Qt 实现Ymodem协议源码分享

一、Ymodem协议介绍

Ymodem协议是一种基于串行通信的文件传输协议，由Xmodem协议改进而来，主要用于通过RS-232等低速链路可靠传输文件。其核心设计目标是提高传输效率和支持批处理传输，以下是分层解析：

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1、协议基础特性

• 数据块大小
  默认采用 1024字节（1KB）数据块（可回退至128字节）。
  数学表达传输效率提升：
  $$\text{效率增益}=\frac{\text{有效数据}}{\text{总传输量}}\propto \frac{1024}{1024+\text{头部开销}}$$
  相比Xmodem的128字节块，传输开销显著降低。

• 错误检测机制
  使用CRC-16（16位循环冗余校验）或可选校验和（Checksum）。
  校验多项式：$ G(x) = x^{16} + x^{15} + x^2 + 1 $（标准CRC-CCITT）。

• 批处理支持
  支持单次会话传输多个文件，通过文件头块传递文件名和大小。

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2、传输流程分阶段

(1) 、初始化阶段

• 接收端发送'C'（ASCII 0x43）请求CRC模式（或NAK请求校验和模式）。
• 发送端响应首个块（块编号 0），包含文件头信息：
  文件名 + 文件大小 + 时间戳（固定128字节，不足补NULL）。

(2) 、数据传输阶段

• 块结构（每块共1028字节）：

  | SOH/STX (1B) | 块号 (1B) | ~块号 (1B) | 数据 (1024B) | CRC (2B) |
  

  • SOH（0x01）标识128字节块，STX（0x02）标识1024字节块。
  • 块号范围：$ 1 \leq \text{块号} \leq 255 $（模256循环）。
  • 数据不足1024字节时以EOF（0x1A）填充。
• 接收端响应：
  • ACK（0x06）：成功接收，请求下一块。
  • NAK（0x15）：校验失败，请求重传。
  • CAN（0x18）：取消传输。

(3) 、结束阶段

• 发送端发出EOT（0x04）表示文件结束。
• 接收端回应ACK后，若需传输下一文件，重复初始化阶段。
• 无后续文件时，发送端发出NULL（0x00）结束会话。

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3、关键改进与变体

• Ymodem-g（流式传输）
  取消接收端确认（ACK/NAK），数据连续发送。要求物理链路0误码率，否则整体重传。
• 与Xmodem对比优势：

  特性	Xmodem	Ymodem
  块大小	128字节	1024字节
  批处理	不支持	支持
  文件名传递	无	文件头块实现
  最大文件大小	8MB限制	理论无限制

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4、典型应用场景

• 嵌入式系统：固件升级（如路由器Bootloader）。
• 工业控制：PLC程序传输。
• 遗留系统：通过串口/Telnet传输文件（如Linuxsz/rz工具）。

注：现代应用中，Ymodem因速率限制（通常<115.2kbps）逐渐被Zmodem取代，但其简洁性仍适用于低资源环境。实际实现需注意超时重传（默认10秒）和块号翻转处理。

二、源码分享

1、效果展示

2、工程结构

3、源码分享

widget.hpp

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include "YmodemFileTransmit.h"
#include "YmodemFileReceive.h"namespace Ui {
class Widget;
}class Widget : public QWidget
{Q_OBJECTpublic:explicit Widget(QWidget *parent = 0);~Widget();private slots:void on_comButton_clicked();void on_transmitBrowse_clicked();void on_receiveBrowse_clicked();void on_transmitButton_clicked();void on_receiveButton_clicked();void transmitProgress(int progress);void receiveProgress(int progress);void transmitStatus(YmodemFileTransmit::Status status);void receiveStatus(YmodemFileReceive::Status status);private:Ui::Widget *ui;QSerialPort *serialPort;YmodemFileTransmit *ymodemFileTransmit;YmodemFileReceive *ymodemFileReceive;bool transmitButtonStatus;bool receiveButtonStatus;
};#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QMessageBox>
#include <QFileDialog>
#include <QSerialPortInfo>Widget::Widget(QWidget *parent) :QWidget(parent),ui(new Ui::Widget),serialPort(new QSerialPort),ymodemFileTransmit(new YmodemFileTransmit),ymodemFileReceive(new YmodemFileReceive)
{transmitButtonStatus = false;receiveButtonStatus  = false;ui->setupUi(this);QSerialPortInfo serialPortInfo;foreach(serialPortInfo, QSerialPortInfo::availablePorts()){ui->comPort->addItem(serialPortInfo.portName());}serialPort->setPortName("COM1");serialPort->setBaudRate(115200);serialPort->setDataBits(QSerialPort::Data8);serialPort->setStopBits(QSerialPort::OneStop);serialPort->setParity(QSerialPort::NoParity);serialPort->setFlowControl(QSerialPort::NoFlowControl);connect(ymodemFileTransmit, SIGNAL(transmitProgress(int)), this, SLOT(transmitProgress(int)));connect(ymodemFileReceive, SIGNAL(receiveProgress(int)), this, SLOT(receiveProgress(int)));connect(ymodemFileTransmit, SIGNAL(transmitStatus(YmodemFileTransmit::Status)), this, SLOT(transmitStatus(YmodemFileTransmit::Status)));connect(ymodemFileReceive, SIGNAL(receiveStatus(YmodemFileReceive::Status)), this, SLOT(receiveStatus(YmodemFileReceive::Status)));
}Widget::~Widget()
{delete ui;delete serialPort;delete ymodemFileTransmit;delete ymodemFileReceive;
}void Widget::on_comButton_clicked()
{static bool button_status = false;if(button_status == false){serialPort->setPortName(ui->comPort->currentText());serialPort->setBaudRate(ui->comBaudRate->currentText().toInt());if(serialPort->open(QSerialPort::ReadWrite) == true){button_status = true;ui->comPort->setDisabled(true);ui->comBaudRate->setDisabled(true);ui->comButton->setText(u8"关闭串口");ui->transmitBrowse->setEnabled(true);ui->receiveBrowse->setEnabled(true);if(ui->transmitPath->text().isEmpty() != true){ui->transmitButton->setEnabled(true);}if(ui->receivePath->text().isEmpty() != true){ui->receiveButton->setEnabled(true);}}else{QMessageBox::warning(this, u8"串口打开失败", u8"请检查串口是否已被占用！", u8"关闭");}}else{button_status = false;serialPort->close();ui->comPort->setEnabled(true);ui->comBaudRate->setEnabled(true);ui->comButton->setText(u8"打开串口");ui->transmitBrowse->setDisabled(true);ui->transmitButton->setDisabled(true);ui->receiveBrowse->setDisabled(true);ui->receiveButton->setDisabled(true);}
}void Widget::on_transmitBrowse_clicked()
{ui->transmitPath->setText(QFileDialog::getOpenFileName(this, u8"打开文件", ".", u8"任意文件 (*.*)"));if(ui->transmitPath->text().isEmpty() != true){ui->transmitButton->setEnabled(true);}else{ui->transmitButton->setDisabled(true);}
}void Widget::on_receiveBrowse_clicked()
{ui->receivePath->setText(QFileDialog::getExistingDirectory(this, u8"选择目录", ".", QFileDialog::ShowDirsOnly));if(ui->receivePath->text().isEmpty() != true){ui->receiveButton->setEnabled(true);}else{ui->receiveButton->setDisabled(true);}
}void Widget::on_transmitButton_clicked()
{if(transmitButtonStatus == false){serialPort->close();ymodemFileTransmit->setFileName(ui->transmitPath->text());ymodemFileTransmit->setPortName(ui->comPort->currentText());ymodemFileTransmit->setPortBaudRate(ui->comBaudRate->currentText().toInt());if(ymodemFileTransmit->startTransmit() == true){transmitButtonStatus = true;ui->comButton->setDisabled(true);ui->receiveBrowse->setDisabled(true);ui->receiveButton->setDisabled(true);ui->transmitBrowse->setDisabled(true);ui->transmitButton->setText(u8"取消");ui->transmitProgress->setValue(0);}else{QMessageBox::warning(this, u8"失败", u8"文件发送失败！", u8"关闭");}}else{ymodemFileTransmit->stopTransmit();}
}void Widget::on_receiveButton_clicked()
{if(receiveButtonStatus == false){serialPort->close();ymodemFileReceive->setFilePath(ui->receivePath->text());ymodemFileReceive->setPortName(ui->comPort->currentText());ymodemFileReceive->setPortBaudRate(ui->comBaudRate->currentText().toInt());if(ymodemFileReceive->startReceive() == true){receiveButtonStatus = true;ui->comButton->setDisabled(true);ui->transmitBrowse->setDisabled(true);ui->transmitButton->setDisabled(true);ui->receiveBrowse->setDisabled(true);ui->receiveButton->setText(u8"取消");ui->receiveProgress->setValue(0);}else{QMessageBox::warning(this, u8"失败", u8"文件接收失败！", u8"关闭");}}else{ymodemFileReceive->stopReceive();}
}void Widget::transmitProgress(int progress)
{ui->transmitProgress->setValue(progress);
}void Widget::receiveProgress(int progress)
{ui->receiveProgress->setValue(progress);
}void Widget::transmitStatus(Ymodem::Status status)
{switch(status){case YmodemFileTransmit::StatusEstablish:{break;}case YmodemFileTransmit::StatusTransmit:{break;}case YmodemFileTransmit::StatusFinish:{transmitButtonStatus = false;ui->comButton->setEnabled(true);ui->receiveBrowse->setEnabled(true);if(ui->receivePath->text().isEmpty() != true){ui->receiveButton->setEnabled(true);}ui->transmitBrowse->setEnabled(true);ui->transmitButton->setText(u8"发送");QMessageBox::warning(this, u8"成功", u8"文件发送成功！", u8"关闭");break;}case YmodemFileTransmit::StatusAbort:{transmitButtonStatus = false;ui->comButton->setEnabled(true);ui->receiveBrowse->setEnabled(true);if(ui->receivePath->text().isEmpty() != true){ui->receiveButton->setEnabled(true);}ui->transmitBrowse->setEnabled(true);ui->transmitButton->setText(u8"发送");QMessageBox::warning(this, u8"失败", u8"文件发送失败！", u8"关闭");break;}case YmodemFileTransmit::StatusTimeout:{transmitButtonStatus = false;ui->comButton->setEnabled(true);ui->receiveBrowse->setEnabled(true);if(ui->receivePath->text().isEmpty() != true){ui->receiveButton->setEnabled(true);}ui->transmitBrowse->setEnabled(true);ui->transmitButton->setText(u8"发送");QMessageBox::warning(this, u8"失败", u8"文件发送失败！", u8"关闭");break;}default:{transmitButtonStatus = false;ui->comButton->setEnabled(true);ui->receiveBrowse->setEnabled(true);if(ui->receivePath->text().isEmpty() != true){ui->receiveButton->setEnabled(true);}ui->transmitBrowse->setEnabled(true);ui->transmitButton->setText(u8"发送");QMessageBox::warning(this, u8"失败", u8"文件发送失败！", u8"关闭");}}
}void Widget::receiveStatus(YmodemFileReceive::Status status)
{switch(status){case YmodemFileReceive::StatusEstablish:{break;}case YmodemFileReceive::StatusTransmit:{break;}case YmodemFileReceive::StatusFinish:{receiveButtonStatus = false;ui->comButton->setEnabled(true);ui->transmitBrowse->setEnabled(true);if(ui->transmitPath->text().isEmpty() != true){ui->transmitButton->setEnabled(true);}ui->receiveBrowse->setEnabled(true);ui->receiveButton->setText(u8"接收");QMessageBox::warning(this, u8"成功", u8"文件接收成功！", u8"关闭");break;}case YmodemFileReceive::StatusAbort:{receiveButtonStatus = false;ui->comButton->setEnabled(true);ui->transmitBrowse->setEnabled(true);if(ui->transmitPath->text().isEmpty() != true){ui->transmitButton->setEnabled(true);}ui->receiveBrowse->setEnabled(true);ui->receiveButton->setText(u8"接收");QMessageBox::warning(this, u8"失败", u8"文件接收失败！", u8"关闭");break;}case YmodemFileReceive::StatusTimeout:{receiveButtonStatus = false;ui->comButton->setEnabled(true);ui->transmitBrowse->setEnabled(true);if(ui->transmitPath->text().isEmpty() != true){ui->transmitButton->setEnabled(true);}ui->receiveBrowse->setEnabled(true);ui->receiveButton->setText(u8"接收");QMessageBox::warning(this, u8"失败", u8"文件接收失败！", u8"关闭");break;}default:{receiveButtonStatus = false;ui->comButton->setEnabled(true);ui->transmitBrowse->setEnabled(true);if(ui->transmitPath->text().isEmpty() != true){ui->transmitButton->setEnabled(true);}ui->receiveBrowse->setEnabled(true);ui->receiveButton->setText(u8"接收");QMessageBox::warning(this, u8"失败", u8"文件接收失败！", u8"关闭");}}
}

三、完整工程下载

https://download.csdn.net/download/qq_15181569/91667788