+#define IV_BITS (IVSIZE * 8)
+
+static UV S_uv_shift(UV uv, int shift, bool left)
+{
+ if (shift < 0) {
+ shift = -shift;
+ left = !left;
+ }
+ if (shift >= IV_BITS) {
+ return 0;
+ }
+ return left ? uv << shift : uv >> shift;
+}
+
+static IV S_iv_shift(IV iv, int shift, bool left)
+{
+ if (shift < 0) {
+ shift = -shift;
+ left = !left;
+ }
+ if (shift >= IV_BITS) {
+ return iv < 0 && !left ? -1 : 0;
+ }
+ return left ? iv << shift : iv >> shift;
+}
+
+#define UV_LEFT_SHIFT(uv, shift) S_uv_shift(uv, shift, TRUE)
+#define UV_RIGHT_SHIFT(uv, shift) S_uv_shift(uv, shift, FALSE)
+#define IV_LEFT_SHIFT(iv, shift) S_iv_shift(iv, shift, TRUE)
+#define IV_RIGHT_SHIFT(iv, shift) S_iv_shift(iv, shift, FALSE)
+