HardwareSerial::peek()

概要

Serial.peek()/HardwareSerial::peek()は、シリアル通信の受信用バッファを変更せずに受信用バッファから文字を読み出します。リファレンスはこちら}。

ソースコード

HardwareSerial::peek()は、hardware/arduino/avr/cores/arduino/HardwareSerial.cppに定義されています。以下に全ソースコードを示します。

1
2
3
4
5
6
7
8

int HardwareSerial::peek(void)
{
  if (_rx_buffer_head == _rx_buffer_tail) {
    return -1;
  } else {
    return _rx_buffer[_rx_buffer_tail];
  }
}

入力はありません。戻り値はintです。

1
2

int HardwareSerial::peek(void)
{

受信バッファのheadとtailが同じ場合は、何も受信していないので、-1を返します。

3
4
5
6

// if the head isn't ahead of the tail, we don't have any characters
if (_rx_buffer_head == _rx_buffer_tail) {
  return -1;
} else {

そうでない場合(headとtailが異なる場合)は、一番古いデータ(buffer[tail]に格納されています)を返却します。

5
6
7
8

  } else {
    return _rx_buffer[_rx_buffer_tail];
  }
}

受信バッファの操作は行いません。

バージョン

Arduino AVR Boards 1.8.6

ライセンス

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

/*
  Copyright (c) 2016 garretlab.
  Added source code explanation by garretlab.
*/

/*
  HardwareSerial.cpp - Hardware serial library for Wiring
  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  Modified 23 November 2006 by David A. Mellis
  Modified 28 September 2010 by Mark Sproul
  Modified 14 August 2012 by Alarus
  Modified 3 December 2013 by Matthijs Kooijman
*/

最終更新日

July 31, 2025

inserted by FC2 system