eaeb4731768886efe4918f9d6f6613e59ded1cb6
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Commits
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  AnachronautandClaude Opus 5
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eaeb473176 |
ls says in green what the shell will start
Directories were already blue. Something the shell will run is green now, and it is asked by LOOKING rather than looked up. This was priced once as needing a runnable bit in the directory entry, set by the filesystem from a list of magic numbers it would have to be taught - declined twice, for putting format knowledge in the filesystem and giving two implementations a registry to keep in step. It costs nothing of the sort any more. The shell decides what to run by reading a file's first block, so "will this run" is a question with an answer already, and this asks the same one the shell would: SBEX for a program, "#!" for a script. Nothing is written down and nothing has to agree about anything. The price is a block read per file, which is exactly what the bit existed to avoid: a listing of thirty seven files went from 260,593 cycles to 635,321. It is paid in ls and not in dir on purpose - dir is the listing you audit and is built into the shell, this is the one you read and was loaded off the disk anyway. The fast one stays fast. plain.script is the proof on the test disk: it sits among a dozen scripts that are green and is not one, because it is the fixture with no shebang and the shell will not start it. The extension is decoration and the colour is the truth, which is the whole of what running by content means, finally visible. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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a13bbeb4db |
ls, a listing laid out to be read
> ls Copy.sbx Say.sbx Where.sbx Walk.sbx ls.sbx Lander where.sh dir says what is there one line each, with sizes and a tally of the disk. This says the names in columns and nothing else, which is what you want ninety times in a hundred. Two programs rather than one with a switch, because they answer different questions and neither answer is a worse version of the other. AND THIS IS A PROGRAM WHERE DIR IS BUILT IN, which is the difference that matters when the disk is what you are doubting: dir is already in memory and this has to be loaded off the disk it is about to list. The daily driver and the diagnostic. Two passes over the directory and no buffer at all. Columns need the longest name before the first line can be printed, which usually means holding every name - twenty four bytes each against a format that allows 1,024 entries. Walking twice costs a read of each directory block, into a buffer that is already there. Across and not down. Real listings go down the columns so that names next to each other alphabetically are next to each other on the screen, and that reason depends on sorting - which nothing here does. With the order arbitrary, down-and-across buys nothing and costs a division. Directories in blue and wearing a separator, unfinished saves in red, everything else plain: whether a file is runnable cannot be known without opening it, and opening every file in a directory to colour a listing is a price nobody agreed to pay. The colour reaches a terminal as well as the screen, so it is one mechanism and not two. ---- Three bugs, and one of them is this machine's oldest trap ---- nameLength answered in A, and a RET puts A back the way the caller had it. So it answered with nothing, and every gap between the columns came out the same width because the padding was subtracting whatever A happened to hold. Q is the ALU's output and nothing puts it back, which is why every answer here comes home in it. The padding subtracted the other way round - the name from the cell - which borrowed on every name that was not the longest, so all of them took the "wider than its cell" path and the listing came out separated by one space. And padding after a name left trailing spaces on every line that did not fill its last column. It goes before the next name now, so spaces only ever fall between two things and a line ends on a name. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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323d7a0330 |
A listing says what is left of the disk, and what will fit
dir said what was there and nothing about what was left. SplitDisk has printed the free figure since it was written, so the machine's own listing was the poorer of the two implementations at describing the same disk. 43 files, 3 directories 46 of 64 entries, 1893 blocks free Entries first, because they are the ceiling nobody notices until they hit it: a disk of small files runs out of directory slots long before it runs out of blocks. COUNTED RATHER THAN ASKED. The superblock keeps a free count and this file calls it "a note rather than the truth" in three places. sbfsSpace reads the whole directory table instead, which costs a read per directory block and is the answer rather than a guess. SplitDisk goes on reading the note and saying when it is stale, which is the right place for that check - the host tool is what you audit a disk with. ---- And it is a fact about the disk, not about where you are ---- The first version added the blocks up as the LISTING walked past them, which cost no extra read and was wrong: that walk stops only on entries in the working directory, so the same disk came out as 1,996 blocks free from the root and 2,025 from /Apps. Comparing against SplitDisk is what said so, which is what having two implementations is for. ---- The longest run, which is what decides whether a file fits ---- 4 of 16 entries, 37 blocks free the longest run is 25 Files are laid down contiguously, so the free total does not say whether a file will fit. Both implementations learn it, from one specification. Said only when it differs from the free total. Deleting is what fragments a contiguous store, and a disk that has only been appended to has one gap at the end - so on a healthy disk this is silent, and a line that appears only when something is wrong is a line somebody reads. There is no sort on this machine and the entries are in no order, so a candidate walks the disk: each pass finds the used extent nearest at or after it, and anything the candidate stands inside pushes it to the far end and starts the pass again. The same trick allocating uses. So it costs a pass per gap rather than per file - nearly nothing on a disk with one gap, more the more fragmented the disk is, which is the right way round. holes.img is six files with the second and fourth deleted, because no other disk here can show any of this: none of them has ever had anything deleted from it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |