Display control circuit and display device

1. A display control circuit for exchanging, with a plurality of masters, attribute information defining conditions for displaying video on a display, the display control circuit comprising:

a memory to store the attribute information;

a plurality of channels to accept access requests to access the memory from the respective masters; and

an arbitration controller to arbitrate the access requests accepted via the respective channels and permit a selected one of the access requests to access the memory, the arbitration controller including:

an acceptor to asynchronously accept the access requests accepted via the channels;

a plurality of latches to synchronize the access requests by using a first arbitration pulse input thereto in response to the access requests;

an arbiter to perform arbitration in accordance with values latched by the respective latches; and

a synchronizer to deterministically settle one of the access requests arbitrated by the arbiter, in response to a second arbitration pulse.

2. The display control circuit according to claim 1 , wherein priorities of the access requests are determined by the channels via which the access requests are accepted, and the arbitration controller arbitrates the access requests in accordance with the priorities.

3. The display control circuit according to claim 1 , wherein the arbitration controller further includes an arbitration pulse generator to generate the first arbitration pulse by delaying the access request, and generate the second arbitration pulse by delaying the first arbitration pulse.

4. The display control circuit according to claim 1 , further comprising:

a comparator to determine whether or not a memory address corresponding to the access request coincides with an address requiring change of data stored therein; and

a replacer to replace the data of a coincident address determined by the comparator, with replacement data and outputting resultant data.

5. The display control circuit according to claim 4 , wherein the replacer has a memory to store the replacement data prepared for the respective masters and replaces the data of the coincident address with suitable one of the replacement data.

6. The display control circuit according to claim 4 , wherein the address requiring change of data has a chain structure addressable by a pointer including code number and byte length, and

wherein the comparator traces the chain to identify the address requiring change of data and holds the identified address.

7. The display control circuit according to claim 6 , further comprising a decision unit to determine whether or not data has been written in an address of the memory holding a checksum,

wherein the chain is traced again as soon as the decision unit makes a decision.

8. A display device for exchanging, with a plurality of masters, attribute information defining conditions for displaying video on a display, the display device comprising:

a display control circuit including a memory to store the attribute information, a plurality of channels to accept access requests to access the memory from the respective masters, and an arbitration controller to arbitrate the access requests accepted via the respective channels and permit a selected one of the access requests to access the memory,

wherein the arbitration controller includes:

an acceptor to asynchronously accept the access requests accepted via the channels;

a plurality of latches to synchronize the access requests by using a first arbitration pulse input thereto in response to the access requests;

an arbiter to perform arbitration in accordance with values latched by the respective latches; and

a synchronizer to deterministically settle one of the access requests arbitrated by the arbiter, in response to a second arbitration pulse.

9. A display control circuit for exchanging, with a plurality of masters, attribute information defining conditions for displaying video on a display, the display control circuit comprising:

a memory to store the attribute information;

a plurality of channels with different priorities to accept a plurality of access requests to access the memory from the respective masters; and

a plurality of arbiter circuits, respectively coupled to the channels, to arbitrate among the access requests accepted by the channels and permit one of the access requests to access the memory, the arbiter circuits each comprising:

a first flip-flop to asynchronously accept the access request of the respective channel,

a delay circuit to produce a delayed signal by delaying the access request accepted by the first flip-flop,

a second flip-flop to produce a permission signal that permits the access request of the respective channel to access the memory, and

a channel arbitration circuit to cause the second flip-flop to produce the permission signal in response to the delayed signal, when none of other arbiter circuits coupled to the channels with higher priorities have accepted the access requests, and when none of other arbiter circuits coupled to the channels with lower priorities are permitting access to the memory.