EarthLCD ezLCD-405, Manual

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© 2016 Earth Computers Tech. Inc.
1.7.40 SD_FILE_SEEK
Description: Moves the File Position Index of the opened SD Flash file by the specified
number of bytes, from the position specified by the 'Whence' parameter.
Supported file systems : FAT12, FAT16, FAT32
Code: 7C hex, 124 dec
7 6 5 4 3 2 1 0
Byte 0: Command
Byte 1: File ID
Byte 2: Offset 0 (LSB)
Byte 3: Offset 1
Byte 4: Offset 2
Byte 5: Offset 3 (MSB)
Byte 6: 0 = from File Beginning (SD_SEEK_SET)
1 = From Current File Position Index (SD_SEEK_CUR)
2 = From File End (SD_SEEK_END)
Notes: SD card has to be formatted in the supported file system.
This command works only if the file is already opened by the SD_FILE_OPEN command, or
created and opened by the SD_FILE_CREATE command.
See Also: SD_FILE_OPEN , SD_FILE_REWIND , SD_FILE_READ , SD_FILE_WRITE ,
SD_FILE_CLOSE , SD_FILE_CLOSE_ALL
About the Offset:
Offset is specified by the 32-­‐bit signed integer. When the offset is negative, the File Position
Index is moved backwards.
About the File Position Index
The File Position Index specifies the Read/Write position offset (in bytes) from the beginning of
the file. Upon opening of the file, the File Position Index is set to 0. The File Position Index is
incremented by the subsequent read or write operations on the opened file.
SD_FILE_READ
FILE ID Offset 0
Offset 1
Offset 3
Offset 2
Whence
32
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