Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1094

pack — Pack
( ) pack2.sss
Format: qp
( ) pack2.uss
qp
( ) pack4.sss
qp
32-bit or 16-bit elements from GR
Description:
elements respectively, and the results are placed GR
treated as signed values. If a source element cannot be represented in the result
element, then saturation clipping is performed. The saturation can either be signed or
unsigned. If an element 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 2-42.
Size
2
2
4
Figure 2-28.
GR r :
3
GR r :
3
Volume 3: Instruction Reference
= ,
r r r
1 2 3
= ,
r r r
1 2 3
= ,
r r r
1 2 3
Table
Pack Saturation Limits
Source Element Result Element
Width
16 bit
16 bit
32 bit
Pack Operation
GR r :
1
GR r :
1
two_byte_form, signed_saturation_form
two_byte_form, unsigned_saturation_form
four_byte_form, signed_saturation_form
and GR are converted into 16-bit or 8-bit
r r
2 3
. The source elements are
r
1
2-42.
Saturation
Width
8 bit signed
8 bit unsigned
16 bit signed
GR r :
2
pack4
GR r :
2
pack2
pack
I2
I2
I2
Upper
Lower Limit
Limit
0x7f 0x80
0xff 0x00
0x7fff 0x8000
3:195