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Volume 3: Instruction Reference
3:227
psub
psub — Parallel Subtract
Format:
(
qp
) psub1
r
1
=
r
2
,
r
3
one_byte_form, modulo_form
(
qp
) psub1.sss
r
1
=
r
2
,
r
3
one_byte_form, sss_saturation_form
(
qp
) psub1.uus
r
1
=
r
2
,
r
3
one_byte_form, uus_saturation_form
(
qp
) psub1.uuu
r
1
=
r
2
,
r
3
one_byte_form, uuu_saturation_form
(
qp
) psub2
r
1
=
r
2
,
r
3
two_byte_form, modulo_form
(
qp
) psub2.sss
r
1
=
r
2
,
r
3
two_byte_form, sss_saturation_form
(
qp
) psub2.uus
r
1
=
r
2
,
r
3
two_byte_form, uus_saturation_form
(
qp
) psub2.uuu
r
1
=
r
2
,
r
3
two_byte_form, uuu_saturation_form
(
qp
) psub4
r
1
=
r
2
,
r
3
four_byte_form, modulo_form
Description:
The sets of elements from the two source operands are subtracted, and the results
placed in GR
r
1
.
If the difference between two elements cannot be represented in the result element
and a saturation completer is specified, then saturation clipping is performed. The
saturation can either be signed or unsigned, as given in
. If the difference of
two elements is larger than the upper limit value, the result is the upper limit value. If
it is smaller than the lower limit value, the result is the lower limit value. The saturation
limits are given in
Table 2-48.
Parallel Subtract Saturation Completers
Completer
Result
r
1
treated as
Source
r
2
treated as
Source
r
3
treated as
sss
signed
signed
signed
uus
unsigned
unsigned
signed
uuu
unsigned
unsigned
unsigned
Table 2-49.
Parallel Subtract Saturation Limits
Size
Element Width
Result
r
1
Signed
Result
r
1
Unsigned
Upper Limit
Lower Limit
Upper Limit
Lower Limit
1
8 bit
0x7f
0x80
0xff
0x00
2
16 bit
0x7fff
0x8000
0xffff
0x0000
Figure 2-40. Parallel Subtract Examples
GR r
2
:
GR r
1
:
GR r
3
:
-
-
-
-
psub1
psub2
GR r
2
:
GR r
1
:
GR r
3
:
-
-
-
-
-
-
-
-
Содержание Itanium 9150M
Страница 1: ......
Страница 209: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault...
Страница 301: ...3 292 Volume 3 Pseudo Code Functions Intel Itanium Architecture Software Developer s Manual Rev 2 3...
Страница 405: ...3 396 Volume 3 Resource and Dependency Semantics...
Страница 406: ...3 397 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index...
Страница 407: ...3 398 Intel Itanium Architecture Software Developer s Manual Rev 2 3...
Страница 419: ...INDEX Index 12 Index for Volumes 1 2 3 and 4...
Страница 420: ......