1 // Copyright 2022 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 15 #include "pw_sys_io/sys_io.h" 16 17 #include <stdio.h> 18 19 #include <cinttypes> 20 21 #include "pico/stdlib.h" 22 #include "pw_status/status.h" 23 #include "pw_sync/thread_notification.h" 24 25 namespace { 26 27 pw::sync::ThreadNotification chars_available_signal; 28 chars_available_callback(void * arg)29void chars_available_callback([[maybe_unused]] void* arg) { 30 chars_available_signal.release(); 31 } 32 LazyInitSysIo()33void LazyInitSysIo() { 34 static bool initialized = false; 35 if (!initialized) { 36 stdio_init_all(); 37 stdio_set_chars_available_callback(chars_available_callback, nullptr); 38 initialized = true; 39 } 40 } 41 42 } // namespace 43 44 // This whole implementation is very inefficient because it only reads / writes 45 // 1 byte at a time. It also does lazy initialization checks with every byte. 46 namespace pw::sys_io { 47 ReadByte(std::byte * dest)48Status ReadByte(std::byte* dest) { 49 LazyInitSysIo(); 50 51 while (true) { 52 int c = getchar_timeout_us(0); 53 if (c != PICO_ERROR_TIMEOUT) { 54 *dest = static_cast<std::byte>(c); 55 return OkStatus(); 56 } 57 58 // Wait for signal from the chars_available_callback(). 59 chars_available_signal.acquire(); 60 } 61 } 62 TryReadByte(std::byte * dest)63Status TryReadByte(std::byte* dest) { 64 LazyInitSysIo(); 65 int c = getchar_timeout_us(0); 66 if (c == PICO_ERROR_TIMEOUT) { 67 return Status::DeadlineExceeded(); 68 } 69 *dest = static_cast<std::byte>(c); 70 return OkStatus(); 71 } 72 WriteByte(std::byte b)73Status WriteByte(std::byte b) { 74 // The return value of this is just the character sent. 75 LazyInitSysIo(); 76 putchar_raw(static_cast<int>(b)); 77 return OkStatus(); 78 } 79 80 // Writes a string using pw::sys_io, and add newline characters at the end. WriteLine(std::string_view s)81StatusWithSize WriteLine(std::string_view s) { 82 size_t chars_written = 0; 83 StatusWithSize result = WriteBytes(as_bytes(span(s))); 84 if (!result.ok()) { 85 return result; 86 } 87 chars_written += result.size(); 88 89 // Write trailing newline. 90 result = WriteBytes(as_bytes(span("\r\n", 2))); 91 chars_written += result.size(); 92 93 return StatusWithSize(OkStatus(), chars_written); 94 } 95 96 } // namespace pw::sys_io 97