Does VNSRA.WX round?
No. It is a narrowing right shift; use VNCLIP/VNCLIPU when fixed-point rounding and saturation are required.
VNSRA.WX
RISC-V VNSRA.WX Instruction Details
Instruction ManualR-typearithmetic narrowing right shift from 2*SEW source elements to SEW results.
Instruction Syntax
vnsra.wx vd, vs2, rs1, vm
Operand Breakdown
Destination rd: register receiving the operation result.
Source rs1: register holding the first operand.
Source rs2: register holding the second operand.
VVector IntegerShift/Narrowing
Instruction Behavior
VNSRA.WX performs a arithmetic right shift on 2*SEW-wide source elements and writes SEW-width destination elements. The shift amount comes from a scalar integer register.
Quick Understanding & Search Notes
VNSRA.WX shrinks wide integer results back to SEW width using a arithmetic right shift.
Source elements are 2*SEW wide and destination elements are SEW wide.
Arithmetic right shift preserves sign-extension semantics.
This instruction does not use vxrm rounding and does not set the vxsat saturation flag.
Common Usage Scenarios
Fixed-Point Scaling
Understand this scenario with real code like «vnsra.wx v8, v12, x5, v0.t».
Precision Reduction
Understand this scenario with real code like «vnsra.wx v8, v12, x5, v0.t».
Pre-Use Checklist
Syntax Check
- Confirm the current instruction format is R-type.
- Confirm the operand order matches the example.
Semantic Check
- Ensure the destination register usage is compatible with the calling convention.
- Confirm this is not the lower-level form of a pseudo-instruction expansion.
Pitfalls / Common Confusions
Shift 0+rs1=x0=narrowing type conversion (pseudo vncvt.x.x.w)