AnachronautandClaude Opus 5
7cd5e34347
The sixteen kilobytes taken back a moment ago all went to the output image, because that was the wall: 13,245 bytes of cosmos.bin against 13,312. Lifting it moved the machine straight into the next one, a hundred and eleven bytes away - the label names, at 8,081 of 8,192 - and the index was a hundred and eighteen entries from the same place. So the room is shared out rather than given to the obvious one. Names and index both double, and the output takes what is left, which is still four and a half thousand bytes more than CosmOS needs. LabLimit and LabRoom in labels.asm have to agree with the map in scratch.asm and are now said to. Worth recording how this was found, because it is the good case. The assembler STOPPED and said "no room left for label names: Mode, at line 3598" - a limit it checks, names, and points at. Every other ceiling this project has hit went unnoticed until something downstream broke: a program loaded over the shell, a path silently cut short, a file reported as itself less 65,536. A limit that announces itself is worth the handful of instructions it costs. The output's eighteen kilobytes are temporary. They exist because the assembler holds a whole finished file in memory before writing it, and the file is produced in order, so it could be written as it is made. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
327 lines
6.5 KiB
NASM
327 lines
6.5 KiB
NASM
; The label table: the only thing that survives between the two passes.
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;
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; Names are packed end to end in an arena and each index entry holds a pointer into it,
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; rather than every entry carrying a field wide enough for the longest name. MEASURED on
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; CosmOS, which is the biggest thing this will ever be asked to assemble: 453 labels
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; averaging 11.3 characters. Packed they come to about 7,400 bytes; in 32 byte fields they
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; would come to 15,400. The arena is worth the handful of extra instructions.
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;
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; Four bytes an index entry: two saying where the name is, two saying what it resolves to.
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;
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; A name is stored WITHOUT its colon, so that a definition and a use of it compare equal
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; without either side having to know which it was looking at.
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;
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; The first pass fills this and the second only reads it. That is what makes a forward
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; reference ordinary rather than special: by the time anything is emitted, every name in
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; the program already has an address.
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;
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; Written by Anachronaut
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#Program
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; Empties the table.
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labReset:
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SETD.0 LabCount
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CALL numZero
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SETD.0 LabUsed
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CALL numZero
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SETD.0 LabNext
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SETD.2 ScratchLabArena
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CALL numSet
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SETD.0 LabBase
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SETD.2 ScratchLabIndex
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CALL numSet
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RET
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; Adds the name at DP0, meaning the address in A and B. Q is zero if it went in.
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;
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; A name already in the table is refused rather than replaced: one name may mean one place,
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; and quietly taking the second would move everything that referred to the first.
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labAdd:
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SETD.2 LabPutAddress
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STA.2
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INCD.2
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STB.2
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SETD.2 LabSubject
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STD.0.2
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CALL labFind
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BNQ labAddFresh
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SETD.0 LabTwice
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CALL labComplain
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BRI labAddNo
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labAddFresh:
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SETD.0 LabCount
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SETD.2 LabLimit
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CALL numCompare
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BNC labAddFull ; The index is as full as it goes.
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; And the arena, counting the zero that ends the name.
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SETD.1 LabSubject
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LDD.0.1
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CALL labLength
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SETD.0 LabEnd
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SETD.2 LabUsed
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CALL numSet
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SETD.0 LabEnd
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SETD.2 LabLength
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CALL numAdd
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SETD.0 LabRoom
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SETD.2 LabEnd
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CALL numCompare
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BRC labAddCrowded ; The arena is smaller than where this name would end.
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; The index entry: where the name is about to go, and what it means.
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SETD.0 LabWhich
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SETD.2 LabCount
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CALL numSet
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CALL labEntryAt
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SETD.1 LabEntry
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LDD.0.1
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SETD.1 LabNext
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LDD.1.1
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PSHD.1
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POPB
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POPA ; The low byte is on top, the way a pointer is pushed.
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STA.0
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INCD.0
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STB.0
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INCD.0
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SETD.2 LabPutAddress
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LDA.2
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STA.0
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INCD.0
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INCD.2
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LDA.2
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STA.0
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; And the name itself, into the arena.
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SETD.1 LabNext
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LDD.1.1
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SETD.2 LabSubject
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LDD.0.2
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labAddLoop:
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LDA.0
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STA.1
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BRA labAddCopied
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INCD.0
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INCD.1
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BRI labAddLoop
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labAddCopied:
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INCD.1 ; Past the zero, which was copied with the rest.
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SETD.0 LabNext
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STD.1.0
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SETD.0 LabUsed
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SETD.2 LabLength
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CALL numAdd
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SETD.0 LabCount
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CALL numStep
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RSTA
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RSTB
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CCF
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ADD
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RET
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labAddFull:
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SETD.0 LabFull
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CALL labComplain
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BRI labAddNo
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labAddCrowded:
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SETD.0 LabNoRoom
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CALL labComplain
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labAddNo:
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RSTA
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INIB 0d1
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CCF
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ADD
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RET
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; Looks up the name at DP0. Q is zero if it is there, and then LabAddress is what it means.
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;
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; A straight walk from the front. With 453 labels and a few thousand uses of them that is
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; the slowest thing the assembler does, and it is deliberately the simple version: sorting
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; the table or bucketing it on the first character are both easy later, and neither is
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; worth writing before anything has been measured.
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labFind:
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SETD.2 LabSought
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STD.0.2
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SETD.0 LabWhich
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CALL numZero
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labFindLoop:
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SETD.0 LabWhich
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SETD.2 LabCount
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CALL numCompare
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BNC labFindMissing ; Walked the whole table without a match.
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CALL labEntryAt
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SETD.1 LabEntry
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LDD.0.1
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LDA.0
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INCD.0
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LDB.0
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SETD.0 LabNamePointer
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STA.0
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INCD.0
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STB.0
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SETD.1 LabNamePointer
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LDD.0.1
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SETD.1 LabSought
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LDD.1.1
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CALL sameText
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BRQ labFindGot
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SETD.0 LabWhich
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CALL numStep
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BRI labFindLoop
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labFindGot:
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SETD.1 LabEntry
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LDD.0.1
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INCD.0
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INCD.0
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LDA.0
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INCD.0
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LDB.0
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SETD.0 LabAddress
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STA.0
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INCD.0
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STB.0
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RSTA
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RSTB
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CCF
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ADD
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RET
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labFindMissing:
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RSTA
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INIB 0d1
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CCF
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ADD
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RET
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; Where entry number LabWhich is, into LabEntry. Four bytes an entry, so the offset is the
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; number doubled twice - there being no multiply on this machine, and none needed.
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labEntryAt:
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SETD.0 LabOffset
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SETD.2 LabWhich
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CALL numSet
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SETD.0 LabOffset
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SETD.2 LabOffset
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CALL numAdd
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SETD.0 LabOffset
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SETD.2 LabOffset
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CALL numAdd
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SETD.0 LabEntry
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SETD.2 LabBase
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CALL numSet
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SETD.0 LabEntry
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SETD.2 LabOffset
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CALL numAdd
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RET
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; How long the string at DP0 is, counting the zero on the end, into LabLength.
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labLength:
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SETD.1 LabLenWalk
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STD.0.1
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SETD.0 LabLength
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CALL numZero
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labLengthLoop:
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SETD.0 LabLength
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CALL numStep
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SETD.1 LabLenWalk
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LDD.0.1
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LDA.0
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BRA labLengthDone
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SETD.0 LabLenWalk
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CALL numStep
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BRI labLengthLoop
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labLengthDone:
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RET
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labComplain:
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SWI osPrintString
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SETD.0 LabNamed
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SWI osPrintString
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SETD.0 TokText
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SWI osPrintString
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SETD.0 LabAtLine
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SWI osPrintString
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SETD.0 TokLine
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LDA.0
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INCD.0
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LDB.0
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SWI osPrintNumber
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SETD.0 LabNewLine
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SWI osPrintString
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RET
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#Data
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LabCount:
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0x00 0x00
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LabUsed:
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0x00 0x00
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LabNext:
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0x00 0x00
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LabBase:
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0x00 0x00
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LabAddress:
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0x00 0x00
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LabPutAddress:
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0x00 0x00
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LabNamePointer:
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0x00 0x00
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LabSought:
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0x00 0x00
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LabSubject:
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0x00 0x00
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LabEntry:
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0x00 0x00
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LabOffset:
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0x00 0x00
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LabWhich:
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0x00 0x00
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LabLength:
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0x00 0x00
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LabLenWalk:
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0x00 0x00
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LabEnd:
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0x00 0x00
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; How many labels there may be, and how many bytes of name between them.
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;
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; SIZED FOR THE ASSEMBLER ITSELF, which turns out to be the largest thing it is asked to
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; build: 555 labels and about 6,800 bytes of name, against CosmOS's 650 and 8,081 - CosmOS is
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; the bigger of the two now, and was the smaller when this was written. Running into either
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; limit says so rather than writing past the end of the table, and that is what it did. The buffers live
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; above the program rather than inside it - see the scratch map in Asm.asm.
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; Fifteen hundred and thirty six names, and sixteen kilobytes to hold them in. Both were
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; half that, and the names ran out first: 8,081 bytes of 8,192, which is a hundred and
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; eleven - and the thing that ran into it was one ordinary piece of work adding eighteen
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; labels. THESE TWO MUST AGREE WITH THE SCRATCH MAP, which says where the room actually is.
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LabLimit:
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0x06 0x00
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LabRoom:
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0x40 0x00
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LabNamed:
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": "
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LabAtLine:
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", at line "
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LabNewLine:
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"
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"
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LabTwice:
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"that label is defined twice"
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LabFull:
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"too many labels"
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LabNoRoom:
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"no room left for label names"
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