Editing Firmware file format (.gdf)

==File format byte by byte==
All multibyte integers are stored LSB first.
==GDF version 300==
===Header===
IDString - 4 bytes, always="GDFW"

BLFileVersion - 2 bytes, value=300

TargetDriveType - 2 bytes, Argon=4000, Ion=11000, Atomi=14000

HostFWbytes - 4 bytes, number of bytes for STM32 CPU

GCFWbytes - 4 bytes, number of bytes for GraniteCore CPU or 0xffffffff if not included

===Data===
Data of HostFW begins. Amount of bytes is HostFWbytes

Data of GCFW begins. Amount of bytes is GCFWbytes

===File checksum===
FileCksum - 4 bytes calculated from the current file. Simply sum of all unsigned bytes in file except CKSum itself


==GDF version 400 - draft==
===Header===
Version 400 described below:
<pre>
        /* GDF version 400 format
         * ----------------------
         *
         * Note: GDF v400 is not limited to firmware files any more,
         * it can be used as general purpose data container for up to 4GB data chunks.
         *
         * Binary file contents
         * --------------------
         *
         * bytes  meaning:
         *
         * 4	ASCII string = "GDFW"
         * 2	GDF version = 400
         * 2	GDF backwards compatible version = 400
         * 4	number of data chunks in file = N
         *
         * repeat N times:
         * 4	data chunk descriptive name string length in bytes = L
         * L	data chunk descriptive name string in UTF8
         * 4	data chunk type
         * 4	data chunk option bits
         * 4	data chunk size in bytes=S
         * S	data
         * end of repeat
         *
         * 4	file's CRC-32
         */
</pre>

<pre>
        /*
         * data chunk types
         * ----------------
         * 0=target device name, UTF8
         * 1=firmware name, UTF8
         * 2=firmware version string, UTF8
         * 3=remarks, UTF8
         * 4=manufacturer, UTF8
         * 5=copyright, UTF8
         * 6=license, UTF8
         * 7=disclaimer, UTF8
         * 8=circulation, UTF8 (i.e. customer name)
         * 20=unix timestamp, S=4
         * 50=target device type ID and mask, S=8
         *   first 4 bytes are target device ID, i.e. 11000=IONI
         *   second 4 bytes are mask/divider for type comparison, must be >0
         *   file is compatible if following eq is true: floor(readID/divider) == floor(targetID/divider)
         * 100=main MCU FW binary, S=any
         * 101=main MCU FW unique identifier number, S=4
         * 102=main MCU FW required HW feature bits, S=4
         *     helps to determine whether FW works on target
         *     device version when compared to a value readable from the device.
         *     0 means no requirements, works on all target ID devices.
         * 200=secondary MCU FW binary, S=any
         *
         * note: firmware may contain many combinations of above chunks. in basic case, it contains just chunk type 100 and nothing else.
         *
         * data chunk option bits
         * ----------------------
         * bit 0: if 1, GDF loading application must support/understand the chunk type to use this file
         * bits 1-31: reserved
         *
         */
</pre>

For practical reading software implementation, see devicedeployment.c from SimpleMotion library.