Memory control apparatus
First Claim
1. A memory control apparatus which performs data transfer between a master and an external memory, said apparatus comprising:
- a master interface operable to receive an access request from the master and issue the access request to the external memory; and
an external memory interface operable to receive the access request from said master interface and access the external memory,wherein said master interface includes;
a data buffer operable to store data transferred from said external memory interface when the access request is issued;
an address buffer operable to store an address for which the access request has been issued;
a first comparison unit operable to compare a new address for which the access request has newly been issued with the address stored in said address buffer, and output first comparison information indicating whether or not the new address matches the address stored in said address buffer which indicates an address range of data stored in said data buffer;
a buffer control unit operable to issue an access request to said external memory interface, in the case where the first comparison information indicates a mismatch between the new address and the stored address, and operable to output data from said data buffer to the master without issuing an access request to said external memory interface, in the case where the first comparison information indicates a match between the new address and the stored address; and
a specific access detection unit operable to detect a new access request made by the master to a specific address on the external memory and determine, irrespective of whether the first comparison information indicates the match or the mismatch, whether or not to issue an access request to said external memory interface so as to control said buffer control unit based on the determination.
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Accused Products
Abstract
A memory control apparatus is capable of surely becoming consistent with an external memory while avoiding a deterioration in access efficiency to the external memory. The memory control apparatus includes: a data buffer and an address buffer which respectively store data and addresses related to past access requests from a first master; a first comparison unit which compares a new address with the address of the address buffer upon receiving the new address; a buffer control unit which performs one of issuing an access request to an external memory I/F or outputting the data in the data buffer to the first master, depending on the comparison result; a specific access detection unit which disables the contents of the data buffer irrespective of the comparison result.
8 Citations
17 Claims
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1. A memory control apparatus which performs data transfer between a master and an external memory, said apparatus comprising:
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a master interface operable to receive an access request from the master and issue the access request to the external memory; and an external memory interface operable to receive the access request from said master interface and access the external memory, wherein said master interface includes; a data buffer operable to store data transferred from said external memory interface when the access request is issued; an address buffer operable to store an address for which the access request has been issued; a first comparison unit operable to compare a new address for which the access request has newly been issued with the address stored in said address buffer, and output first comparison information indicating whether or not the new address matches the address stored in said address buffer which indicates an address range of data stored in said data buffer; a buffer control unit operable to issue an access request to said external memory interface, in the case where the first comparison information indicates a mismatch between the new address and the stored address, and operable to output data from said data buffer to the master without issuing an access request to said external memory interface, in the case where the first comparison information indicates a match between the new address and the stored address; and a specific access detection unit operable to detect a new access request made by the master to a specific address on the external memory and determine, irrespective of whether the first comparison information indicates the match or the mismatch, whether or not to issue an access request to said external memory interface so as to control said buffer control unit based on the determination. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A memory control method for performing data transfer between a master and an external memory, using a memory control apparatus which includes:
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a master interface which receives an access request from the master and issue the access request to the external memory; and an external memory interface operable to receive the access request from the master interface and access the external memory, wherein the master interface includes; a data buffer which stores data transferred from the external memory interface when the access request is issued; and an address buffer which stores an address for which the access request has been issued, and wherein said memory control method comprises; comparing a new address for which the access request has newly been issued with the address stored in the address buffer, and outputting first comparison information indicating whether or not the new address matches the address stored in said address buffer which indicates an address range of data stored in the data buffer; issuing an access request to the external memory interface, in the case where the first comparison information indicates a mismatch between the new address and the stored address, and outputting data from the data buffer to the master without issuing an access request to the external memory interface, in the case where the first comparison information indicates a match between the new address and the stored address; and detecting a new access request made by the master to a specific address on the external memory and determining, irrespective of whether the first comparison information indicates the match or the mismatch, whether or not to issue an access request to the external memory interface so as to control the buffer control unit based on the determination.
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Specification