Block device peripheral and SBFS file system implemented.

2026-08-16 14:03:29 -04:00
parent 04dfcd707b
commit eff6902bcf
36 changed files with 3251 additions and 31 deletions
@@ -0,0 +1,156 @@
+; Reading the SplitBit Filesystem.
+;
+; The disk this reads was made by SplitDisk, which is the other implementation of the same
+; format. That is what makes this worth running: the library is being checked against
+; something written by different code working from the same written specification, rather
+; than against itself. If the two ever drift, this is where it shows.
+;
+; The cases here are the ones most likely to be wrong. across.txt is longer than a block,
+; so reading it has to carry on from one to the next. Its entry, and the two after it, are
+; in the second directory block, so finding it has to walk past the end of the first.
+; aName22CharactersLong! fills the name field exactly, so there is no zero on the end of
+; it to stop a comparison. empty.txt has no blocks at all.
+;
+; Correct output is:
+;   greeting.txt 0000 11 hello from a file
+;   across.txt 0002 BC ABCDEFGH...
+;   aName22CharactersLong! 0000 16 exactly twenty two!!!!
+;   empty.txt 0000 00
+;   absent.txt missing
+
+#Include print.asm
+#Include sbfs.asm
+
+#Program
+
+start:
+  CALL sbfsMount
+  BRQ mounted
+  SETD.0 NoMount
+  CALL printString
+  CALL lineFeed
+  HALT
+
+mounted:
+  SETD.0 WantGreeting
+  CALL showFile
+  SETD.0 WantAcross
+  CALL showFile
+  SETD.0 WantLongName
+  CALL showFile
+  SETD.0 WantEmpty
+  CALL showFile
+  SETD.0 WantAbsent
+  CALL showFile
+  HALT
+
+; DP0 names a file. Prints its name, what the directory says about it, and then the file
+; itself. DP3 keeps the name across the calls, because it is the pointer a CALL does not
+; put back.
+showFile:
+  PSHD.0
+  POPD.3
+  CALL printString
+  CALL blankSpace
+
+  PSHD.3
+  POPD.0
+  CALL sbfsFind
+  BRQ showFound
+  SETD.0 Missing
+  CALL printString
+  CALL lineFeed
+  RET
+
+showFound:
+  SETD.0 SbfsFileBlocks
+  LDA.0
+  CALL printByteHex
+  INCD.0
+  LDA.0
+  CALL printByteHex
+  CALL blankSpace
+  SETD.0 SbfsFileTail
+  LDA.0
+  CALL printByteHex
+  CALL blankSpace
+
+  SETD.1 Landing
+  CALL sbfsRead
+  BRQ showContents
+  SETD.0 Failed
+  CALL printString
+  CALL lineFeed
+  RET
+
+; Writes out exactly as many bytes as the file has, and no more. The length is the block
+; count and the tail side by side: blocks times 256 plus the tail is the same as putting
+; the count in the high byte and the tail in the low one.
+showContents:
+  SETD.0 Landing
+  SETD.1 SbfsFileBlocks
+  DPUP.1 0d01
+  LDA.1
+  SETD.1 LeftHigh
+  STA.1
+  SETD.1 SbfsFileTail
+  LDA.1
+  SETD.1 LeftLow
+  STA.1
+
+showLoop:
+  SETD.1 LeftHigh
+  LDA.1
+  SETD.2 LeftLow
+  LDB.2
+  OR
+  BRQ showEnd           ; Nothing left of it.
+
+  LDA.0
+  OUTA 0x00
+  INCD.0
+
+  SETD.1 LeftLow
+  LDA.1
+  DECA
+  STA.1
+  BRC showBorrow        ; It went under, so the high byte owes one.
+  BRI showLoop
+showBorrow:
+  SETD.1 LeftHigh
+  LDA.1
+  DECA
+  STA.1
+  BRI showLoop
+
+showEnd:
+  CALL lineFeed
+  RET
+
+#Data
+
+WantGreeting:
+"greeting.txt"
+WantAcross:
+"across.txt"
+WantLongName:
+"aName22CharactersLong!"
+WantEmpty:
+"empty.txt"
+WantAbsent:
+"absent.txt"
+
+NoMount:
+"no mount"
+Missing:
+"missing"
+Failed:
+"failed"
+
+LeftHigh:
+  0x00
+LeftLow:
+  0x00
+
+Landing:
+  #Reserve 0d1024