import E script from bell labs

1 files changed, 18 insertions, 0 deletions

diff --git a/sys/src/libsec/port/const.c b/sys/src/libsec/port/const.c
new file mode 100644
index 000000000..0cf400178
--- /dev/null
+++ b/sys/src/libsec/port/const.c
@@ -0,0 +1,18 @@
+#include <u.h>
+
+/*
+ * returns 0 if the the len bytes in x are equal to len bytes in y,
+ * otherwise returns -1.
+ */
+int
+constcmp(uchar *x, uchar *y, int len)
+{
+	uint z;
+	int i;
+
+	for(z = 0, i = 0; i < len; i++) {
+		z |= x[i] ^ y[i];
+	}
+
+	return (1 & ((z - 1) >> 8)) - 1;
+}