Overview

Kasm 0.34.0 (in development) is a small C assembler with a limited x86-64 instruction set and initial 16-bit MOV/ADD/SUB support. It owns source text, lexes tokens, parses expressions and statements, validates operands, assigns image offsets, resolves labels and relocations, emits machine-code bytes, and can decode supported instruction images back into a listing.

The project also emits raw data directives and assembly-time repetition. The default target is hosted x86-64 code; --bits 16 selects the developing 16-bit encoding path, while --bits 32 remains rejected. A raw data image is not automatically a bootable program. Kasm can also generate Windows x64 COFF objects containing one instruction-only .text section and an exported label; standalone executable formats are not yet supported.

COFF output

COFF output requires -o <output-path>. To choose the filename and directory:

.\build\windows-debug\Debug\kasm.exe --format coff --export answer -o .\build\coff_answer.obj examples/coff_answer.asm

The output directory must already exist; quote paths containing spaces. The export must name a label with instructions after it. Raw output remains the default. The COFF writer uses dynamically allocated storage with the existing 16 MiB image limit, supports long symbol names, and accepts REL32 and ADDR64 relocation records. Source-level external declarations and separate data sections remain future frontend work. Existing load-time absolute-jump patches are rejected for object output because they require conversion into linker relocations.

Raw output uses the source filename with its last extension replaced: for example, examples/coff_answer.asm writes coff_answer.bin and coff_answer.h in the current working directory. The runner and inspector examples default to program.h from program.asm; define KASM_GENERATED_HEADER when using another generated header.

See Using a release to try Kasm without a source checkout, or Building and testing to build it from source.