Serial data decoding using state machine with selectable decoding tables
First Claim
1. A serial data decoder for generating output data words according to a selectable one of a plurality of decoding tables from serial data comprising a plurality of data sections, differing sets of decoding tables being used for differing data sections and differing decoding tables being used for differing parts of each data section, said serial data decoder comprising a state machine comprising:
- a memory with a plurality of address locations each storing a control data word;
a latch for storing a most recent control data word output from said memory;
means for generating a table selecting word in response to a number of received bytes of said serial data, said means for generating including a table counter for generating a table count value, indicative of which decoding table is to be used within a data section, that is concatenated with a data section value, indicative of which set of decoding tables are to be used for a current data section, to form a table selecting word, each table selecting word corresponding to a different decoding table;
a read address bus for supplying a read address to said memory, said read address being formed from a concatenation of at least part of said control data word read from said latch, said table selecting word and a received bit of said serial data and said memory being responsive to said read address to output a new control word to said latch corresponding to moving said state machine to a new state; and
means responsive to a valid code flag within a control data word output from said memory at a state of said state machine corresponding to receipt of a valid code for outputting said control data word as an identifier of said valid code.
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Abstract
A serial data decoding system is described in which a state machine (FIG. 5) is provided having a plurality of branching hierarchies of states, each branching hierarchy of states corresponding to a different decoding table. The state machine incorporates a memory 72 storing control data words (FIG. 7). A latch 74 stores the most recent control data word to be output from the memory. The memory 72 is addressed with a read address formed from a concatenation of the latched value 84, a table selecting word 86, Y/C and a received bit of serial data. When the state machine enters a state 88 corresponding to valid code, the current control data word is output as an identifier of that valid code.
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Citations
10 Claims
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1. A serial data decoder for generating output data words according to a selectable one of a plurality of decoding tables from serial data comprising a plurality of data sections, differing sets of decoding tables being used for differing data sections and differing decoding tables being used for differing parts of each data section, said serial data decoder comprising a state machine comprising:
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a memory with a plurality of address locations each storing a control data word; a latch for storing a most recent control data word output from said memory; means for generating a table selecting word in response to a number of received bytes of said serial data, said means for generating including a table counter for generating a table count value, indicative of which decoding table is to be used within a data section, that is concatenated with a data section value, indicative of which set of decoding tables are to be used for a current data section, to form a table selecting word, each table selecting word corresponding to a different decoding table; a read address bus for supplying a read address to said memory, said read address being formed from a concatenation of at least part of said control data word read from said latch, said table selecting word and a received bit of said serial data and said memory being responsive to said read address to output a new control word to said latch corresponding to moving said state machine to a new state; and means responsive to a valid code flag within a control data word output from said memory at a state of said state machine corresponding to receipt of a valid code for outputting said control data word as an identifier of said valid code. - View Dependent Claims (2, 3, 4, 5)
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6. A method of serial data decoding for generating output data words using a state machine according to a selectable one of a plurality of decoding tables from serial data comprising a plurality of data sections, differing sets of decoding tables being used for differing data sections and differing decoding tables being used for differing parts of each data section, said method comprising the steps of:
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outputting a control data word from a memory with a plurality of address locations each storing a control data word; storing in a latch a most recent control data word output from said memory; generating a table count value, indicative of which decoding table is to be used within a data section, in response to a number of received bytes of said serial data; concatenating said table count value with a data section value, indicative of which set of decoding tables are to be used for a current data section to form a table selecting word, each table selecting word corresponding to a different decoding table; supplying a read address to said memory, said read address being formed from a concatenation of at least part of said control data word read from said latch, said table selecting word and a received bit of said serial data and said memory being responsive to said read address to output a new control word to said latch corresponding to moving said state machine to a new state; and in response to a valid code flag within a control data word output from said memory at a state of said state machine corresponding to receipt of a valid code, outputting said control data word as an identifier of said valid code. - View Dependent Claims (7, 8, 9, 10)
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Specification