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starkernel: item 4.3.3b -- geometry drawing wordset, fixed Q.TO-INT sign bug

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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.
This commit is contained in:
Robert Allan James
2026-08-07 15:20:58 -04:00
parent 01822585f6
commit cb4326c712
8 changed files with 188 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files
capsules/BLOCK_MAP.md
+15 -5
View File
@@ -1,5 +1,5 @@
# Capsule Block Manifest — Auto-generated
<!-- Generated by mkcapsule --manifest 2026-08-07T17:37:50Z -->
<!-- Generated by mkcapsule --manifest 2026-08-07T19:19:40Z -->
<!-- DO NOT EDIT — re-run mkcapsule --manifest to refresh. -->
<!-- Hand-written justifications and immutability notes live -->
<!-- in MANIFEST.md alongside this auto-generated index. -->
@@ -13,7 +13,7 @@
| `common:msg.4th` | 4055 | `0xa99c5bcd3877f80e` |
| `doe-campaign.4th` | 4060, 4061, 4062, 4063, 4064, 4065 | `0x3d4549142d91ec20` |
| `doe.4th` | 2100, 2101, 2102, 2103, 2104, 2105, 2106, 2107 | `0xb6ecf5374e8ee77c` |
| `fabric.4th` | 4900, 4901, 4902 | `0xb7db7380ec4a42a0` |
| `fabric.4th` | 4900, 4901, 4902, 4903, 4904, 4905, 4906, 4907, 4908, 4909, 4910, 4911, 4912 | `0x355ccc154aac15b3` |
| `hermes:init.4th` | 4100, 4101, 4102, 4103, 4104, 4105, 4106, 4107, 4108, 4109, 4114, 4115, 4116, 4117, 4118, 4119, 4120, 4121, 4142, 4143, 4144, 4145, 4146, 4147, 4148, 4149, 4150, 4151, 4152, 4153, 4154, 4155, 4156, 4157, 4158, 4159, 4175, 4176 | `0x85c7b311d1e5bf97` |
| `init-0.4th` | 2200, 2201 | `0xd0a9550baf786bb3` |
| `init-1.4th` | 4406, 4415, 4425, 4435 | `0x63e251adb0a03613` |
@@ -225,9 +225,19 @@
| 4842 | `init-l8-transition.4th` | `0xbcc1a81976f0a4c9` | ok |
| 4851 | `artemis:init.4th` | `0xc9e92cd18f4c7b49` | ok |
| 4852 | `artemis:init.4th` | `0xc9e92cd18f4c7b49` | ok |
| 4900 | `fabric.4th` | `0xb7db7380ec4a42a0` | ok |
| 4901 | `fabric.4th` | `0xb7db7380ec4a42a0` | ok |
| 4902 | `fabric.4th` | `0xb7db7380ec4a42a0` | ok |
| 4900 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4901 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4902 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4903 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4904 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4905 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4906 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4907 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4908 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4909 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4910 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4911 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
| 4912 | `fabric.4th` | `0x355ccc154aac15b3` | ok |
## Conflicts