Development Notes

This document contains a collection of unorganized notes. The information here should be organized better at some point but in the meantime it is better here than lost.

Extend existing / add a new Processor Architecture

OpenWatcom has still no support for many Processors:

• MMX, SIMD,AVX, ... Modern instruction sets for x86
• amd64/x86_64 (internal Name: x64)
• aarch64 (Internal Name: a64)
• arm

Things to consider, when extending to 64bit or adding a new architecture.
(This list is long, not sorted and incomplete)

• 64 bit CPUs: Alignment of functions / stack / args ... must increase to 16 Byte
• 32+64bit: Many currently unsupported CPU commands need higher alignments (MMX/SIMD/AVX)
• orl & owl: (Object Reader Library & Object Writer Library)
  
  • ELF Support and COFF Support for RISC architecture
• many projects: Object reading/writing for the x86 family
• wdis (ndisasm): Disassembler for all file formats and architectures
• wdump (exedump): Executable/DLL/Library/Object dumping tool
• wlink (wl): Linker for all file formats and architectures
• wlib (nwlib): Object file archive tool for all file formats and architectures
• dwarf: Debug info support for ELF file format
• wd & wdw (wv): Debugger for all file formats and architectures
• dig / dig: Debug format support
• wasarm / wasa64: RISC Assembler for arm and aarch64/a64
• wasm: Assembler for the x86 family
• wcpp: preprocessor for all C/C++ Compiler
• cg: The code generator (backend for C/C++/FORTRAN compiler)
• wccarm / wcca64 / wccx64: C compiler for arm, aarch64, x86_64
• wpparm / wppa64 / wppx64: C++ compiler for arm, aarch64, x86_64
• wfc (f77): FORTRAN compiler
• clib: C Runtime library
• cpplib: C++ Runtime library
• mathlib: Math support library
• fpuemu: FPU emulation
• owcc: Compile and Link utility (posix style command line args)
• wclarm / wcla64 / wclx64: Compile and Link utility (OW style command line args)
  There are a lot more modules in the bld directory

Probably resuable work (for backports / tests / comparsion):

• Forks of wasm & wlink, extended for x86_64 and new CPU instructions
  (with 'Sybase Open Watcom Public License')
  • jwasm Homepage
  • jwasm on github
  • jwlink Homepage
  • jwlink on github
    There are more forks of wasm/jwasm and wlink/jwlink on Github
• FASM / FASMARM: A free Assembler
  • fasm Homepage
  • fasm Source on github

Links to online infos:

• Agner Fog: Optimize Manuals and Instruction tables
• Agner Fog: calling conventions
• Wikibooks: x86 calling conventions
• Wikipedia: calling conventions
• ARM ABI
• ARM: arm/aarch64 ELF/DWARF/ABI-Infos
• Linux ABI
• Linus kernel Interface
• Microsoft: Windows arm 32bit ABI
• Microsoft: Windows aarch64 ABI