Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1096

padd — Parallel Add
( ) padd1
Format: qp
( ) padd1.sss
qp
( ) padd1.uus
qp
( ) padd1.uuu
qp
( ) padd2
qp
( ) padd2.sss
qp
( ) padd2.uus
qp
( ) padd2.uuu
qp
( ) padd4
qp
The sets of elements from the two source operands are added, and the results placed in
Description:
GR .
r
1
If a sum of 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
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 2-44.
Table 2-43.
Completer
sss
uus
uuu
Table 2-44.
Size
1
2
Figure 2-29.
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
Parallel Add Saturation Completers
Result r treated as
1
signed
unsigned
unsigned
Parallel Add Saturation Limits
Result
Element Width
Upper Limit
8 bit 0x7f
16 bit 0x7fff
Parallel Add Examples
+ + + + + +
padd1
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 2-43. If the sum of two elements is larger than
Source r treated as
2
signed
unsigned
unsigned
r Signed
1
Lower Limit
0x80
0x8000
GR r :
3
GR r :
2
+ + +
GR r :
1
Source r treated as
3
signed
signed
unsigned
Result r Unsigned
1
Upper Limit Lower Limit
0xff 0x00
0xffff 0x0000
+ + +
padd2
padd
A9
A9
A9
A9
A9
A9
A9
A9
A9
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