loop
loop 语句创建一个标签,稍后可以使用 br 指令跳转到该标签。loop 指令本身不会循环;您需要跳转到它才能实际创建循环。
loop 语句与 block 语句是相反的,因为跳转到 loop 会跳到循环的开头,而跳转到 block 会跳到块的末尾,也就是跳出该块。
试一试
(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 });
语法
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
)
| 指令 | 二进制操作码 |
|---|---|
loop |
0x03 |