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ARM Compiler armasm User Guide : Advanced SIMD data types in A32/T32 instructions

Advanced SIMD data types in A32/T32 instructions

Most Advanced SIMD instructions use a data type specifier to define the size and type of data that the instruction operates on.

Data type specifiers in Advanced SIMD instructions consist of a letter indicating the type of data, usually followed by a number indicating the width. They are separated from the instruction mnemonic by a point. The following table shows the data types available in Advanced SIMD instructions:

Table 9-2 Advanced SIMD data types

  8-bit 16-bit 32-bit 64-bit
Unsigned integer U8 U16 U32 U64
Signed integer S8 S16 S32 S64
Integer of unspecified type I8 I16 I32 I64
Floating-point number not available F16 F32 (or F) not available
Polynomial over {0,1} P8 P16 not available not available

The datatype of the second (or only) operand is specified in the instruction.


Most instructions have a restricted range of permitted data types. See the instruction descriptions for details. However, the data type description is flexible:
  • If the description specifies I, you can also use the S or U data types.

  • If only the data size is specified, you can specify a type (I, S, U, P or F).
  • If no data type is specified, you can specify a data type.
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