fsFileRead (Function)

This function reads a block of data from a FILE and returns the number of bytes read. All data is addressed as 8 bit, and after each successful read operation, the file data pointer is automatically incremented.

Please see fsFileReadString for string read.

Input:                

fd : FILE

FILE descriptor for the file retrieved from fsFileOpen or fsFileCreate.

buffer : PTR

Address of the buffer to receive the data in.

length : INT

Number of bytes to read.

Returns: INT

Number of bytes read from file.

Declaration:

FUNCTION fsFileRead : INT;
VAR_INPUT
  fd     : FILE;
  buffer : PTR;
  length : INT;
END_VAR;

Example:

...
IF fsFileExists(name := "\gpslog.dat") THEN
  fdGpslog := fsFileOpen(name := "\gpslog.dat");
  IF fsFileStatus(fd := fdGpslog) = 0 THEN
    // Is file empty?
    IF fsFilePosition(fd := fdGpslog) > 0 THEN
        rc := fsFileSeek(fd := fsGpslog, offset := 0);
        IF rc = 0 THEN
          // Iterate file
          REPEAT
              // Read data fields
              len1 := fsFileRead(fd := fdGpslog, buffer := ADDR(linsec), length := SIZEOF(linsec));
              len2 := fsFileRead(fd := fdGpslog, buffer := ADDR(lat), length := SIZEOF(lat));
              len3 := fsFileRead(fd := fdGpslog, buffer := ADDR(lon), length := SIZEOF(lon));
              // Is data valid?
              IF len1 = SIZEOF(linsec) AND len2 = SIZEOF(lat) AND len3 = SIZEOF(lon) THEN
                // Data is read
                 ...
              END_IF;
          UNTIL len1 <> SIZEOF(linsec) OR len2 <> SIZEOF(lat) OR len3 <> SIZEOF(lon)
          END_REPEAT;
        ELSE
          // Error
        END_IF;
    ELSE
        // No data
    END_IF;
    fsFileClose(fd := fdGpslog);
  ELSE
    // Could not open file
  END_IF;
ELSE
  // File dont exist
END_IF;
...