Hardware circuit and method for automatically configuring on-the-fly a sub-unit in a SCSI message
View Patent ↗A SCSI message manipulation circuit in a SCSI expander detects a specified SCSI message from either a SCSI initiator, or a SCSI target. After detecting the specified SCSI message, the SCSI message manipulation circuit detects a pre-selected message-unit, e.g., a specific byte, within the message. Upon detecting the pre-selected message unit, the SCSI message manipulation circuit sets a pre-selected sub-unit, e.g., a bit, within the pre-selected message-unit to a state, which is programmable, as the SCSI message passes through the SCSI expander.
1. A device comprising:
a first I/O bus-interface circuit; and
an on-the-fly message manipulation circuit connected to said first I/O bus-interface circuit, wherein said on-the-fly message manipulation circuit sets on-the-fly a pre-selected sub-unit of a pre-selected message-unit of a message to a pre-selected state as said pre-selected message-unit is passed through said device, wherein said message is a SCSI Parallel Protocol Request Message.
2. The device of claim 1 wherein on-the-fly manipulation circuit further comprises:
a message detector module comprising:
an input coupled to said first I/O bus-interface circuit; and
a message-detected line, wherein in response to information indicative of said message on said input, said message detector module generates an active signal on said message-detected line.
3. The device of claim 2 wherein said on-the-fly message manipulation circuit further comprises:
a message-unit detector module having a message-unit detected line, wherein said message-unit detector module generates an active signal on said message-unit detected line upon detecting said pre-selected message-unit of said message.
4. The device of claim 3 wherein said on-the-fly message manipulation circuit further comprises:
a message sub-unit state selection module coupled to said message-detected line and to said message-unit detected line, wherein said message sub-unit state selection module sets said pre-selected sub-unit of said pre-selected message-unit of said message to said pre-selected state after receiving said active signal on said message-detected line, and said active signal on said message-unit detected line.
5. The device of claim 1 wherein said on-the-fly message manipulation circuit further comprises:
a message-unit detector module having a message-unit detected line, wherein said message-unit detector module generates an active signal on said message-unit detected line upon detecting said pre-selected message-unit of said message.
6. The device of claim 1 wherein said pre-selected message-unit has a size of one byte.
7. The device of claim 6 wherein said pre-selected sub-unit is a precompensation enable control bit.
8. The device of claim 1 further comprising:
a second I/O bus-interface circuit connected to said on-the-fly message manipulation circuit.
9. A device comprising:
a first I/O bus-interface circuit; and
an on-the-fly message manipulation circuit connected to said first I/O bus-interface circuit, wherein said on-the-fly message manipulation circuit sets on-the-fly a pre-selected sub-unit of a pre-selected message-unit of a message to a pre-selected state as said pre-selected message-unit is passed through said device, wherein said device is a SCSI expander that does not support adjustable active filtering.
10. A device comprising:
a first I/O bus-interface circuit; and
an on-the-fly message manipulation circuit connected to said first I/O bus-interface circuit, wherein said on-the-fly message manipulation circuit sets on-the-fly a pre-selected sub-unit of a pre-selected message-unit of a message to a pre-selected state as said pre-selected message-unit is passed through said device, wherein said device is a SCSI expander that supports adjustable active filtering.
11. A SCSI expander comprising:
a SCSI message manipulation circuit comprising:
a message-detected line;
a message-unit detected line; and
a message sub-unit state selection module connected to said message-detected line and to said message-unit detected line, wherein said message sub-unit state selection module sets a pre-selected sub-unit of a pre-selected message-unit of a SCSI message to a pre-selected state after receiving an active signal on said message-detected line, and an active signal on said message-unit detected line.
12. The SCSI expander of claim 11 wherein said SCSI message manipulation circuit further comprises:
a message detector module comprising said message-detected line wherein in response to information indicative of said SCSI message, said message detector module generates said active signal on said message-detected line.
13. The SCSI expander of claim 12 wherein said SCSI message manipulation circuit further comprises:
a message-unit detector module having said message-unit detected line wherein said message-unit detector module generates said active signal on said message-unit detected line upon detecting said pre-selected message-unit of said SCSI message.
14. The SCSI expander of claim 11 wherein said SCSI message manipulation circuit further comprises:
a message-unit detector module having said message-unit detected line wherein said message-unit detector module generates said active signal on said message-unit detected line upon detecting said pre-selected message-unit of said SCSI message.
15. The SCSI expander of claim 11 wherein said SCSI message is a SCSI Parallel Protocol Request Message.
16. The SCSI expander of claim 15 wherein said pre-selected message-unit has a size of one byte.
17. The SCSI expander of claim 16 wherein said pre-selected sub-unit is a precompensation enable control bit.
18. The SCSI expander of claim 11 wherein said SCSI expander is a SCSI expander that supports adjustable active filtering.
19. The SCSI expander of claim 11 wherein said SCSI expander supports adjustable active filtering.
20. A SCSI expander comprising:
a SCSI message manipulation circuit comprising:
a message detector module comprising:
a message decoder coupled to receive information indicative of a SCSI message from a SCSI bus; and
a message-detected line connected to said message decoder wherein said message decoder generates an active signal on said message-detected line upon decoding said information indicative of said SCSI message;
a message-unit detector module comprising:
a counter wherein said counter counts message-units in said SCSI message;
a message-unit selection register;
a comparator connected to said counter and to said message-unit selection register; and
a message-unit detected line connected to said comparator, wherein said comparator generates an active signal on said message-unit detected line upon receiving a value from said counter that has a pre-selected relationship to a value stored in said message-unit selection register to indicate that a pre-selected message unit has been detected; and
a message sub-unit state selection module connected to said message-detected line and to said message-unit detected line wherein said message sub-unit state selection module sets a pre-selected sub-unit of said pre-selected message-unit of said SCSI message to a pre-selected state upon receiving said active signal on said message-detected line, and said active signal on said message-unit detected line, as said pre-selected message-unit passes through said SCSI expander.
21. The SCSI expander of claim 20 wherein said message sub-unit state selection module further comprises:
an encoder connected to an enable sub-unit bus.
22. The SCSI expander of claim 21 wherein said message sub-unit state selection module further comprises:
a sub-unit selection register connected to said encoder.
23. The SCSI expander of claim 20 wherein said message sub-unit state selection module further comprises:
an output bus having a plurality of output lines.
24. The SCSI expander of claim 23 wherein said message sub-unit state selection module further comprises:
a first plurality of logic gates wherein an output terminal of each logic gate of said first plurality of logic gates is selectively coupled to and selectively decoupled from a different output line of said output bus.
25. The SCSI expander of claim 24 wherein said message sub-unit state selection module further comprises:
an input bus having a plurality of input lines wherein each line in said plurality of input lines is connected to a first input terminal of a different logic gate in said first plurality of logic gates.
26. The SCSI expander of claim 25 wherein said message sub-unit state selection module further comprises:
a second plurality of logic gates wherein an output terminal of each logic gate of said second plurality of logic gates is connected to a second input terminal of said different logic gate in said first plurality of logic gates.
27. The SCSI expander of claim 26 wherein said message-detected line is connected to a first input terminal of each logic gate of said second plurality of logic gates.
28. The SCSI expander of claim 27 wherein said message-unit detected line is connected to a second input terminal of each logic gate of said second plurality of logic gates.
29. The SCSI expander of claim 28 wherein said message sub-unit state selection module further comprises:
an encoder having an enable sub-unit output bus-including a plurality of lines wherein each line in said enable sub-unit output bus is connected to a third input terminal of a different logic gate in said second plurality of logic gates.
30. The SCSI expander of claim 29 wherein said message sub-unit state selection module further comprises:
a sub-unit selection register connected to said encoder.
31. A method for configuring a pre-selected sub-unit of a message on-the-fly comprising:
detecting said message using a hardware circuit;
detecting a pre-selected message-unit of said message using said hardware circuit; and
configuring said pre-selected sub-unit of said pre-selected message-unit of said message to a pre-selected state using said hardware circuit as said pre-selected message-unit is passed through a device including said hardware circuit wherein said message is a SCSI Parallel Protocol Request message.
32. The method claim 31 wherein said sub-unit is a bit in said SCSI Parallel Protocol Request message specifying signal conditioning supported by said expander.