[Linux]串口调试小工具

#include <string>
#include <sstream>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

void Helper();
bool IsNumber(const std::string& str);
std::string ToHex(const std::string& hex);

//quart tty0 -d 60
int main(int argc, char *argv[])
{
    if(argc < 4)
    {
        Helper();
        return -1;
    }

    int fd = open(argv[1], O_RDWR);
    if (fd < 0)
    {
        printf("open %s failed!=> %s\n",argv[1], strerror(errno));
        close(fd);
        //return -1;
    }

    if(argv[2][0] !='-')
    {
        printf("Data type error!\n");
        Helper();
        close(fd);
        return -1;
    }
    std::string str = argv[3];
    switch (argv[2][1])
    {
        case 'd':
        {
            //decimal
            if(!IsNumber(str))
            {
                printf("Parameter error!\n");
                Helper();
                close(fd);
                return -1;
            }
            write(fd, str.c_str(), str.length());
            break;
        }
        case 'h':
        {
            //hexadecimal
            std::string tmp = ToHex(str);
            if(tmp.length() == 0)
            {
                printf("Parameter error!\n");
                Helper();
                close(fd);
                return -1;
            }
            write(fd, tmp.c_str(), tmp.length());
            break;
        }
        case 's':
        {
            //string
            write(fd, str.c_str(), str.length());
            break;
        }
        default:
            Helper();
            break;
    }
    close(fd);
    return 0;
}

void Helper()
{
    printf("Useage:\n");
    printf("  quart tty0 -i 60\n");
    printf("  quart tty0 -h 60\n");
    printf("  quart tty0 -s \"60\"\n");
}

bool IsNumber(const std::string& str)
{
    std::istringstream iss(str);
    double d;
    if (!(iss >> d))
        return false;
    char c;
    if (iss >> c)
        return false;
    return true;
}

std::string ToHex(const std::string& hex)
{
    if (hex.length() % 2 != 0)
    {
        return std::string();
    }
    auto hexCharToVal = [](char c) -> unsigned char
    {
        if (c >= '0' && c <= '9') return static_cast<unsigned char>(c - '0');
        if (c >= 'A' && c <= 'F') return static_cast<unsigned char>(c - 'A' + 10);
        if (c >= 'a' && c <= 'f') return static_cast<unsigned char>(c - 'a' + 10);
        return static_cast<unsigned char>(0);
    };
    std::string result;
    result.reserve(hex.length() / 2);
    for (size_t i = 0; i < hex.length(); i += 2)
    {
        unsigned char high = hexCharToVal(hex[i]);
        unsigned char low  = hexCharToVal(hex[i + 1]);
        unsigned char byte = (high << 4) | low;
        result.push_back(static_cast<char>(byte));
    }
    return result;
}