Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3, Manual

Page: 1155 / 1898

3:256 Volume 3: Instruction Reference
sub
sub — Subtract
Format: (
qp
) sub
r
1
=
r
2
,
r
3
register_form A1
(
qp
) sub
r
1
=
r
2
,
r
3
, 1 minus1_form, register_form A1
(
qp
) sub
r
1
=
imm
8
,
r
3
imm8_form A3
Description:
The second source operand (and an optional constant 1) are subtracted from the first
operand and the result placed in GR
r
1
. In the register form the first operand is GR
r
2
; in
the immediate form the first operand is taken from the sign-extended
imm
8
encoding
field.
The minus1_form is available only in the register_form (although the equivalent effect
can be achieved by adjusting the immediate).
Operation: if (PR[ qp ]) {
check_target_register( r
1
);
tmp_src = (register_form ? GR[ r
2
] : sign_ext( imm
8
, 8));
tmp_nat = (register_form ? GR[ r
2
].nat : 0);
if (minus1_form)
GR[ r
1
] = tmp_src - GR[ r
3
] - 1;
else
GR[ r
1
] = tmp_src - GR[ r
3
];
GR[ r
1
].nat = tmp_nat || GR[ r
3
].nat;
}
Interruptions:
Illegal Operation fault