wrap: Wasm text instruction - Content

The wrap instruction, is used to convert numbers of type i64 to type i32. If the number is larger than what an i32 can hold this operation will wrap, resulting in a different number.

One can think of wrap either as reducing the value mod 2<sup>32</sup>, or as discarding the high 32 bits to produce a value containing just the low 32 bits.

wat

(module
  (import "console" "log" (func $log (param i32)))
  (func $main

    i64.const 10 ;; push an i64 onto the stack

    i32.wrap_i64 ;; wrap from i64 to i32

    call $log ;; log the result
  )
  (start $main)
)

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

Syntax

wat

;; push an i64 onto the stack
i64.const 10

;; wrap from i64 to i32
i32.wrap_i64

;; the top item on the stack will now be the value 10 of type `i32`

Instruction	Binary opcode
`i32.wrap_i64`	`0xa7`