How do I know the .txt file size with FatFS?

[Macun]

Hello everyone,

Thanks in advance.

I create a .txt file and write data in it. When this .txt file reaches 1GB, I want it to open a new .txt file and write the data to the new .txt file. It should continue from where it left off...

I have 2 folders, one with configuration information and the other with data saved.

I tried many ways but I could not solve the problem.

Which path should I follow?

void check_or_create_initial_setting(void) {
    UINT br;
   // FRESULT fr;
if(f_mount(&SDFatFS, (TCHAR const*)SDPath, 0) != FR_OK)
{
Error_Handler();
}
else
{
// Check if the "System" folder exists
if (f_opendir(&dir, "/System")== FR_OK) {
	// The "system" folder exists, now check for "config.txt"
	if (f_open(&SDFile, "/System/Config.txt", FA_READ)== FR_OK) {
		// The "config.txt" file exists, read and extract the coefficient value
		while (f_gets(line, sizeof(line), &SDFile)) {
			if (sscanf(line, "coefficient = %d", &multiplication) == 1) {
			  // Coefficient value found and extracted
			   break;
             }
        }
        f_close(&SDFile); // Close the file after reading
    } else {
                // "config.txt" does not exist, create it and write "coefficient = 12"
    	  if (f_open(&SDFile, "/System/config.txt", FA_CREATE_NEW | FA_WRITE)== FR_OK) {
                    char *configData = "coefficient = 12";
                    f_write(&SDFile, configData, strlen(configData), &br);
                    f_close(&SDFile); // Close the file after writing
                }
            }
            f_closedir(&dir); // Close the directory
        } else {
// "system" folder does not exist, create it
f_mkdir("/System");
	// "config.txt" does not exist, create it and write "coefficient = 12"
	 if (f_open(&SDFile, "/System/config.txt", FA_CREATE_NEW | FA_WRITE)== FR_OK) {
		char *configData = "coefficient = 12";
		f_write(&SDFile, configData, strlen(configData), &br);
		f_close(&SDFile); // Close the file after writing
	}
f_closedir(&dir); // Close the directory
        }
    }
        // Unmount the file system
        //  f_mount(&SDFatFS, (TCHAR const*)NULL, 0);
          f_mount(NULL, "", 0);
}
void create_and_write_to_file(void) {

	if(f_mount(&SDFatFS, (TCHAR const*)SDPath, 0) != FR_OK)
	{
	Error_Handler();
	}
	else
	{
    // Check if the data folder exists
    if (f_opendir(&dir, "/Data") != FR_OK) {
        // Folder doesn't exist, create it
        f_mkdir("/Data");
    } else {
        f_closedir(&dir);
    }
    //char path[32] = "/Data/Data";
    int maxNumber = 0;
    // Open the directory
    if (f_opendir(&dir, "/Data") == FR_OK) {
        // Read directory items
        while (f_readdir(&dir, &fno) == FR_OK && fno.fname[0]) {
            // Check if it's a file
            if (!(fno.fattrib & AM_DIR)) {
                // Check if the file name matches the pattern (e.g., data1.txt)
                int num;
                if (sscanf(fno.fname, "Data%d.txt", &num) == 1) {
                    if (num > maxNumber) {
                        maxNumber = num; // Update max number
                    }
                }
            }
        }
        f_closedir(&dir);
    }
    // Create new file with incremented name
    sprintf(newFileName, "/Data/Data%d.txt", maxNumber + 1);
    if (f_open(&SDFile, newFileName, FA_OPEN_APPEND | FA_WRITE) == FR_OK) {
			while (SWICH==1) {
			f_write(&SDFile, sd_buf_write_char, 10240, &byteswritten);
			 while (iindex < sizeof(sd_buf_write_char) - 1 && cont0 < 65535) {
			           int written = snprintf(&sd_buf_write_char[iindex], sizeof(sd_buf_write_char) - iindex, "%d", cont0);
			           if (written > 0) {
			        	   iindex += written; // Advance the index by the number of characters written
			               cont0++; // Increment the counter
			           } else {
			               // Handle error
			               break;
			           }
			       }
	 }
	 f_close(&SDFile);
    }
	}
    f_mount(&SDFatFS, (TCHAR const*)NULL, 0);
}

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[Andrew Neil]

Simply keep a count each time you write to the file?

The FatFs f_write() function tells you how much it actually wrote:

http://elm-chan.org/fsw/ff/doc/write.html

FatFs also has an f_size() function - it tells you the current size of an existing file:

http://elm-chan.org/fsw/ff/doc/size.html

You can also get the size of an existing file via directory functions; eg,

http://elm-chan.org/fsw/ff/doc/readdir.html