The store8_lane SIMD load/store instruction stores a specified lane of a v128 i8x16 value interpretation at a given memory address.

(module
  (import "console" "log" (func $log (param i32)))
  (memory $memory 1)
  (func $main
    i32.const 0
    v128.const i8x16 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
    v128.store8_lane 15

    i32.const 0
    v128.load
    i8x16.extract_lane_u 0
    call $log
  )
  (start $main)
)

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

Syntax

;; Common usage
v128.store8_lane lane_idx

;; With optional immediate operands
v128.store8_lane mem_idx offset=int align=int lane_idx

• v128.store8_lane

  • : The v128.store8_lane instruction.

  mem_idx

  • : An integer representing the memory index, in cases where the module uses multiple memories. The default is 0.

  offset=int

  • : An integer representing a constant number of bytes to add to the address before storing. The default is 0.

  align=int

  • : An integer representing a hint to the Wasm engine about what alignment to expect for the final address. The minimum value is 1 and the default and maximum value is 1. An align value has to be a power of 2.

  lane_idx

  • : The index of the lane whose value you want to store.

Type

[memory_address, input] -> []

• memory_address

  • : An integer representing the memory address to store the input at.

  input

  • : The v128 type from which to extract a lane value to store.

Binary encoding

InstructionBinary formatExample text => binaryv128.store8_lane0xfd 88:u32 mem_idx:u8 offset:u32 align:u32 l:laneidxv128.store8_lane 0 offset=0 align=1 15 => 0xfd 0x58 0x00 0x00 0x0fWhile Wasm text format specifies the literal align value, the binary equivalent represents the exponent of the formula 2^x used to calculate the alignment. So for example, align=1 is equivalent to 0x00 (2^0).

Specifications

Browser compatibility