--- /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>
+
+/* unsigned subtraction ||a|| >= ||b|| ALWAYS! */
+void s_fp_sub(fp_int *a, fp_int *b, fp_int *c)
+{
+ int x, oldbused, oldused;
+ fp_word t;
+
+ oldused = c->used;
+ oldbused = b->used;
+ c->used = a->used;
+ t = 0;
+ for (x = 0; x < oldbused; x++) {
+ t = ((fp_word)a->dp[x]) - (((fp_word)b->dp[x]) + t);
+ c->dp[x] = (fp_digit)t;
+ t = (t >> DIGIT_BIT)&1;
+ }
+ for (; x < a->used; x++) {
+ t = ((fp_word)a->dp[x]) - t;
+ c->dp[x] = (fp_digit)t;
+ t = (t >> DIGIT_BIT)&1;
+ }
+ for (; x < oldused; x++) {
+ c->dp[x] = 0;
+ }
+ fp_clamp(c);
+}
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */