A carry-lookahead adder is provided. First XOR gate receives a first mask value and a second mask value to provide a variable. First mask unit performs a first mask operation on first input data with the variable to obtain first masked data. A half adder receives the first masked data and second input data to generate a propagation value and an intermediate generation value. Second mask unit performs a second mask operation on the propagation value with a third mask value to obtain second masked data. A logic circuit provides a generation value according to the propagation value, the intermediate generation value and the second mask value. A carry-lookahead generator provides a carry output and a carry value according to a carry input, the generation value and the propagation value. Second XOR gate receives the second masked data and the carry value to provide a sum output.

A carry-lookahead adder is provided. First XOR gate receives a first mask value and a second mask value to provide a variable. First mask unit performs a first mask operation on first input data with the variable to obtain first masked data. A half adder receives the first masked data and second input data to generate a propagation value and an intermediate generation value. Second mask unit performs a second mask operation on the propagation value with a third mask value to obtain second masked data. A logic circuit provides a generation value according to the propagation value, the intermediate generation value and the second mask value. A carry-lookahead generator provides a carry output and a carry value according to a carry input, the generation value and the propagation value. Second XOR gate receives the second masked data and the carry value to provide a sum output.

The present disclosure relates to a carry chain logic system that leverages carry in and carry out signals from logic blocks to implement logic functions on programmable hardware (e.g., FPGA hardware). In particular, implementations of the carry chain logic system facilitate implementation of logic gates (e.g., AND/OR gates) having high number of input signals without incurring routing delays caused by routing output signals between logic components implemented across different logic stages. For example, implementations described herein involve feeding carry out signals between adders of a logic chain across multiple logic components on a common logic stage, thus reducing routing penalties caused by routing signals via a routing fabric of the programmable hardware.

A carry-lookahead adder is provided. A first mask unit performs first mask operation on first input data with the first mask value to obtain first masked data. A second mask unit performs second mask operation on second input data with the second mask value to obtain second masked data. A first XOR gate receives the first and second mask values to provide a variable value. A half adder receives the first and second masked data to generate a propagation value and an intermediate generation value. A third mask unit performs third mask operation on the propagation value with the third mask value to obtain the third masked data. A carry-lookahead generator provides the carry output and the carry value according to carry input, the generation value, and the propagation value. The second XOR gate receives the third masked data and the carry value to provide the sum output.

Configurable circuits include an input selection region, a computation region, a switching region, and an output region. The input selection region includes a set of input multiplexers and selects and routes input signals. The computation region includes a set of lookup tables, each lookup table being coupled to selected signals from the input selection stage to generate a respective output signal. The switching region includes a set of output multiplexers, each output multiplexer being coupled to output signals from the set of lookup tables to provide circuit outputs responsive to respective output selection signals. The output region includes a domino logic stage, having a set of transistors, coupled to output signals from the set of lookup tables to provide circuit outputs that determine combinations of the signals output by the set of lookup tables.

Configurable circuits include an input selection region, a computation region, a switching region, and an output region. The input selection region includes a set of input multiplexers and selects and routes input signals. The computation region includes a set of lookup tables, each lookup table being coupled to selected signals from the input selection stage to generate a respective output signal. The switching region includes a set of output multiplexers, each output multiplexer being coupled to output signals from the set of lookup tables to provide circuit outputs responsive to respective output selection signals. The output region includes a domino logic stage, having a set of transistors, coupled to output signals from the set of lookup tables to provide circuit outputs that determine combinations of the signals output by the set of lookup tables.

A synaptic coprocessor may include a memory configured to store a plurality of Very Long Data Words, each as a test Very Long Data Word (VLDW) having a length in the range of about one thousand bits to one million or more bits and containing encoded information that is distributed across the length of the VLDW. A processor generates search terms and a processing logic unit receives a test VLDW from the memory, receives a search term from the processor, and computes a Boolean inner product between the search term and the test VLDW read from memory indicative of the measure of similarity between the test VLDW and the search term. Optionally, buffers within logic circuits of processing pipelines may receive the test VLDWs.

A coprocessor may include a memory configured to store a plurality of Very Long Data Words, each as a test Very Long Data Word (VLDW) having a length in the range of about one thousand bits to one million or more bits and containing encoded information that is distributed across the length of the VLDW. A processor generates search terms and a processing logic unit receives a test VLDW from the memory, receives a search term from the processor, and computes a Boolean inner product between the search term and the test VLDW read from memory indicative of the measure of similarity between the test VLDW and the search term. Optionally, buffers within logic circuits of processing pipelines may receive the test VLDWs.

A method for an associative memory device includes storing a plurality of pairs of N-bit numbers A and B to be added together in columns of a memory array of the associative memory device, each pair in a column, each bit in a row of the column, and dividing each N-bit number A and B into groups containing M bits each, having group carry-out predictions for every group except a first group, the group carry-out predictions calculated for any possible group carry-in value, and, once the carry-out value for a first group is calculated, selecting the next group carry out value from the group carry-out predictions. The method also includes repeating the ripple selecting group carry-out values, until all group carry out values have been selected.

A method for an associative memory device includes storing a plurality of pairs of N-bit numbers A and B to be added together in columns of a memory array of the associative memory device, each pair in a column, each bit in a row of the column, and dividing each N-bit number A and B into groups containing M bits each, having group carry-out predictions for every group except a first group, the group carry-out predictions calculated for any possible group carry-in value, and, once the carry-out value for a first group is calculated, selecting the next group carry out value from the group carry-out predictions. The method also includes repeating the ripple selecting group carry-out values, until all group carry out values have been selected.