81 lines
2.6 KiB
C++
81 lines
2.6 KiB
C++
// Copyright 2021 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_sys_io/sys_io.h"
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#include <cinttypes>
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#include <string_view>
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#include "board.h"
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#include "fsl_common.h"
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#include "fsl_debug_console.h"
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#include "pw_status/status.h"
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#include "pw_status/status_with_size.h"
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extern "C" void pw_sys_io_mcuxpresso_Init(void) { BOARD_InitDebugConsole(); }
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namespace pw::sys_io {
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// Wait for a byte to read on USART0. This blocks until a byte is read. This is
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// extremely inefficient as it requires the target to burn CPU cycles polling to
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// see if a byte is ready yet.
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Status ReadByte(std::byte* dest) {
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*dest = static_cast<std::byte>(DbgConsole_Getchar());
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return OkStatus();
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}
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#if DEBUG_CONSOLE_TRANSFER_NON_BLOCKING
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// Read a byte from USART0 if one is available.
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Status TryReadByte(std::byte* dest) {
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char ch = 0;
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status_t status = DbgConsole_TryGetchar(&ch);
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if (status != kStatus_Success) {
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return Status::Unavailable();
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}
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*dest = static_cast<std::byte>(ch);
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return OkStatus();
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}
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#else // !DEBUG_CONSOLE_TRANSFER_NONBLOCKING
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Status TryReadByte(std::byte* /*dest*/) { return Status::Unimplemented(); }
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#endif // DEBUG_CONSOLE_TRANSFER_NONBLOCKING
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// Send a byte over USART0. Since this blocks on every byte, it's rather
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// inefficient. At the default baud rate of 115200, one byte blocks the CPU for
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// ~87 micro seconds. This means it takes only 10 bytes to block the CPU for
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// 1ms!
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Status WriteByte(std::byte b) {
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int ch = static_cast<int>(b);
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int len = DbgConsole_Putchar(ch);
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return len == 1 ? OkStatus() : Status::Unknown();
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}
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// Writes a string using pw::sys_io, and add newline characters at the end.
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StatusWithSize WriteLine(const std::string_view& s) {
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size_t chars_written = 0;
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StatusWithSize result = WriteBytes(std::as_bytes(std::span(s)));
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if (!result.ok()) {
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return result;
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}
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chars_written += result.size();
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// Write trailing newline.
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result = WriteBytes(std::as_bytes(std::span("\r\n", 2)));
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chars_written += result.size();
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return StatusWithSize(result.status(), chars_written);
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}
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} // namespace pw::sys_io
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