`#` held the high quotient on the return stack across its second
UM/MOD, which was the deepest point of pictured output once C! was made
call-free. It now rotates it under the division on the data stack
(-ROT in line: SWAP push SWAP pop).
Headroom, return entries: <# #S #> 2 -> 3, the signed picture 1 -> 2.
Data room is unchanged.
Same 4716 checks per width at 32- and 64-bit cells, optimised and
ASan+UBSan (`make test`, `make sanitize`); the headroom checks now
require the new figures.
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>
C! as written in 5.3 called RSHIFT and LSHIFT (which call SWAP) and OR.
It is now one straight-line case per byte position: the byte is shifted
up with a `2* unext` loop, that byte of the cell cleared with a constant
mask, and the two added. The word address is `2/ 2/` of the byte
address. The upper half of a 64-bit cell is still preserved.
Headroom (data cells under args / return entries): 5/4 -> 7/7.
Same checks as before (every byte of two adjacent words, eight values,
neighbours and the upper half untouched) at 32- and 64-bit cells,
optimised and ASan+UBSan (`make test`, `make sanitize`). Four mutations
fail, one of them only at 64-bit cells, where it differs.
test_pictured.c carries the same C!. The pictured words did not gain
return-stack room from this: <# #S #> still leaves 2 entries and the
signed picture 1. With C! shallow, the deepest point is now inside `#`,
which holds the high quotient on the return stack across its second
UM/MOD. Recorded in 5.8; `#` is unchanged.
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>
DECOMPOSITION.md 5.8 only named these as "standard pictured-output
definitions over UM/MOD and a hold buffer". They are now written out
(5.8) and run on the golden model.
D-13 (ruled 2026-10-03): the hold buffer takes 63 characters, as v3's;
HOLD of a value outside 0-255, or into a full buffer, stores nothing and
sets NODE-ERROR, which is what v3 did with its error flag.
Behaviour follows v3 otherwise: digits 0-9 then A-Z, BASE outside 2..36
reads as 10, SIGN ( n -- ). Stack effects are the standard ones, as 5.8
already ruled (v3 took its double low cell on top). The buffer is 64
bytes, filled backwards from its end through HLD; `#` divides by the
base in two UM/MOD steps. HOLD, SIGN and # end in a jump to the next
word instead of a call, which saves two return-stack entries: with
calls, the signed picture `.` needs overflowed the 9-deep return stack.
New test file v4/tests/test_pictured.c, on a node of its own:
test_foundation.c's hand-assembled words already fill 901 of a node's
1024 words. It re-assembles SWAP, OR, UM/MOD, LSHIFT, RSHIFT and C! as
they are in test_foundation.c.
Checked against a C reference (short division on 16-bit limbs) at 32-
and 64-bit cells, optimised and ASan+UBSan (`make test`, `make
sanitize`), 4716 checks per width: <# #S #>, <# # # 46 HOLD #S #> and
the signed picture, in bases 10, 16, 2, 8, 36, 3 and the invalid 0, 1,
37, -5, on every pair of 15 edge cells; HOLD of 12 values; and a base-2
number that overflows the buffer (63 characters kept, NODE-ERROR set,
nothing outside the buffer written). Six mutations all fail.
Headroom: <# #S #> leaves 3 data cells and 2 return entries; the signed
picture leaves 1 return entry. The depth is C!'s as written (C! ->
LSHIFT -> SWAP), which is unchanged.
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>
