printf.ts
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printf.ts
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	import { dlopen, suffix, FFIType } from 'ant:ffi';

	let libcName: string;
	if (process.platform === 'darwin') {
	libcName = `libSystem.${suffix}`;
	} else if (process.platform === 'linux') {
	libcName = `libc.${suffix}`;
	} else if (process.platform === 'win32') {
	libcName = `msvcrt.${suffix}`;
	} else throw new Error(`Unsupported platform: ${process.platform}`);

	interface libC {
	putchar(c: number): number;
	printf(format: string, ...args: unknown[]): number;
	}

	const libc = dlopen<libC>(libcName);

	libc.define('putchar', {
	args: [FFIType.int],
	returns: FFIType.int
	});

	libc.define('printf', {
	args: [FFIType.string, FFIType.spread],
	returns: FFIType.int
	});

	console.log(libc);

	console.log('calling putchar(65):');
	libc.putchar(65); // 'A'

	console.log('\ncalling printf:');
	libc.printf('Hello FFI! I see %d\n', 42);

	console.log('calling putchar(66):');
	libc.call('putchar', 66); // 'B'