Data processor with block transfer control
View Patent ↗A data processor arranged so that a block transfer control unit ( 12 ) can initiate block transfer in response to the execution of a particular instruction by a CPU, in order to increase the speed and efficiency of the data transfer between a CPU-accessible internal memory ( 5 ) and an external memory ( 25,26 ). When an address specified by the addressing field coincides with an address mapped to the internal memory, the particular instruction sets a logical address as one of the transfer source or transfer destination addresses of the data block transfer. The internal memory is allotted to a part of virtual address space; the internal memory allotted so is associated with the physical address space, to which the external memory set as the other address is allotted, by a process in which a TLB is used when the MMU is in ON, and a given register is used when the MMU is in OFF.
1. A data processor comprising:
a CPU;
an internal memory accessible by said CPU; and
a control circuit capable of responding to a particular access request issued by said CPU to control a block transfer, in which said internal memory is used as a first transfer object;
a cache memory coupled to a first bus which is coupled to said CPU, said internal memory, and said control circuit; and
a bus interface controller connected to said control circuit, and operable to perform interface control for a second transfer object,
wherein a set of instructions for said CPU includes a particular instruction for making said CPU issue the particular access request,
the particular instruction has an address field,
when an address specified by the address field is a logical address mapped to said internal memory, the address is set as one of a transfer source address or a transfer destination address of the block transfer, and
a transfer source address or transfer destination address for said second transfer object of the block transfer is a physical address corresponding to a logical address of said address field,
said internal memory is assigned a cache non-object address for said cache memory,
the particular instruction includes a first cache memory-operating instruction, and
when the logical address specified by the address field directs a cache object address for said cache memory, the first cache memory-operating instruction causes an operation of making said cache memory retain data of an external memory associated with the physical address corresponding to the different logical address, at a cache object address specified by the logical address.
2. The data processor of claim 1 , wherein the particular instruction includes a second cache memory-operating instruction, and
when the logical address specified by the address field directs a cache object address and a cache hit is detected at a data location specified by the logical address and a cache entry associated with the cache hit is dirty, the second cache memory-operating instruction causes an operation of writing back to the external memory.
3. The data processor of claim 1 , wherein the particular instruction has an operation code identical to that of the first cache memory-operating instruction, and sets the cache non-object address of the address field as the destination address.
4. The data processor of claim 2 , wherein the particular instruction has an operation code identical to that of the second cache memory-operating instruction, and sets the cache non-object address of the address field as the source address.
5. The data processor of claim 1 , wherein said control circuit is capable of performing memory control in regard to a cache hit and a cache miss with respect to said cache memory.