1 files changed, 15 insertions, 0 deletions
diff --git a/src/libmp/port/mpmod.c b/src/libmp/port/mpmod.c
new file mode 100644
index 00000000..91bebfa2
--- /dev/null
+++ b/src/libmp/port/mpmod.c
@@ -0,0 +1,15 @@
+#include "os.h"
+#include <mp.h>
+#include "dat.h"
+
+// remainder = b mod m
+//
+// knuth, vol 2, pp 398-400
+
+void
+mpmod(mpint *b, mpint *m, mpint *remainder)
+{
+	mpdiv(b, m, nil, remainder);
+	if(remainder->sign < 0)
+		mpadd(m, remainder, remainder);
+}