64 lines
1.8 KiB
Zig
64 lines
1.8 KiB
Zig
const std = @import("std");
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const allocator = std.heap.page_allocator;
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extern "env" fn log(ptr: [*]const u8, size: u32) void;
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// _log prints a message to the console using log.
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pub fn _log(message: []const u8) void {
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log(message.ptr, message.len);
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}
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pub export fn malloc(length: usize) ?[*]u8 {
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const buff = allocator.alloc(u8, length) catch return null;
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return buff.ptr;
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}
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pub export fn free(buf: [*]u8, length: usize) void {
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allocator.free(buf[0..length]);
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}
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pub fn _greeting(name: []const u8) ![]u8 {
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return try std.fmt.allocPrint(
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allocator,
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"Hello, {s}!",
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.{name},
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);
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}
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// _greet prints a greeting to the console.
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pub fn _greet(name: []const u8) !void {
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const s = try std.fmt.allocPrint(
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allocator,
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"wasm >> {s}",
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.{name},
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);
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_log(s);
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}
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// greet is a WebAssembly export that accepts a string pointer (linear memory offset) and calls greet.
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pub export fn greet(message: [*]const u8, size: u32) void {
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const name = _greeting(message[0..size]) catch |err| @panic(switch (err) {
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error.OutOfMemory => "out of memory",
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});
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_greet(name) catch |err| @panic(switch (err) {
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error.OutOfMemory => "out of memory",
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});
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}
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// greeting is a WebAssembly export that accepts a string pointer (linear memory
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// offset) and returns a pointer/size pair packed into a uint64.
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//
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// Note: This uses a uint64 instead of two result values for compatibility with
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// WebAssembly 1.0.
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pub export fn greeting(message: [*]const u8, size: u32) u64 {
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const g = _greeting(message[0..size]) catch return 0;
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return stringToPtr(g);
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}
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// stringToPtr returns a pointer and size pair for the given string in a way
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// compatible with WebAssembly numeric types.
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pub fn stringToPtr(s: []const u8) u64 {
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const p: u64 = @intFromPtr(s.ptr);
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return p << 32 | s.len;
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}
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