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MPC823e Instruction Set
NOTATION/
CONVENTION
0b nnnn
A number expressed in binary format.
0x nnnn
A number expressed in hexadecimal format.
( n )x
The replication of x, n times (that is, x concatenated to itself n – 1 times).
(n)0 and (n)1 are special cases. A description of the special cases follows:
• (n)0 means a field of n bits with each bit equal to 0. Thus (5)0 is equivalent to
0b00000.
• (n)1 means a field of n bits with each bit equal to 1. Thus (5)1 is equivalent to
0b11111.
( r A|0)
The contents of rA if the rA field has the value 1–31, or the value 0 if the rA field is 0.
( r X)
The contents of rX
x[ n ]
n is a bit or field within x, where x is a register
n
x is raised to the nth power
x
ABS(x)
Absolute value of x
Least integer ≥ x
CEIL(x)
Characterization
Reference to the setting of status bits in a standard way that is explained in the text.
CIA
Current instruction address.
The 32-bit address of the instruction being described by a sequence of pseudocode. Used
by relative branches to set the next instruction address (NIA) and by branch instructions
with LK = 1 to set the link register. Does not correspond to any architected register.
Clear
Clear the leftmost or rightmost n bits of a register to 0. This operation is used for rotate and
shift instructions.
Clear left and shift left
Clear the leftmost b bits of a register, then shift the register left by n bits. This operation
can be used to scale a known non-negative array index by the width of an element. These
operations are used for rotate and shift instructions.
Cleared
Bits are set to 0.
Do
Do loop.
• Indenting shows range.
• "To" and/or "by" clauses specify incrementing an iteration variable.
• "While" clauses give termination conditions.
Extract
Select a field of n bits starting at bit position b in the source register, right or left justify this
field in the target register, and clear all other bits of the target register to zero. This
operation is used for rotate and shift instructions.
EXTS(x)
Result of extending x on the left with sign bits
GPR(x)
General-purpose register x
if...then...else...
Conditional execution, indenting shows range, else is optional.
Insert
Select a field of n bits in the source register, insert this field starting at bit position b of the
target register, and leave other bits of the target register unchanged. (No simplified
mnemonic is provided for insertion of a field when operating on double words; such an
insertion requires more than one instruction.) This operation is used for rotate and shift
instructions. (Note that simplified mnemonics are referred to as extended mnemonics in
the architecture specification.)
Leave
Leave innermost do loop, or the do loop described in leave statement.
MASK(x, y)
Mask having ones in positions x through y (wrapping if x > y) and zeros elsewhere.
MEM(x, y)
Contents of y bytes of memory starting at address x.
B-4
DEFINITION
MPC823e REFERENCE MANUAL
MOTOROLA
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