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Merge pull request #2523 from shritesh/wasmdoc

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docs: wasm
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Andrew Kelley 2019-05-27 22:37:15 -04:00 committed by GitHub
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doc/langref.html.in
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@ -8466,6 +8466,8 @@ fn concat(allocator: *Allocator, a: []const u8, b: []const u8) ![]u8 {
</li>
<li>Are you linking libc? In this case, {#syntax#}std.heap.c_allocator{#endsyntax#} is likely
the right choice, at least for your main allocator.</li>
<li>Are you building for WebAssembly? In this case, {#syntax#}std.heap.wasm_allocator{#endsyntax#} is likely
the right choice for your main allocator as it uses WebAssembly's memory instructions.</li>
<li>
Is the maximum number of bytes that you will need bounded by a number known at
{#link|comptime#}? In this case, use {#syntax#}std.heap.FixedBufferAllocator{#endsyntax#} or
@ -8996,8 +8998,12 @@ all your base are belong to us</code></pre>
{#header_close#}
{#header_close#}
{#header_open|WebAssembly#}
<p>Zig supports building for WebAssembly out of the box. There is also a specialized {#syntax#}std.heap.wasm_allocator{#endsyntax#}
memory allocator for WebAssembly environments.</p>
{#header_open|Freestanding#}
{#code_begin|lib|wasm#}
<p>For host environments like the web browser and nodejs, build as a library using the freestanding OS target.
Here's an example of running Zig code compiled to WebAssembly with nodejs.</p>
{#code_begin|lib|math#}
{#target_wasm#}
extern fn print(i32) void;
@ -9006,7 +9012,22 @@ export fn add(a: i32, b: i32) void {
}
{#code_end#}
{#header_close#}
<p class="file">test.js</p>
<pre><code>const fs = require('fs');
const source = fs.readFileSync("./math.wasm");
const typedArray = new Uint8Array(source);
WebAssembly.instantiate(typedArray, {
env: {
print: (result) =&gt; { console.log(`The result is ${result}`); }
}}).then(result =&gt; {
const add = result.instance.exports.add;
add(1, 2);
});</code></pre>
<pre><code>$ node test.js
The result is 3</code></pre>
{#header_open|WASI#}
<p>Zig's support for WebAssembly System Interface (WASI) is under active development. Example of using the standard library and reading command line arguments:</p>
{#code_begin|exe|wasi#}
{#target_wasi#}
const std = @import("std");
@ -9020,6 +9041,10 @@ pub fn main() !void {
}
}
{#code_end#}
<pre><code>$ wasmer run wasi.wasm 123 hello
0: wasi.wasm
1: 123
2: hello</code></pre>
{#header_close#}
{#header_close#}
{#header_open|Targets#}
@ -9260,6 +9285,7 @@ Available libcs:
s390x-linux-musl
sparc-linux-gnu
sparcv9-linux-gnu
wasm32-freestanding-musl
x86_64-linux-gnu
x86_64-linux-gnux32
x86_64-linux-musl</code></pre>