src/core/bitop.d

@@ -706,3 +706,56 @@ version (D_InlineAsm_X86_64)
         }
     }
 }
+
+/**
+ *  Bitwise rotate `value` left (`rol`) or right (`ror`) by
+ *  `count` bit positions.
+ */
+pure T rol(T)(in T value, in uint count)
+    if (__traits(isIntegral, T) && __traits(isUnsigned, T))
+{
+    assert(count < 8 * T.sizeof);
+    return cast(T) ((value << count) | (value >> (-count & (T.sizeof * 8 - 1))));
+}
+/// ditto
+pure T ror(T)(in T value, in uint count)
+    if (__traits(isIntegral, T) && __traits(isUnsigned, T))
+{
+    assert(count < 8 * T.sizeof);
+    return cast(T) ((value >> count) | (value << (-count & (T.sizeof * 8 - 1))));
+}
+/// ditto
+pure T rol(uint count, T)(in T value)
+    if (__traits(isIntegral, T) && __traits(isUnsigned, T))
+{
+    static assert(count < 8 * T.sizeof);
+    return cast(T) ((value << count) | (value >> (-count & (T.sizeof * 8 - 1))));
+}
+/// ditto
+pure T ror(uint count, T)(in T value)
+    if (__traits(isIntegral, T) && __traits(isUnsigned, T))
+{
+    static assert(count < 8 * T.sizeof);
+    return cast(T) ((value >> count) | (value << (-count & (T.sizeof * 8 - 1))));
+}
+
+///
+unittest
+{
+    ubyte a = 0b10101010U;
+    ulong b = ulong.max;
+
+    assert(rol(a, 1) == 0b01010101);
+    assert(ror(a, 1) == 0b01010101);
+    assert(rol(a, 3) == 0b01010101);
+    assert(ror(a, 3) == 0b01010101);
+
+    assert(rol(a, 0) == a);
+    assert(ror(a, 0) == a);
+
+    assert(rol(b, 63) == ulong.max);
+    assert(ror(b, 63) == ulong.max);
+
+    assert(rol!3(a) == 0b01010101);
+    assert(ror!3(a) == 0b01010101);
+}