--- /dev/null
+/* TomsFastMath, a fast ISO C bignum library.
+ *
+ * This project is meant to fill in where LibTomMath
+ * falls short. That is speed ;-)
+ *
+ * This project is public domain and free for all purposes.
+ *
+ * Tom St Denis, tomstdenis@gmail.com
+ */
+#include <tfm_private.h>
+
+/* c = a mod 2**d */
+void fp_mod_2d(fp_int *a, int b, fp_int *c)
+{
+ int x;
+
+ /* zero if count less than or equal to zero */
+ if (b <= 0) {
+ fp_zero(c);
+ return;
+ }
+
+ /* get copy of input */
+ fp_copy(a, c);
+
+ /* if 2**d is larger than we just return */
+ if (b >= (DIGIT_BIT * a->used)) {
+ return;
+ }
+
+ /* zero digits above the last digit of the modulus */
+ for (x = (b / DIGIT_BIT) + ((b % DIGIT_BIT) == 0 ? 0 : 1); x < c->used; x++) {
+ c->dp[x] = 0;
+ }
+ /* clear the digit that is not completely outside/inside the modulus */
+ c->dp[b / DIGIT_BIT] &= ~((fp_digit)0) >> (DIGIT_BIT - b);
+ fp_clamp (c);
+}
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */