Preference programmable first-one detector and quadrature based random grant generator
View Patent ↗A preference programmable first-one detector and quadrature based random grant generator in a crossbar switch is disclosed. The crossbar switch emulates a FIFO switching function in a single chip crossbar switch architecture that operates at a high switching speed with a large bandwidth and supports multiple QoS levels, yet do not demand an inordinately large number of input and output queues or otherwise excessively tax memory requirements. The system and method operate at a high switching speed with a large bandwidth and support multiple QoS levels, yet do not require a complex pointer management system, nor constrain switching speeds and bandwidth capacity therein. The system and method efficiently select data for switching within a crossbar switch based structure based on an urgency counter based WRR grant selection. This switching is achieved with economy of hardware by quadrature basing and quadrature preference selection.
1. A grant generator for switching service section, comprising:
a structure comprising a plurality of binary round robin tree (BRRT) cells, each BRRT cell having one or more request inputs and a request output, a grant input and one or more grant signal outputs, and a control signal input, each of the BRRT cells providing a request output to another BRRT cell or to a final request output for the structure; and
a preference pointer coupled to the plurality of BRRT cells wherein the preference pointer is to provide one or more control signals to each of the BRRT cells at the control signal input of each BRRT cell.
2. The grant generator as recited in claim 1 , wherein the grant generator is a functionality within a crossbar switch structure.
3. The grant generator as recited in claim 1 , wherein the grant generator comprises a quadrature based grant generator.
4. The grant generator as recited in claim 3 , wherein the quadrature based grant generator services four quadrants.
5. The grant generator as recited in claim 4 , wherein each of the four quadrants corresponds to a plurality of ports, wherein each quadrant comprises a plane, and wherein the structure is expressed within each plane.
6. The grant generator as recited in claim 4 , wherein the plurality of ports comprises eight ports and wherein a total of 32 ports is serviced.
7. The grant generator as recited in claim 1 , wherein each of the plurality of BRRT cells comprises a type selected from the group consisting of ‘basic’ BRRT cells, ‘enable’ BRRT cells further including an enabling input, and ‘single grant’ BRRT cells having a single request input and a single grant output.
8. The grant generator as recited in claim 7 , wherein the structure comprises an arrangement of the BRRT cells, and wherein the arrangement comprises a cascade of BRRT cells.
9. The grant generator as recited in claim 8 , wherein the cascade comprises:
a first stage of BRRT cells, wherein the first stage comprises a first even positive whole number of BRRT cells;
a second stage of BRRT cells coupled to the first stage, wherein the second stage comprises a second even positive whole number of BRRT cells; and
a third stage of one or more BRRT cells coupled to the second stage.
10. The grant generator as recited in claim 9 , wherein a first half of the BRRT cells of the first stage cascades into a first half of the BRRT cells of the second stage.
11. The grant generator as recited in claim 10 , wherein a second half of the BRRT cells of the first stage cascades into a second half of the BRRT cells of the second stage.
12. The grant generator as recited in claim 9 , wherein the BRRT cells of the second stage cascade into the one or more BRRT cells of the third stage.
13. The grant generator as recited in claim 9 , wherein the cascade further comprises a fourth stage of one or more BRRT cells coupled to the third stage.
14. The grant generator as recited in claim 13 , wherein the cascade further comprises a fifth stage of one or more BRRT cells coupled to the fourth stage.
15. The grant generator as recited in claim 14 , wherein the BRRT cells of the first stage comprise ‘enable’ BRRT cells.
16. The grant generator as recited in claim 14 , wherein the BRRT cells of the second stage and the third stage comprise ‘basic’ BRRT cells.
17. The grant generator as recited in claim 14 , wherein the BRRT cells of the fourth stage and the fifth stage comprise ‘single grant’ BRRT cells.