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15.4 sb-rotate-byte

The sb-rotate-byte module offers an interface to bitwise rotation, with an efficient implementation for operations which can be performed directly using the platform's arithmetic routines. It implements the specification at http://www.cliki.net/ROTATE-BYTE.

Bitwise rotation is a component of various cryptographic or hashing algorithms: MD5, SHA-1, etc.; often these algorithms are specified on 32-bit rings. [FIXME cite cite cite].

— Function: sb-rotate-byte:rotate-byte count bytespec integer

Rotates a field of bits within integer; specifically, returns an integer that contains the bits of integer rotated count times leftwards within the byte specified by bytespec, and elsewhere contains the bits of integer.