LEGO NXT ignores the file size when it is created

Question

Answer

• Wrong command arguments- The size argument contains 4 bytes LSB first. If the bytes are mixed (MSB first), the file that is created will be different;
• Automatically file size reduction by the firmware- When a text file is created, its size is determined by the file size argument of the command; however, its size can be reduced to its actual size (according to the number of written bytes) when the file is automatically closed by the firmware;

• The name of the file in the file create command is exactly 19 characters and 0x00 byte as NULL terminator. In case the file name is less than 19 characters, add 0x00 byte for each missing character. The bytes of file name and type characters should be ASCII encoded;
• The file size is constructed from 4 bytes. LSB first. Check how to convert decimal to a byte array (MSB first) at the Robopedia and reverse the array to get the LSB first;
• The file create command size is exactly 26 bytes 0x1A 0x00;
• There is enough space for this size;
• Use the FileWrite command to fill the file with data;
• Call the FileClose command to save changes and prevent from the firmware to close the file automatically and reduce its size (if you need the extra space for future edit);

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