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LithosAnanake/include/starkernel/vm/stadium.h
T
Robert Allan JamesandClaude Sonnet 5 d55ec3241b starkernel: item 3.1 -- the Stadium cell and header
Punch list §25 item 3.1 complete.

Defines StadiumPatronHeader and StadiumContinuationCell in new
include/starkernel/vm/stadium.h, unioned as StadiumCell per §3's
closed two-valued union. src/starkernel/vm/stadium.c added to
Makefile.starkernel's LOADER_EXTRA_SRCS/KERNEL_EXTRA_SRCS so the
header's compile-time size checks are actually compiled, not merely
included by something that never builds.

Discriminator ruled an external side bitmap (Captain Bob), not a
header field -- amended into §3 and §23.3 before this code was
written. Item 3.1 declares the bitmap's purpose/indexing in a comment
only; allocating it is item 3.2's scope.

Both cell shapes counted for real at exactly 64 bytes with zero
compiler-inserted padding (three C99-portable negative-array-size
assertions -- no _Static_assert, this project targets C99). Header
matches §23.3's original 32+32 split unchanged, since the
discriminator moving outside the cell left nothing to compete for that
space. Continuation cell matches item 1.12's 4+60 figure unchanged for
the same reason.

Verified the size assertion is actually live: broke it to 63,
confirmed the build failed with the expected negative-array-size
error, restored it, confirmed a clean compile.

Verified: three-architecture boot (amd64, aarch64, riscv64), all
reaching ok> with identical dict_hash=0x3d4e1daf289da94f matching the
item-2.2 baseline. Confirmed stadium.o present in both obj/loader/vm
and obj/kernel/vm post-build on amd64, closing the gap the item-2.2 WIP
exposed (an uncompiled header proves nothing).

Left open, not fabricated: §23.4 #2 ("does a typical message fit in
one cell") is unanswerable today -- no message patron struct exists
anywhere in this tree yet.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-08-04 14:55:30 -04:00

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/*
StarForth — Steady-State Virtual Machine Runtime
Copyright (c) 20232025 Robert A. James
All rights reserved.
This file is part of the StarForth project.
Licensed under the StarForth License, Version 1.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at:
https://github.com/star.4th@proton.me/StarForth/LICENSE.txt
This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
express or implied, including but not limited to the warranties of
merchantability, fitness for a particular purpose, and noninfringement.
See the License for the specific language governing permissions and
limitations under the License.
*/
/**
* stadium.h - The Stadium cell and header (FABRIC.md §3, punch list item 3.1)
*
* A cell is one of exactly two things: a patron header, or a continuation
* cell owned by exactly one patron. The union is closed, two-valued, and
* fixed at build time -- not a type field. See FABRIC.md §3.
*/
#ifndef STARKERNEL_VM_STADIUM_H
#define STARKERNEL_VM_STADIUM_H
#ifdef __STARKERNEL__
#include <stdint.h>
#define STADIUM_CELL_BYTES 64
/*
* StadiumPatronHeader - one member of the closed two-valued cell union
* (FABRIC.md §3). Nine wires: identity, heat, TTL, pin (a bit in `flags`),
* link, code field (`behaviour`), mass, payload, contains. `flags` bit 0 is
* `pin`; the remaining bits are reserved. `behaviour` is the closed code-field
* enumeration (§18.3) -- not yet defined, item 3.3's scope.
*
* Field order is largest-to-smallest so natural C99 alignment adds zero
* padding: every offset below is already a multiple of that field's own
* alignment, and the struct's total size (64) is a multiple of its max
* alignment (8), so no compiler inserts trailing padding either. Do not
* reorder without re-checking this holds on all three ISAs.
*/
typedef struct {
uint64_t identity; /* offset 0 -- handle or name, never a content hash while resident (§24.4) */
uint64_t heat; /* offset 8 -- Q48.16, conserved share of 1.0 (§19.1) */
uint32_t ttl; /* offset 16 -- remaining lifetime; messages and ACLs only (§17.1) */
uint32_t link; /* offset 20 -- index into the Stadium, not a pointer */
uint32_t contains; /* offset 24 -- index of the patron held inside this one, or none (item 1.1) */
uint16_t mass; /* offset 28 -- cells this patron occupies (§19.2) */
uint8_t flags; /* offset 30 -- bit 0 = pin; remaining bits reserved */
uint8_t behaviour; /* offset 31 -- code field, closed enumeration (§18.3) */
uint8_t payload[32]; /* offset 32 -- inline payload, used when mass == 1 */
} StadiumPatronHeader;
/*
* StadiumContinuationCell - the other member of the union. Owned by exactly
* one patron header, chained by `next`. Never ranked, never reaped, never
* dispatched (§3) -- pure floor space, accounted for in its owner's mass.
*/
typedef struct {
uint32_t next; /* offset 0 -- index of the next continuation cell, or none */
uint8_t payload[60]; /* offset 4 */
} StadiumContinuationCell;
/*
* StadiumCell - the closed two-valued union itself (§3). Which member is
* valid for a given array slot is NOT stored in the cell -- FABRIC.md's item
* 3.1 amendment to §3 rules this an external side bitmap, one bit per cell,
* kept outside the cell array. Declared here as the indexing contract this
* type expects; item 3.2 (boot-time allocation) allocates the bitmap itself.
*/
typedef union {
StadiumPatronHeader header;
StadiumContinuationCell continuation;
} StadiumCell;
/* C99-portable compile-time size assertions (no _Static_assert -- that's C11). */
typedef char stadium_header_size_check[(sizeof(StadiumPatronHeader) == STADIUM_CELL_BYTES) ? 1 : -1];
typedef char stadium_continuation_size_check[(sizeof(StadiumContinuationCell) == STADIUM_CELL_BYTES) ? 1 : -1];
typedef char stadium_cell_size_check[(sizeof(StadiumCell) == STADIUM_CELL_BYTES) ? 1 : -1];
#endif /* __STARKERNEL__ */
#endif /* STARKERNEL_VM_STADIUM_H */