Xilinx Virtex-II Pro PPC405, User Manual

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Virtex-II Pro™ Platform FPGA Documentation 1-800-255-7778
Time-Base Registers
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Time-Base Registers
Table A-7 lists the time-base registers accessed (read) using the mftb instruction. These
registers can be written using the mtspr instruction (see Special-Purpose Registers ,
page 770 for information on the time-base SPRs). The TBRN is the time-base number that
appears in the assembler syntax. The TBRF is the split-field version of the TBRN that
appears in the instruction encoding.
Device Control Registers
Device control registers (DCRs) are not architecturally part of the PPC405. DCRs are used
to control, configure, and record status for functional units implemented outside the
PPC405 processor but on the same chip. Although the PPC405 does not contain DCRs, the
mfdcr and mtdcr instructions are used by privileged software to access their contents.
Table A-7: Time-Base Registers
Name Descriptive Name
TBRN TBRF
Privileged Access Reset Value
Dec Hex Hex Binary
TBL Time-Base Lower 268 0x10C 0x188 0b01100_01000 No Read-Only Undefined
TBU Time-Base Upper 269 0x10D 0x1A8 0b01101_01000 No Read-Only Undefined