shuffle: Wasm SIMD conversion instruction

The shuffle SIMD conversion instruction returns a new v128 value with its lane values selected from two input v128 values, determined by provided index values.

Try it

(module
  (import "console" "log" (func $log (param i32)))
  (func $main
    v128.const i8x16 10 23 56 15 25 29 92 45 36 4 78 12 34 25 72 82
    v128.const i8x16 0 80 5 7 3 5 9 2 4 6 1 7 0 3 5 1
    i8x16.shuffle 0 17 2 3 8 9 10 11 31 30 28 27 16 17 18 19

    i8x16.extract_lane_u 14
    call $log ;; log the result
  )
  (start $main)
)

WebAssembly.instantiateStreaming(fetch("{%wasm-url%}"), { console });

In the above example, we extract and log the value at index position 14 of the shuffle instruction output value. This will be 5, because the shuffle instruction has selected the value at index position 3 of the second v128 input (represented by the index value 18) to be put at index position 14 of the output.

Syntax

value_type.shuffle indices

value_type

The type of value the instruction is being run on. The following v128 value interpretations support shuffle:

• i8x16

shuffle

The shuffle instruction. Must always be included after the value_type and a period (.).

indices

16 integers in the range 0 to 31 inclusive, representing the indices of the values to take from the two input values. Values of 0 to 15 represent the 16 indices of the first input value, and values of 16 to 31 represent the 16 indices of the second input value.

Type

[input1, input2] -> [output]

input1

The first input v128 i8x16 value interpretation.

input2

The second input v128 i8x16 value interpretation.

output

The output v128 value interpretation.

Binary encoding

Specifications

• WebAssembly Core Specification