NULL);
+   return EXIT_FAILURE;
+}
 
 static int test_mp_incr(void)
 {
@@ -1678,7 +1840,8 @@ int unit_tests(void)
       T(mp_tc_xor),
       T(mp_incr),
       T(mp_decr),
-      T(mp_balance_mul)
+      T(mp_balance_mul),
+      T(mp_ilogb)
 #undef T
    };
    unsigned long i;
diff --git a/doc/bn.tex b/doc/bn.tex
index c83b2e3..197f4fa 100644
--- a/doc/bn.tex
+++ b/doc/bn.tex
@@ -1844,6 +1844,71 @@ int mp_sqrt (mp_int * a, mp_digit b, mp_int * c)
 \end{alltt}
 
 
+\chapter{Logarithm}
+\section{Integer Logarithm}
+A logarithm function for positive integer input \texttt{a, base} computing  $\floor{\log_bx}$ such that $(\ilog_bx)^b \le x$.
+\index{mp\_ilogb}
+\begin{alltt}
+int mp_ilogb(mp_int *a, mp_digit base, mp_int *c)
+\end{alltt}
+\subsection{Example}
+\begin{alltt}
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+
+#include <tommath.h>
+
+int main(int argc, char **argv)
+{
+   mp_int x, output;
+   mp_digit base;
+   int e;
+
+   if (argc != 3) {
+      fprintf(stderr,"Usage %s base x\textbackslash{}n", argv[0]);
+      exit(EXIT_FAILURE);
+   }
+   if ((e = mp_init_multi(&x, &output, NULL)) != MP_OKAY) {
+      fprintf(stderr,"mp_init failed: \textbackslash{}"%s\textbackslash{}"\textbackslash{}n",
+                     mp_error_to_string(e));
+              exit(EXIT_FAILURE);
+   }
+   errno = 0;
+#ifdef MP_64BIT
+   base = (mp_digit)strtoull(argv[1], NULL, 10);
+#else
+   base = (mp_digit)strtoul(argv[1], NULL, 10);
+#endif
+   if ((errno == ERANGE) || (base > (base & MP_MASK))) {
+      fprintf(stderr,"strtoul(l) failed: input out of range\textbackslash{}n");
+      exit(EXIT_FAILURE);
+   }
+   if ((e = mp_read_radix(&x, argv[2], 10)) != MP_OKAY) {
+      fprintf(stderr,"mp_read_radix failed: \textbackslash{}"%s\textbackslash{}"\textbackslash{}n",
+                      mp_error_to_string(e));
+      exit(EXIT_FAILURE);
+   }
+   if ((e = mp_ilogb(&x, base, &output)) != MP_OKAY) {
+      fprintf(stderr,"mp_ilogb failed: \textbackslash{}"%s\textbackslash{}"\textbackslash{}n",
+                      mp_error_to_string(e));
+      exit(EXIT_FAILURE);
+   }
+
+   if ((e = mp_fwrite(&output, 10, stdout)) != MP_OKAY) {
+      fprintf(stderr,"mp_fwrite failed: \textbackslash{}"%s\textbackslash{}"\textbackslash{}n",
+                      mp_error_to_string(e));
+      exit(EXIT_FAILURE);
+   }
+   putchar('\textbackslash{}n');
+
+   mp_clear_multi(&x, &output, NULL);
+   exit(EXIT_SUCCESS);
+}
+\end{alltt}
+
+
+
 \chapter{Prime Numbers}
 \section{Trial Division}
 \index{mp\_prime\_is\_divisible}
diff --git a/libtommath_VS2008.vcproj b/libtommath_VS2008.vcproj
index 69bce87..3623e2f 100644
--- a/libtommath_VS2008.vcproj
+++ b/libtommath_VS2008.vcproj
@@ -505,6 +505,10 @@
 			>
 		</File>
 		<File
+			RelativePath="bn_mp_ilogb.c"
+			>
+		</File>
+		<File
 			RelativePath="bn_mp_import.c"
 			>
 		</File>
diff --git a/makefile b/makefile
index 4ca43ec..a19d5bd 100644
--- a/makefile
+++ b/makefile
@@ -34,19 +34,19 @@ 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.
 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 \
-bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o bn_mp_read_unsigned_bin.o bn_mp_reduce.o \
-bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o bn_mp_reduce_2k_setup_l.o \
-bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o bn_mp_set.o \
-bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
+bn_mp_ilogb.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 bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o \
+bn_mp_read_unsigned_bin.o bn_mp_reduce.o bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o \
+bn_mp_reduce_2k_setup_l.o bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o \
+bn_mp_set.o bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
 bn_mp_signed_bin_size.o bn_mp_sqr.o bn_mp_sqrmod.o bn_mp_sqrt.o bn_mp_sqrtmod_prime.o bn_mp_sub.o \
 bn_mp_sub_d.o bn_mp_submod.o bn_mp_tc_and.o bn_mp_tc_div_2d.o bn_mp_tc_or.o bn_mp_tc_xor.o \
 bn_mp_to_signed_bin.o bn_mp_to_signed_bin_n.o bn_mp_to_unsigned_bin.o bn_mp_to_unsigned_bin_n.o \
diff --git a/makefile.mingw b/makefile.mingw
index bb2552d..945bf88 100644
--- a/makefile.mingw
+++ b/makefile.mingw
@@ -37,19 +37,19 @@ 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.
 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 \
-bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o bn_mp_read_unsigned_bin.o bn_mp_reduce.o \
-bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o bn_mp_reduce_2k_setup_l.o \
-bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o bn_mp_set.o \
-bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
+bn_mp_ilogb.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 bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o \
+bn_mp_read_unsigned_bin.o bn_mp_reduce.o bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o \
+bn_mp_reduce_2k_setup_l.o bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o \
+bn_mp_set.o bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
 bn_mp_signed_bin_size.o bn_mp_sqr.o bn_mp_sqrmod.o bn_mp_sqrt.o bn_mp_sqrtmod_prime.o bn_mp_sub.o \
 bn_mp_sub_d.o bn_mp_submod.o bn_mp_tc_and.o bn_mp_tc_div_2d.o bn_mp_tc_or.o bn_mp_tc_xor.o \
 bn_mp_to_signed_bin.o bn_mp_to_signed_bin_n.o bn_mp_to_unsigned_bin.o bn_mp_to_unsigned_bin_n.o \
diff --git a/makefile.msvc b/makefile.msvc
index 43f1c6d..775857b 100644
--- a/makefile.msvc
+++ b/makefile.msvc
@@ -29,19 +29,19 @@ bn_mp_decr.obj bn_mp_div.obj bn_mp_div_2.obj bn_mp_div_2d.obj bn_mp_div_3.obj bn
 bn_mp_dr_reduce.obj bn_mp_dr_setup.obj bn_mp_exch.obj bn_mp_export.obj bn_mp_expt_d.obj bn_mp_expt_d_ex.obj \
 bn_mp_exptmod.obj bn_mp_exptmod_fast.obj bn_mp_exteuclid.obj bn_mp_fread.obj bn_mp_fwrite.obj bn_mp_gcd.obj \
 bn_mp_get_bit.obj bn_mp_get_double.obj bn_mp_get_int.obj bn_mp_get_long.obj bn_mp_get_long_long.obj bn_mp_grow.obj \
-bn_mp_import.obj bn_mp_incr.obj bn_mp_init.obj bn_mp_init_copy.obj bn_mp_init_multi.obj bn_mp_init_set.obj \
-bn_mp_init_set_int.obj bn_mp_init_size.obj bn_mp_invmod.obj bn_mp_invmod_slow.obj bn_mp_is_square.obj \
-bn_mp_iseven.obj bn_mp_isodd.obj bn_mp_jacobi.obj bn_mp_karatsuba_mul.obj bn_mp_karatsuba_sqr.obj bn_mp_kronecker.obj \
-bn_mp_lcm.obj bn_mp_lshd.obj bn_mp_mod.obj bn_mp_mod_2d.obj bn_mp_mod_d.obj bn_mp_montgomery_calc_normalization.obj \
-bn_mp_montgomery_reduce.obj bn_mp_montgomery_setup.obj bn_mp_mul.obj bn_mp_mul_2.obj bn_mp_mul_2d.obj bn_mp_mul_d.obj \
-bn_mp_mulmod.obj bn_mp_n_root.obj bn_mp_n_root_ex.obj bn_mp_neg.obj bn_mp_or.obj bn_mp_prime_fermat.obj \
-bn_mp_prime_frobenius_underwood.obj bn_mp_prime_is_divisible.obj bn_mp_prime_is_prime.obj \
-bn_mp_prime_miller_rabin.obj bn_mp_prime_next_prime.obj bn_mp_prime_rabin_miller_trials.obj \
-bn_mp_prime_random_ex.obj bn_mp_prime_strong_lucas_selfridge.obj bn_mp_radix_size.obj bn_mp_radix_smap.obj \
-bn_mp_rand.obj bn_mp_read_radix.obj bn_mp_read_signed_bin.obj bn_mp_read_unsigned_bin.obj bn_mp_reduce.obj \
-bn_mp_reduce_2k.obj bn_mp_reduce_2k_l.obj bn_mp_reduce_2k_setup.obj bn_mp_reduce_2k_setup_l.obj \
-bn_mp_reduce_is_2k.obj bn_mp_reduce_is_2k_l.obj bn_mp_reduce_setup.obj bn_mp_rshd.obj bn_mp_set.obj \
-bn_mp_set_double.obj bn_mp_set_int.obj bn_mp_set_long.obj bn_mp_set_long_long.obj bn_mp_shrink.obj \
+bn_mp_ilogb.obj bn_mp_import.obj bn_mp_incr.obj bn_mp_init.obj bn_mp_init_copy.obj bn_mp_init_multi.obj \
+bn_mp_init_set.obj bn_mp_init_set_int.obj bn_mp_init_size.obj bn_mp_invmod.obj bn_mp_invmod_slow.obj \
+bn_mp_is_square.obj bn_mp_iseven.obj bn_mp_isodd.obj bn_mp_jacobi.obj bn_mp_karatsuba_mul.obj bn_mp_karatsuba_sqr.obj \
+bn_mp_kronecker.obj bn_mp_lcm.obj bn_mp_lshd.obj bn_mp_mod.obj bn_mp_mod_2d.obj bn_mp_mod_d.obj \
+bn_mp_montgomery_calc_normalization.obj bn_mp_montgomery_reduce.obj bn_mp_montgomery_setup.obj bn_mp_mul.obj \
+bn_mp_mul_2.obj bn_mp_mul_2d.obj bn_mp_mul_d.obj bn_mp_mulmod.obj bn_mp_n_root.obj bn_mp_n_root_ex.obj bn_mp_neg.obj \
+bn_mp_or.obj bn_mp_prime_fermat.obj bn_mp_prime_frobenius_underwood.obj bn_mp_prime_is_divisible.obj \
+bn_mp_prime_is_prime.obj bn_mp_prime_miller_rabin.obj bn_mp_prime_next_prime.obj \
+bn_mp_prime_rabin_miller_trials.obj bn_mp_prime_random_ex.obj bn_mp_prime_strong_lucas_selfridge.obj \
+bn_mp_radix_size.obj bn_mp_radix_smap.obj bn_mp_rand.obj bn_mp_read_radix.obj bn_mp_read_signed_bin.obj \
+bn_mp_read_unsigned_bin.obj bn_mp_reduce.obj bn_mp_reduce_2k.obj bn_mp_reduce_2k_l.obj bn_mp_reduce_2k_setup.obj \
+bn_mp_reduce_2k_setup_l.obj bn_mp_reduce_is_2k.obj bn_mp_reduce_is_2k_l.obj bn_mp_reduce_setup.obj bn_mp_rshd.obj \
+bn_mp_set.obj bn_mp_set_double.obj bn_mp_set_int.obj bn_mp_set_long.obj bn_mp_set_long_long.obj bn_mp_shrink.obj \
 bn_mp_signed_bin_size.obj bn_mp_sqr.obj bn_mp_sqrmod.obj bn_mp_sqrt.obj bn_mp_sqrtmod_prime.obj bn_mp_sub.obj \
 bn_mp_sub_d.obj bn_mp_submod.obj bn_mp_tc_and.obj bn_mp_tc_div_2d.obj bn_mp_tc_or.obj bn_mp_tc_xor.obj \
 bn_mp_to_signed_bin.obj bn_mp_to_signed_bin_n.obj bn_mp_to_unsigned_bin.obj bn_mp_to_unsigned_bin_n.obj \
diff --git a/makefile.shared b/makefile.shared
index 012cd5b..7604d60 100644
--- a/makefile.shared
+++ b/makefile.shared
@@ -31,19 +31,19 @@ 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.
 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 \
-bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o bn_mp_read_unsigned_bin.o bn_mp_reduce.o \
-bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o bn_mp_reduce_2k_setup_l.o \
-bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o bn_mp_set.o \
-bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
+bn_mp_ilogb.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 bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o \
+bn_mp_read_unsigned_bin.o bn_mp_reduce.o bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o \
+bn_mp_reduce_2k_setup_l.o bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o \
+bn_mp_set.o bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
 bn_mp_signed_bin_size.o bn_mp_sqr.o bn_mp_sqrmod.o bn_mp_sqrt.o bn_mp_sqrtmod_prime.o bn_mp_sub.o \
 bn_mp_sub_d.o bn_mp_submod.o bn_mp_tc_and.o bn_mp_tc_div_2d.o bn_mp_tc_or.o bn_mp_tc_xor.o \
 bn_mp_to_signed_bin.o bn_mp_to_signed_bin_n.o bn_mp_to_unsigned_bin.o bn_mp_to_unsigned_bin_n.o \
diff --git a/makefile.unix b/makefile.unix
index 856e18c..06c9691 100644
--- a/makefile.unix
+++ b/makefile.unix
@@ -38,19 +38,19 @@ 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.
 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 \
-bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o bn_mp_read_unsigned_bin.o bn_mp_reduce.o \
-bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o bn_mp_reduce_2k_setup_l.o \
-bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o bn_mp_set.o \
-bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
+bn_mp_ilogb.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 bn_mp_rand.o bn_mp_read_radix.o bn_mp_read_signed_bin.o \
+bn_mp_read_unsigned_bin.o bn_mp_reduce.o bn_mp_reduce_2k.o bn_mp_reduce_2k_l.o bn_mp_reduce_2k_setup.o \
+bn_mp_reduce_2k_setup_l.o bn_mp_reduce_is_2k.o bn_mp_reduce_is_2k_l.o bn_mp_reduce_setup.o bn_mp_rshd.o \
+bn_mp_set.o bn_mp_set_double.o bn_mp_set_int.o bn_mp_set_long.o bn_mp_set_long_long.o bn_mp_shrink.o \
 bn_mp_signed_bin_size.o bn_mp_sqr.o bn_mp_sqrmod.o bn_mp_sqrt.o bn_mp_sqrtmod_prime.o bn_mp_sub.o \
 bn_mp_sub_d.o bn_mp_submod.o bn_mp_tc_and.o bn_mp_tc_div_2d.o bn_mp_tc_or.o bn_mp_tc_xor.o \
 bn_mp_to_signed_bin.o bn_mp_to_signed_bin_n.o bn_mp_to_unsigned_bin.o bn_mp_to_unsigned_bin_n.o \
diff --git a/tommath.h b/tommath.h
index 41c9ec0..b817117 100644
--- a/tommath.h
+++ b/tommath.h
@@ -567,6 +567,11 @@ int mp_prime_next_prime(mp_int *a, int t, int bbs_style);
  */
 int mp_prime_random_ex(mp_int *a, int t, int size, int flags, ltm_prime_callback cb, void *dat);
 
+
+/* Integer logarithm to integer base */
+int mp_ilogb(mp_int *a, mp_digit base, mp_int *c);
+
+
 /* ---> radix conversion <--- */
 int mp_count_bits(const mp_int *a);
 
diff --git a/tommath_class.h b/tommath_class.h
index 56a6cf2..a0bce2c 100644
--- a/tommath_class.h
+++ b/tommath_class.h
@@ -58,6 +58,7 @@
 #   define BN_MP_GET_LONG_C
 #   define BN_MP_GET_LONG_LONG_C
 #   define BN_MP_GROW_C
+#   define BN_MP_ILOGB_C
 #   define BN_MP_IMPORT_C
 #   define BN_MP_INCR_C
 #   define BN_MP_INIT_C
@@ -466,6 +467,24 @@
 #if defined(BN_MP_GROW_C)
 #endif
 
+#if defined(BN_MP_ILOGB_C)
+#   define BN_MP_RADIX_SIZE_C
+#   define BN_MP_BITCOUNT_C
+#   define BN_MP_COUNT_BITS_C
+#   define BN_MP_SET_INT_C
+#   define BN_MP_SET_C
+#   define BN_MP_CMP_D_C
+#   define BN_MP_ZERO_C
+#   define BN_MP_INIT_MULTI_C
+#   define BN_MP_CMP_C
+#   define BN_MP_COPY_C
+#   define BN_MP_SQR_C
+#   define BN_MP_EXPT_D_C
+#   define BN_MP_MUL_C
+#   define BN_MP_EXCH_C
+#   define BN_MP_CLEAR_MULTI_C
+#endif
+
 #if defined(BN_MP_IMPORT_C)
 #   define BN_MP_ZERO_C
 #   define BN_MP_MUL_2D_C