0.23.0–0.25.1 — Data Directives and Location-Aware Layout

Up to 0.22.0, every statement in a Kasm program was an instruction. This era added a second category entirely: data that isn’t an instruction at all.

0.23.0 — DB/DW, then DD/DQ

4af6afc added db/byte and dw/word directives; two follow-up commits (ca576ae, 63bc4b3) added dd/dword and dq/qword. All four accept comma-separated expression lists terminated by ;, emit little-endian values, and are range-checked against their declared width:

The README is explicit that DD and DQ’s storage is wider than the expression evaluator’s current range — the evaluator rejects results above 2147483647 before a value ever reaches the wider storage, so the diagnostic range and the storage width intentionally don’t match yet.

Because data isn’t an instruction, the CLI had to stop assuming every image was disassemblable: images containing data print Data emitted; instruction- only decoding skipped. instead of attempting a listing.

45ab217 — Refactor instruction size calculation for ST_SUB_RIM and ST_ADD_RIM landed alongside this work, fixing layout’s instruction-size accounting to account for register codes correctly — a reminder that adding a second statement category (data) forced a re-check of assumptions the layout pass had made when everything was an instruction.

0.24.0 / 0.24.1 — Repetition, then a compatibility fix

4c160d6 — Implement TIMES/FILL support for data directives added times <count> / fill <count> prefixes that repeat a directive’s entire value list, with overflow-safe size_t count validation. 642c3d3 — Bump version to 0.24.1 immediately followed to restore the default single-source-file CLI invocation to 64-bit mode — the explicit --bits flag from 0.22.0 had apparently changed default behavior in a way that broke existing tests and installed-package smoke checks, and 0.24.1 exists purely to fix that compatibility regression.

0.25.0 / 0.25.1 — $ and $$, and a CI portability fix

7ff337f — Bump version to 0.25.0; add location-aware expressions let $ (current image offset) and $$ (image section start) appear inside TIMES/FILL counts, resolved during layout after preceding statement sizes are known. The canonical example is NASM-style boot-sector padding:

mov eax, 42;
times 510-($-$$) db 0;
dw 0xAA55;

28d1e4e — Bump version to 0.25.1 fixed the regression test for this exact example: the original 512-byte padding check compared binary output directly, but CMake strings can’t safely carry embedded NUL bytes, which made the test’s behavior differ between Windows and Linux CI. The fix measures length through the CLI’s hex output instead, which is NUL-safe and portable — a small but instructive lesson about testing binary output through text-based tooling.

Data directives, once added, immediately needed most of the same infrastructure instructions had — layout, range checks, tests — which is why this era reads as dense as the arithmetic-ISA growth in the previous chapter, just for a different statement kind.