www.usr.com/support/gpl/USR9107_release.1.4.tar.gz

[bcm963xx.git] / userapps / opensource / sshd / libtommath / bn_mp_dr_reduce.c

diff --git a/userapps/opensource/sshd/libtommath/bn_mp_dr_reduce.c b/userapps/opensource/sshd/libtommath/bn_mp_dr_reduce.c
index 7d7259e..9bb7ad7 100755 (executable)
--- a/userapps/opensource/sshd/libtommath/bn_mp_dr_reduce.c
+++ b/userapps/opensource/sshd/libtommath/bn_mp_dr_reduce.c
@@ -1,9 +1,11 @@
+#include <tommath.h>
+#ifdef BN_MP_DR_REDUCE_C
 /* LibTomMath, multiple-precision integer library -- Tom St Denis
  *
- * LibTomMath is library that provides for multiple-precision
+ * LibTomMath is a library that provides multiple-precision
  * integer arithmetic as well as number theoretic functionality.
  *
- * The library is designed directly after the MPI library by
+ * The library was designed directly after the MPI library by
  * Michael Fromberger but has been written from scratch with
  * additional optimizations in place.
  *
@@ -12,19 +14,20 @@
  *
  * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
  */
-#include <tommath.h>
 
 /* reduce "x" in place modulo "n" using the Diminished Radix algorithm.
  *
  * Based on algorithm from the paper
  *
  * "Generating Efficient Primes for Discrete Log Cryptosystems"
- *                 Chae Hoon Lim, Pil Loong Lee,
+ *                 Chae Hoon Lim, Pil Joong Lee,
  *          POSTECH Information Research Laboratories
  *
  * The modulus must be of a special format [see manual]
  *
  * Has been modified to use algorithm 7.10 from the LTM book instead
+ *
+ * Input x must be in the range 0 <= x <= (n-1)**2
  */
 int
 mp_dr_reduce (mp_int * x, mp_int * n, mp_digit k)
@@ -32,10 +35,10 @@ mp_dr_reduce (mp_int * x, mp_int * n, mp_digit k)
   int      err, i, m;
   mp_word  r;
   mp_digit mu, *tmpx1, *tmpx2;
-  
+
   /* m = digits in modulus */
   m = n->used;
-  
+
   /* ensure that "x" has at least 2m digits */
   if (x->alloc < m + m) {
     if ((err = mp_grow (x, m + m)) != MP_OKAY) {
@@ -43,30 +46,30 @@ mp_dr_reduce (mp_int * x, mp_int * n, mp_digit k)
     }
   }
 
-/* top of loop, this is where the code resumes if 
+/* top of loop, this is where the code resumes if
  * another reduction pass is required.
  */
 top:
   /* aliases for digits */
   /* alias for lower half of x */
   tmpx1 = x->dp;
-  
+
   /* alias for upper half of x, or x/B**m */
   tmpx2 = x->dp + m;
-  
+
   /* set carry to zero */
   mu = 0;
-  
-  /* compute (x mod B**m) + mp * [x/B**m] inline and inplace */
+
+  /* compute (x mod B**m) + k * [x/B**m] inline and inplace */
   for (i = 0; i < m; i++) {
       r         = ((mp_word)*tmpx2++) * ((mp_word)k) + *tmpx1 + mu;
       *tmpx1++  = (mp_digit)(r & MP_MASK);
       mu        = (mp_digit)(r >> ((mp_word)DIGIT_BIT));
   }
-  
+
   /* set final carry */
   *tmpx1++ = mu;
-  
+
   /* zero words above m */
   for (i = m + 1; i < x->used; i++) {
       *tmpx1++ = 0;
@@ -75,7 +78,7 @@ top:
   /* clamp, sub and return */
   mp_clamp (x);
 
-  /* if x >= n then subtract and reduce again 
+  /* if x >= n then subtract and reduce again
    * Each successive "recursion" makes the input smaller and smaller.
    */
   if (mp_cmp_mag (x, n) != MP_LT) {
@@ -84,3 +87,4 @@ top:
   }
   return MP_OKAY;
 }
+#endif