Xilinx Virtex-II Pro PPC405, User Manual

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424 www.xilinx.com March 2002 Release
1-800-255-7778 Virtex-II Pro™ Platform FPGA Documentation
Chapter 3: User Programming Model
R
Special-Purpose Register Instructions
The special-purpose register instructions shown in Table 3-50 are used to read and write the
special-purpose registers (SPRs) using a GPR as a destination or source register. The SPR
number (SPRN) shown in the operand syntax column appears as a
decimal value in the
assembler listing. Within the instruction opcode, this number is encoded using a split-field
notation . For more information, see Split-Field Notation , page 571 .
Synchronizing Instructions
Table 3-51 lists the PowerPC synchronization instructions. The types of synchronization
defined by the PowerPC architecture are described in Synchronization Operations ,
page 342 .
Figure 3-38: mtcrf Example
r S
4 8 12 16 20 24 0 28 31
CRM
0 1 1 0 0 1 0 0
UG011_32_033101
CR1 CR2 CR3 CR4 CR5 CR6
rS[4:7] rS[8:11] rS[20:23]
CR0 CR7
CR
Unchanged
Table 3-50: Special-Purpose Register Instructions
Mnemonic Name Operation
Operand
Syntax
mfspr Move from Special Purpose Register
r D is loaded with the contents of the SPR specified
by SPRN.
r D,SPRN
mtspr Move to Special Purpose Register
The SPR specified by SPRN is loaded with the
contents of
r S.
SPRN, r S