Granted Patent B2

US 7,702,860 · App. 11/832,536 · Granted Apr 20, 2010

Abstract

Claims (49)

1. A memory access apparatus for accessing a first memory and a second memory, comprising:

an address outputting unit configured to output a read address to at least one of the first and the second memories based on a data size and an address in an address space of a read data;

an access request outputting unit configured to output a read request to at least one of the first and the second memories based on the data size and the address in the address space of the read data;

a data information outputting unit configured to output an information on the data size, and an information on the address, of the read data; and

a read data outputting unit configured to generate the read data to be output, from the data output from at least one of the first and the second memories in response to the read address output from the address outputting unit and the read request output from the access request outputting unit, based on the information on the data size and the information on the address that are output from the data information outputting unit.

2. The memory access apparatus of claim 1 , wherein

the first memory is configured to store data of an N-bit width and of an even-number address in the address space and the second memory is configured to store data of an N-bit width and of an odd-number address in the address space, wherein

the address outputting unit is configured to output the read address corresponding to the address in the address space

to the first or the second memory when the data size of the read data is N bits and

to the first and the second memories when the data size of the read data is 2N bits, and wherein

the read data outputting unit is configured

to output the data output from the first or the second memory as the read data when the data size of the read data is N bits,

to generate the read data to be output, with the data output from the first memory being assigned as high-order bits of the read data and the data output from the second memory being assigned as low-order bits of the read data, when the data size of the read data is 2N bits and the address in the address space of the read data is an even-number address, and

to generate the read data to be output, with the data output from the second memory being assigned as high-order bits of the read data and the data output from the first memory being assigned as low-order bits of the read data, when the data size of the read data is 2N bits and the address in the address space of the read data is an odd-number address.

3. The memory access apparatus of claim 1 , wherein

the address outputting unit is configured to output a write address to at least one of the first and the second memories, based on a data size and an address in an address space of a write data, wherein

the access request outputting unit is configured to output a write request to at least one of the first and the second memories, based on the data size and the address in the address space of the write data, and wherein

the data information outputting unit is configured to output an information on the data size, and an information on the address, of the write data,

the memory access apparatus further comprising a write data outputting unit configured to output the write data to at least one of the first and the second memories, based on the information on the data size and the information on the address that are output from the data information outputting unit.

4. The memory access apparatus of claim 3 , wherein

the first memory is configured to store data of an N-bit width and of an even-number address in the address space and the second memory is configured to store data of an N-bit width and of an odd-number address in the address space, wherein

the address outputting unit is configured to output the write address corresponding to the address in the address space

to the first or the second memory when the data size of the write data is N bits and

to the first and the second memories when the data size of the write data is 2N bits, and wherein

the write data outputting unit is configured

to output the write data to the first memory when the data size of the write data is N bits and the address in the address space of the write data is an even-number address,

to output the write data to the second memory when the data size of the write data is N bits and the address in the address space of the write data is an odd-number address,

to output high-order N bits of the write data to the first memory and low-order N bits of the write data to the second memory when the data size of the write data is 2N bits and the address in the address space of the write data is an even-number address, and

to output high-order N bits of the write data to the second memory and low-order N bits of the write data to the first memory when the data size of the write data is 2N bits and the address in the address space of the write data is an odd-number address.

5. The memory access apparatus of claim 3 , further comprising:

a write address memorizing unit configured to memorize the write address output from the address outputting unit;

a write data memorizing unit configured to memorize the write data output from the write data outputting unit before the write data is written to the first or the second memory; and

an address selecting circuit configured to output the read address to the first or the second memory, when the read address output from the address outputting unit and the write address memorized in the write address memorizing unit are different, wherein

the read data outputting unit is configured

to generate the read data to be output, from the data output from at least one of the first and the second memories when the read address output from the address outputting unit and the write address memorized in the write address memorizing unit are different and

to output the write data memorized in the write data memorizing unit when the read address output from the address outputting unit and the write address memorized in the write address memorizing unit are the same.

6. The memory access apparatus of claim 4 , further comprising:

a write address memorizing unit configured to memorize the write address output from the address outputting unit;

a write data memorizing unit configured to memorize the write data output from the write data outputting unit before the write data is written to the first or the second memory; and

an address selecting circuit configured to output the read address to the first or the second memory, when the read address output from the address outputting unit and the write address memorized in the write address memorizing unit are different, wherein

the read data outputting unit is configured

to generate the read data to be output, from the data output from at least one of the first and the second memories when the read address output from the address outputting unit and the write address memorized in the write address memorizing unit are different and

to output the write data memorized in the write data memorizing unit when the read address output from the address outputting unit and the write address memorized in the write address memorizing unit are the same.

7. The memory access apparatus of claim 1 , wherein

the address outputting unit is configured to output the read address at a first timing when a clock changes from one logic level to the other logic level, and wherein

the access request outputting unit is configured to output the read request at a second timing when the clock changes from the one logic level to the other logic level, next to the first timing.

8. The memory access apparatus of claim 5 , wherein

the address outputting unit is configured to output the write address at a first timing when a clock changes from one logic level to the other logic level, and wherein

the access request outputting unit is configured to have the write address memorizing unit memorize the write address output from the address outputting unit, and at the same time, to have the write data memorizing unit memorize the write data output from the write data outputting unit, at a second timing when the clock changes from the one logic level to the other logic level, next to the first timing.

Assignments (9)