71 lines · cpp
1//===---------- Baremetal implementation of IO utils ------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "io.h"10 11#include "src/__support/CPP/string_view.h"12#include "src/__support/macros/config.h"13 14namespace LIBC_NAMESPACE_DECL {15 16// These are intended to be provided by the vendor.17//18// The signature of these types and functions intentionally match `fopencookie`19// which allows the following:20//21// ```22// struct __llvm_libc_stdio_cookie { ... };23// ...24// struct __llvm_libc_stdio_cookie __llvm_libc_stdin_cookie;25// cookie_io_functions_t stdin_func = { .read = __llvm_libc_stdio_read };26// FILE *stdin = fopencookie(&__llvm_libc_stdin_cookie, "r", stdin_func);27// ...28// struct __llvm_libc_stdio_cookie __llvm_libc_stdout_cookie;29// cookie_io_functions_t stdout_func = { .write = __llvm_libc_stdio_write };30// FILE *stdout = fopencookie(&__llvm_libc_stdout_cookie, "w", stdout_func);31// ...32// struct __llvm_libc_stdio_cookie __llvm_libc_stderr_cookie;33// cookie_io_functions_t stderr_func = { .write = __llvm_libc_stdio_write };34// FILE *stderr = fopencookie(&__llvm_libc_stderr_cookie, "w", stderr_func);35// ```36//37// At the same time, implementation of functions like `printf` and `scanf` can38// use `__llvm_libc_stdio_read` and `__llvm_libc_stdio_write` directly to avoid39// the extra indirection.40//41// All three symbols `__llvm_libc_stdin_cookie`, `__llvm_libc_stdout_cookie`,42// and `__llvm_libc_stderr_cookie` must be provided, even if they don't point43// at anything.44 45struct __llvm_libc_stdio_cookie;46 47extern "C" struct __llvm_libc_stdio_cookie __llvm_libc_stdin_cookie;48extern "C" struct __llvm_libc_stdio_cookie __llvm_libc_stdout_cookie;49extern "C" struct __llvm_libc_stdio_cookie __llvm_libc_stderr_cookie;50 51extern "C" ssize_t __llvm_libc_stdio_read(void *cookie, char *buf, size_t size);52extern "C" ssize_t __llvm_libc_stdio_write(void *cookie, const char *buf,53 size_t size);54 55ssize_t read_from_stdin(char *buf, size_t size) {56 return __llvm_libc_stdio_read(static_cast<void *>(&__llvm_libc_stdin_cookie),57 buf, size);58}59 60void write_to_stdout(cpp::string_view msg) {61 __llvm_libc_stdio_write(static_cast<void *>(&__llvm_libc_stdout_cookie),62 msg.data(), msg.size());63}64 65void write_to_stderr(cpp::string_view msg) {66 __llvm_libc_stdio_write(static_cast<void *>(&__llvm_libc_stderr_cookie),67 msg.data(), msg.size());68}69 70} // namespace LIBC_NAMESPACE_DECL71