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FLTQ.H

RISC-V FLTQ.H Instruction Details

Instruction ManualR-type

Half-precision floating-point quiet less-than comparison; writes x[rd]=1 when true, otherwise 0.

Instruction Syntax

fltq.h rd, rs1, rs2
Operand Breakdown
rd: destination integer register receiving a 0 or 1 comparison result.
rs1/rs2: source floating-point registers; compare instructions do not use an rm rounding mode.
ZfaZfhFloating-Point Compare
Related Search Terms
FLTQ.H instructionRISC-V FLTQ.Hfltq.h syntaxfltq.h NaNfltq.h NV flaghalf-precision floating compare

Instruction Behavior

FLTQ.H compares the half-precision floating-point values in f[rs1] and f[rs2] and writes the Boolean result to integer register rd. It is a quiet comparison: quiet NaNs do not set NV, signaling NaNs set NV, and any NaN operand makes the result 0. The result is not a floating-point value and is not rounded by rm.

Quick Understanding & Search Notes

FLTQ.H writes the floating-point comparison result to integer register x[rd]. It has quiet-comparison semantics, useful when quiet NaNs should not raise NV.

It writes 1 when rs1 < rs2 is true, otherwise 0; any NaN operand writes 0.
The instruction does not produce a floating-point result and has no rm rounding field.
RISC-V Unprivileged ISA Manual: Zfa Extension

Common Usage Scenarios

Comparison & Detection

Understand this scenario with real code like «fltq.h x10, f0, f1 # x10 = (f0<f1) quiet».

Floating-Point Conditions

Understand this scenario with real code like «fltq.h x10, f0, f1 # x10 = (f0<f1) quiet».

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

Quiet comparisons set NV only for signaling NaNs; a quiet NaN only makes the result 0.
rd is an integer register and receives 0 or 1, not a floating-point value.
The comparison does not use the rm rounding mode.

FAQ

Is rd a floating-point register for FLTQ.H?

No. rd is an integer register holding the Boolean result 0 or 1.

What happens on NaN operands?

Any NaN operand makes the result 0; only signaling NaNs set NV.