[crypto] Add bit-rotation functions for 8-bit and 16-bit values

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/rotate.h

 
 #include <stdint.h>
 
+static inline __attribute__ (( always_inline )) uint8_t
+rol8 ( uint8_t data, unsigned int rotation ) {
+        return ( ( data << rotation ) | ( data >> ( 8 - rotation ) ) );
+}
+
+static inline __attribute__ (( always_inline )) uint8_t
+ror8 ( uint8_t data, unsigned int rotation ) {
+        return ( ( data >> rotation ) | ( data << ( 8 - rotation ) ) );
+}
+
+static inline __attribute__ (( always_inline )) uint16_t
+rol16 ( uint16_t data, unsigned int rotation ) {
+        return ( ( data << rotation ) | ( data >> ( 16 - rotation ) ) );
+}
+
+static inline __attribute__ (( always_inline )) uint16_t
+ror16 ( uint16_t data, unsigned int rotation ) {
+        return ( ( data >> rotation ) | ( data << ( 16 - rotation ) ) );
+}
+
 static inline __attribute__ (( always_inline )) uint32_t
 rol32 ( uint32_t data, unsigned int rotation ) {
         return ( ( data << rotation ) | ( data >> ( 32 - rotation ) ) );