diff tomsfastmath/src/addsub/s_fp_add.c @ 643:a362b62d38b2 dropbear-tfm

Add tomsfastmath from git rev bfa4582842bc3bab42e4be4aed5703437049502a with Makefile.in renamed
author Matt Johnston <matt@ucc.asn.au>
date Wed, 23 Nov 2011 18:10:20 +0700
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tomsfastmath/src/addsub/s_fp_add.c	Wed Nov 23 18:10:20 2011 +0700
@@ -0,0 +1,42 @@
+/* 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, [email protected]
+ */
+#include <tfm.h>
+
+/* unsigned addition */
+void s_fp_add(fp_int *a, fp_int *b, fp_int *c)
+{
+  int      x, y, oldused;
+  register fp_word  t;
+
+  y       = MAX(a->used, b->used);
+  oldused = c->used;
+  c->used = y;
+ 
+  t = 0;
+  for (x = 0; x < y; x++) {
+      t         += ((fp_word)a->dp[x]) + ((fp_word)b->dp[x]);
+      c->dp[x]   = (fp_digit)t;
+      t        >>= DIGIT_BIT;
+  }
+  if (t != 0 && x < FP_SIZE) {
+     c->dp[c->used++] = (fp_digit)t;
+     ++x;
+  }
+
+  c->used = x;
+  for (; x < oldused; x++) {
+     c->dp[x] = 0;
+  }
+  fp_clamp(c);
+}
+
+/* $Source$ */
+/* $Revision$ */
+/* $Date$ */