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
Summary of Contents for SuperH SH-4A
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