Tab lists its matches in columns, and says what it can in colour
Tab's listing was six instructions: print the name, print two spaces. It was the crown of this shell for a while and looks plain next to ls. Columns cost NOTHING EXTRA. Tab already walks its candidates twice - once to find the answer, once to show the matches, and tabRunSources exists because those are the same walk asked two questions. The longest match is counted on the first, which already visits every one of them, so the listing needs no walk of its own to know how wide a column should be. Padding goes before a name rather than after, so a row ends on a name. Directories are blue and the shell's own commands are green. Both are free: Tab appends the separator itself, and a built-in is not a file at all - which is also the only way anybody could know it will run. A FILE IS NOT COLOURED, and that is a decision. Whether a file will run is a read of its first block, which is what ls does and what makes ls cost twice what it otherwise would. Here it would be worse than slow: candidates are offered from inside a directory walk, and looking a file up would overwrite the very fields holding the walk's own position. Doing it safely means holding every candidate name in memory, which is a buffer the shell would carry whether anybody pressed Tab or not - and ls is one keystroke away. A Tab press already costs about 200,000 cycles, so the read was not the objection. ---- And the machine could no longer build itself ---- Found by make test, not by reading. The native assembler ran out of room for label names on cosmos.asm: 16,758 bytes against 16,384. The index was 1,341 of 1,536 in the same breath. Which is scratch.asm's own warning happening a second time - "two ceilings a hundred bytes apart look like one ceiling until the first is lifted" - so both were raised, out of the seventeen kilobyte page that file deliberately left unclaimed against exactly this. Names to 26,624 and the index to 2,048, both left about a third clear, with 1,792 bytes still unclaimed for the same reason. A name is thirteen bytes on average and an index entry is four, so the arena will always be the one that speaks first. That is now written down where the two numbers are. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
This commit is contained in:
Anachronaut
co-authored by
Claude Opus 5
Claude Opus 5
parent
eaeb473176
commit
563bc20a75
@@ -1739,6 +1739,8 @@ tabIsFirst:
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STA.1
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SETD.1 TabBestLen
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STA.1
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SETD.1 TabLongest
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STA.1
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; A path in the word says which directory to look in, and narrows what is being matched to
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; the part after the last separator.
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@@ -1929,6 +1931,16 @@ tabOfferTake:
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LDA.1
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INCA
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STA.1
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; ---- How wide the widest of them is, counted on the pass that is already here ----
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;
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; Listing wants it and listing happens on the SECOND pass, by which time this one is over.
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; Working it out there would mean a third walk of everything; working it out here costs a
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; walk of one name, and only of names that matched.
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CALL tabWidest
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SETD.1 TabCount
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LDA.1
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INIB 0d1
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XOR
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BRQ tabOfferFirst
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@@ -1939,12 +1951,62 @@ tabOfferFirst:
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BRI tabOfferSkip
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tabOfferPrint:
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; ---- The cell the last one started, finished now ----
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;
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; Padding before rather than after, so a line ends on the last character of a name instead
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; of on a run of spaces. The same reason ls does it that way.
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SETD.1 TabAcross
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LDA.1
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BRA tabOfferInk
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CALL tabPad
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tabOfferInk:
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; A directory in blue and a built-in command in green, which are the two things that can be
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; known for nothing. Whether a FILE will run cannot: that is a read of its first block, and
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; this is a keystroke.
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SETD.1 TabKind
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LDA.1
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BRA tabOfferSay
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DECA
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BRA tabOfferBlue
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INIA 0d2
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BRI tabOfferInked
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tabOfferBlue:
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INIA 0d4
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BRI tabOfferInked
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tabOfferSay:
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RSTA
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tabOfferInked:
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OUTA 0x06
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SETD.1 TabStart
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LDD.0.1
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CALL printString
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INIA 0x20
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OUTA 0x00
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OUTA 0x00 ; Two spaces between them, and A already holds one.
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RSTA
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OUTA 0x06
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; How much of the cell it took, for whoever finishes it, and one more across the line.
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SETD.1 TabStart
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LDD.0.1
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CALL tabTextLength
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MVQA
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SETD.1 TabUsed
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STA.1
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SETD.1 TabAcross
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LDA.1
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INCA
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STA.1
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SETD.1 TabColumns
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LDB.1
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CCF
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SUB
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BNQ tabOfferSkip
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RSTA
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SETD.1 TabAcross
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STA.1
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CALL newLine
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tabOfferSkip:
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; Past the end of this candidate, from wherever the comparison stopped.
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@@ -2258,6 +2320,9 @@ tabEntry:
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; same question the same way round.
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; A directory, and the separator goes on the end of it.
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INIA 0d1
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SETD.1 TabKind
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STA.1
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SETD.3 TabCandidate
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CALL tabEnd
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INIA 0x2F
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@@ -2267,6 +2332,10 @@ tabEntry:
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STA.3
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tabEntryFile:
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RSTA
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SETD.1 TabKind
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STA.1
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; A file, offered under the name it actually has - so nothing happens to it here at all.
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; A first word used to be offered with ".sbx" taken off, and anything without that ending
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; not offered, which was right while the extension was what made a file reachable by name.
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@@ -2323,11 +2392,73 @@ tabNameNext:
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BRA tabNamesDone
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DECA
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STA.1
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INIA 0d2
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SETD.1 TabKind
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STA.1 ; A command of the shell's own, which no disk read could say.
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CALL tabOffer
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BRI tabNameNext
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tabNamesDone:
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RET
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; DP0 names a string. Q is how long it is. Q rather than A, because a RET puts A back - which
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; is the oldest trap on this machine and cost an afternoon in ls.
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tabTextLength:
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RSTA
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tabTextNext:
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LDB.0
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BRB tabTextDone
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INCA
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INCD.0
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BRI tabTextNext
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tabTextDone:
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RSTB
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CCF
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ADD
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RET
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; The candidate at TabStart against the longest seen so far, called on the pass that finds the
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; answer - so listing costs no walk of its own to know how wide a column should be.
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tabWidest:
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SETD.1 TabStart
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LDD.0.1
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CALL tabTextLength
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MVQA
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SETD.1 TabLongest
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LDB.1
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CCF
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SUB
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BRC tabWidestKept ; Borrowed, so this one is not the longest.
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STA.1
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tabWidestKept:
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RET
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; Fills out the cell the last name started.
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tabPad:
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SETD.1 TabCell
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LDA.1
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SETD.1 TabUsed
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LDB.1
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CCF
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SUB
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BRC tabPadOne ; Wider than its cell, so one space keeps them apart.
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MVQA
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BRA tabPadOne
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SETD.1 TabPadLeft
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STA.1
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tabPadNext:
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INIA 0x20
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OUTA 0x00
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SETD.1 TabPadLeft
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LDA.1
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DECA
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STA.1
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BNA tabPadNext
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RET
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tabPadOne:
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INIA 0x20
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OUTA 0x00
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RET
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; ---- Showing them when they cannot be narrowed further ----
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;
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; The line is reprinted underneath afterwards, and where it now BEGINS is asked rather than
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@@ -2335,6 +2466,52 @@ tabNamesDone:
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; editor's idea of where things are hangs off those two registers.
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tabList:
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CALL newLine
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; ---- How many of them fit across ----
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;
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; The longest was counted on the pass that found the answer, so this is arithmetic and not
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; another walk. Two spaces between columns, and the screen says how wide it is - the same
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; sum ls does, for the same reason and with the same answer.
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SETD.1 TabLongest
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LDA.1
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INCA
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INCA
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SETD.1 TabCell
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STA.1
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INA 0x32
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SETD.1 TabRoom
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STA.1
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RSTA
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SETD.1 TabColumns
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STA.1
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tabFitting:
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SETD.1 TabRoom
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LDA.1
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SETD.1 TabCell
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LDB.1
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CCF
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SUB
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BRC tabFitted
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MVQA
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SETD.1 TabRoom
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STA.1
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SETD.1 TabColumns
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LDA.1
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INCA
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STA.1
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BRI tabFitting
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tabFitted:
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; A candidate wider than the screen still gets a column to itself.
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SETD.1 TabColumns
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LDA.1
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BNA tabListing
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INIA 0d1
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STA.1
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tabListing:
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RSTA
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SETD.1 TabAcross
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STA.1
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INIA 0x01
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SETD.1 TabShowing
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STA.1
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@@ -2342,7 +2519,14 @@ tabList:
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RSTA
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SETD.1 TabShowing
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STA.1
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; A row with something in it needs ending. One that filled its last column does not, and a
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; blank line under a listing looks like a listing with a gap in it.
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SETD.1 TabAcross
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LDA.1
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BRA tabListed
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CALL newLine
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tabListed:
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CALL sayPrompt
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INA 0x03
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@@ -8728,6 +8912,27 @@ TabCopyAt:
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0x00
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TabFirst:
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0x00
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; ---- Laying the matches out in columns ----
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;
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; What kind of thing the candidate being offered is, how wide the widest of them was, and how
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; far along a row the listing has got. The kind is set where the candidate comes FROM, since
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; that is the only place that knows: 0 a file, 1 a directory, 2 one of the shell's own words.
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TabKind:
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0x00
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TabLongest:
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0x00
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TabCell:
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0x00
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TabColumns:
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0x00
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TabRoom:
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0x00
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TabAcross:
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0x00
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TabUsed:
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0x00
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TabPadLeft:
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0x00
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; Whether the walk is looking for the answer or showing what the answers were.
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TabShowing:
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0x00
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