Files
LithosAnanake/include/starkernel
Robert Allan James cb4326c712 starkernel: item 4.3.3b -- geometry drawing wordset, fixed Q.TO-INT sign bug
Adds LINE (Bresenham in raster space, endpoints projected once each --
valid because the cavalier projection is linear), CIRCLE/ELLIPSE
(36-segment polygon approximation), and ARC (18 segments over a caller
radian range) to capsules/fabric.4th (blocks 4903-4912). TO-RASTER
factored out of CART-PLOT (same behavior) so LINE can reuse the
projection+flip for both endpoints.

Found mid-implementation: colon definitions cannot span block boundaries
in this capsule loader -- verified with a throwaway test capsule, the
continuation lands in a [CAPSULE][DEFER] path that never resolves. LINE's
body is split across LINE-SETUP/LINE-DONE?/LINE-STUCK?/LINE-STEP, each
self-contained within its block, rather than one long definition.

A fourth real bug, serious this time: CIRCLE's first live test rendered
only one quadrant, then hung the VM for several minutes on a follow-up
call. Root cause: q48_to_u64() (include/q48_16.h and
include/starkernel/q48_16.h, backing Q.TO-INT) did an unsigned logical
shift, corrupting any negative Q48.16 value into a huge garbage integer
instead of sign-extending -- inevitable once Q.SIN/Q.COS leave the first
quadrant. That garbage became a bogus LINE target with no bound on
LINE-STEP's Bresenham loop. Fixed q48_to_u64 to shift through a signed
int64_t intermediate (bit-identical for the non-negative case). Also added
LINE-STUCK? (LSTEPS vs FB-WIDTH+FB-HEIGHT, the true worst case for an
on-screen line) as a defense-in-depth cap against any future bad target.

Verified live on amd64 after both fixes: -65536 Q.TO-INT . now prints -1;
LINE/CIRCLE/ARC/ELLIPSE all complete without hanging or erroring, and a
combined screendump shows all four rendering correctly and distinctly.

All three architectures boot clean to ok> with the DoE completing;
dict_hash identical across all three and unchanged from 4.3.3a (expected
-- fabric.4th isn't loaded at boot, and the Q.TO-INT fix doesn't change
dictionary structure).

FABRIC.md item 4.3.3b marked done with full acceptance evidence.
2026-08-07 15:20:58 -04:00
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include/starkernel/

Headers for LithosAnanke, the bare-metal UEFI kernel (src/starkernel/). Built only via Makefile.starkernel; gated by __STARKERNEL__ when shared with hosted code.

  • uefi.h — UEFI protocol/type definitions consumed by the loader.
  • elf64.h, elf_loader.h — ELF64 parsing and kernel-image loading.
  • boot_info_offsets.h — struct-offset constants shared between the assembly bootstrap and the C boot path.
  • arch.h, apic.h, timer.h — architecture init, APIC interrupt controller, timer (TSC/HPET/APIC, 100 Hz heartbeat).
  • console.h, framebuffer.h, vt100.h — UART 16550 console, framebuffer driver, and VT100 terminal emulation over the framebuffer.
  • pmm.h, vmm.h, kmalloc.h — physical memory manager (bitmap allocator), 4-level x86_64 paging, kernel heap allocator.
  • pci.h, virtio_blk.h — PCI enumeration and the VirtIO block device driver (disk backend for the kernel block subsystem).
  • capsule.h, capsule_birth.h, capsule_loader.h, capsule_run.h, capsule_vm_physics.h, capsule_generated.h — capsule system types, birth protocol, physics-runtime capsule bindings, and the build-time- generated capsule directory (see tools/mkcapsule.c).
  • kernel_args.h, cmdline.h — boot-time kernel argument parsing (starforth.cfg / command line).
  • repl.h — kernel REPL.
  • log.h, doe_log.h — kernel logging and DoE metrics logging.
  • q48_16.h — kernel-build copy of Q48.16 fixed-point arithmetic.
  • xxhash64.h — content-addressing hash used for capsule IDs.
  • hal_memory.h — hardware-abstraction-layer memory interface.

Subdirectories:

  • hal/ — top-level hardware-abstraction-layer interface.
  • vm/ — kernel VM subsystem headers (capsule arena, parity logging, bootstrap wiring).
  • freestanding/ — minimal libc-shim headers (assert.h, ctype.h, errno.h, inttypes.h, math.h, sched.h, signal.h, stdio.h, stdlib.h, string.h, time.h, sys/time.h, sys/types.h) for building shared VM code in the freestanding kernel environment, where no real libc is available.