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loop - WebAssembly | MDN
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loop
The loop
statement creates a label that can later be branched to with a br
. The loop instruction doesn't loop by itself; you need to branch to it to actually create a loop.
The loop
statement is the opposite of the block
statement, in the sense that while branching to a loop
jumps to the beginning of the loop, branching to a block
jumps to the end of the block, that is, out of the block.
Try it
(module
;; import the browser console object, you'll need to pass this in from JavaScript
(import "console" "log" (func $log (param i32)))
(func
;; create a local variable and initialize it to 0
(local $i i32)
(loop $my_loop
;; add one to $i
local.get $i
i32.const 1
i32.add
local.set $i
;; log the current value of $i
local.get $i
call $log
;; if $i is less than 10 branch to loop
local.get $i
i32.const 10
i32.lt_s
br_if $my_loop
)
)
(start 1) ;; run the first function automatically
)
const url = "{%wasm-url%}";
await WebAssembly.instantiateStreaming(fetch(url), { console });
Syntax
wat
;; label the loop so that it can be branched to
(loop $my_loop
;; branch to the loop.
;; most of the time you'll want to put this in an if statement and only branch on condition,
;; otherwise you have an infinite loop.
br $my_loop
)
Instruction | Binary opcode |
---|---|
loop |
0x03 |