Squish It !!

Add-in Compressor/Decompressor for fx-CG100 / Graph Math+

Overview

The Graph Math+, released in late 2024, is very similar to the G90+E but suffers from a severe reduction in available user flash memory: only 4.5 MB, compared to 16 MB previously. For regular users, this limitation is acceptable. For power users and developers who maintain and test multiple add-ins, this drastically reduced storage becomes a daily obstruction.

Squish It !! was created to address this limitation by providing on-calculator compression and decompression for add-ins, allowing users to effectively expand their usable storage. The tool introduces a custom compressed format (G3Z) and integrates several efficient compression algorithms.

Squish It !! is based on:

• cZlib 1.2.5 --- https://git.planet-casio.com/Slyvtt/cZlib
• cLZ4 1.10.0 --- https://git.planet-casio.com/Fcalva/cLZ4

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Compatibility and Requirements

Model	Supported
Graph Math+	✔ Yes
fx-CG100	✔ Yes
fx-CG10 / 20 / 50	❌ No (OS crash when writing G3A)

Minimum OS version: 2.00 Prerequisite: Jailbreak via the latest MPM (Planète Casio Forge)

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How Squish It !! Works

The program lists:

• G3A files --- uncompressed add-ins
• G3Z files --- compressed add-ins using the Squish It !! proprietary format

The interface allows:

• Compressing a G3A → G3Z
• Decompressing a G3Z → G3A

The operation starts by pressing EXE or OK. Squish It !! automatically detects:

• File type
• Compression algorithm
• Required buffer size

Available Compression Algorithms

• ZlibMax --- zlib, maximum compression ratio
• ZlibFst --- zlib, optimized for speed
• LZ4Max --- LZ4 HC, level 9
• LZ4Fst --- LZ4 HC, level 3 (fast)

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Reliability

To ensure reliability, 31 different add-ins were processed through all methods:

• Compressed
• Decompressed
• Executed after decompression

All tests passed successfully. A safety mechanism prevents compressing Squish It !! itself.

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Performance Evaluation

Average Compression

Typical ratios are:

• 50% to 60% on average
• Possible compression range: 25% to 80%, depending on the structure of the add-in

Comparison Table

Method	Total Size (kB)	Avg. Compression	Functional Add-ins	Compression Time (s)	Decompression Time (s)
Uncompressed	10136.1	0%	31	—	—
ZLibMax	4192.2	58.6%	31	940	1859
ZLibFast	4480.1	55.80%	31	924	1935
LZ4Max	4865.9	51.99%	31	999	2024
LZ4Fast	4992.4	50.75%	31	1010	1921

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Charts and Benchmarks

Compression Ratios

Compression Time

Decompression Time

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Detailed Benchmark Data

ZLibMax (cZlib 1.2.5 --- Z_BEST_COMPRESSION)

ZLibFast (cZlib 1.2.5 --- Z_BEST_SPEED)

LZ4Max (cLZ4 1.10.0 --- HC = 9)

LZ4Fast (cLZ4 1.10.0 --- HC = 3)

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TODO List --- Future Enhancements

Short-Term (High Priority)

• Add an abort key for current operations with safe cleanup
• Add estimated processing times based on benchmark data
• Detailed G3Z metadata view (original name, size, algorithm, Squish version)
• Display of free flash memory
• Space availability check before operation
• Support for multiple algorithms (zlib + LZ4)
• Compression level selection (multiple press on PAGE_UP to select)
• Multi-language support (French / English)

Long-Term (Possible Future Work)

• Overclock support to accelerate compression/decompression
• Persistent user settings (language, overclock, algorithm saved to SquishIt.ini)
• Add integrity checksum verification after decompression
• Folder support and multi-file compression
• Direct execution of an add-in by decompressing into RAM
• Make Squish It !! work on fx-CG10/20/50 by loading binary code to RAM
• Merge Squish It !! inside MPM.bin

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G3Z Proprietary File Format

Format Version 1.00

• Bytes 0--3: Magic tag "SQIT"
• Bytes 4--7: Squish It !! version string (e.g., "1.00")
• Bytes 8--9: Filename length (N, little endian)
• Bytes 10--(9+N): Original filename
• Bytes 10+N -- 13+N: Original file size (uncompressed)
• Bytes 14+N -- end: Compressed data

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Format Version 1.10

• Bytes 0--3: Magic tag "SQIT"
• Bytes 4--7: Version string ("1.10")
• Byte 8: Compression algorithm used
  • A --- ZLIB Best Compression
  • B --- ZLIB Best Speed
  • C --- LZ4 High Compression
  • D --- LZ4 Fast Compression
• Byte 9: Checksum enabled flag (0x01 yes / 0x00 no)
• Bytes 10--13: Checksum value (or 0xFFFFFFFF)
• Bytes 14--20: Reserved (0xFF)
• Bytes 21--22: Filename length (N, little endian)
• Bytes 23--(22+N): Filename
• Bytes 23+N -- 26+N: Original file size
• Bytes 27+N -- end: Compressed data

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Format Version 1.11

Similar to 1.10

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Format Version 1.12

Similar to 1.10 and 1.11

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Format Version 1.13

Similar to 1.10, 1.11 and 1.12

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Format Version 1.20

• Bytes 0--3: Magic tag "SQIT"
• Bytes 4--7: Version string ("1.20")
• Byte 8: Compression algorithm (A=ZLIB Max, B=ZLIB Fast, C=LZ4 Max, D=LZ4 Fast)
• Byte 9: Checksum enabled flag (0x01 yes / 0x00 no)
• Bytes 10--13: xxHash32 of the original uncompressed data (or value 0xFFFFFFFF if flag is 0x00)
• Bytes 14--20: Reserved for future usage (all set to the value 0xFF)
• Bytes 21--22: Filename length (N, little endian)
• Bytes 23--(22+N): Filename
• Bytes 23+N -- 26+N: Original file size
• Bytes 27+N -- end: Compressed data

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Format Version 1.21

Similar to 1.20

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Version History

Version 1.00

• Initial public release
• Compression / decompression system
• Zlib (best compression mode)
• Basic interface

Version 1.10

• Added Zlib Fast mode
• Added LZ4 Max and LZ4 Fast modes
• Introduced G3Z file format version 1.10

Version 1.11

• Added free flash memory display
• Added file information popup
• Added pre-operation free space verification

Version 1.12

• Added an Abort Key to stop current compression/decompression operation (mapped to BACK key)
• Added an estimator of the operation duration (Compression & Decompression)
• Corrected some hidden bugs when Information popup window was opened
• Remove temporary files created before user abort

Version 1.13

• Corrected a bug in the calculation of compression ratio of G3Z file (visible in File Info Popup)
• Improvement of texts within the program

Version 1.20

New features

• Added xxHash32 integrity checksum: every compressed G3Z file now stores a 32-bit hash of the original uncompressed data, verified automatically on decompression
• Checksum is algorithm-agnostic: works identically for zlib and LZ4 compressed files
• Old G3Z files (versions 1.10--1.13) without a checksum are still decompressed normally (flag 0x00 skips verification)
• Named constants for algorithm byte codes (ALGO_BYTE_ZLIB_MAX/FAST, ALGO_BYTE_LZ4_MAX/FAST) replacing bare character literals in the file format layer
• Checksum value in the file information popup is now displayed in hexadecimal (e.g. 0xA3F2C1B0) consistent with how hash values are conventionally represented

Bug fixes

• Fixed use-after-free: partial .g3z output is now correctly deleted before the path buffer is freed when compression is aborted
• Fixed jpopup_add_empty_line(): empty separator lines were allocated but never inserted into the list and never displayed
• Fixed popup widget used before NULL guard: jpopup_set_size() and jpopup_set_font() were called before the NULL check in init_app()
• Fixed missing FileData argument in the non-FXCG100 build path of SquishIt_GetFileInformation() (crash / undefined behaviour on simulator)
• Fixed buffer overflow in getfileinformation(): name_len read from file was not clamped before fread() into the 256-byte originalfilename field
• Fixed delete_file() returning the raw remove() value (-1 on failure) instead of a defined SQUISHIT_* error code
• Fixed unchecked fwrite() in LZ4 compression and decompression loops: write failures now propagate as SQUISHIT_WRITE_ERROR
• Fixed unchecked fwrite() when writing the filename into the G3Z header
• Fixed LZ4 chunk size stored/read as platform-dependent int; now explicitly uint32_t (no format change on SH4 where int is 32 bits, but correct by specification)
• Fixed strcpy() without bounds check on FileData->filename; replaced with strncpy()

Code quality

• Refactored event_handling() (~215 lines) into three focused static helpers: handle_compress(), handle_decompress(), handle_info_popup()
• Removed stale TODO comment from read_checksum() (error handling was already complete)
• Removed dead commented-out decompress_file_zlib() function
• Added static to clamp() in jprogressbar.c to avoid link-scope name pollution
• Removed dead l = NULL assignment after free(l) in jpopup_poly_destroy()
• Corrected misleading copy-paste header comment in jpopup.h (was describing a progress bar)
• Replaced unexplained commented-out jwidget_emit() calls with an explanatory comment
• Updated G3Z file format to version 1.20

Version 1.21

New features in 1.21

• Multi-language support (English / French): all user-facing strings are now fully translated; the active language is selectable from the Settings menu
• Persistent user settings: language, CPU overclock level and default compression algorithm are saved automatically to SquishIt.ini on the calculator storage and restored on the next launch
• INI configuration file (SquishIt.ini): plain-text format with [Key] value entries and # comment lines; human-readable and hand-editable directly on a PC; a default file with full comments is provided and auto-created on first launch if absent
• CPU overclock is now accessible from the Settings menu (SHIFT+MENU), allowing the user to select speeds F1 (default) through F5 without leaving the application
• Default compression algorithm is now remembered across sessions and pre-selected on startup

Code quality in 1.21

• Introduced src/lang/ subsystem: lang.h (string ID enum + API), lang_en.h, lang_fr.h (translation tables), lang.c (runtime dispatch); adding a new language requires only a new lang_XX.h file
• Introduced src/core/ini_file.h / ini_file.c: self-contained INI parser and writer; all filesystem calls are wrapped in gint_world_switch for safe OS-world access
• Widget strings (jpopup title, jjackintheboxmenu hint bar, jfileselect empty-folder and save-as labels) are now configurable at runtime via dedicated setters, enabling live language switching without rebuilding the widget tree

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Disclaimer

This software is a Work in Progress and is provided "as is", without warranty of any kind. Although extensive testing has been performed, unexpected behavior may occur.

Please:

• Avoid using it on sensitive or irreplaceable data
• Ensure regular backups of your calculator storage
• Send bugs reports when you find some (with possibly the way to reproduce it as accurately as possible)

The author cannot be held responsible for any data loss or damage.

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