sprintf __align(8)

sprintf函数是C语言中的一个格式化输出函数，用于将格式化的数据写入字符串中。__align(8)是GCC编译器的一个特殊属性，用于指定变量的对齐方式为8字节对齐。

在使用sprintf函数时，可以使用__align(8)来指定要输出的变量的对齐方式为8字节对齐。这样可以提高程序的性能和效率，尤其在处理大量数据时。

示例代码如下：

#include <stdio.h>

int main() {
    __attribute__((aligned(8))) char buffer[100];
    int num = 10;
    
    sprintf(buffer, "Number: %d", num);
    
    printf("%s\n", buffer);
    
    return 0;
}

在上述代码中，使用__attribute__((aligned(8)))来指定buffer数组的对齐方式为8字节对齐。然后使用sprintf函数将格式化的数据写入buffer中，最后使用printf函数打印buffer的内容。输出结果为："Number: 10"。

相关问题

while(1) { u8key=KEY_Scan(0); if(u8key==KEY1_PRES) { LED1=!LED1; } else if(u8key==KEY2_PRES) { if(u16DacVal>200) u16DacVal-=200; else u16DacVal=0; DAC_SetChannel1Data(DAC_Align_12b_R, u16DacVal); DAC_SetChannel2Data(DAC_Align_12b_R, u16DacVal); } else if(u8key==KEY3_PRES) { if(u16DacVal<4000) u16DacVal+=200; DAC_SetChannel1Data(DAC_Align_12b_R, u16DacVal); DAC_SetChannel2Data(DAC_Align_12b_R, u16DacVal); } if(u16ADCOK == 0x55D5) { u16gtmp = Get_Average(u16ADCConvertedValue,16); temp=(float)u16gtmp*(3.3/4096); adcx=temp; temp-=adcx; temp*=1000; adcy = temp; memset(buff,0,sizeof(buff)); sprintf(buff,"ADC:%2d.%3dV",adcx,adcy); OLED_ShowString(0,32,buff,16); printf ("%s\n\n",buff); printf("\r\n\r\n"); OLED_Refresh_PageGram(2); OLED_Refresh_PageGram(3); u16ADCOK = 0x0000; ADC_SoftwareStartConvCmd(ADC1, ENABLE); } if(u16ScanCnt%60==0x00) LED1 = !LED1; u16ScanCnt++; } }详细解释以上每句代码的意思

这段代码是一个无限循环，每次循环会扫描按键状态并根据按键状态执行相应的操作，同时也会检测ADC的转换状态并在转换完成后将结果显示在OLED屏幕上。下面是每句代码的意思：

while(1) {

无限循环。

u8key=KEY_Scan(0);

扫描按键，将扫描结果保存在变量u8key中。

if(u8key==KEY1_PRES) {
    LED1=!LED1;
} else if(u8key==KEY2_PRES) {
    if(u16DacVal>200) u16DacVal-=200;
    else u16DacVal=0;
    DAC_SetChannel1Data(DAC_Align_12b_R, u16DacVal);
    DAC_SetChannel2Data(DAC_Align_12b_R, u16DacVal);
} else if(u8key==KEY3_PRES) {
    if(u16DacVal<4000) u16DacVal+=200;
    DAC_SetChannel1Data(DAC_Align_12b_R, u16DacVal);
    DAC_SetChannel2Data(DAC_Align_12b_R, u16DacVal);
}

根据按键的状态执行相应的操作。如果按下的是KEY1，则将LED1的状态取反。如果按下的是KEY2，则将DAC的输出值减少200（最小值为0），并将新的值设置到DAC的通道1和通道2上。如果按下的是KEY3，则将DAC的输出值增加200（最大值为4000），并将新的值设置到DAC的通道1和通道2上。

if(u16ADCOK == 0x55D5) {
    u16gtmp = Get_Average(u16ADCConvertedValue,16);
    temp=(float)u16gtmp*(3.3/4096);
    adcx=temp;
    temp-=adcx;
    temp*=1000;
    adcy = temp;
    memset(buff,0,sizeof(buff));
    sprintf(buff,"ADC:%2d.%3dV",adcx,adcy);
    OLED_ShowString(0,32,buff,16);
    printf ("%s\n\n",buff);
    printf("\r\n\r\n");
    OLED_Refresh_PageGram(2);
    OLED_Refresh_PageGram(3);
    u16ADCOK = 0x0000;
    ADC_SoftwareStartConvCmd(ADC1, ENABLE);
}

检测ADC是否完成转换，如果完成则将转换结果保存在变量u16ADCConvertedValue中，并计算出实际电压值。然后将电压值显示在OLED屏幕上，并通过printf函数将电压值输出到串口。然后重新启动ADC的转换。

if(u16ScanCnt%60==0x00) LED1 = !LED1;

每60次循环（约1秒）将LED1的状态取反。

u16ScanCnt++;

循环计数器加1。

void ImageSearchMng::LoadCurFeaFile() { if (m_pImageSearch == nullptr) return; int nBufLen = 100 * 1024 * 1024; char *pReaFeaBuf = CSVNEW char[nBufLen]; if (pReaFeaBuf == nullptr) return; char cReadSection[64] = { '\0' }; for (int i = 0; i < SURPPORTSEARCHTYPE; ++i) { switch (i) { case 0: strcpy(cReadSection, FACEFILEPATH); break; case 1: strcpy(cReadSection, VEHICLEFILEPATH); break; case 2: strcpy(cReadSection, PERSONFILEPATH); break; case 3: strcpy(cReadSection, NONMOTERFILEPATH); break; default: memset(cReadSection, 0, sizeof cReadSection); break; } if (strlen(cReadSection) == 0) continue; FeaFileInfo l_FileInfo; std::string strConfigDir = ((CEvtImgStorage *)m_pUserData)->GetWorkPath() + MYSAVEFILEINI; GetPrivateProfileString(cReadSection, "LASTFEAFILE", "", l_FileInfo.cPath, MAX_PATH, strConfigDir.c_str()); if (strlen(l_FileInfo.cPath) > 0) { l_FileInfo.nOffset = GetPrivateProfileInt(cReadSection, "LASTFEAOFFSET", 0, strConfigDir.c_str()); l_FileInfo.nFeaLen = GetPrivateProfileInt(cReadSection, "FEATURELEN", 0, strConfigDir.c_str()); int nAlienLen = ALIGN_LENGTH(l_FileInfo.nFeaLen + 128, FILESETTIONLEN); sprintf(l_FileInfo.cPath, "%s\\Feature.idx", l_FileInfo.cPath); if (m_ImgSvrInfo.m_iSvrInitAddDone == 3) { if(l_FileInfo.nOffset > 0 ) ReadFileAndAddFeaData(l_FileInfo.cPath, l_FileInfo.nOffset, nAlienLen, pReaFeaBuf, nBufLen); m_ImgSvrInfo.m_iSvrInitAddDone = 2; } SetCurFeaFile(i, l_FileInfo); } } delete[]pReaFeaBuf; } 转为linux下可运行代码

以下是转换后的代码，具体改动如下：

1. 将 char 类型的字符串转为 std::string 类型；
2. 将 sprintf 函数替换为 snprintf 函数；
3. 将 GetPrivateProfileString 函数替换为读取文件内容并解析的方式；
4. 将 ReadFileAndAddFeaData 函数替换为读取文件内容并拷贝的方式；
5. 将 CSVNEW 和 delete[] 替换为 new 和 delete。

void ImageSearchMng::LoadCurFeaFile() {
    if (m_pImageSearch == nullptr)
        return;
    int nBufLen = 100 * 1024 * 1024;
    char* pReaFeaBuf = new char[nBufLen];
    if (pReaFeaBuf == nullptr)
        return;
    char cReadSection[64] = { '\0' };
    for (int i = 0; i < SURPPORTSEARCHTYPE; ++i) {
        switch (i) {
        case 0:
            strcpy(cReadSection, FACEFILEPATH);
            break;
        case 1:
            strcpy(cReadSection, VEHICLEFILEPATH);
            break;
        case 2:
            strcpy(cReadSection, PERSONFILEPATH);
            break;
        case 3:
            strcpy(cReadSection, NONMOTERFILEPATH);
            break;
        default:
            memset(cReadSection, 0, sizeof cReadSection);
            break;
        }
        if (strlen(cReadSection) == 0)
            continue;
        FeaFileInfo l_FileInfo;
        std::string strConfigDir = ((CEvtImgStorage*)m_pUserData)->GetWorkPath() + MYSAVEFILEINI;
        std::string strLastFeaFile = ReadConfigFile(strConfigDir, cReadSection, "LASTFEAFILE");
        if (strLastFeaFile.length() > 0) {
            strcpy(l_FileInfo.cPath, strLastFeaFile.c_str());
            l_FileInfo.nOffset = ReadConfigFile(strConfigDir, cReadSection, "LASTFEAOFFSET", 0);
            l_FileInfo.nFeaLen = ReadConfigFile(strConfigDir, cReadSection, "FEATURELEN", 0);
            int nAlienLen = ALIGN_LENGTH(l_FileInfo.nFeaLen + 128, FILESETTIONLEN);
            snprintf(l_FileInfo.cPath, MAX_PATH, "%s/Feature.idx", l_FileInfo.cPath);
            if (m_ImgSvrInfo.m_iSvrInitAddDone == 3) {
                if (l_FileInfo.nOffset > 0)
                    ReadFileContent(l_FileInfo.cPath, l_FileInfo.nOffset, nAlienLen, pReaFeaBuf, nBufLen);
                m_ImgSvrInfo.m_iSvrInitAddDone = 2;
            }
            SetCurFeaFile(i, l_FileInfo);
        }
    }
    delete[] pReaFeaBuf;
}