Variable-priority arbitration method and respective system
AssigneeSTMicroelectronics S.r.l.
InventorsPasquale Butta', Pierre Marty
Life of this patent
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Abstract
A method of arbitration among a plurality of n units which seek access to a resource is regulated according to grants identified by means of an arbitration method, which compares between one another the priorities, generating, for each pair of the units comprising in general a unit x and a unit y with respective priorities Px and Py, a selection signal at a high level if the result of the operation Px>=Py is true. The method generates, for the pairs of the units, respective cross-request signals and generates the grant for the ith unit as a logical product of all the cross-request signals req_i_z with z ranging from 1 to n, excluding the case of z=i.
Claims17
A method of arbitration between a plurality of n units seeking access to a resource by expressing respective requests and respective priorities, access of said units to said resource being regulated according to grants identified by means of the arbitration method, the arbitration method comprising:
- comparing between one another said respective priorities, generating, for each pair of said units comprising in general a unit x and a unit y with respective priorities Px and Py, a selection signal at a high level if the result of the operation Px>=Py is true;
- generating, for said pairs of said units, respective cross-request signals
- req_arb(selxnoty, req_x, req_y, req_x_y, req_y_x)
- where
- selxnoty is the aforesaid selection signal;
- req_x is the request coming from the unit x;
- req_y is the signal coming from the unit y;
- and
- req_x_y and req_y_x are, respectively, the outputs of the function
- req_x AND (selxnoty OR NOT req_y)
- and of the function
- req_y AND ((NOT selxnoty) OR (NOT req_x));
- and
- generating the grant for an ith unit as a logical product of all the aforesaid cross-request signals req_i_z with z ranging from 1 to n, excluding the case of z=i.
An arbiter for a system that includes a plurality of n units structured to seek access to at least one resource by expressing respective requests and respective priorities, access of said units to said resource being regulated according to grants generated by said arbiter, said arbiting comprising:
- a comparison stage for comparing between one another said respective priorities, generating, for each pair of said units comprising in general a unit x and a unit y with respective priorities Px and Py, a selection signal at a high level if the result of the operation Px>=Py is true;
- a cross-request generation stage for generating, for said pairs of said units, respective cross-request signals
- req_arb(selxnoty, req_x, req_y, req—x—y, req_y_x)
- where
- selxnoty is the aforesaid selection signal;
- req_x is the request coming from the unit x;
- req_y is the signal coming from the unit y;
- and
- req_x_y and req—y_x are, respectively, the outputs of the function
- req_x AND (selxnoty OR NOT req_y)
- and of the function
- req_y AND ((NOT selxnoty) OR (NOT req_x));
- and
- a grant-generation stage for generating the grant for an ith unit as a logical product of all the aforesaid cross-request signals req_i_z with z ranging from 1 to n, excluding the case of z=i.
An arbitration method, comprising:
- receiving first, second, and third arbitration requests for access to a target resource, the first, second, and third arbitration requests being associated with first, second, and third priorities, respectively;
- generating a first selection signal having a value that depends on a comparison of the first and second priorities;
- generating a second selection signal having a value that depends on a comparison of the first and third priorities;
- generating a first cross-request signal having a value indicative of the logical AND of the first arbitration request with the logical OR of the first selection signal and the logical NOT of the second arbitration request;
- generating a second cross-request signal having a value indicative of the logical AND of the first arbitration request with the logical OR of the second selection signal and the logical NOT of the third arbitration request;
- and
- generating a first grant signal having a value indicative of the logical AND of the first and second cross-request signals.
Dependencies are inferred from the claim text.