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libg1m/include/libg1m/format.h

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C

/* ************************************************************************** */
/* _____ _ */
/* libg1m/format/main.h |_ _|__ _ _| |__ ___ _ _ */
/* | Project: libg1m | |/ _ \| | | | '_ \ / _ \ | | | */
/* | | (_) | |_| | | | | __/ |_| | */
/* By: thomas <thomas@touhey.fr> |_|\___/ \__,_|_| |_|\___|\__, |.fr */
/* Last updated: 2016/11/02 14:15:46 |___/ */
/* */
/* ************************************************************************** */
#ifndef LIBG1M_FORMAT_H
# define LIBG1M_FORMAT_H
# include <stdint.h>
# pragma pack(1)
/* Welcome on this new episode of Monster Circus! Today we'll present to you
* something that you might not be able to forget: the G1M format.
*
* This format is used by CASIO with its calculator for storing things
* like add-ins (compiled programs), MCS (main memory saves), and others.
* In fact, there is no name for the general format, only names for the
* "subformats" based on this one.
*
* It all starts with a header, called Standard Header by Simon Lothar.
* This Standard Header contains the total filesize, the G1M type (add-in,
* MCS, e-acts), some data that will be useful for the MCS type, and some
* magic and control bytes.
*
* For some reason, this StandardHeader is INVERTED on every file it's on,
* you will have to apply a NOT operation on its bytes for it to make sense.
*
* Keep in mind that, everywhere in the header, multi-bytes integers
* are BIG ENDIAN.
*
* The LSB is the Least Significant Byte: once adapted to the host endianness,
* it can simply be obtained by bitwise-AND-ing with 0xff. */
struct standard_header {
/* the file identifier - see below */
uint8_t main_id[8];
/* our filetype! */
uint8_t type;
/* magic numbers, not always the same:
* - for fx-CG formats: {0x00, 0x01, 0x00, 0x01, 0x00}
* - otherwise: {0x00, 0x10, 0x00, 0x10, 0x00} */
uint8_t magic[5];
/* first control byte: filesize LSB + 0x41 */
uint8_t control;
/* said to be 0x01, but doesn't need to */
uint8_t align_one;
/* total filesize */
uint32_t filesize;
/* second control byte: filesize LSB + 0xb8 */
uint8_t control2;
/* alignment */
uint8_t align[8];
/* is obfuscated - useful for G3P */
uint8_t obfuscated;
/* number of objects contained (useful for MCS filetype) */
uint16_t number;
};
/* At the beginning, we thought "USBPower" was some magic sequence we would
* systematically find in the "main_id" field. But a counter example came:
* the G3L, where the main ID was "Ly755 ".
*
* So here are the known main IDs: */
enum g1m_main_id {
/* "USBPower": the most common one */
g1m_mid_usbpower,
/* "Ly755 ": fx-CG specific types */
g1m_mid_ly755,
};
/* Each main ID have their own types. Here are the USBPower types: */
enum g1m_usbpower_type {
/* fx language file */
g1m_usbpower_type_lang = 0x12,
/* fx-CG add-in */
g1m_usbpower_type_addin_cg = 0x2c,
/* mcs (main memory) save */
g1m_usbpower_type_mcs = 0x31,
/* e-activity (document) */
g1m_usbpower_type_eact = 0x49,
/* g1r equivalent */
g1m_usbpower_type_g2r = 0x62,
/* g3m (fx-CG program) */
g1m_usbpower_type_g3m = 0x75,
/* g3p (fx-CG picture) */
g1m_usbpower_type_g3p = 0x7d,
/* add-in (compiled program) */
g1m_usbpower_type_addin = 0xf3,
};
/* And here are Ly755 types: */
enum g1m_ly755_type {
/* language file */
g1m_ly755_type_lang = 0x2c
};
# pragma pack()
/* After the Standard Header is read and the G1M type is read, we have parts,
* each with their own subheaders and their own subtilities.
*
* Where do you want to start? Pick your poison. */
# include <libg1m/format/addin.h>
# include <libg1m/format/eact.h>
# include <libg1m/format/mcs.h>
# include <libg1m/format/picture.h>
# include <libg1m/format/lang.h>
#endif /* LIBG1M_FORMAT_H */