New and expanded log n

.gitignore

@@ -85,6 +85,16 @@ etc/tune
 tommath.tex
 libtommath.pc
 
+# ignore files generated by bibtex/biber
+83aea75e0c59d1de027747003151d53dcb2a51c9.bib
+*.bbl
+*.bcf
+*.blg
+*.loa
+*.lol
+*.run.xml
+
+
 # ignore files generated by testme.sh
 gcc_errors_*.txt
 test_*.txt

demo/test.c

@@ -1383,6 +1383,70 @@ static int test_mp_log_n(void)
    return EXIT_FAILURE;
 }
 
+static int test_mp_log(void)
+{
+   mp_int a, base, bn, t;
+   int lb, lb2, i, j;
+
+   DOR(mp_init_multi(&a, &base, &bn, &t, NULL));
+
+   /*
+      The small values got tested above for mp_log_n already, leaving the big stuff
+      with bases larger than INT_MAX.
+   */
+
+   /* Edgecases a^b and -1+a^b (floor(log_2(256^129)) = 1032) */
+   for (i = 2; i < 256; i++) {
+      mp_set_i32(&a,i);
+      for (j = 2; j < ((i/2)+1); j++) {
+         DO(mp_expt_n(&a, j, &bn));
+         mp_set_i32(&base,j);
+         /* i^j a perfect power */
+         DO(mp_log(&bn, &a, &lb));
+         DO(mp_expt_n(&a, lb, &t));
+         if (mp_cmp(&t, &bn) != MP_EQ) {
+            fprintf(stderr,"FAILURE mp_log for perf. power at i = %d, j = %d\n", i, j);
+            goto LBL_ERR;
+         }
+         /* -1 + i^j */
+         DO(mp_decr(&bn));
+         DO(mp_log(&bn, &a, &lb2));
+         if (lb != (lb2+1)) {
+            fprintf(stderr,"FAILURE mp_log for -1 + i^j at i = %d, j = %d\n", i, j);
+            goto LBL_ERR;
+         }
+      }
+   }
+
+   /* Random a, base */
+   for (i = 1; i < 256; i++) {
+      DO(mp_rand(&a, i));
+      for (j = 1; j < ((i/2)+1); j++) {
+         DO(mp_rand(&base, j));
+         DO(mp_log(&a, &base, &lb));
+         DO(mp_expt_n(&base, lb, &bn));
+         /* "bn" must be smaller than or equal to "a" at this point. */
+         if (mp_cmp(&bn, &a) == MP_GT) {
+            fprintf(stderr,"FAILURE mp_log random in GT check");
+            goto LBL_ERR;
+         }
+         DO(mp_mul(&bn, &base, &bn));
+         /* "bn" must be bigger than "a" at this point. */
+         if (mp_cmp(&bn, &a) != MP_GT) {
+            fprintf(stderr,"FAILURE mp_log random in NOT GT check");
+            goto LBL_ERR;
+         }
+      }
+   }
+
+   mp_clear_multi(&a, &base, &bn, &t, NULL);
+   return EXIT_SUCCESS;
+LBL_ERR:
+   mp_clear_multi(&a, &base, &bn, &t, NULL);
+   return EXIT_FAILURE;
+}
+
+
 static int test_mp_incr(void)
 {
    mp_int a, b;
@@ -2167,6 +2231,7 @@ static int unit_tests(int argc, char **argv)
       T1(mp_get_u64, MP_GET_I64),
       T1(mp_get_ul, MP_GET_L),
       T1(mp_log_n, MP_LOG_N),
+      T1(mp_log, MP_LOG),
       T1(mp_incr, MP_ADD_D),
       T1(mp_invmod, MP_INVMOD),
       T1(mp_is_square, MP_IS_SQUARE),

doc/bn.tex

@@ -1936,14 +1936,21 @@ \section{Root Finding}
 \chapter{Logarithm}
 \section{Integer Logarithm}
 A logarithm function for positive integer input \texttt{a, base} computing  $\floor{\log_bx}$ such
-that $(\log_b x)^b \le x$.
+that $(\log_b x)^b \le x$. The function \texttt{mp\_log\_n} is just a wrapper that converts \texttt{base}
+to a bigint and calls \texttt{mp\_log\_n}.
+
+\index{mp\_log}
+\begin{alltt}
+mp_err mp_log(const mp_int *a, const mp_int *base, int *c)
+\end{alltt}
 
 \index{mp\_log\_n}
 \begin{alltt}
-mp_err mp_log_n(const mp_int *a, int base, int *c)
+mp_err mp_log_u32(const mp_int *a, uint32_t base, uint32_t *c)
 \end{alltt}
 
 \subsection{Example}
+Example given for \texttt{mp\_log\_n} only because the single difference is the type of \texttt{base}.
 \begin{small}
   \begin{alltt}
 #include <stdlib.h>
@@ -1954,15 +1961,15 @@ \subsection{Example}
 
 int main(int argc, char **argv)
 {
-   mp_int x, output;
-   int base;
+   mp_int x;
+   int base, output;
    mp_err 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) {
+   if ((e = mp_init(&x)) != MP_OKAY) {
       fprintf(stderr,"mp_init failed: \textbackslash{}"%s\textbackslash{}"\textbackslash{}n",
                      mp_error_to_string(e));
               exit(EXIT_FAILURE);
@@ -1984,15 +1991,9 @@ \subsection{Example}
                       mp_error_to_string(e));
       exit(EXIT_FAILURE);
    }
+   printf("%d\n",output);
 
-   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);
+   mp_clear(&x);
    exit(EXIT_SUCCESS);
 }
 \end{alltt}