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THE
80286
INSTRUCTION SET
CALL-Call Procedure
Opcode
Instruction
Clocks'
Description
E8
cw
CALL
cw
7
Call near, offset relative to next instruction
FF
/2
CALL
ew
7,mem=11 Call near, offset absolute at
EA
word
9A
cd
CALL cd
13,pm=26
Call inter-segment, immediate 4-byte address
9A
cd
CALL cd
41
Call gate, same privilege
9A
cd
CALL cd
82
Call gate, more privilege, no parameters
9A
cd
CALL cd
86+4X
Call gate, more privilege, X parameters
9A
cd
CALL cd 177
Call via Task State Segment·
9A
cd
CALL cd 182 Call via task gate
FF
/3
CALL ed
16,mem=29
Call inter-segment, address at
EA
doubleword
FF
/3
CALL ed
44
Call gate, same privilege
FF
/3
CALL ed
83
Call gate, more privilege, no parameters
FF
/3
CALL ed
90+4X
Call gate, more privilege, X parameters
FF
/3
CALL ed 180
Call
via Task State Segment
FF
/3
CALL ed
185
Call via task gate
·Add one clock for each byte
in
the next instruction executed.
FLAGS MODIFIED
None, except when a task switch occurs
FLAGS UNDEFINED
None
OPERATION
The CALL instruction causes the procedure named
in
the operand to be executed. When the procedure
is
complete (a return instruction
is
executed within the procedure), execution continues at the instruc-
tion that follows the CALL instruction.
The CALL
cw
form of the instruction adds modulo 65536 (the 2-byte operand) to the offset of the
instruction following the CALL and sets
IP
to the resulting offset. The 2-byte offset of the instruction
that follows the CALL
is
pushed onto the stack.
It
will
be popped by a near RET instruction within
the procedure. The
CS
register
is
not changed by this form.
The CALL
ew form of the instruction
is
the same
as
CALL
cw
except· that the operand specifies a
memory location from which the absolute 2-byte offset for the procedure
is
fetched.
The CALL
cd
form of the instruction uses the 4-byte operand as a pointer to the procedure called.
The CALL
ed
form fetches the long pointer from the memory location specified. Both
long
pointer
forms consult the AR byte
in
the descriptor indexed by the selector part of the long pointer. The
AR
byte can indicate one of the following descriptor types:
l.
Code
Segment-The
access rights are checked, the return pointer
is
pushed onto the stack, and
the procedure
is
jumped to.
B-23