Parallel Subtract Examples; Parallel Subtract Saturation Completers; Parallel Subtract Saturation Limits - Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 3 REV 2.3 Manual

psub — Parallel Subtract
( ) psub1
Format: qp
( ) psub1.sss
qp
( ) psub1.uus
qp
( ) psub1.uuu
qp
( ) psub2
qp
( ) psub2.sss
qp
( ) psub2.uus
qp
( ) psub2.uuu
qp
( ) psub4
qp
The sets of elements from the two source operands are subtracted, and the results
Description:
placed in GR
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
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.
Completer
sss
uus
uuu
Table 2-49.
Size
1
2
Figure 2-40.
GR r :
3
GR r :
2
GR r :
1
Volume 3: Instruction Reference
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
.
r
1
Table 2-49.

Parallel Subtract Saturation Completers

Result r treated as
1
signed
unsigned
unsigned

Parallel Subtract Saturation Limits

Element Width
Upper Limit
8 bit 0x7f
16 bit 0x7fff

Parallel Subtract Examples

- - - - - -
psub1
one_byte_form, modulo_form
one_byte_form, sss_saturation_form
one_byte_form, uus_saturation_form
one_byte_form, uuu_saturation_form
two_byte_form, modulo_form
two_byte_form, sss_saturation_form
two_byte_form, uus_saturation_form
two_byte_form, uuu_saturation_form
four_byte_form, modulo_form
Table
Source r treated as
2
signed
unsigned
unsigned
Result r Signed
1
Lower Limit
0x80
0x8000
GR r :
3
GR r :
2
- - -
GR r :
1
2-48. If the difference of
Source r treated as
3
signed
signed
unsigned
Result r Unsigned
1
Upper Limit Lower Limit
0xff 0x00
0xffff 0x0000
- - -
psub2
psub
A9
A9
A9
A9
A9
A9
A9
A9
A9
3:227