ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

A7.2 Advanced SIMD and VFP instruction syntax
Advanced SIMD and VFP Instruction Encoding
Advanced SIMD and VFP instructions use the general conventions of the ARM instruction set.
Advanced SIMD and VFP data-processing instructions use the following general format:
V{}{}{.} {,} ,
All Advanced SIMD and VFP instructions begin with a V. This distinguishes Advanced SIMD vector and
VFP instructions from ARM scalar instructions.
The main operation is specified in the field. It is usually a three letter mnemonic the same as or
similar to the corresponding scalar integer instruction.
The and fields are standard assembler syntax fields. For details see Standard assembler syntax fields
on page A8-7.
A7.2.1 Advanced SIMD Instruction modifiers
The field provides additional variants of some instructions. Table A7-1 provides definitions of
the modifiers. Modifiers are not available for every instruction.
Meaning
Table A7-1 Advanced SIMD instruction modifiers
Q The operation uses saturating arithmetic.
R The operation performs rounding.
D The operation doubles the result (before accumulation, if any).
H The operation halves the result.
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