Abstract: A disk drive is disclosed comprising a disk, a head actuated over the disk, and a read channel for processing a read signal generated by the head. The disk drive further comprises a plurality of code segments including a read channel interface procedure having an input parameter comprising a pointer to a data structure. The data structure comprises a command ID identifying one of a plurality of routines, input data for use by the routine identified by the command ID, a pointer to a data structure for use by the routine identified by the command ID, and output data returned by the routine identified by the command ID.

Abstract: A method of estimating a writer/reader gap in a disk drive is disclosed. During a first revolution of the disk, a clock is synchronized to a first preamble and used to measure a write delay to write a second sync mark to the disk relative to a first sync mark. During a second revolution of the disk, the clock is again synchronized to the first preamble and used to measure a read delay required to detect the second sync mark relative to the first sync mark. The writer/reader gap is then estimated in response to the measured write delay and the measured read delay, for example, by computing a difference between the measured write delay and the measured read delay.