Ficl 3.06 Release Notes

Release Date: February 2026

Ficl 3.06 represents a major evolution of Ficl, featuring significant performance improvements, enhanced floating-point support, robustness enhancements, and enhancements to testmain.

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Major Features

Hybrid Token Threading

Contributed by Giuseppe Stanghellini

• 2x-3x performance improvement over subroutine threading
• Implemented token threading optimization using x-macros for performance tuning
• Revised virtual machine instruction dispatch mechanism
• Refactored VM instruction execution (2,326 lines changed in vm.c)

Floating Point Enhancements

Comprehensive improvements to floating-point support:

• Non-CELL Float Stack: Implemented FICL_FSTACK for 64-bit float support on 32-bit targets
• Approximate Float Equality: Added f~= word modeled on Python's math.isclose() for better floating-point comparisons
• Float Environment Variable: Added float-epsilon environment variable for precision control
• Float Locals Support: Extended local variable support to include float locals (moved from softwords to jhlocal.fr for proper scoping)
• Float TO Support: Completed implementation of TO for floats, single cells, double cells, and constants
• Float Exception Words: Added floating-point exception handling words
• Bug Fix: Fixed falign bug in float operations

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Interactive Testing Improvements

• Line Editing: Added simple line editing capabilities to testmain
• Test Framework: Updated standard test file ttester.fr adapted for Ficl
• REPL Improvements: Exit REPL cleanly on EOF (Ctrl-D) (Periklis Akritidis), SIGINT handling on POSIX systems. vmInterrupt() can connect a watchdog timer on embedded targets.

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Code Quality and Refactoring

• Replaced all sprintf calls with snprintf throughout the codebase to prevent buffer overrun vulnerabilities
• Changed ultoa, ltoa, strrev to ficlLtoa, ficlUltoa, ficlStrrev to avoid naming conflicts with system libraries
• Removed duplicate and dead code - now committed to hybrid token threading

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Build and Platform Improvements

Conditional Compilation

• FICL_WANT_FLOAT sets FICL_WANT_LOCAL as well. Thank me later.
• FICL_ scalar and float types are now auto-sized unless you override, simplifying porting.
• Float size auto-selected or you can select 64 bit floats in a 32 bit machine. (Giouseppe Stanghellini)
• Known-width data types now use stdint.h (C11)

Platform Support

• WASM Support: Asyncified demo.html and updated wasm_main.c
• Makefile Updates: Added minimal target to makefile.macos
• EOL Standardization: Converted entire codebase to Unix EOL sequences

Environment Words

• .env now prints values of environment parameters

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Bug Fixes

• Fixed falign bug in float operations
• Fixed sprintf buffer overflow vulnerability in line editor
• Fixed output overwrite issue in testmain
• Fixed FICL_WANT_FLOAT conditional compilation issues
• testmain now exits with Ctrl-D (Periklis Akritidis)
• Fixed sprintf buffer overflow issues (Periklis Akritidis)
• Removed sscanf() from the code to reduce lib dependency
• Fixed a comment bug in ficlSprintf

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Upgrading from 3.05

This release maintains backward compatibility for most use cases. Notable changes that may affect existing code:

1. Float Stack: If using FICL_WANT_FLOAT, 32-bit targets may now elect 64 bit floats.
2. Function Names: ultoa, ltoa, and strrev are now ficlUltoa, ficlUltoa, and ficlStrrev
3. Float Locals: FICL_WANT_FLOAT now implies FICL_WANT_LOCAL. Float stack words are not as rich as scalar stack words, so local variables are very helpful.

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Acknowledgments

Special thanks to:

• Giuseppe Stanghellini for contributing hybrid token threading and enhanced float support.
• Periklis Akriditis for bug fixes and helpful suggestions.

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Links

• Git Tag: ficl306
• Previous Release: ficl305 (Version 3.05)