rajamesandClaude Opus 5.5
8df6c16766
ENGINE.md step 2, the carrier. Ruled 2026-10-05 (V3-PARITY.md 1i), on DECOMPOSITION.md section 6: a write to a port blocks until the neighbour reads. - node: v4_node_port_attach, v4_node_port_served; a store to the port keeps the value as the request and blocks the node - exec: a blocked node executes nothing; served, it goes on from the opcode after the store, in the same instruction word; a fault meanwhile abandons the rest of the word - compile.v4: n KERNEL-WORD name makes a word whose body writes n to the port; its arguments and results are on the data stack - boot: the kernel's words are made by handing the node text, and requests are served between the node's opcodes; one no one serves is error 12 - BYE, the first kernel word: hosted it leaves the program, as hosted v3; on the lone node it is v3's cold restart - ENGINE.md 3a: multiuser, multitasking, preemptive and cooperative, and what that asks of the engine Verified: make -C v4 test passes at both widths, with tests/test_port.c; hosted-check passes on three ISAs; clean qemu with STARFORTH_V4=1 on amd64, aarch64 and riscv64 passes POST with the same hashes as hosted, and a kernel word no one serves and BYE typed at each prompt are answered (logs/20261005-185506, -185734, -190101; -185234 is an amd64 run in which those two lines were not typed). Not done: v3's own C functions serving a node. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
134 lines
6.5 KiB
Markdown
134 lines
6.5 KiB
Markdown
# v4/
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StarForth v4: the 32-instruction F18-derived core. The design lives in
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`docs/v4.0.0/JUSTIFICATION.md` (why) and `docs/v4.0.0/DECOMPOSITION.md`
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(every v3 word mapped to a v4 fate).
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The first deliverable is the hosted C99 golden model (`JUSTIFICATION.md` §10,
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step 1). It must pass POST and hold K≡1.0 with 32- and 64-bit cells on all
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three host ISAs.
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Acceptance (`JUSTIFICATION.md` §16): v4 must be equivalent to v3 at any point
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in time, with the same vocabularies and behaviour, on the F18-derived engine;
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and every ISA, hosted and bare metal, must still reach its `ok` prompt.
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`make -C v4 test` passing is a development check, not acceptance.
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What exists so far is the single node: registers, circular stacks, memory, all
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32 opcodes, per-opcode and per-call-target heat, and three console
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registers (`CONSOLE-TX`, which captures output, and `CONSOLE-RX` and `CONSOLE-STATUS`, which hand out
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input a test feeds) standing in for the console node until the mesh exists. The tests load definitions
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onto a node either opcode by opcode (`v4/include/v4/asm.h`) or as text in the notation `DECOMPOSITION.md`
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uses (`v4/include/v4/text.h`). `make -C v4 test` builds
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and runs the tests at both cell widths; `make -C v4 sanitize` repeats them
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under ASan and UBSan. There is no POST and no K measurement yet.
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## The system: nucleus, capsules, prompt
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`docs/v4.0.0/NUCLEUS.md` is the design. A v4 system is four things:
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| Part | Where | What it is |
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|---|---|---|
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| Engine | `v4/src` | The golden model of the 32-opcode node |
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| Nucleus | `v4/capsule/*.v4`, built by `v4/tools/mkimage.c` | The assembled words, as a memory image linked into the binary |
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| Capsules | `capsules/v4/*.4th`, baked by `tools/mkcapsule.c` | FORTH source, loaded when the system comes up |
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| Boot | `v4/system/boot.c` | Starts the nucleus, checks and loads each capsule, prints the parity lines, gives the prompt |
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Two products link the same four and differ only in the console:
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- **Hosted Linux**, `v4/tools/hosted.c`: `make -C v4 hosted` builds
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`v4/build/starforth4-amd64`, `-aarch64` and `-riscv64`, static, 64-bit cells.
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- **Bare metal**, `kernel/src/v4/sk_v4.c`: `make -f kernel/Makefile ARCH=<arch> STARFORTH_V4=1`.
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A boot prints:
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```
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PARITY:V4_NUCLEUS words=292 image_hash=0x...
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PARITY:V4_CAPSULE name=v4:forth79.4th capsule_id=0x... capsule_hash=0x... dict_hash=0x...
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PARITY:OK
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ok>
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```
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Every build of one commit prints the same hashes. `make -C v4 hosted-check`
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boots the three hosted binaries (the two foreign ones under user-mode QEMU)
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and fails unless their output is identical and ends in `PARITY:OK`.
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A capsule line the node does not answer ` ok` to ends the boot, naming the
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capsule, block and line, with `PARITY:FAIL` and `POST: FAILED`.
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State, 2026-10-05, after `ENGINE.md` step 1: all six builds start the nucleus,
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load `v4:forth79.4th`, pass POST and reach `ok>`, with the same lines:
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```
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PARITY:V4_NUCLEUS words=296 image_hash=0x736921433a2e0e97
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PARITY:V4_CAPSULE name=v4:forth79.4th capsule_id=... dict_hash=0x01a3a48159f28a3e
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PARITY:V4_POST tests=550 pass=550 fail=0
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PARITY:V4_CAPSULE name=v4:post79.4th capsule_id=... dict_hash=0x212b7b70848080e7
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PARITY:OK
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POST: PASSED
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ok>
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```
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Bare-metal logs: `logs/20261005-185506/amd64/`, `logs/20261005-185734/aarch64/`,
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`logs/20261005-190101/riscv64/`. On each, six lines were then typed at the
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prompt through the serial port — a definition, its use with the capsule's
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`U*`, an unknown word, a kernel word no one serves, and `BYE` — and each
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was answered as the hosted binary answers it. The
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capsules were unsigned (no signing key on this machine).
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**A node is handed a line** (`docs/v4.0.0/ENGINE.md` 3.1). It does not read
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its own command line and prints no prompt. Its host puts the text in the
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node's input buffer and starts it at `(LINE)`; the node interprets the text
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and stops at `(IDLE)`, leaving in `(LINE-STATUS)` how it ended. The host says
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` ok` or ` ERROR` and prompts, as the kernel's REPL does for a v3 VM. A line
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may be 1024 characters, a block. `v4_line_begin`, `v4_line_done` and
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`v4_line_status` (`v4/include/v4/image.h`) are that interface;
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`v4_boot_line` (`v4/system/boot.c`) is the one loop the hosted binary, the
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kernel and the capsule loader all run it with.
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**A node asks its kernel by writing to its port** (`ENGINE.md` 3.3). The
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write blocks the node until it has been served. A kernel word is a
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dictionary entry made by `n KERNEL-WORD name`, whose body writes `n` to the
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port; its arguments and results are on the data stack. `BYE` is the one
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kernel word so far. A node can be stopped between any two instruction
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words and is blocked while it waits at its port, which is what a system of
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many users and tasks, preemptive and cooperative, needs of it
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(`ENGINE.md` 3a).
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**This is still the lone node.** On bare metal `kernel_main.c` starts it
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before the fleet tables, beside the kernel's own system and not in the VM's
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place. `ENGINE.md` sets out the steps from here; step 1 is done and step 2 is
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part done. `V3-PARITY.md` records the rulings it is built from.
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**What this does not yet show.** `forth79.4th` holds two definitions, `U*`
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and `U/MOD`. Every other word is still in the assembled nucleus, so POST is
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so far a test of the assembled words. Moving them to the capsule, a group at
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a time with POST after each, is the next step (`NUCLEUS.md` section 8).
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## POST
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`capsules/v4/post79.4th`: 550 cases in blocks 7000 up, covering 126 of the
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130 words of the FORTH-79 Required Word Set. 443 are v3's cases with what
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the hosted v3 binary did as the expected result. The other 107, and the 27
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v3 cases left out, are listed with reasons in `docs/v4.0.0/POST79.md`.
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- `make -C v4 post` boots the amd64 system: the quick check after a change.
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- `make -C v4 hosted-check` boots all three hosted ISAs and compares them.
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- `make -C v4 post79` writes the capsule again (`tools/mkpost.py`,
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`tools/post79_rules.py`); it needs the hosted v3 binary.
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POST is FORTH: a harness of FORTH-79 words and two nucleus hooks, `(CATCH)`
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and `(EMIT-HOOK)`. It forgets itself when it has finished. The boot passes
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only on seeing POST's tally line with `fail=0` (`v4/system/boot.c`). A colon
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definition broken on purpose (`U/MOD` without its last `SWAP`) fails five
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cases and the boot stops with `POST: FAILED`.
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Not tested: `KEY`, `EXPECT`, `QUERY` (the keyboard) and `QUIT` (it returns
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without ` ok`).
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Open: `PAD 42 OVER !` faults on v4, because `PAD` is a byte address and `!`
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takes a cell address (D-1). FORTH-79 expects it to work. The v3 case for it
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is left out until that is ruled.
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The Required Word Set list in `tools/mkpost.py` was written from memory of
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the standard and has not been checked against the document.
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