
MOTOROLA
Chapter 3. Instruction Set Model
3-21
Instruction Set Summary
an update form, in which
r
A is updated with the EA. For these forms, the following rules
apply:
If
r
A
≠
0, the EA is placed into
r
A.
If
r
S =
r
A, the contents of
r
S are copied to the target memory element, then the
generated EA is placed into
r
A (
r
S).
The
G2 core defines store with update instructions with
r
A = 0 and integer store
instructions with the CR update option enabled (Rc field, bit 31, in the instruction encoding
= 1) to be invalid forms. Table 3-15 provides a list of the integer store instructions for the
core.
3.2.4.3.5
Integer Load and Store with Byte-Reverse Instructions
Table 3-16 describes integer load and store with byte-reverse instructions. When used in a
system operating with the default big-endian byte order, these instructions have the effect
of loading and storing data in little-endian order. Likewise, when used in a system operating
with little-endian byte order, these instructions have the effect of loading and storing data
in big-endian order. When used in a G2_LE core-based system operating with true
little-endian byte order, these instructions have the effect of loading and storing data in true
little-endian order. For more information about big- and little-endian byte ordering, see
Section 3.1.2, “Byte Ordering,” in the
Programming Environments Manual
. For more
information about true little-endian operation, see Section 3.1.2, “Endian Modes and Byte
Ordering.”
Table 3-15. Integer Store Instructions
Name
Mnemonic
Operand Syntax
Store Byte
stb
r
S
,
d(
r
A)
Store Byte Indexed
stbx
r
S
,r
A
,r
B
Store Byte with Update
stbu
r
S
,
d(
r
A)
Store Byte with Update Indexed
stbux
r
S
,r
A
,r
B
Store Half Word
sth
r
S
,
d(
r
A)
Store Half Word Indexed
sthx
r
S
,r
A
,r
B
Store Half Word with Update
sthu
r
S
,
d(
r
A)
Store Half Word with Update Indexed
sthux
r
S
,r
A
,r
B
Store Word
stw
r
S
,
d(
r
A)
Store Word Indexed
stwx
r
S
,r
A
,r
B
Store Word with Update
stwu
r
S
,
d(
r
A)
Store Word with Update Indexed
stwux
r
S
,r
A
,r
B
F
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n
.