shuffle: Wasm SIMD conversion instruction

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

Instruction	Binary format	Example text => binary
`i8x16.shuffle`	`0xfd 13:u32 l:laneidx¹⁶`	`i8x16.shuffle 0 17 2 3 8 9 10 11 31 30 28 27 16 17 18 19` => `0xfd 0x0d 0x00 0x11 0x02 0x03 0x08 0x09 0x0a 0x0b 0x1f 0x1e 0x1c 0x1b 0x10 0x11 0x12 0x13`