SameSameC (ButDifferent)

Yet Another ANSI C89 Like Language Cross Compiler Targeting 8-bit CPUs. Written by 2021 Ville Helin.

This is currently under early development, use it on your own risk. SameSameC is GPL v2 software. Read the LICENSE file for more information. Some pieces of code were taken from WLA DX (https://github.com/vhelin/wla-dx), but not so many. The compiler produces WLA DX ASM files which the linker links together and assembles with WLA DX (included as a Git submodule).

I will not in general approve pull requests as I want to do this myself, up to the point when I decide I've learned enough. :) Ideas, bug reports and feature requests are welcome, though. And build scripts for platforms currently not supported.

Azure Pipelines CI

• - Linux
• - macOS
• - Windows
• - Windows MSVC

Features

Features missing when compared with ANSI C89

• No const strings. Will be implemented later.
• No pointer usage like *ptr = 1; Instead do ptr[0] = 1;
• No syntactic sugar for multidimensional arrays. Perhaps implemented later. Meanwhile create your own using a one dimensional array.
• No floats or doubles or typedefs. All you have are u8 (8-bit unsigned int), s8 (8-bit signed int), u16 (16-bit unsigned int), s16 (16-bit signed int) and structs/unions.
• No casting. Perhaps implemented later. In calculations all involved will be automatically casted to the highest type in the calculation.
• No code blocks inside blocks

Features not in ANSI C89

• No need to define a function or a global variable before referencing it unless the function or variable is in another source file.
• Binary values can be defined with the prefix 0b (e.g., 0b10001101)
• One line comments with //
• Local variables can be defined anywhere, not just at the begining of a block

Bonuses

• Write WLA DX ASM using __asm()
• Include binary files using __incbin()
• The "object file" is actually plain WLA DX ASM

TODO

Optimize

• Optimize user written calculations like 2+a-1 -> a+2-1 -> a+1
• If a variable is only written to, remove the variable and all assignments
• Local array variable initialization
• Reduce code bloat (pass_2.c)
• Z80: Keep stack frame in IX and possibly IY all the time
• Z80: Remove unnecessary stack writes/reads (i.e., temp "register" access)

Fix

• Currently "data[i++] += 1;" increments i twice...
• Check that all pointer operations work properly
• When defining an array sometimes [] takes only an integer and not an expression
• When defining an array of pointers to structs/unions it's possible to give too many items
• Add a proper register allocator; what currently is done is not good enough as we are getting too bloated asm

Add

• Add support for function overloading
• Add support for free const strings
• Add more backends (GB-Z80, 6502, 65816...)
• Add more test projects
• Document all TREE_NODE_TYPE_* use cases
• Document all TAC_OP_* use cases
• Add support for explicit casting and type checks
• Add support for arrays with more than one dimension
• Create a list of supported ANSI C89 features (and the new features)

Releases

No releases yet

NOTE

Programmed using

• "Basics of Compiler Design"
  • http://web.archive.org/web/20120915222417/http://www.diku.dk/hjemmesider/ansatte/torbenm/Basics/basics_lulu2.pdf
• Emacs
• Cygwin under Windows 10

Should compile anywhere ANSI C89 source code can be compiled.