Rev. 1.50, 10/04, page 184 of 448
8.7.4 Determination
of SQ Access Exception
Determination of an exception in a write to an SQ or transfer to external memory (PREF
instruction) is performed as follows according to whether the MMU is enabled or disabled. If an
exception occurs during a write to an SQ, the SQ contents before the write are retained. If an
exception occurs in a data transfer from an SQ to external memory, the transfer to external
memory will be aborted.
•
When MMU is enabled (AT = 1 in MMUCR)
Operation is in accordance with the address translation information recorded in the UTLB, and
the SQMD bit in MMUCR. Write type exception judgment is performed for writes to the SQs,
and read type exception judgment for transfer from the SQs to external memory (using a PREF
instruction). As a result, a TLB miss exception or protection violation exception is generated
as required. However, if SQ access is enabled in privileged mode only by the SQMD bit in
MMUCR, an address error will occur even if address translation is successful in user mode.
•
When MMU is disabled (AT = 0 in MMUCR)
Operation is in accordance with the SQMD bit in MMUCR.
0: Privileged/user mode access possible
1: Privileged mode access possible
If the SQ area is accessed in user mode when the SQMD bit in MMUCR is set to 1, an address
error will occur.
8.7.5
Reading from SQ
In privileged mode in the SH-4A, reading the contents of the SQs may be performed by means of
a load instruction for addresses H'FF00 1000 to H'FF00 103C in the P4 area. Only longword
access is possible.
[31:6]
: H'FF00 1000
Store queue specification
[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
Page 2: ...Rev 1 50 10 04 page ii of xx ...
Page 8: ...Rev 1 50 10 04 page viii of xx ...
Page 116: ...Rev 1 50 10 04 page 96 of 448 ...
Page 178: ...Rev 1 50 10 04 page 158 of 448 ...
Page 206: ...Rev 1 50 10 04 page 186 of 448 ...
Page 231: ...Rev 1 50 10 04 page 211 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 235: ...Rev 1 50 10 04 page 215 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 238: ...Rev 1 50 10 04 page 218 of 448 Possible Exceptions Slot illegal instruction exception ...
Page 408: ...Rev 1 50 10 04 page 388 of 448 Possible Exceptions Inexact Not generated when FPSCR PR 1 ...
Page 446: ...Rev 1 50 10 04 page 426 of 448 ...
Page 468: ...Rev 1 50 10 04 page 448 of 448 ...
Page 471: ......
Page 472: ...SH 4A Software Manual ...