Circuit for aligning logical sectors with physical sectors in a disk storage system
AssigneeInternational Business Machines Corporation
InventorCharles Lee Still
Life of this patent
Estimating the term…
Abstract
A circuit manages the conversion of data between a logical sector format and a physical sector format. In a padding mode, the circuit appends a padding value to a data stream in the logical sector format having a logical length to produce a data stream in a physical sector format having a physical length. In an extracting mode, the circuit extracts a data stream in the logical sector format from a data stream in the physical sector format.
Claims21
A circuit for appending a padding value to a first data stream having a logical length, to produce a second data stream that when recorded in a recording device will occupy a determined physical length on said recording device that matches an operating requirement of said recording device, said logical length and said physical length measured in data units, said circuit comprising:
- a switch having a first input for receiving said first data stream, a second input for receiving said padding value, and an output for transmitting said second data stream, said switch controllable to route either said first input or said second input to said output;
- a logical length counter to count data units of said first data stream, and having an output indicating when said logical length has been counted;
- a physical length counter to count data units of said second data stream, and having an output indicating when said physical length has been counted;
- a controller, responsive to said outputs from said logical length counter and said physical length counter, for controlling said switch to select said first data stream until said logical length has been counted, and then to control said switch to select said padding value until said physical length has been counted.
A circuit for extracting a first data stream having a logical length, from a second data stream having a determined physical length that matches an operating requirement of a recording device, said logical length and said physical length measured in data units, said circuit comprising:
- a data latch having an input for receiving said second data stream, and an output for transmitting said first data stream, said data latch controllable to enable or disable said input for receiving said second data stream;
- a logical length counter to count said data units of said first data stream, and having a n output indicating when said logical length has been counted;
- a physical length counter to count said data units of said second data stream, and having an output indicating when said physical length has been counted;
- a controller, responsive to said outputs from said logical length counter and said physical length counter, for controlling said data latch to enable said input for receiving said second data stream until said logical length has been counted, and then to control said data latch to disable said input for receiving said second data stream until said physical length has been counted.
A circuit, capable of operating in a padding mode or an extracting mode, said padding mode for appending a padding value to a first data stream having a logical length, to produce a second data stream that when recorded in a recording device will occupy a determined physical length on said recording device that matches an operating requirement of said recording device, and said extracting mode for extracting said first data stream from said second data stream, said logical length and said physical length measured in data units, said circuit comprising:
- a switch having a first input for receiving said first data stream, a second input for receiving said padding value, and an output for transmitting said second data stream, said switch controllable to route either said first input or said second input to said output;
- a first data latch having an input for receiving said second data stream, and an output for transmitting said first data stream, said first data latch controllable to enable or disable said input for receiving said second data stream;
- a logical length counter to count said data units of said first data stream, and having an output indicating when said logical length has been counted;
- a physical length counter to count said data units of said second data stream, and having an output indicating when said physical length has been counted;
- a controller, responsive to said outputs from said logical length counter and said physical length counter, wherein
- in said padding mode, said controller controls said switch to select said first data stream until said logical length has been counted, and then to control said switch to select said padding value until said physical length has been counted;
- and
- in said extracting mode, said controller controls said first data latch to enable said input for receiving said second data stream until said logical length has been counted, and then to control said first data latch to disable said input for receiving said second data stream until said physical length has been counted.
Dependencies are inferred from the claim text.