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test(v4.0.0): execute the in-line constants Q.1, Q.0 and Q.SCALE

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DECOMPOSITION.md 5.26 gives them fate IN: the compiler places two
literals, low cell first. Q.1 and Q.SCALE are `65536 0`, Q.0 is `0 0`;
v3's are 65536, 0 and 65536.

Each expansion is assembled and run, and checked against v3's value;
then in use: Q.1 Q.TO-INT is 1, 1 Q.FROM-INT is Q.1, and q Q.1 Q.* and
q Q.0 Q.+ return q for 2000 pseudo-random q plus 0, Q max and Q min.
At 32- and 64-bit cells, optimised and ASan+UBSan (`make test`,
`make sanitize`). A wrong value in any of the three fails.

Test results on the amd64 host only. This is a development check, not
acceptance (JUSTIFICATION.md section 16).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
rajames
2026-10-03 11:03:57 -04:00
co-authored by Claude Opus 5.5
parent 8235078b3b
commit 13ec4b1b6c
2 changed files with 52 additions and 3 deletions
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@@ -676,7 +676,7 @@ word. Per D-10 it occupies two cells on a 64-bit node too. Per D-8, v4 Q values
| `(QE)` | CAP | Variable, 8 cells: `Q.EXP`'s `x`, term, sum, sign and term index. |
| `Q.FROM-INT` | CAP | `push 0 a! 0 pop 15 FOR +* UNEXT push drop a pop` — `n * 2^16` as a signed double. `+*` with `S = 0` never adds, so each step is an exact arithmetic right shift of `T:A`; starting from `T:A = n:0` (that is, `n * 2^N`) and shifting `N-16` bits leaves `n * 2^16`. The count is `N-17`: 15 at 32-bit cells, 47 at 64. Negative values are no longer clamped to 0. Executed on the golden model (2026-10-02): matches v3's `q48_from_u64` for `n >= 0` (at 64-bit cells in the low cell, where v3 wraps for `n >= 2^47`, per D-10). Clobbers `A`. |
| `Q.TO-INT` | CAP | `push a! 0 pop 15 FOR +* UNEXT drop drop a` — the same `+*` shift, 16 bits at every cell width, leaving the low cell in `A`. Rounds toward minus infinity, as v3's arithmetic shift does (−1.5 gives −2). Executed on the golden model (2026-10-02): v3's `q48_to_u64` exactly at 64-bit cells, its low cell at 32. Clobbers `A`. |
| `Q.1` `Q.0` `Q.SCALE` | IN | Double-cell constants. |
| `Q.1` `Q.0` `Q.SCALE` | IN | Double-cell constants, placed in line as two literals, low cell first: `Q.1` and `Q.SCALE` are `65536 0` (1.0), `Q.0` is `0 0`. v3's are 65536, 0 and 65536. Executed on the golden model (2026-10-03): the values match v3's, `Q.1 Q.TO-INT` is 1, `1 Q.FROM-INT` is `Q.1`, and `q Q.1 Q.*` and `q Q.0 Q.+` return `q`. |
| `Q.=` `Q.<` `Q.>` `Q.0=` `Q.MAX` `Q.MIN` | CAP | `D=`, `D<`, `2SWAP D<` (for `Q.>`), `D0=`, `DMAX`, `DMIN`. Signed (D-8); v3 compared unsigned, so v3 agrees only when both values have the same sign. Executed on the golden model (2026-10-02). `Q.>` was given here as `SWAP D<`, which swaps single cells, not Q values, and gave a wrong answer in 11702 of 20169 test cases. |
| `Q.PRINT` | CAP | Pictured output, five fractional digits. |