Rev. 1.50, 10/04, page 182 of 448
8.7 Store Queues
The SH-4A supports two 32-byte store queues (SQs) to perform high-speed writes to external
memory.
8.7.1 SQ Configuration
There are two 32-byte store queues, SQ0 and SQ1, as shown in figure 8.9. These two store queues
can be set independently.
SQ0
SQ0[0] SQ0[1] SQ0[2] SQ0[3] SQ0[4] SQ0[5] SQ0[6] SQ0[7]
SQ1
SQ1[0] SQ1[1] SQ1[2] SQ1[3] SQ1[4] SQ1[5] SQ1[6] SQ1[7]
4 byte 4 byte 4 byte 4 byte 4 byte 4 byte 4 byte 4 byte
Figure 8.9 Store Queue Configuration
8.7.2 Writing to SQ
A write to the SQs can be performed using a store instruction for addresses H'E000 0000 to
H'E3FF FFFC in the P4 area. A longword or quadword access size can be used. The meanings of
the address bits are as follows:
[31:26] : 111000 Store queue specification
[25:6] : Don't care Used for external memory transfer/access right
[5] : 0/1 0: SQ0 specification
1: SQ1 specification
[4:2] : LW specification Specifies longword position in SQ0/SQ1
[1:0] : 00 Fixed at 0
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