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APPLICATION ARCHITECTURE
registers, respectively.
The
Push
instruction
pushes a
dword
onto
the stack
and
the
Pop
instruction
pops
the
top
d word from the stack
into a register
or
to memory.
Push
All pushes
the
general registers
onto
the
stack
and
Pop
All does
the
reverse.
The
Enter
and
Leave instructions are provided
for block-structured high-level languages.
The
Enter instruction builds the stack frame and
display
that
compilers use to link procedure
calls. The Leave instruction removes the dis-
play and stack frame from the stack in prepara-
tion
for
returning to the calling procedure.
" INCREASING SIGNIFICANCE
2.3.3.2 Control Transfer
Instructions
The
Jump
instruction transfers
control
to
another
instruction by changing the value
of
the Instruction Pointer.
The
target instruction
may be in
the
same
code
segment
(up
to 2
32
bytes a way)
or
in a different one. The
operand
of
an
intrasegment
Jump
is
a
near
pointer,
that
is, the offset
of
the target instruction
in
the
current
code segment; thus, a
Jump
can be
directed
to
any
location
in the largest possible
segment. The
operand
of
an
intersegment
Jump
is
a far pointer. allowing
control
to be
I RELATIVE ADDRESSES
7 0
o BYTE ORDINAL
MAGNITUDE
___
-It
47
~
0
...
IIL-
__________
.....
I DWORD INTEGER
t,--I
----MAGNITUDE------'
'-------SIGN
7 0
o UNPACKED DECIMAL
7 3 0
OJ
PACKED DECIMAL
d~.,...I
____
-------.-1
BYTE STRING
LEFTMOST
BYTE------'t
~
0
1L-
__________
-.l1
NEAR POINTER
31
I
FAR
POINTER
L-
______
~
____________
~
L SELECTOR
~~I----
OFFSET -
___
~
Figure
2-7.
Data Type Storage
2-8