초록 ▼

A method and apparatus for controlling access to a plurality of resources based on multiple received requests is provided. The system includes a priority register configured to receive each individual request, determine a priority for the request, and transmit the request to a priority appropriate

A method and apparatus for controlling access to a plurality of resources based on multiple received requests is provided. The system includes a priority register configured to receive each individual request, determine a priority for the request, and transmit the request to a priority appropriate path. A first high priority arbiter receives and arbitrates among highest priority requests in a round robin manner to determine a high priority suggested grant vector. At least one lower priority arbiter receiving and arbitrating among lower priority requests in a round robin manner to determine at least one lower priority suggested grant vector. Grant circuitry passes the high priority suggested grant vector unless said grant circuitry receives a low priority indication, whereby the grant circuitry passes a lower priority grant vector.

대표청구항 ▼

What is claimed is: 1. A system for controlling access to a plurality of resources based on at least one individual request received from at least one requestor seeking access to said resources, comprising: a priority register configured to receive each individual request and determine a priority f

What is claimed is: 1. A system for controlling access to a plurality of resources based on at least one individual request received from at least one requestor seeking access to said resources, comprising: a priority register configured to receive each individual request and determine a priority for said request and transmit said request to a priority appropriate path; a first high priority arbiter receiving and arbitrating among highest priority requests in a round robin manner to determine a high priority suggested grant vector, wherein a predetermined quantity of request vector slots are allocated to lower priority requests, said first higher priority arbiter having an ability to generate a lower priority indication; a second lower priority arbiter receiving and arbitrating among lower priority requests in a round robin manner to determine a lower priority suggested grant vector; and grant circuitry connected to said first high priority arbiter and said second lower priority arbiter, said grant circuitry configured to receive high priority suggested grant vectors and lower priority suggested grant vectors and configured to pass the high priority suggested grant vector unless said grant circuitry receives the lower priority indication from the first higher priority arbiter, whereby the grant circuitry passes the lower priority suggested grant vector. 2. The system of claim 1, wherein said grant circuitry comprises a multiplexor capable of receiving the low priority indication and passing the high priority suggested grant vector unless the low priority indication has been received. 3. The system of claim 1, wherein priority in the priority register is determined by receiving a priority along with the individual request, and further wherein each high priority individual request is transmitted to the first high priority arbiter and each lower priority individual request is transmitted to the second lower priority arbiter. 4. The system of claim 1, wherein priority in the priority register is determined according to a priority level accorded the requester, and further wherein each high priority individual request is transmitted to the first high priority arbiter and each lower priority individual request is transmitted to the second lower priority arbiter. 5. The system of claim 1, further comprising an OR gate, wherein the OR gate receives lower priority requests and passes an OR function of the lower priority requests to the first high priority arbiter as an indication lower priority requests are available. 6. The system of claim 5, wherein the first high priority arbiter provides at least one round robin slot for at least one low priority request when the OR gate indicates low priority requests are available. 7. The system of claim 1, wherein the second lower priority arbiter comprises a series of lower priority vector slots and one lower priority request vector slot is allocated. 8. The system of claim 1, further comprising a third low priority arbiter receiving and arbitrating among low priority requests in a round robin manner to determine a low priority suggested grant vector. 9. The system of claim 8, wherein the low priority indication indicates whether a lower priority suggested grant vector or a low priority suggested grant vector is warranted. 10. The system of claim 1, wherein once the grant circuitry passes one from the group including the lower priority grant vector and the high priority grant vector, the second lower priority arbiter rearbitrates all received lower priority requests. 11. A method for arbitrating between different priority requests for access to resources, comprising: separating requests into priority groups; arbitrating among the highest priority requests and lower priority requests using a high priority arbiter including: granting a first selected number of grant requests to requests having highest priority using grant circuitry connected to the high priority arbiter and configured to receive highest priority requests and lower priority requests when highest priority requests are indicated from said high priority arbiter to said grant circuitry, and granting a second selected number of grant requests having lower priority only when lower priority requests are indicated from said high priority arbiter to said grant circuitry, wherein said high priority arbiter operates in a round robin manner. 12. The method of claim 11, wherein said arbitrating is performed by a plurality of arbiters that arbitrate among incoming requests and determine candidate grant vectors. 13. The method of claim 12, wherein said arbitrating further comprises the highest priority arbitrator providing an indication when in the round robin manner a highest priority request is unwarranted, enabling granting a lower priority request. 14. The method of claim 11, wherein said priority groups comprise a highest priority group and at least one lower priority group. 15. The method of claim 11, further comprising rearbitrating lower priority requests after granting a grant request. 16. The method of claim 12, wherein separating requests comprises determining a priority associated with each request and passing high priority requests to a first arbiter and each lower level of priority request to an arbiter associated with that lower level of priority. 17. An apparatus for controlling access to a plurality of resources based on at least one individual request seeking access to said resources, comprising: means for receiving each individual request, determining a priority for said request, and transmitting said request to a priority appropriate path; high priority arbitrating means for receiving and arbitrating among highest priority requests in a round robin manner to determine a high priority suggested grant vector; lower priority arbitrating means for receiving and arbitrating among lower priority requests in a round robin manner to determine a lower priority suggested grant vector; and grant means connected to said high priority arbitrating means and said lower priority arbitrating means, said grant means configured to receive at least one high priority suggested grant vector and at least one lower priority suggested grant vector and configured to pass the high priority suggested grant vector under a first set of circumstances and said lower priority suggested grant vector when an indication is presented from the high priority arbitrating means to the grant means that at least one lower priority request may be granted. 18. The apparatus of claim 17, wherein said high priority arbitrating means generates a lower priority indication to the grant means in predetermined circumstances. 19. The apparatus of claim 18, wherein the predetermined circumstances comprise a low priority position in a round robin sequence. 20. The apparatus of claim 18, wherein the grant means passes the lower priority grant vector once the grant means has received the low priority indication.