r8a77850anbg Renesas Electronics Corporation., r8a77850anbg Datasheet - Page 269

• Manufacturer Part Number: r8a77850anbg
• Description: Renesas 32-bit Risc Microcomputer Superh? Risc Engine Family
• Manufacturer: Renesas Electronics Corporation.

8.7.3
Transfer from the SQs to external memory can be performed with a prefetch instruction (PREF).
Issuing a PREF instruction for addresses H'E000 0000 to H'E3FF FFFC in the P4 area starts a
transfer from the SQs to external memory. The transfer length is fixed at 32 bytes, and the start
address is always at a 32-byte boundary. While the contents of one SQ are being transferred to
external memory, the other SQ can be written to without a penalty cycle. However, writing to the
SQ involved in the transfer to external memory is kept waiting until the transfer is completed.
The physical address bits [28:0] of the SQ transfer destination are specified as shown below,
according to whether the MMU is enabled or disabled.
• When MMU is enabled (AT = 1 in MMUCR)
• When MMU is disabled (AT = 0 in MMUCR)
The SQ area (H'E000 0000 to H'E3FF FFFF) is set in VPN of the UTLB, and the transfer
destination physical address in PPN. The ASID, V, SZ, SH, PR, and D bits have the same
meaning as for normal address translation, but the C and WT bits have no meaning with regard
to this page. When a prefetch instruction is issued for the SQ area, address translation is
performed and physical address bits [28:10] are generated in accordance with the SZ bit
specification. For physical address bits [9:5], the address prior to address translation is
generated in the same way as when the MMU is disabled. Physical address bits [4:0] are fixed
at 0. Transfer from the SQs to external memory is performed to this address.
The SQ area (H'E000 0000 to H'E3FF FFFF) is specified as the address at which a PREF
instruction is issued. The meanings of address bits [31:0] are as follows:
[31:26]
[25:6]
[5]
[4:2]
[1:0]
Physical address bits [28:26], which cannot be generated from the above address, are generated
from QACR0 and QACR1.
QACR0[4:2]
QACR1[4:2]
Transfer to External Memory
: 111000
: Address
: 0/1
: Don't care
: 00
: Physical address bits [28:26] corresponding to SQ0
: Physical address bits [28:26] corresponding to SQ1
Store queue specification
Transfer destination physical address bits [25:6]
0: SQ0 specification
1: SQ1 specification and transfer destination physical
No meaning in a prefetch
Fixed at 0
address bit [5]
Rev.1.00 Jan. 10, 2008 Page 239 of 1658
REJ09B0261-0100
8. Caches