AnachronautandClaude Opus 5
4e3258e3f7
Sieve-16.asm, Life.asm and Fib-16.asm could be read on the machine and not assembled on it. All three #Include print.asm, and print.asm was not on the disk. /LIB WAS STILL A HAND-WRITTEN LIST. Programs/Libraries is what an #Include means when it is not a CosmOS source - print, the integer helpers, the maths - and nobody had thought to name them, which is the exact failure mirroring the sources was meant to end. It is mirrored now, so the next one nobody thinks of is there anyway. AND THE ASSEMBLER SAID NOTHING USEFUL. A missing include returned a failure and printed no message, so the catch-all at the top said "nothing was written", which is true and useless - finding out why meant reading the assembler rather than the message. It names the file now, and where it looked: cannot find print.asm, not beside the file that asked and not as /Lib/print.asm Both halves are worth having, because a name that is in neither place is usually one or the other spelt wrong. The same shape as More's "error 2": a program that knows exactly what happened, reporting a number or nothing at all. The disk also depends on the recipe that lays it out now. It did not, so adding the libraries left an image built without them and the next run reported the same thing missing - which sends you looking at the change you just made rather than at the stale thing in front of you. It cost twenty minutes to notice. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
631 lines
14 KiB
NASM
631 lines
14 KiB
NASM
; The source reader: characters out of a file of any size.
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;
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; Everything else in the assembler sits on this, so it is the first thing built and the
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; thing most worth getting right. It hands out one character at a time and keeps a line
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; number, which is what lets an error say where it happened rather than only what it was.
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;
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; A FILE IS NEVER HELD WHOLE. It arrives a block at a time through osFileBlock, into one
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; buffer of 256 bytes, and is fetched again when the buffer runs out. That is why the
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; assembler can read a source file bigger than the memory it runs in - which cosmos.asm,
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; at 56,047 bytes, already is.
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;
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; The file is read TWICE, once per pass, and srcRewind is how the second pass starts over.
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; Nothing is kept between the passes but the label table.
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;
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; ---- A stack of readers ----
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;
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; #Include splices another file in where it stands, so the reader is a stack: srcInclude
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; puts the current file's whole state aside, opens the new one, and the end of that file
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; pops the old one back and carries on where it left off. Everything above works on "the
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; current file" and does not know the stack is there.
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;
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; THE WHOLE STATE GOES ASIDE, buffer and all, 293 bytes of it. Keeping only the position
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; and re-reading the block on the way back would be cheaper in memory and would cost a disk
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; read per pop; at six levels of nesting the copy costs less than the arithmetic to avoid it.
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; The buffer pointer survives the trip because it points into the buffer, which is always at
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; the same address - the state is saved from and restored to the same variables.
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;
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; A FILE IS INCLUDED ONCE. Including it twice is not an error, it just does nothing, which
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; is what lets two libraries depend on a third. The names are remembered for the length of
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; one pass and forgotten between them, because the second pass has to walk exactly the same
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; tree the first one did.
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;
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; Written by Anachronaut
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#Program
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; Opens the file DP0 names. Q is zero if it is there.
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;
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; The name is copied rather than pointed at, because the caller's copy is in the caller's
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; memory and every later block read has to name the file again - there being no such thing
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; as an open file to hold on to.
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srcOpen:
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SETD.1 SrcTopName
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CALL srcKeepName ; Kept apart, so that each pass can open it again.
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CALL srcRestart
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RET
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; Back to the top of the tree: the first file, no includes taken yet, nothing on the stack.
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; This is what starts each pass.
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srcRestart:
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RSTA
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SETD.0 SrcDepth
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STA.0
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SETD.0 IncCount
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STA.0
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SETD.0 SrcTopName
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SETD.1 SrcName
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CALL srcKeepName
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CALL srcRewind
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RET
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; Back to the first character, for the second pass.
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srcRewind:
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SETD.0 SrcIndex
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CALL numZero
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SETD.0 SrcAt
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CALL numZero
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SETD.0 SrcCount
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CALL numZero
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RSTA
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SETD.0 SrcEnded
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STA.0
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; The line number counts from one, the way an editor does.
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SETD.0 SrcLine
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CALL numZero
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SETD.0 SrcLine
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CALL numStep
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; Ask how big it is, which is both the answer to "is it there" and the thing that says
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; when to stop asking for blocks.
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SETD.0 SrcName
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SWI osFileInfo
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BNQ srcRewindNo
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PSHD.3
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POPB
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POPA
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SETD.0 SrcBlocks
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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 ; Q is zero: it is there.
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RET
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srcRewindNo:
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INIA 0d1
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SETD.0 SrcEnded
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STA.0
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RSTA
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INIB 0d1
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CCF
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ADD ; Q is not zero: it is not.
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RET
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; The next character of the file, into SrcChar. Q is zero if there was one, and something
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; else at the end of the file.
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srcNext:
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SETD.0 SrcEnded
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LDA.0
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BNA srcAtEnd
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; Is the buffer used up? SrcAt counts how far into it we have read and SrcCount how many
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; of its bytes are the file's, which is 256 for every block but a short last one.
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SETD.0 SrcAt
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SETD.2 SrcCount
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CALL numCompare
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BNQ srcHaveByte
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CALL srcLoad
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BNQ srcAtEnd
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srcHaveByte:
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SETD.1 SrcPointer
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LDD.0.1
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LDA.0
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INCD.0
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STD.0.1
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SETD.0 SrcChar
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STA.0
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SETD.0 SrcAt
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CALL numStep
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; A newline is what makes the next character part of the next line. Counting it here,
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; as it is handed out, means the line number always describes the character just given.
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SETD.0 SrcChar
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LDA.0
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INIB 0x0A
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XOR
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BNQ srcNextDone
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SETD.0 SrcLine
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CALL numStep
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srcNextDone:
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RSTA
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RSTB
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CCF
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ADD ; Q is zero: there was a character.
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RET
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srcAtEnd:
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; This file is finished. If it was included by another, that one is not: it goes back on
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; and the next character comes from where it left off, which is what makes an include
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; read as though the text had been written there.
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INIA 0d1
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SETD.0 SrcEnded
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STA.0
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SETD.0 SrcDepth
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LDA.0
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BRA srcNothingLeft
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CALL srcPop
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BRI srcNext
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srcNothingLeft:
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RSTA
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INIB 0d1
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CCF
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ADD ; Q is not zero: there is no more source anywhere.
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RET
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; ---- The stack ----
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; Opens the file named at DP0 as though its text were written here. Q is zero if the
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; reader is now inside it, or if it had already been included and there is nothing to do.
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srcInclude:
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SETD.1 IncWanted
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CALL srcKeepName
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CALL srcSeenAlready
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BRQ srcIncludeSkip
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SETD.0 SrcDepth
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LDA.0
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SETD.2 SrcDepthLimit
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LDB.2
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CCF
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SUB
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BNC srcTooDeep
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CALL srcRemember
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CALL srcPush
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; TWO PLACES, TRIED IN ORDER: where you are, and then /Lib. The same rule the shell uses
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; for a program it does not recognise, which is where it came from - a name means the
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; one beside you if there is one, and the system's otherwise.
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;
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; It is what a search path is for, and the host assembler has had one since before there
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; was a machine to run this on. Without it every source that calls a service has to sit
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; in the same directory as services.asm, and the disk cannot be organised at all.
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SETD.0 IncWanted
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SETD.1 SrcName
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CALL srcKeepName
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CALL srcRewind
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BRQ srcIncludeIn
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CALL srcInLibrary
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CALL srcRewind
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BNQ srcIncludeGone
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srcIncludeIn:
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RET ; Q is zero, out of srcRewind.
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; SrcName becomes the same name inside the library directory. Built here rather than kept
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; as a second buffer, because what has to survive is the name the file was ASKED for -
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; that is what the include-once list holds, and a file found in the library on one line
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; and beside you on another is still the same include.
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srcInLibrary:
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SETD.0 SrcLibrary
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SETD.1 SrcName
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srcLibraryPrefix:
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LDA.0
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BRA srcLibraryName
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STA.1
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INCD.0
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INCD.1
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BRI srcLibraryPrefix
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srcLibraryName:
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SETD.0 IncWanted
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srcLibraryCopy:
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LDA.0
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STA.1
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BRA srcLibraryDone
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INCD.0
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INCD.1
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BRI srcLibraryCopy
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srcLibraryDone:
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RET
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srcIncludeSkip:
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RSTA
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RSTB
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CCF
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ADD ; Already in, so this line does nothing at all.
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RET
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srcIncludeGone:
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; ---- Say which one ----
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;
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; It said nothing at all, and the assembler's catch-all then said "nothing was written" -
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; which is true and useless. Three programs on the disk could be read and not assembled,
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; and finding out why meant reading the assembler rather than the message.
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;
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; SrcName holds the library path by now, because that was the second place tried, so this
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; says where it looked as well as what for. Both are worth having: a name that is not in
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; /Lib and not beside you is usually one or the other spelt wrong.
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SETD.0 GoneText
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SWI osPrintString
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SETD.0 IncWanted
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SWI osPrintString
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SETD.0 GoneWhereText
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SWI osPrintString
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SETD.0 SrcName
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SWI osPrintString
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SETD.0 GoneEndText
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SWI osPrintString
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; The file is not there. The stack is left as it is: the caller stops the assembly, and
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; unwinding for the sake of tidiness would only hide where it happened.
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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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srcTooDeep:
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SETD.0 TooDeepText
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SWI osPrintString
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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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; Puts the current file aside and makes room for another.
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srcPush:
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CALL srcSlot
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SETD.0 SrcState
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SETD.1 SrcSlot
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LDD.1.1
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CALL srcCopyState
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SETD.0 SrcDepth
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LDA.0
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INCA
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STA.0
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RET
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; And takes it back.
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srcPop:
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SETD.0 SrcDepth
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LDA.0
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DECA
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STA.0
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CALL srcSlot
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SETD.1 SrcSlot
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LDD.0.1
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SETD.1 SrcState
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CALL srcCopyState
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RET
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; Puts one character back, so that the next read produces it again. The character itself
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; is in A, because whether it was a newline decides whether a line goes back too.
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;
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; The tokenizer holds one character of lookahead, and at an #Include that character belongs
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; to the file about to be put aside. Undoing the read is how it stays with that file: when
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; the file is opened again the character is simply still there, and nothing has to be
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; carried across the include or handed back at some moment chosen by the reader.
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;
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; CARRYING IT ACROSS WAS THE OBVIOUS THING AND IT WAS WRONG. A file runs out in the middle
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; of whatever the tokenizer happens to be doing, so handing the character back then injects
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; it into the middle of a word: `start:` came back as `s` and then `tart:`, which assembles
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; into a file that looks entirely reasonable.
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srcStepBack:
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INIB 0x0A
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XOR
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BNQ srcStepBackAt
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SETD.0 SrcLine
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SETD.2 SrcOne
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CALL numTake ; A newline not yet read has not started a line either.
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srcStepBackAt:
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SETD.0 SrcAt
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SETD.2 SrcOne
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CALL numTake
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SETD.0 SrcPointer
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SETD.2 SrcOne
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CALL numTake
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RET
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; Where the slot for the current depth is, into SrcSlot.
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srcSlot:
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SETD.0 SrcSlot
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SETD.2 ScratchSrcStack
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CALL numSet ; WHERE the stack is, not what is in it.
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SETD.0 SrcSlotLeft
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SETD.2 SrcDepth
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LDA.2
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STA.0
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srcSlotLoop:
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SETD.0 SrcSlotLeft
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LDA.0
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BRA srcSlotDone
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DECA
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STA.0
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SETD.0 SrcSlot
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SETD.2 SrcStateBytes
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CALL numAdd
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BRI srcSlotLoop
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srcSlotDone:
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RET
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; The whole reader state, from DP0 to DP1.
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srcCopyState:
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SETD.2 SrcCopyFrom
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STD.0.2
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SETD.2 SrcCopyTo
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STD.1.2
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SETD.0 SrcCopyLeft
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SETD.2 SrcStateBytes
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CALL numSet
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srcCopyLoop:
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SETD.1 SrcCopyFrom
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LDD.0.1
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LDA.0
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SETD.1 SrcCopyTo
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LDD.0.1
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STA.0
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SETD.0 SrcCopyFrom
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CALL numStep
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SETD.0 SrcCopyTo
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CALL numStep
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SETD.0 SrcCopyLeft
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SETD.2 SrcOne
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CALL numTake
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SETD.0 SrcCopyLeft
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LDA.0
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INCD.0
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LDB.0
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OR
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BNQ srcCopyLoop
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RET
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; ---- Which files have been in ----
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; Q is zero if IncWanted has already been included in this pass.
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srcSeenAlready:
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RSTA
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SETD.0 IncLeft
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STA.0
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srcSeenLoop:
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SETD.0 IncLeft
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LDA.0
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SETD.2 IncCount
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LDB.2
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CCF
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SUB
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BRQ srcSeenNo
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CALL srcSeenSlot
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SETD.1 IncSlot
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LDD.0.1
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SETD.1 IncWanted
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CALL sameText
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BRQ srcSeenYes
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SETD.0 IncLeft
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LDA.0
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INCA
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STA.0
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BRI srcSeenLoop
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srcSeenYes:
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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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srcSeenNo:
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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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; Writes IncWanted down as having been included.
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srcRemember:
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SETD.0 IncLeft
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SETD.2 IncCount
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LDA.2
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STA.0
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CALL srcSeenSlot
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SETD.0 IncWanted
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SETD.1 IncSlot
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LDD.1.1
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CALL srcKeepName
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SETD.0 IncCount
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LDA.0
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INCA
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STA.0
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RET
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; Where name number IncLeft sits, into IncSlot. Fixed fields of 23 bytes: there are few of
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; these and they are short, so an arena would cost more code than it saved.
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srcSeenSlot:
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SETD.0 IncSlot
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SETD.2 ScratchIncNames
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CALL numSet
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SETD.0 IncSlotLeft
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SETD.2 IncLeft
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LDA.2
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STA.0
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srcSeenSlotLoop:
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SETD.0 IncSlotLeft
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LDA.0
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BRA srcSeenSlotDone
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DECA
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STA.0
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INIA 0d23
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SETD.0 IncSlot
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CALL numAddByte
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BRI srcSeenSlotLoop
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srcSeenSlotDone:
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RET
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; Fetches the block SrcIndex names, and steps SrcIndex past it. Q is zero if there was one.
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;
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; Running off the end is not a failure here: osFileBlock answers three for a block past the
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; end of the file, which is how a reader finds out it has finished. Any other refusal is a
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; real one, and both come back the same way because there is nothing useful to do about
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; either except stop.
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srcLoad:
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SETD.0 SrcName
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SETD.1 SrcBuffer
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SETD.2 SrcIndex
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LDA.2
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INCD.2
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LDB.2
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SWI osFileBlock
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BNQ srcLoadNo
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; DP3 says how many of the block's bytes belong to the file: a whole 256 except in a
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; short last one, which is why it comes back in a pointer and not a register.
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PSHD.3
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POPB
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POPA
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SETD.0 SrcCount
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STA.0
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INCD.0
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STB.0
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SETD.0 SrcAt
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CALL numZero
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SETD.0 SrcIndex
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CALL numStep
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; The walking pointer starts at the front of the buffer again.
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SETD.0 SrcBuffer
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SETD.1 SrcPointer
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STD.0.1
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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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srcLoadNo:
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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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; Copies the name at DP0 into DP1, up to 22 characters of it and the zero after them,
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; which is as long as a name on this filesystem may be.
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srcKeepName:
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INIA 0d22
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SETD.2 SrcLeft
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STA.2
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srcKeepLoop:
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LDA.0
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BRA srcKeepEnd
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STA.1
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INCD.0
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INCD.1
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LDA.2
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DECA
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STA.2
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BNA srcKeepLoop
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srcKeepEnd:
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RSTA
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STA.1 ; The zero that makes it a string.
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RET
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#Data
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|
; ---- The current file, as one block so that it can be put aside in one piece ----
|
|
;
|
|
SrcState:
|
|
; THIRTY TWO RATHER THAN THE TWENTY THREE A NAME NEEDS, because what goes here is a PATH:
|
|
; an include not found beside you is looked for in the library, and "/Lib/" plus a name of
|
|
; twenty two plus the zero that ends it is twenty eight. Every block of the file is asked
|
|
; for by this name, so it has to be the one that resolves, not the one that was typed.
|
|
SrcName:
|
|
#Reserve 0d32
|
|
SrcBlocks:
|
|
0x00 0x00
|
|
SrcIndex:
|
|
0x00 0x00
|
|
SrcCount:
|
|
0x00 0x00
|
|
SrcAt:
|
|
0x00 0x00
|
|
SrcLine:
|
|
0x00 0x00
|
|
SrcPointer:
|
|
0x00 0x00
|
|
SrcEnded:
|
|
0x00
|
|
|
|
; One block, which is the whole of what a source file costs in memory however big it is.
|
|
SrcBuffer:
|
|
#Reserve 0d256
|
|
|
|
; 301 bytes: a name of 32, six numbers of two, one single byte, and the buffer. NOTHING MAY
|
|
; BE ADDED IN THE MIDDLE OF THE BLOCK ABOVE without changing this to match, and the room
|
|
; set aside for six of them in scratch.asm has to be at least six times it.
|
|
SrcStateBytes:
|
|
0x01 0x2D
|
|
SrcDepthLimit:
|
|
0d6
|
|
|
|
; Where an include is looked for when it is not beside you. One fixed place rather than a
|
|
; list somebody sets, for the same reason the shell has one fixed place for programs: a
|
|
; list would need somewhere to live between one boot and the next.
|
|
SrcLibrary:
|
|
"/Lib/"
|
|
SrcOne:
|
|
0x00 0x01
|
|
|
|
SrcChar:
|
|
0x00
|
|
SrcLeft:
|
|
0x00
|
|
SrcDepth:
|
|
0x00
|
|
SrcSlot:
|
|
0x00 0x00
|
|
SrcSlotLeft:
|
|
0x00
|
|
SrcCopyFrom:
|
|
0x00 0x00
|
|
SrcCopyTo:
|
|
0x00 0x00
|
|
SrcCopyLeft:
|
|
0x00 0x00
|
|
|
|
; The file the assembly started from, so that each pass can open it again.
|
|
SrcTopName:
|
|
#Reserve 0d23
|
|
|
|
IncWanted:
|
|
#Reserve 0d23
|
|
IncCount:
|
|
0x00
|
|
IncLeft:
|
|
0x00
|
|
IncSlot:
|
|
0x00 0x00
|
|
IncSlotLeft:
|
|
0x00
|
|
|
|
GoneText:
|
|
"cannot find "
|
|
GoneWhereText:
|
|
", not beside the file that asked and not as "
|
|
GoneEndText:
|
|
"
|
|
"
|
|
TooDeepText:
|
|
"included files are nested deeper than this assembler will follow
|
|
"
|
|
|
|
|