Page 386 - ARM 64 Bit Assembly Language

376 Chapter 10

qshrn Saturating Shift Right Narrow,
qrshrn Saturating Rounding Shift Right Narrow,
sqshrun Signed Saturating Shift Right Unsigned Narrow, and
sqrshrun Signed Saturating Rounding Shift Right Unsigned Immediate.

10.8.3.1 Syntax

(s|u)q{r}shrn Vd.Td, Vn.Ts, #shift
sq{r}shrun Vd.Td2, Vn.Ts2, #shift

• If 2 is present, the Td/Ts is 16b/8h, 8h/4s,or 4s/2d
• If 2 is not present, the Td/Ts is 8b/8h, 4h/4s,or 2s/2d to elsize(Td).
• shift is in the range 1 to size(Td).
10.8.3.2 Operations

Name Effect Description
xq{r}shrn if r is present then Each element of Vm is shifted right
Vd[] ← with sign extension by the imme-
Vm[] imm ≺ diate value, optionally rounded,
else then saturated and narrowed, and
Vd[] ← stored in the corresponding ele-
Vm[] imm ≺ ment of Vd.
end if
sq{r}shrun if r is present then Each element of Vm is shifted right
Vd[] ← with zero extension by the imme-
Vm[] imm ≺ diate value, optionally rounded,
else then saturated and narrowed, and
Vd[] ← stored in the corresponding ele-
Vm[] imm ≺ ment of Vd.
end if

10.8.3.3 Examples

1 uqshrn v1.4h,v6.4s,#4 // shift, saturate and narrow
2 sqrshrn v1.8b,v6.8h,#4 // shift, round, saturate, and narrow

10.8.4 Shift left or right by variable

These instructions shift each element in a vector left or right, using the least significant byte
of the corresponding element of a second vector as the shift amount: