Apparatus and method for the arithmetic over-ride of look up table outputs in a programmable logic device
First Claim
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1. A programmable logic device, comprisinga plurality of logic blocks organized in an array, each of the logic blocks including logic elements, a plurality of the logic elements including:
- an N-stage look up table (LUT) structure having configuration bit inputs and a LUT output;
dedicated hardware for performing a non-LUT logic function and for generating a non-LUT logic function output, wherein the non-LUT logic function is one of the following;
addition, subtraction, multiplication, division, and digital signal processing; and
an over-ride element coupled to the LUT and configured to selectively force a stage within the N stage look up table to select either one or more of the configuration bit inputs or the non-LUT logic function output so that the selected one or more of the configuration bit inputs or the non-LUT logic function output is provided at the LUT output, wherein the over-ride element comprises a register and a configuration random access memory (RAM) bit that allows a user to selectively enable or disable the over-ride function.
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Abstract
A programmable logic device having a Logic Element with an N-stage Look Up Table (LUT), dedicated hardware for performing a non-LUT logic function, and an over-ride element configured to selectively force a muxing stage within the N-stage LUT to select either one or more LUT configuration bit inputs or the output of the non-LUT logic function as the output of the LUT. In various embodiments, the non-LUT functions can include addition, subtraction, multiplication, division, digital signal processing, memory storage, etc.
18 Citations
28 Claims
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1. A programmable logic device, comprising
a plurality of logic blocks organized in an array, each of the logic blocks including logic elements, a plurality of the logic elements including: -
an N-stage look up table (LUT) structure having configuration bit inputs and a LUT output; dedicated hardware for performing a non-LUT logic function and for generating a non-LUT logic function output, wherein the non-LUT logic function is one of the following;
addition, subtraction, multiplication, division, and digital signal processing; andan over-ride element coupled to the LUT and configured to selectively force a stage within the N stage look up table to select either one or more of the configuration bit inputs or the non-LUT logic function output so that the selected one or more of the configuration bit inputs or the non-LUT logic function output is provided at the LUT output, wherein the over-ride element comprises a register and a configuration random access memory (RAM) bit that allows a user to selectively enable or disable the over-ride function. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 23, 24, 25, 26, 27, 28)
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16. A logic element, comprising:
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an N-stage look up table (LUT) having configuration bit inputs and a LUT output; dedicated hardware for performing a non-LUT logic function and for generating a non-LUT logic function output, the non-LUT logic function output coupled to a selected stage of the N stage LUT, wherein the non-LUT logic function is one of the following;
addition, subtraction, multiplication, division, and digital signal processing; andan over-ride element coupled to the selected stage of the N stage LUT and configured to control the output of the LUT to be either one of the configuration bit inputs or the non-LUT logic function output, wherein the over-ride element comprises a register and a configuration random access memory (RAM) bit that allows a user to selectively enable or disable the over-ride function. - View Dependent Claims (17, 18)
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19. A method comprising:
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providing an N-stage look up table (LUT) having configuration bit inputs and a LUT output; providing dedicated hardware for performing a non-LUT logic function and for generating a non-LUT logic function output, the non-LUT logic function output coupled to a selected stage of the N stage LUT, wherein the non-LUT logic function is one of the following;
addition, subtraction, multiplication, division, and digital signal processing; andproviding an over-ride element, coupled to the selected stage of the N stage LUT and configured to control the output of the LUT to be either one of the configuration bit inputs or the non-LUT logic function output, wherein the over-ride element comprises a register and a configuration random access memory (RAM) bit that allows a user to selectively enable or disable the over-ride function. - View Dependent Claims (20, 21)
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22. A programmable logic device comprising a dedicated circuit and a look up table (LUT), the LUT having multiple stages and an output circuit, wherein the dedicated circuit is coupled directly to a stage of the LUT, wherein the LUT is configurable so that a signal generated by the dedicated circuit and output by the LUT is routed through the stage, and wherein the dedicated circuit is configured to perform one of the following functions:
- addition, subtraction, multiplication, division, and digital signal processing, wherein the over-ride element comprises a register and a configuration random access memory (RAM) bit that allows a user to selectively enable or disable the over-ride function.
Specification