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PowerPC Architecture Compliance
MOTOROLA
MPC823 USER’S MANUAL
7-3
PPC
ARCHITECTURE
7
COMPLIANCE
7.1.8.1 MOVE TO/FROM SYSTEM REGISTER INSTRUCTIONS. Move to/from invalid
special registers in which spr0 =1 invokes the privilege instruction error interrupt handler if
the processor is in problem state (user mode). For a list of all implemented special registers,
7.1.8.2 FIXED-POINT ARITHMETIC INSTRUCTIONS. If you try to perform any of the
following divisions using the divw[o][.] instruction
0x80000000
÷ -1
<anything>
÷ 0
then, the contents of RT are 0x80000000 and if Rc =1, the contents of the bits in the CR field
0 are LT = 1, GT = 0, EQ = 0, and SO is set to the correct value.
In the cmpi, cmp, cmpli, and cmpl instructions, the L bit is applicable for 64-bit
implementations. For the MPC823, if L = 1 the instruction form is invalid. The core ignores
this bit and, therefore, the behavior when L = 1 is identical to the valid form instruction with
L = 0.
7.1.9 The Load/Store Processor
The load/store processor supports all of the 32-bit implementation fixed-point PowerPC
load/store instructions in the hardware.
7.1.9.1 FIXED-POINT LOAD WITH UPDATE AND STORE WITH UPDATE
INSTRUCTIONS. For load with update and store with update instructions where RA =0, the
EA is written into R0. For load with update instructions where RA = RT, RA is boundedly
undefined.
7.1.9.2 FIXED-POINT LOAD AND STORE MULTIPLE INSTRUCTIONS. For these types
of instructions, EA must be a multiple of four. If it is not, the system alignment error handler
is invoked. For a lmw instruction (if RA is in the range of registers to be loaded), the
instruction completes normally. RA is then loaded from the memory location as follows:
RA <- MEM(EA+(RA-RT)*4, 4)
7.1.9.3 FIXED-POINT LOAD STRING INSTRUCTIONS. Load string instructions behave
the same as load multiple instructions, with respect to invalid format in which RA is in the
range of registers to be loaded. If RA is in the range, it is updated from memory.
7.1.9.4 STORAGE SYNCHRONIZATION INSTRUCTIONS. For these type of instructions,
EA must be a multiple of four. If it is not, the system alignment error handler is invoked.
7.1.9.5 OPTIONAL INSTRUCTIONS. No optional instructions are supported.
7.1.9.6 LITTLE-ENDIAN BYTE ORDERING. The load/store unit supports little-endian byte
ordering as specified in the PowerPC User Instruction Set Architecture (Book I). In
little-endian mode, if an attempt is made to execute an individual scalar unaligned transfer,
as well as a multiple or string instruction, an alignment interrupt is taken.