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

A7.3.1 Advanced SIMD scalars
Advanced SIMD and VFP Instruction Encoding
Advanced SIMD scalars can be 8-bit, 16-bit, 32-bit, or 64-bit. Instructions other than multiply instructions
can access any element in the register set. The instruction syntax refers to the scalars using an index into a
doubleword vector. The descriptions of the individual instructions contain details of the encodings.
Table A7-7 shows the form of encoding for scalars used in multiply instructions. These instructions cannot
access scalars in some registers. The descriptions of the individual instructions contain cross references to
this section where appropriate.
32-bit Advanced SIMD scalars, when used as single-precision floating-point numbers, are equivalent to
VFP single-precision registers. That is, Dm[x] in a 32-bit context (0