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

Application Level Programmers’ Model
Figure A2-2 Advanced SIMD data type hierarchy
For example, a multiply instruction must distinguish between integer and floating-point data types.
However, some multiply instructions use modulo arithmetic for integer instructions and therefore do not
need to distinguish between signed and unsigned inputs.
A multiply instruction that generates a double-width (long) result must specify the input data types as signed
or unsigned, because for this operation it does make a difference.
A2.6.3 Advanced SIMD vectors
.S8
.I8
.U8
.P8
-
.S16
.I16
.U16
.P16
.F16 ‡
.S32
.I32
.U32
-
.F32
.S64
.I64
.U64
-
-
When the Advanced SIMD extension is implemented, a register can hold one or more packed elements, all
of the same size and type. The combination of a register and a data type describes a vector of elements. The
vector is considered to be an array of elements of the data type specified in the instruction. The number of
elements in the vector is implied by the size of the data elements and the size of the register.
Vector indices are in the range 0 to (number of elements – 1). An index of 0 refers to the least significant
end of the vector. Figure A2-3 on page A2-27 shows examples of Advanced SIMD vectors:
A2-26 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B
.8
.16
.32
.64
‡ Supported only if the half-precision extensions are implemented